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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Janz MODULbus VMOD-ICAN3 CAN Interface Driver
  *
  * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
  */
 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/ethtool.h>
 #include <linux/platform_device.h>
 
 #include <linux/netdevice.h>
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/skb.h>
 #include <linux/can/error.h>
 
 #include <linux/mfd/janz.h>
 #include <asm/io.h>
 
 /* the DPM has 64k of memory, organized into 256x 256 byte pages */
 #define DPM_NUM_PAGES       256
 #define DPM_PAGE_SIZE       256
 #define DPM_PAGE_ADDR(p)    ((p) * DPM_PAGE_SIZE)
 
 /* JANZ ICAN3 "old-style" host interface queue page numbers */
 #define QUEUE_OLD_CONTROL   0
 #define QUEUE_OLD_RB0       1
 #define QUEUE_OLD_RB1       2
 #define QUEUE_OLD_WB0       3
 #define QUEUE_OLD_WB1       4
 
 /* Janz ICAN3 "old-style" host interface control registers */
 #define MSYNC_PEER      0x00        /* ICAN only */
 #define MSYNC_LOCL      0x01        /* host only */
 #define TARGET_RUNNING      0x02
 #define FIRMWARE_STAMP      0x60        /* big endian firmware stamp */
 
 #define MSYNC_RB0       0x01
 #define MSYNC_RB1       0x02
 #define MSYNC_RBLW      0x04
 #define MSYNC_RB_MASK       (MSYNC_RB0 | MSYNC_RB1)
 
 #define MSYNC_WB0       0x10
 #define MSYNC_WB1       0x20
 #define MSYNC_WBLW      0x40
 #define MSYNC_WB_MASK       (MSYNC_WB0 | MSYNC_WB1)
 
 /* Janz ICAN3 "new-style" host interface queue page numbers */
 #define QUEUE_TOHOST        5
 #define QUEUE_FROMHOST_MID  6
 #define QUEUE_FROMHOST_HIGH 7
 #define QUEUE_FROMHOST_LOW  8
 
 /* The first free page in the DPM is #9 */
 #define DPM_FREE_START      9
 
 /* Janz ICAN3 "new-style" and "fast" host interface descriptor flags */
 #define DESC_VALID      0x80
 #define DESC_WRAP       0x40
 #define DESC_INTERRUPT      0x20
 #define DESC_IVALID     0x10
 #define DESC_LEN(len)       (len)
 
 /* Janz ICAN3 Firmware Messages */
 #define MSG_CONNECTI        0x02
 #define MSG_DISCONNECT      0x03
 #define MSG_IDVERS      0x04
 #define MSG_MSGLOST     0x05
 #define MSG_NEWHOSTIF       0x08
 #define MSG_INQUIRY     0x0a
 #define MSG_SETAFILMASK     0x10
 #define MSG_INITFDPMQUEUE   0x11
 #define MSG_HWCONF      0x12
 #define MSG_FMSGLOST        0x15
 #define MSG_CEVTIND     0x37
 #define MSG_CBTRREQ     0x41
 #define MSG_COFFREQ     0x42
 #define MSG_CONREQ      0x43
 #define MSG_CCONFREQ        0x47
 #define MSG_NMTS        0xb0
 #define MSG_LMTS        0xb4
 
 /*
  * Janz ICAN3 CAN Inquiry Message Types
  *
  * NOTE: there appears to be a firmware bug here. You must send
  * NOTE: INQUIRY_STATUS and expect to receive an INQUIRY_EXTENDED
  * NOTE: response. The controller never responds to a message with
  * NOTE: the INQUIRY_EXTENDED subspec :(
  */
 #define INQUIRY_STATUS      0x00
 #define INQUIRY_TERMINATION 0x01
 #define INQUIRY_EXTENDED    0x04
 
 /* Janz ICAN3 CAN Set Acceptance Filter Mask Message Types */
 #define SETAFILMASK_REJECT  0x00
 #define SETAFILMASK_FASTIF  0x02
 
 /* Janz ICAN3 CAN Hardware Configuration Message Types */
 #define HWCONF_TERMINATE_ON 0x01
 #define HWCONF_TERMINATE_OFF    0x00
 
 /* Janz ICAN3 CAN Event Indication Message Types */
 #define CEVTIND_EI      0x01
 #define CEVTIND_DOI     0x02
 #define CEVTIND_LOST        0x04
 #define CEVTIND_FULL        0x08
 #define CEVTIND_BEI     0x10
 
 #define CEVTIND_CHIP_SJA1000    0x02
 
 #define ICAN3_BUSERR_QUOTA_MAX  255
 
 /* Janz ICAN3 CAN Frame Conversion */
 #define ICAN3_SNGL  0x02
 #define ICAN3_ECHO  0x10
 #define ICAN3_EFF_RTR   0x40
 #define ICAN3_SFF_RTR   0x10
 #define ICAN3_EFF   0x80
 
 #define ICAN3_CAN_TYPE_MASK 0x0f
 #define ICAN3_CAN_TYPE_SFF  0x00
 #define ICAN3_CAN_TYPE_EFF  0x01
 
 #define ICAN3_CAN_DLC_MASK  0x0f
 
 /* Janz ICAN3 NMTS subtypes */
 #define NMTS_CREATE_NODE_REQ    0x0
 #define NMTS_SLAVE_STATE_IND    0x8
 #define NMTS_SLAVE_EVENT_IND    0x9
 
 /* Janz ICAN3 LMTS subtypes */
 #define LMTS_BUSON_REQ      0x0
 #define LMTS_BUSOFF_REQ     0x1
 #define LMTS_CAN_CONF_REQ   0x2
 
 /* Janz ICAN3 NMTS Event indications */
 #define NE_LOCAL_OCCURRED   0x3
 #define NE_LOCAL_RESOLVED   0x2
 #define NE_REMOTE_OCCURRED  0xc
 #define NE_REMOTE_RESOLVED  0x8
 
 /*
  * SJA1000 Status and Error Register Definitions
  *
  * Copied from drivers/net/can/sja1000/sja1000.h
  */
 
 /* status register content */
 #define SR_BS       0x80
 #define SR_ES       0x40
 #define SR_TS       0x20
 #define SR_RS       0x10
 #define SR_TCS      0x08
 #define SR_TBS      0x04
 #define SR_DOS      0x02
 #define SR_RBS      0x01
 
 #define SR_CRIT (SR_BS|SR_ES)
 
 /* ECC register */
 #define ECC_SEG     0x1F
 #define ECC_DIR     0x20
 #define ECC_ERR     6
 #define ECC_BIT     0x00
 #define ECC_FORM    0x40
 #define ECC_STUFF   0x80
 #define ECC_MASK    0xc0
 
 /* Number of buffers for use in the "new-style" host interface */
 #define ICAN3_NEW_BUFFERS   16
 
 /* Number of buffers for use in the "fast" host interface */
 #define ICAN3_TX_BUFFERS    512
 #define ICAN3_RX_BUFFERS    1024
 
 /* SJA1000 Clock Input */
 #define ICAN3_CAN_CLOCK     8000000
 
 /* Janz ICAN3 firmware types */
 enum ican3_fwtype {
     ICAN3_FWTYPE_ICANOS,
     ICAN3_FWTYPE_CAL_CANOPEN,
 };
 
 /* Driver Name */
 #define DRV_NAME "janz-ican3"
 
 /* DPM Control Registers -- starts at offset 0x100 in the MODULbus registers */
 struct ican3_dpm_control {
     /* window address register */
     u8 window_address;
     u8 unused1;
 
     /*
      * Read access: clear interrupt from microcontroller
      * Write access: send interrupt to microcontroller
      */
     u8 interrupt;
     u8 unused2;
 
     /* write-only: reset all hardware on the module */
     u8 hwreset;
     u8 unused3;
 
     /* write-only: generate an interrupt to the TPU */
     u8 tpuinterrupt;
 };
 
 struct ican3_dev {
 
     /* must be the first member */
     struct can_priv can;
 
     /* CAN network device */
     struct net_device *ndev;
     struct napi_struct napi;
 
     /* module number */
     unsigned int num;
 
     /* base address of registers and IRQ */
     struct janz_cmodio_onboard_regs __iomem *ctrl;
     struct ican3_dpm_control __iomem *dpmctrl;
     void __iomem *dpm;
     int irq;
 
     /* CAN bus termination status */
     struct completion termination_comp;
     bool termination_enabled;
 
     /* CAN bus error status registers */
     struct completion buserror_comp;
     struct can_berr_counter bec;
 
     /* firmware type */
     enum ican3_fwtype fwtype;
     char fwinfo[32];
 
     /* old and new style host interface */
     unsigned int iftype;
 
     /* queue for echo packets */
     struct sk_buff_head echoq;
 
     /*
      * Any function which changes the current DPM page must hold this
      * lock while it is performing data accesses. This ensures that the
      * function will not be preempted and end up reading data from a
      * different DPM page than it expects.
      */
     spinlock_t lock;
 
     /* new host interface */
     unsigned int rx_int;
     unsigned int rx_num;
     unsigned int tx_num;
 
     /* fast host interface */
     unsigned int fastrx_start;
     unsigned int fastrx_num;
     unsigned int fasttx_start;
     unsigned int fasttx_num;
 
     /* first free DPM page */
     unsigned int free_page;
 };
 
 struct ican3_msg {
     u8 control;
     u8 spec;
     __le16 len;
     u8 data[252];
 };
 
 struct ican3_new_desc {
     u8 control;
     u8 pointer;
 };
 
 struct ican3_fast_desc {
     u8 control;
     u8 command;
     u8 data[14];
 };
 
 /* write to the window basic address register */
 static inline void ican3_set_page(struct ican3_dev *mod, unsigned int page)
 {
     BUG_ON(page >= DPM_NUM_PAGES);
     iowrite8(page, &mod->dpmctrl->window_address);
 }
 
 /*
  * ICAN3 "old-style" host interface
  */
 
 /*
  * Receive a message from the ICAN3 "old-style" firmware interface
  *
  * LOCKING: must hold mod->lock
  *
  * returns 0 on success, -ENOMEM when no message exists
  */
 static int ican3_old_recv_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     unsigned int mbox, mbox_page;
     u8 locl, peer, xord;
 
     /* get the MSYNC registers */
     ican3_set_page(mod, QUEUE_OLD_CONTROL);
     peer = ioread8(mod->dpm + MSYNC_PEER);
     locl = ioread8(mod->dpm + MSYNC_LOCL);
     xord = locl ^ peer;
 
     if ((xord & MSYNC_RB_MASK) == 0x00) {
         netdev_dbg(mod->ndev, "no mbox for reading\n");
         return -ENOMEM;
     }
 
     /* find the first free mbox to read */
     if ((xord & MSYNC_RB_MASK) == MSYNC_RB_MASK)
         mbox = (xord & MSYNC_RBLW) ? MSYNC_RB0 : MSYNC_RB1;
     else
         mbox = (xord & MSYNC_RB0) ? MSYNC_RB0 : MSYNC_RB1;
 
     /* copy the message */
     mbox_page = (mbox == MSYNC_RB0) ? QUEUE_OLD_RB0 : QUEUE_OLD_RB1;
     ican3_set_page(mod, mbox_page);
     memcpy_fromio(msg, mod->dpm, sizeof(*msg));
 
     /*
      * notify the firmware that the read buffer is available
      * for it to fill again
      */
     locl ^= mbox;
 
     ican3_set_page(mod, QUEUE_OLD_CONTROL);
     iowrite8(locl, mod->dpm + MSYNC_LOCL);
     return 0;
 }
 
 /*
  * Send a message through the "old-style" firmware interface
  *
  * LOCKING: must hold mod->lock
  *
  * returns 0 on success, -ENOMEM when no free space exists
  */
 static int ican3_old_send_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     unsigned int mbox, mbox_page;
     u8 locl, peer, xord;
 
     /* get the MSYNC registers */
     ican3_set_page(mod, QUEUE_OLD_CONTROL);
     peer = ioread8(mod->dpm + MSYNC_PEER);
     locl = ioread8(mod->dpm + MSYNC_LOCL);
     xord = locl ^ peer;
 
     if ((xord & MSYNC_WB_MASK) == MSYNC_WB_MASK) {
         netdev_err(mod->ndev, "no mbox for writing\n");
         return -ENOMEM;
     }
 
     /* calculate a free mbox to use */
     mbox = (xord & MSYNC_WB0) ? MSYNC_WB1 : MSYNC_WB0;
 
     /* copy the message to the DPM */
     mbox_page = (mbox == MSYNC_WB0) ? QUEUE_OLD_WB0 : QUEUE_OLD_WB1;
     ican3_set_page(mod, mbox_page);
     memcpy_toio(mod->dpm, msg, sizeof(*msg));
 
     locl ^= mbox;
     if (mbox == MSYNC_WB1)
         locl |= MSYNC_WBLW;
 
     ican3_set_page(mod, QUEUE_OLD_CONTROL);
     iowrite8(locl, mod->dpm + MSYNC_LOCL);
     return 0;
 }
 
 /*
  * ICAN3 "new-style" Host Interface Setup
  */
 
 static void ican3_init_new_host_interface(struct ican3_dev *mod)
 {
     struct ican3_new_desc desc;
     unsigned long flags;
     void __iomem *dst;
     int i;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     /* setup the internal datastructures for RX */
     mod->rx_num = 0;
     mod->rx_int = 0;
 
     /* tohost queue descriptors are in page 5 */
     ican3_set_page(mod, QUEUE_TOHOST);
     dst = mod->dpm;
 
     /* initialize the tohost (rx) queue descriptors: pages 9-24 */
     for (i = 0; i < ICAN3_NEW_BUFFERS; i++) {
         desc.control = DESC_INTERRUPT | DESC_LEN(1); /* I L=1 */
         desc.pointer = mod->free_page;
 
         /* set wrap flag on last buffer */
         if (i == ICAN3_NEW_BUFFERS - 1)
             desc.control |= DESC_WRAP;
 
         memcpy_toio(dst, &desc, sizeof(desc));
         dst += sizeof(desc);
         mod->free_page++;
     }
 
     /* fromhost (tx) mid queue descriptors are in page 6 */
     ican3_set_page(mod, QUEUE_FROMHOST_MID);
     dst = mod->dpm;
 
     /* setup the internal datastructures for TX */
     mod->tx_num = 0;
 
     /* initialize the fromhost mid queue descriptors: pages 25-40 */
     for (i = 0; i < ICAN3_NEW_BUFFERS; i++) {
         desc.control = DESC_VALID | DESC_LEN(1); /* V L=1 */
         desc.pointer = mod->free_page;
 
         /* set wrap flag on last buffer */
         if (i == ICAN3_NEW_BUFFERS - 1)
             desc.control |= DESC_WRAP;
 
         memcpy_toio(dst, &desc, sizeof(desc));
         dst += sizeof(desc);
         mod->free_page++;
     }
 
     /* fromhost hi queue descriptors are in page 7 */
     ican3_set_page(mod, QUEUE_FROMHOST_HIGH);
     dst = mod->dpm;
 
     /* initialize only a single buffer in the fromhost hi queue (unused) */
     desc.control = DESC_VALID | DESC_WRAP | DESC_LEN(1); /* VW L=1 */
     desc.pointer = mod->free_page;
     memcpy_toio(dst, &desc, sizeof(desc));
     mod->free_page++;
 
     /* fromhost low queue descriptors are in page 8 */
     ican3_set_page(mod, QUEUE_FROMHOST_LOW);
     dst = mod->dpm;
 
     /* initialize only a single buffer in the fromhost low queue (unused) */
     desc.control = DESC_VALID | DESC_WRAP | DESC_LEN(1); /* VW L=1 */
     desc.pointer = mod->free_page;
     memcpy_toio(dst, &desc, sizeof(desc));
     mod->free_page++;
 
     spin_unlock_irqrestore(&mod->lock, flags);
 }
 
 /*
  * ICAN3 Fast Host Interface Setup
  */
 
 static void ican3_init_fast_host_interface(struct ican3_dev *mod)
 {
     struct ican3_fast_desc desc;
     unsigned long flags;
     unsigned int addr;
     void __iomem *dst;
     int i;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     /* save the start recv page */
     mod->fastrx_start = mod->free_page;
     mod->fastrx_num = 0;
 
     /* build a single fast tohost queue descriptor */
     memset(&desc, 0, sizeof(desc));
     desc.control = 0x00;
     desc.command = 1;
 
     /* build the tohost queue descriptor ring in memory */
     addr = 0;
     for (i = 0; i < ICAN3_RX_BUFFERS; i++) {
 
         /* set the wrap bit on the last buffer */
         if (i == ICAN3_RX_BUFFERS - 1)
             desc.control |= DESC_WRAP;
 
         /* switch to the correct page */
         ican3_set_page(mod, mod->free_page);
 
         /* copy the descriptor to the DPM */
         dst = mod->dpm + addr;
         memcpy_toio(dst, &desc, sizeof(desc));
         addr += sizeof(desc);
 
         /* move to the next page if necessary */
         if (addr >= DPM_PAGE_SIZE) {
             addr = 0;
             mod->free_page++;
         }
     }
 
     /* make sure we page-align the next queue */
     if (addr != 0)
         mod->free_page++;
 
     /* save the start xmit page */
     mod->fasttx_start = mod->free_page;
     mod->fasttx_num = 0;
 
     /* build a single fast fromhost queue descriptor */
     memset(&desc, 0, sizeof(desc));
     desc.control = DESC_VALID;
     desc.command = 1;
 
     /* build the fromhost queue descriptor ring in memory */
     addr = 0;
     for (i = 0; i < ICAN3_TX_BUFFERS; i++) {
 
         /* set the wrap bit on the last buffer */
         if (i == ICAN3_TX_BUFFERS - 1)
             desc.control |= DESC_WRAP;
 
         /* switch to the correct page */
         ican3_set_page(mod, mod->free_page);
 
         /* copy the descriptor to the DPM */
         dst = mod->dpm + addr;
         memcpy_toio(dst, &desc, sizeof(desc));
         addr += sizeof(desc);
 
         /* move to the next page if necessary */
         if (addr >= DPM_PAGE_SIZE) {
             addr = 0;
             mod->free_page++;
         }
     }
 
     spin_unlock_irqrestore(&mod->lock, flags);
 }
 
 /*
  * ICAN3 "new-style" Host Interface Message Helpers
  */
 
 /*
  * LOCKING: must hold mod->lock
  */
 static int ican3_new_send_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     struct ican3_new_desc desc;
     void __iomem *desc_addr = mod->dpm + (mod->tx_num * sizeof(desc));
 
     /* switch to the fromhost mid queue, and read the buffer descriptor */
     ican3_set_page(mod, QUEUE_FROMHOST_MID);
     memcpy_fromio(&desc, desc_addr, sizeof(desc));
 
     if (!(desc.control & DESC_VALID)) {
         netdev_dbg(mod->ndev, "%s: no free buffers\n", __func__);
         return -ENOMEM;
     }
 
     /* switch to the data page, copy the data */
     ican3_set_page(mod, desc.pointer);
     memcpy_toio(mod->dpm, msg, sizeof(*msg));
 
     /* switch back to the descriptor, set the valid bit, write it back */
     ican3_set_page(mod, QUEUE_FROMHOST_MID);
     desc.control ^= DESC_VALID;
     memcpy_toio(desc_addr, &desc, sizeof(desc));
 
     /* update the tx number */
     mod->tx_num = (desc.control & DESC_WRAP) ? 0 : (mod->tx_num + 1);
     return 0;
 }
 
 /*
  * LOCKING: must hold mod->lock
  */
 static int ican3_new_recv_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     struct ican3_new_desc desc;
     void __iomem *desc_addr = mod->dpm + (mod->rx_num * sizeof(desc));
 
     /* switch to the tohost queue, and read the buffer descriptor */
     ican3_set_page(mod, QUEUE_TOHOST);
     memcpy_fromio(&desc, desc_addr, sizeof(desc));
 
     if (!(desc.control & DESC_VALID)) {
         netdev_dbg(mod->ndev, "%s: no buffers to recv\n", __func__);
         return -ENOMEM;
     }
 
     /* switch to the data page, copy the data */
     ican3_set_page(mod, desc.pointer);
     memcpy_fromio(msg, mod->dpm, sizeof(*msg));
 
     /* switch back to the descriptor, toggle the valid bit, write it back */
     ican3_set_page(mod, QUEUE_TOHOST);
     desc.control ^= DESC_VALID;
     memcpy_toio(desc_addr, &desc, sizeof(desc));
 
     /* update the rx number */
     mod->rx_num = (desc.control & DESC_WRAP) ? 0 : (mod->rx_num + 1);
     return 0;
 }
 
 /*
  * Message Send / Recv Helpers
  */
 
 static int ican3_send_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     unsigned long flags;
     int ret;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     if (mod->iftype == 0)
         ret = ican3_old_send_msg(mod, msg);
     else
         ret = ican3_new_send_msg(mod, msg);
 
     spin_unlock_irqrestore(&mod->lock, flags);
     return ret;
 }
 
 static int ican3_recv_msg(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     unsigned long flags;
     int ret;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     if (mod->iftype == 0)
         ret = ican3_old_recv_msg(mod, msg);
     else
         ret = ican3_new_recv_msg(mod, msg);
 
     spin_unlock_irqrestore(&mod->lock, flags);
     return ret;
 }
 
 /*
  * Quick Pre-constructed Messages
  */
 
 static int ican3_msg_connect(struct ican3_dev *mod)
 {
     struct ican3_msg msg;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_CONNECTI;
     msg.len = cpu_to_le16(0);
 
     return ican3_send_msg(mod, &msg);
 }
 
 static int ican3_msg_disconnect(struct ican3_dev *mod)
 {
     struct ican3_msg msg;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_DISCONNECT;
     msg.len = cpu_to_le16(0);
 
     return ican3_send_msg(mod, &msg);
 }
 
 static int ican3_msg_newhostif(struct ican3_dev *mod)
 {
     struct ican3_msg msg;
     int ret;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_NEWHOSTIF;
     msg.len = cpu_to_le16(0);
 
     /* If we're not using the old interface, switching seems bogus */
     WARN_ON(mod->iftype != 0);
 
     ret = ican3_send_msg(mod, &msg);
     if (ret)
         return ret;
 
     /* mark the module as using the new host interface */
     mod->iftype = 1;
     return 0;
 }
 
 static int ican3_msg_fasthostif(struct ican3_dev *mod)
 {
     struct ican3_msg msg;
     unsigned int addr;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_INITFDPMQUEUE;
     msg.len = cpu_to_le16(8);
 
     /* write the tohost queue start address */
     addr = DPM_PAGE_ADDR(mod->fastrx_start);
     msg.data[0] = addr & 0xff;
     msg.data[1] = (addr >> 8) & 0xff;
     msg.data[2] = (addr >> 16) & 0xff;
     msg.data[3] = (addr >> 24) & 0xff;
 
     /* write the fromhost queue start address */
     addr = DPM_PAGE_ADDR(mod->fasttx_start);
     msg.data[4] = addr & 0xff;
     msg.data[5] = (addr >> 8) & 0xff;
     msg.data[6] = (addr >> 16) & 0xff;
     msg.data[7] = (addr >> 24) & 0xff;
 
     /* If we're not using the new interface yet, we cannot do this */
     WARN_ON(mod->iftype != 1);
 
     return ican3_send_msg(mod, &msg);
 }
 
 /*
  * Setup the CAN filter to either accept or reject all
  * messages from the CAN bus.
  */
 static int ican3_set_id_filter(struct ican3_dev *mod, bool accept)
 {
     struct ican3_msg msg;
     int ret;
 
     /* Standard Frame Format */
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_SETAFILMASK;
     msg.len = cpu_to_le16(5);
     msg.data[0] = 0x00; /* IDLo LSB */
     msg.data[1] = 0x00; /* IDLo MSB */
     msg.data[2] = 0xff; /* IDHi LSB */
     msg.data[3] = 0x07; /* IDHi MSB */
 
     /* accept all frames for fast host if, or reject all frames */
     msg.data[4] = accept ? SETAFILMASK_FASTIF : SETAFILMASK_REJECT;
 
     ret = ican3_send_msg(mod, &msg);
     if (ret)
         return ret;
 
     /* Extended Frame Format */
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_SETAFILMASK;
     msg.len = cpu_to_le16(13);
     msg.data[0] = 0;    /* MUX = 0 */
     msg.data[1] = 0x00; /* IDLo LSB */
     msg.data[2] = 0x00;
     msg.data[3] = 0x00;
     msg.data[4] = 0x20; /* IDLo MSB */
     msg.data[5] = 0xff; /* IDHi LSB */
     msg.data[6] = 0xff;
     msg.data[7] = 0xff;
     msg.data[8] = 0x3f; /* IDHi MSB */
 
     /* accept all frames for fast host if, or reject all frames */
     msg.data[9] = accept ? SETAFILMASK_FASTIF : SETAFILMASK_REJECT;
 
     return ican3_send_msg(mod, &msg);
 }
 
 /*
  * Bring the CAN bus online or offline
  */
 static int ican3_set_bus_state(struct ican3_dev *mod, bool on)
 {
     struct can_bittiming *bt = &mod->can.bittiming;
     struct ican3_msg msg;
     u8 btr0, btr1;
     int res;
 
     /* This algorithm was stolen from drivers/net/can/sja1000/sja1000.c      */
     /* The bittiming register command for the ICAN3 just sets the bit timing */
     /* registers on the SJA1000 chip directly                                */
     btr0 = ((bt->brp - 1) & 0x3f) | (((bt->sjw - 1) & 0x3) << 6);
     btr1 = ((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) |
         (((bt->phase_seg2 - 1) & 0x7) << 4);
     if (mod->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
         btr1 |= 0x80;
 
     if (mod->fwtype == ICAN3_FWTYPE_ICANOS) {
         if (on) {
             /* set bittiming */
             memset(&msg, 0, sizeof(msg));
             msg.spec = MSG_CBTRREQ;
             msg.len = cpu_to_le16(4);
             msg.data[0] = 0x00;
             msg.data[1] = 0x00;
             msg.data[2] = btr0;
             msg.data[3] = btr1;
 
             res = ican3_send_msg(mod, &msg);
             if (res)
                 return res;
         }
 
         /* can-on/off request */
         memset(&msg, 0, sizeof(msg));
         msg.spec = on ? MSG_CONREQ : MSG_COFFREQ;
         msg.len = cpu_to_le16(0);
 
         return ican3_send_msg(mod, &msg);
 
     } else if (mod->fwtype == ICAN3_FWTYPE_CAL_CANOPEN) {
         /* bittiming + can-on/off request */
         memset(&msg, 0, sizeof(msg));
         msg.spec = MSG_LMTS;
         if (on) {
             msg.len = cpu_to_le16(4);
             msg.data[0] = LMTS_BUSON_REQ;
             msg.data[1] = 0;
             msg.data[2] = btr0;
             msg.data[3] = btr1;
         } else {
             msg.len = cpu_to_le16(2);
             msg.data[0] = LMTS_BUSOFF_REQ;
             msg.data[1] = 0;
         }
         res = ican3_send_msg(mod, &msg);
         if (res)
             return res;
 
         if (on) {
             /* create NMT Slave Node for error processing
              *   class 2 (with error capability, see CiA/DS203-1)
              *   id    1
              *   name  locnod1 (must be exactly 7 bytes)
              */
             memset(&msg, 0, sizeof(msg));
             msg.spec = MSG_NMTS;
             msg.len = cpu_to_le16(11);
             msg.data[0] = NMTS_CREATE_NODE_REQ;
             msg.data[1] = 0;
             msg.data[2] = 2;                 /* node class */
             msg.data[3] = 1;                 /* node id */
             strcpy(msg.data + 4, "locnod1"); /* node name  */
             return ican3_send_msg(mod, &msg);
         }
         return 0;
     }
     return -ENOTSUPP;
 }
 
 static int ican3_set_termination(struct ican3_dev *mod, bool on)
 {
     struct ican3_msg msg;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_HWCONF;
     msg.len = cpu_to_le16(2);
     msg.data[0] = 0x00;
     msg.data[1] = on ? HWCONF_TERMINATE_ON : HWCONF_TERMINATE_OFF;
 
     return ican3_send_msg(mod, &msg);
 }
 
 static int ican3_send_inquiry(struct ican3_dev *mod, u8 subspec)
 {
     struct ican3_msg msg;
 
     memset(&msg, 0, sizeof(msg));
     msg.spec = MSG_INQUIRY;
     msg.len = cpu_to_le16(2);
     msg.data[0] = subspec;
     msg.data[1] = 0x00;
 
     return ican3_send_msg(mod, &msg);
 }
 
 static int ican3_set_buserror(struct ican3_dev *mod, u8 quota)
 {
     struct ican3_msg msg;
 
     if (mod->fwtype == ICAN3_FWTYPE_ICANOS) {
         memset(&msg, 0, sizeof(msg));
         msg.spec = MSG_CCONFREQ;
         msg.len = cpu_to_le16(2);
         msg.data[0] = 0x00;
         msg.data[1] = quota;
     } else if (mod->fwtype == ICAN3_FWTYPE_CAL_CANOPEN) {
         memset(&msg, 0, sizeof(msg));
         msg.spec = MSG_LMTS;
         msg.len = cpu_to_le16(4);
         msg.data[0] = LMTS_CAN_CONF_REQ;
         msg.data[1] = 0x00;
         msg.data[2] = 0x00;
         msg.data[3] = quota;
     } else {
         return -ENOTSUPP;
     }
     return ican3_send_msg(mod, &msg);
 }
 
 /*
  * ICAN3 to Linux CAN Frame Conversion
  */
 
 static void ican3_to_can_frame(struct ican3_dev *mod,
                    struct ican3_fast_desc *desc,
                    struct can_frame *cf)
 {
     if ((desc->command & ICAN3_CAN_TYPE_MASK) == ICAN3_CAN_TYPE_SFF) {
         if (desc->data[1] & ICAN3_SFF_RTR)
             cf->can_id |= CAN_RTR_FLAG;
 
         cf->can_id |= desc->data[0] << 3;
         cf->can_id |= (desc->data[1] & 0xe0) >> 5;
         cf->len = can_cc_dlc2len(desc->data[1] & ICAN3_CAN_DLC_MASK);
         memcpy(cf->data, &desc->data[2], cf->len);
     } else {
         cf->len = can_cc_dlc2len(desc->data[0] & ICAN3_CAN_DLC_MASK);
         if (desc->data[0] & ICAN3_EFF_RTR)
             cf->can_id |= CAN_RTR_FLAG;
 
         if (desc->data[0] & ICAN3_EFF) {
             cf->can_id |= CAN_EFF_FLAG;
             cf->can_id |= desc->data[2] << 21; /* 28-21 */
             cf->can_id |= desc->data[3] << 13; /* 20-13 */
             cf->can_id |= desc->data[4] << 5;  /* 12-5  */
             cf->can_id |= (desc->data[5] & 0xf8) >> 3;
         } else {
             cf->can_id |= desc->data[2] << 3;  /* 10-3  */
             cf->can_id |= desc->data[3] >> 5;  /* 2-0   */
         }
 
         memcpy(cf->data, &desc->data[6], cf->len);
     }
 }
 
 static void can_frame_to_ican3(struct ican3_dev *mod,
                    struct can_frame *cf,
                    struct ican3_fast_desc *desc)
 {
     /* clear out any stale data in the descriptor */
     memset(desc->data, 0, sizeof(desc->data));
 
     /* we always use the extended format, with the ECHO flag set */
     desc->command = ICAN3_CAN_TYPE_EFF;
     desc->data[0] |= cf->len;
     desc->data[1] |= ICAN3_ECHO;
 
     /* support single transmission (no retries) mode */
     if (mod->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
         desc->data[1] |= ICAN3_SNGL;
 
     if (cf->can_id & CAN_RTR_FLAG)
         desc->data[0] |= ICAN3_EFF_RTR;
 
     /* pack the id into the correct places */
     if (cf->can_id & CAN_EFF_FLAG) {
         desc->data[0] |= ICAN3_EFF;
         desc->data[2] = (cf->can_id & 0x1fe00000) >> 21; /* 28-21 */
         desc->data[3] = (cf->can_id & 0x001fe000) >> 13; /* 20-13 */
         desc->data[4] = (cf->can_id & 0x00001fe0) >> 5;  /* 12-5  */
         desc->data[5] = (cf->can_id & 0x0000001f) << 3;  /* 4-0   */
     } else {
         desc->data[2] = (cf->can_id & 0x7F8) >> 3; /* bits 10-3 */
         desc->data[3] = (cf->can_id & 0x007) << 5; /* bits 2-0  */
     }
 
     /* copy the data bits into the descriptor */
     memcpy(&desc->data[6], cf->data, cf->len);
 }
 
 /*
  * Interrupt Handling
  */
 
 /*
  * Handle an ID + Version message response from the firmware. We never generate
  * this message in production code, but it is very useful when debugging to be
  * able to display this message.
  */
 static void ican3_handle_idvers(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     netdev_dbg(mod->ndev, "IDVERS response: %s\n", msg->data);
 }
 
 static void ican3_handle_msglost(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     struct net_device *dev = mod->ndev;
     struct net_device_stats *stats = &dev->stats;
     struct can_frame *cf;
     struct sk_buff *skb;
 
     /*
      * Report that communication messages with the microcontroller firmware
      * are being lost. These are never CAN frames, so we do not generate an
      * error frame for userspace
      */
     if (msg->spec == MSG_MSGLOST) {
         netdev_err(mod->ndev, "lost %d control messages\n", msg->data[0]);
         return;
     }
 
     /*
      * Oops, this indicates that we have lost messages in the fast queue,
      * which are exclusively CAN messages. Our driver isn't reading CAN
      * frames fast enough.
      *
      * We'll pretend that the SJA1000 told us that it ran out of buffer
      * space, because there is not a better message for this.
      */
     skb = alloc_can_err_skb(dev, &cf);
     if (skb) {
         cf->can_id |= CAN_ERR_CRTL;
         cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
         stats->rx_over_errors++;
         stats->rx_errors++;
         netif_rx(skb);
     }
 }
 
 /*
  * Handle CAN Event Indication Messages from the firmware
  *
  * The ICAN3 firmware provides the values of some SJA1000 registers when it
  * generates this message. The code below is largely copied from the
  * drivers/net/can/sja1000/sja1000.c file, and adapted as necessary
  */
 static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     struct net_device *dev = mod->ndev;
     struct net_device_stats *stats = &dev->stats;
     enum can_state state = mod->can.state;
     u8 isrc, ecc, status, rxerr, txerr;
     struct can_frame *cf;
     struct sk_buff *skb;
 
     /* we can only handle the SJA1000 part */
     if (msg->data[1] != CEVTIND_CHIP_SJA1000) {
         netdev_err(mod->ndev, "unable to handle errors on non-SJA1000\n");
         return -ENODEV;
     }
 
     /* check the message length for sanity */
     if (le16_to_cpu(msg->len) < 6) {
         netdev_err(mod->ndev, "error message too short\n");
         return -EINVAL;
     }
 
     isrc = msg->data[0];
     ecc = msg->data[2];
     status = msg->data[3];
     rxerr = msg->data[4];
     txerr = msg->data[5];
 
     /*
      * This hardware lacks any support other than bus error messages to
      * determine if packet transmission has failed.
      *
      * When TX errors happen, one echo skb needs to be dropped from the
      * front of the queue.
      *
      * A small bit of code is duplicated here and below, to avoid error
      * skb allocation when it will just be freed immediately.
      */
     if (isrc == CEVTIND_BEI) {
         int ret;
         netdev_dbg(mod->ndev, "bus error interrupt\n");
 
         /* TX error */
         if (!(ecc & ECC_DIR)) {
             kfree_skb(skb_dequeue(&mod->echoq));
             stats->tx_errors++;
         } else {
             stats->rx_errors++;
         }
 
         /*
          * The controller automatically disables bus-error interrupts
          * and therefore we must re-enable them.
          */
         ret = ican3_set_buserror(mod, 1);
         if (ret) {
             netdev_err(mod->ndev, "unable to re-enable bus-error\n");
             return ret;
         }
 
         /* bus error reporting is off, return immediately */
         if (!(mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
             return 0;
     }
 
     skb = alloc_can_err_skb(dev, &cf);
     if (skb == NULL)
         return -ENOMEM;
 
     /* data overrun interrupt */
     if (isrc == CEVTIND_DOI || isrc == CEVTIND_LOST) {
         netdev_dbg(mod->ndev, "data overrun interrupt\n");
         cf->can_id |= CAN_ERR_CRTL;
         cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
         stats->rx_over_errors++;
         stats->rx_errors++;
     }
 
     /* error warning + passive interrupt */
     if (isrc == CEVTIND_EI) {
         netdev_dbg(mod->ndev, "error warning + passive interrupt\n");
         if (status & SR_BS) {
             state = CAN_STATE_BUS_OFF;
             cf->can_id |= CAN_ERR_BUSOFF;
             mod->can.can_stats.bus_off++;
             can_bus_off(dev);
         } else if (status & SR_ES) {
             if (rxerr >= 128 || txerr >= 128)
                 state = CAN_STATE_ERROR_PASSIVE;
             else
                 state = CAN_STATE_ERROR_WARNING;
         } else {
             state = CAN_STATE_ERROR_ACTIVE;
         }
     }
 
     /* bus error interrupt */
     if (isrc == CEVTIND_BEI) {
         mod->can.can_stats.bus_error++;
         cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR | CAN_ERR_CNT;
 
         switch (ecc & ECC_MASK) {
         case ECC_BIT:
             cf->data[2] |= CAN_ERR_PROT_BIT;
             break;
         case ECC_FORM:
             cf->data[2] |= CAN_ERR_PROT_FORM;
             break;
         case ECC_STUFF:
             cf->data[2] |= CAN_ERR_PROT_STUFF;
             break;
         default:
             cf->data[3] = ecc & ECC_SEG;
             break;
         }
 
         if (!(ecc & ECC_DIR))
             cf->data[2] |= CAN_ERR_PROT_TX;
 
         cf->data[6] = txerr;
         cf->data[7] = rxerr;
     }
 
     if (state != mod->can.state && (state == CAN_STATE_ERROR_WARNING ||
                     state == CAN_STATE_ERROR_PASSIVE)) {
         cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
         if (state == CAN_STATE_ERROR_WARNING) {
             mod->can.can_stats.error_warning++;
             cf->data[1] = (txerr > rxerr) ?
                 CAN_ERR_CRTL_TX_WARNING :
                 CAN_ERR_CRTL_RX_WARNING;
         } else {
             mod->can.can_stats.error_passive++;
             cf->data[1] = (txerr > rxerr) ?
                 CAN_ERR_CRTL_TX_PASSIVE :
                 CAN_ERR_CRTL_RX_PASSIVE;
         }
 
         cf->data[6] = txerr;
         cf->data[7] = rxerr;
     }
 
     mod->can.state = state;
     netif_rx(skb);
     return 0;
 }
 
 static void ican3_handle_inquiry(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     switch (msg->data[0]) {
     case INQUIRY_STATUS:
     case INQUIRY_EXTENDED:
         mod->bec.rxerr = msg->data[5];
         mod->bec.txerr = msg->data[6];
         complete(&mod->buserror_comp);
         break;
     case INQUIRY_TERMINATION:
         mod->termination_enabled = msg->data[6] & HWCONF_TERMINATE_ON;
         complete(&mod->termination_comp);
         break;
     default:
         netdev_err(mod->ndev, "received an unknown inquiry response\n");
         break;
     }
 }
 
 /* Handle NMTS Slave Event Indication Messages from the firmware */
 static void ican3_handle_nmtsind(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     u16 subspec;
 
     subspec = msg->data[0] + msg->data[1] * 0x100;
     if (subspec == NMTS_SLAVE_EVENT_IND) {
         switch (msg->data[2]) {
         case NE_LOCAL_OCCURRED:
         case NE_LOCAL_RESOLVED:
             /* now follows the same message as Raw ICANOS CEVTIND
              * shift the data at the same place and call this method
              */
             le16_add_cpu(&msg->len, -3);
             memmove(msg->data, msg->data + 3, le16_to_cpu(msg->len));
             ican3_handle_cevtind(mod, msg);
             break;
         case NE_REMOTE_OCCURRED:
         case NE_REMOTE_RESOLVED:
             /* should not occurre, ignore */
             break;
         default:
             netdev_warn(mod->ndev, "unknown NMTS event indication %x\n",
                     msg->data[2]);
             break;
         }
     } else if (subspec == NMTS_SLAVE_STATE_IND) {
         /* ignore state indications */
     } else {
         netdev_warn(mod->ndev, "unhandled NMTS indication %x\n",
                 subspec);
         return;
     }
 }
 
 static void ican3_handle_unknown_message(struct ican3_dev *mod,
                     struct ican3_msg *msg)
 {
     netdev_warn(mod->ndev, "received unknown message: spec 0x%.2x length %d\n",
                msg->spec, le16_to_cpu(msg->len));
 }
 
 /*
  * Handle a control message from the firmware
  */
 static void ican3_handle_message(struct ican3_dev *mod, struct ican3_msg *msg)
 {
     netdev_dbg(mod->ndev, "%s: modno %d spec 0x%.2x len %d bytes\n", __func__,
                mod->num, msg->spec, le16_to_cpu(msg->len));
 
     switch (msg->spec) {
     case MSG_IDVERS:
         ican3_handle_idvers(mod, msg);
         break;
     case MSG_MSGLOST:
     case MSG_FMSGLOST:
         ican3_handle_msglost(mod, msg);
         break;
     case MSG_CEVTIND:
         ican3_handle_cevtind(mod, msg);
         break;
     case MSG_INQUIRY:
         ican3_handle_inquiry(mod, msg);
         break;
     case MSG_NMTS:
         ican3_handle_nmtsind(mod, msg);
         break;
     default:
         ican3_handle_unknown_message(mod, msg);
         break;
     }
 }
 
 /*
  * The ican3 needs to store all echo skbs, and therefore cannot
  * use the generic infrastructure for this.
  */
 static void ican3_put_echo_skb(struct ican3_dev *mod, struct sk_buff *skb)
 {
     skb = can_create_echo_skb(skb);
     if (!skb)
         return;
 
     skb_tx_timestamp(skb);
 
     /* save this skb for tx interrupt echo handling */
     skb_queue_tail(&mod->echoq, skb);
 }
 
 static unsigned int ican3_get_echo_skb(struct ican3_dev *mod)
 {
     struct sk_buff *skb = skb_dequeue(&mod->echoq);
     struct can_frame *cf;
     u8 dlc = 0;
 
     /* this should never trigger unless there is a driver bug */
     if (!skb) {
         netdev_err(mod->ndev, "BUG: echo skb not occupied\n");
         return 0;
     }
 
     cf = (struct can_frame *)skb->data;
     if (!(cf->can_id & CAN_RTR_FLAG))
         dlc = cf->len;
 
     /* check flag whether this packet has to be looped back */
     if (skb->pkt_type != PACKET_LOOPBACK) {
         kfree_skb(skb);
         return dlc;
     }
 
     skb->protocol = htons(ETH_P_CAN);
     skb->pkt_type = PACKET_BROADCAST;
     skb->ip_summed = CHECKSUM_UNNECESSARY;
     skb->dev = mod->ndev;
     netif_receive_skb(skb);
     return dlc;
 }
 
 /*
  * Compare an skb with an existing echo skb
  *
  * This function will be used on devices which have a hardware loopback.
  * On these devices, this function can be used to compare a received skb
  * with the saved echo skbs so that the hardware echo skb can be dropped.
  *
  * Returns true if the skb's are identical, false otherwise.
  */
 static bool ican3_echo_skb_matches(struct ican3_dev *mod, struct sk_buff *skb)
 {
     struct can_frame *cf = (struct can_frame *)skb->data;
     struct sk_buff *echo_skb = skb_peek(&mod->echoq);
     struct can_frame *echo_cf;
 
     if (!echo_skb)
         return false;
 
     echo_cf = (struct can_frame *)echo_skb->data;
     if (cf->can_id != echo_cf->can_id)
         return false;
 
     if (cf->len != echo_cf->len)
         return false;
 
     return memcmp(cf->data, echo_cf->data, cf->len) == 0;
 }
 
 /*
  * Check that there is room in the TX ring to transmit another skb
  *
  * LOCKING: must hold mod->lock
  */
 static bool ican3_txok(struct ican3_dev *mod)
 {
     struct ican3_fast_desc __iomem *desc;
     u8 control;
 
     /* check that we have echo queue space */
     if (skb_queue_len(&mod->echoq) >= ICAN3_TX_BUFFERS)
         return false;
 
     /* copy the control bits of the descriptor */
     ican3_set_page(mod, mod->fasttx_start + (mod->fasttx_num / 16));
     desc = mod->dpm + ((mod->fasttx_num % 16) * sizeof(*desc));
     control = ioread8(&desc->control);
 
     /* if the control bits are not valid, then we have no more space */
     if (!(control & DESC_VALID))
         return false;
 
     return true;
 }
 
 /*
  * Receive one CAN frame from the hardware
  *
  * CONTEXT: must be called from user context
  */
 static int ican3_recv_skb(struct ican3_dev *mod)
 {
     struct net_device *ndev = mod->ndev;
     struct net_device_stats *stats = &ndev->stats;
     struct ican3_fast_desc desc;
     void __iomem *desc_addr;
     struct can_frame *cf;
     struct sk_buff *skb;
     unsigned long flags;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     /* copy the whole descriptor */
     ican3_set_page(mod, mod->fastrx_start + (mod->fastrx_num / 16));
     desc_addr = mod->dpm + ((mod->fastrx_num % 16) * sizeof(desc));
     memcpy_fromio(&desc, desc_addr, sizeof(desc));
 
     spin_unlock_irqrestore(&mod->lock, flags);
 
     /* check that we actually have a CAN frame */
     if (!(desc.control & DESC_VALID))
         return -ENOBUFS;
 
     /* allocate an skb */
     skb = alloc_can_skb(ndev, &cf);
     if (unlikely(skb == NULL)) {
         stats->rx_dropped++;
         goto err_noalloc;
     }
 
     /* convert the ICAN3 frame into Linux CAN format */
     ican3_to_can_frame(mod, &desc, cf);
 
     /*
      * If this is an ECHO frame received from the hardware loopback
      * feature, use the skb saved in the ECHO stack instead. This allows
      * the Linux CAN core to support CAN_RAW_RECV_OWN_MSGS correctly.
      *
      * Since this is a confirmation of a successfully transmitted packet
      * sent from this host, update the transmit statistics.
      *
      * Also, the netdevice queue needs to be allowed to send packets again.
      */
     if (ican3_echo_skb_matches(mod, skb)) {
         stats->tx_packets++;
         stats->tx_bytes += ican3_get_echo_skb(mod);
         kfree_skb(skb);
         goto err_noalloc;
     }
 
     /* update statistics, receive the skb */
     stats->rx_packets++;
     if (!(cf->can_id & CAN_RTR_FLAG))
         stats->rx_bytes += cf->len;
     netif_receive_skb(skb);
 
 err_noalloc:
     /* toggle the valid bit and return the descriptor to the ring */
     desc.control ^= DESC_VALID;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     ican3_set_page(mod, mod->fastrx_start + (mod->fastrx_num / 16));
     memcpy_toio(desc_addr, &desc, 1);
 
     /* update the next buffer pointer */
     mod->fastrx_num = (desc.control & DESC_WRAP) ? 0
                              : (mod->fastrx_num + 1);
 
     /* there are still more buffers to process */
     spin_unlock_irqrestore(&mod->lock, flags);
     return 0;
 }
 
 static int ican3_napi(struct napi_struct *napi, int budget)
 {
     struct ican3_dev *mod = container_of(napi, struct ican3_dev, napi);
     unsigned long flags;
     int received = 0;
     int ret;
 
     /* process all communication messages */
     while (true) {
         struct ican3_msg msg;
         ret = ican3_recv_msg(mod, &msg);
         if (ret)
             break;
 
         ican3_handle_message(mod, &msg);
     }
 
     /* process all CAN frames from the fast interface */
     while (received < budget) {
         ret = ican3_recv_skb(mod);
         if (ret)
             break;
 
         received++;
     }
 
     /* We have processed all packets that the adapter had, but it
      * was less than our budget, stop polling */
     if (received < budget)
         napi_complete_done(napi, received);
 
     spin_lock_irqsave(&mod->lock, flags);
 
     /* Wake up the transmit queue if necessary */
     if (netif_queue_stopped(mod->ndev) && ican3_txok(mod))
         netif_wake_queue(mod->ndev);
 
     spin_unlock_irqrestore(&mod->lock, flags);
 
     /* re-enable interrupt generation */
     iowrite8(1 << mod->num, &mod->ctrl->int_enable);
     return received;
 }
 
 static irqreturn_t ican3_irq(int irq, void *dev_id)
 {
     struct ican3_dev *mod = dev_id;
     u8 stat;
 
     /*
      * The interrupt status register on this device reports interrupts
      * as zeroes instead of using ones like most other devices
      */
     stat = ioread8(&mod->ctrl->int_disable) & (1 << mod->num);
     if (stat == (1 << mod->num))
         return IRQ_NONE;
 
     /* clear the MODULbus interrupt from the microcontroller */
     ioread8(&mod->dpmctrl->interrupt);
 
     /* disable interrupt generation, schedule the NAPI poller */
     iowrite8(1 << mod->num, &mod->ctrl->int_disable);
     napi_schedule(&mod->napi);
     return IRQ_HANDLED;
 }
 
 /*
  * Firmware reset, startup, and shutdown
  */
 
 /*
  * Reset an ICAN module to its power-on state
  *
  * CONTEXT: no network device registered
  */
 static int ican3_reset_module(struct ican3_dev *mod)
 {
     unsigned long start;
     u8 runold, runnew;
 
     /* disable interrupts so no more work is scheduled */
     iowrite8(1 << mod->num, &mod->ctrl->int_disable);
 
     /* the first unallocated page in the DPM is #9 */
     mod->free_page = DPM_FREE_START;
 
     ican3_set_page(mod, QUEUE_OLD_CONTROL);
     runold = ioread8(mod->dpm + TARGET_RUNNING);
 
     /* reset the module */
     iowrite8(0x00, &mod->dpmctrl->hwreset);
 
     /* wait until the module has finished resetting and is running */
     start = jiffies;
     do {
         ican3_set_page(mod, QUEUE_OLD_CONTROL);
         runnew = ioread8(mod->dpm + TARGET_RUNNING);
         if (runnew == (runold ^ 0xff))
             return 0;
 
         msleep(10);
     } while (time_before(jiffies, start + HZ / 2));
 
     netdev_err(mod->ndev, "failed to reset CAN module\n");
     return -ETIMEDOUT;
 }
 
 static void ican3_shutdown_module(struct ican3_dev *mod)
 {
     ican3_msg_disconnect(mod);
     ican3_reset_module(mod);
 }
 
 /*
  * Startup an ICAN module, bringing it into fast mode
  */
 static int ican3_startup_module(struct ican3_dev *mod)
 {
     int ret;
 
     ret = ican3_reset_module(mod);
     if (ret) {
         netdev_err(mod->ndev, "unable to reset module\n");
         return ret;
     }
 
     /* detect firmware */
     memcpy_fromio(mod->fwinfo, mod->dpm + FIRMWARE_STAMP, sizeof(mod->fwinfo) - 1);
     if (strncmp(mod->fwinfo, "JANZ-ICAN3", 10)) {
         netdev_err(mod->ndev, "ICAN3 not detected (found %s)\n", mod->fwinfo);
         return -ENODEV;
     }
     if (strstr(mod->fwinfo, "CAL/CANopen"))
         mod->fwtype = ICAN3_FWTYPE_CAL_CANOPEN;
     else
         mod->fwtype = ICAN3_FWTYPE_ICANOS;
 
     /* re-enable interrupts so we can send messages */
     iowrite8(1 << mod->num, &mod->ctrl->int_enable);
 
     ret = ican3_msg_connect(mod);
     if (ret) {
         netdev_err(mod->ndev, "unable to connect to module\n");
         return ret;
     }
 
     ican3_init_new_host_interface(mod);
     ret = ican3_msg_newhostif(mod);
     if (ret) {
         netdev_err(mod->ndev, "unable to switch to new-style interface\n");
         return ret;
     }
 
     /* default to "termination on" */
     ret = ican3_set_termination(mod, true);
     if (ret) {
         netdev_err(mod->ndev, "unable to enable termination\n");
         return ret;
     }
 
     /* default to "bus errors enabled" */
     ret = ican3_set_buserror(mod, 1);
     if (ret) {
         netdev_err(mod->ndev, "unable to set bus-error\n");
         return ret;
     }
 
     ican3_init_fast_host_interface(mod);
     ret = ican3_msg_fasthostif(mod);
     if (ret) {
         netdev_err(mod->ndev, "unable to switch to fast host interface\n");
         return ret;
     }
 
     ret = ican3_set_id_filter(mod, true);
     if (ret) {
         netdev_err(mod->ndev, "unable to set acceptance filter\n");
         return ret;
     }
 
     return 0;
 }
 
 /*
  * CAN Network Device
  */
 
 static int ican3_open(struct net_device *ndev)
 {
     struct ican3_dev *mod = netdev_priv(ndev);
     int ret;
 
     /* open the CAN layer */
     ret = open_candev(ndev);
     if (ret) {
         netdev_err(mod->ndev, "unable to start CAN layer\n");
         return ret;
     }
 
     /* bring the bus online */
     ret = ican3_set_bus_state(mod, true);
     if (ret) {
         netdev_err(mod->ndev, "unable to set bus-on\n");
         close_candev(ndev);
         return ret;
     }
 
     /* start up the network device */
     mod->can.state = CAN_STATE_ERROR_ACTIVE;
     netif_start_queue(ndev);
 
     return 0;
 }
 
 static int ican3_stop(struct net_device *ndev)
 {
     struct ican3_dev *mod = netdev_priv(ndev);
     int ret;
 
     /* stop the network device xmit routine */
     netif_stop_queue(ndev);
     mod->can.state = CAN_STATE_STOPPED;
 
     /* bring the bus offline, stop receiving packets */
     ret = ican3_set_bus_state(mod, false);
     if (ret) {
         netdev_err(mod->ndev, "unable to set bus-off\n");
         return ret;
     }
 
     /* drop all outstanding echo skbs */
     skb_queue_purge(&mod->echoq);
 
     /* close the CAN layer */
     close_candev(ndev);
     return 0;
 }
 
 static netdev_tx_t ican3_xmit(struct sk_buff *skb, struct net_device *ndev)
 {
     struct ican3_dev *mod = netdev_priv(ndev);
     struct can_frame *cf = (struct can_frame *)skb->data;
     struct ican3_fast_desc desc;
     void __iomem *desc_addr;
     unsigned long flags;
 
     if (can_dropped_invalid_skb(ndev, skb))
         return NETDEV_TX_OK;
 
     spin_lock_irqsave(&mod->lock, flags);
 
     /* check that we can actually transmit */
     if (!ican3_txok(mod)) {
         netdev_err(mod->ndev, "BUG: no free descriptors\n");
         spin_unlock_irqrestore(&mod->lock, flags);
         return NETDEV_TX_BUSY;
     }
 
     /* copy the control bits of the descriptor */
     ican3_set_page(mod, mod->fasttx_start + (mod->fasttx_num / 16));
     desc_addr = mod->dpm + ((mod->fasttx_num % 16) * sizeof(desc));
     memset(&desc, 0, sizeof(desc));
     memcpy_fromio(&desc, desc_addr, 1);
 
     /* convert the Linux CAN frame into ICAN3 format */
     can_frame_to_ican3(mod, cf, &desc);
 
     /*
      * This hardware doesn't have TX-done notifications, so we'll try and
      * emulate it the best we can using ECHO skbs. Add the skb to the ECHO
      * stack. Upon packet reception, check if the ECHO skb and received
      * skb match, and use that to wake the queue.
      */
     ican3_put_echo_skb(mod, skb);
 
     /*
      * the programming manual says that you must set the IVALID bit, then
      * interrupt, then set the valid bit. Quite weird, but it seems to be
      * required for this to work
      */
     desc.control |= DESC_IVALID;
     memcpy_toio(desc_addr, &desc, sizeof(desc));
 
     /* generate a MODULbus interrupt to the microcontroller */
     iowrite8(0x01, &mod->dpmctrl->interrupt);
 
     desc.control ^= DESC_VALID;
     memcpy_toio(desc_addr, &desc, sizeof(desc));
 
     /* update the next buffer pointer */
     mod->fasttx_num = (desc.control & DESC_WRAP) ? 0
                              : (mod->fasttx_num + 1);
 
     /* if there is no free descriptor space, stop the transmit queue */
     if (!ican3_txok(mod))
         netif_stop_queue(ndev);
 
     spin_unlock_irqrestore(&mod->lock, flags);
     return NETDEV_TX_OK;
 }
 
 static const struct net_device_ops ican3_netdev_ops = {
     .ndo_open   = ican3_open,
     .ndo_stop   = ican3_stop,
     .ndo_start_xmit = ican3_xmit,
     .ndo_change_mtu = can_change_mtu,
 };
 
 static const struct ethtool_ops ican3_ethtool_ops = {
     .get_ts_info = ethtool_op_get_ts_info,
 };
 
 /*
  * Low-level CAN Device
  */
 
 /* This structure was stolen from drivers/net/can/sja1000/sja1000.c */
 static const struct can_bittiming_const ican3_bittiming_const = {
     .name = DRV_NAME,
     .tseg1_min = 1,
     .tseg1_max = 16,
     .tseg2_min = 1,
     .tseg2_max = 8,
     .sjw_max = 4,
     .brp_min = 1,
     .brp_max = 64,
     .brp_inc = 1,
 };
 
 static int ican3_set_mode(struct net_device *ndev, enum can_mode mode)
 {
     struct ican3_dev *mod = netdev_priv(ndev);
     int ret;
 
     if (mode != CAN_MODE_START)
         return -ENOTSUPP;
 
     /* bring the bus online */
     ret = ican3_set_bus_state(mod, true);
     if (ret) {
         netdev_err(ndev, "unable to set bus-on\n");
         return ret;
     }
 
     /* start up the network device */
     mod->can.state = CAN_STATE_ERROR_ACTIVE;
 
     if (netif_queue_stopped(ndev))
         netif_wake_queue(ndev);
 
     return 0;
 }
 
 static int ican3_get_berr_counter(const struct net_device *ndev,
                   struct can_berr_counter *bec)
 {
     struct ican3_dev *mod = netdev_priv(ndev);
     int ret;
 
     ret = ican3_send_inquiry(mod, INQUIRY_STATUS);
     if (ret)
         return ret;
 
     if (!wait_for_completion_timeout(&mod->buserror_comp, HZ)) {
         netdev_info(mod->ndev, "%s timed out\n", __func__);
         return -ETIMEDOUT;
     }
 
     bec->rxerr = mod->bec.rxerr;
     bec->txerr = mod->bec.txerr;
     return 0;
 }
 
 /*
  * Sysfs Attributes
  */
 
 static ssize_t termination_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     struct ican3_dev *mod = netdev_priv(to_net_dev(dev));
     int ret;
 
     ret = ican3_send_inquiry(mod, INQUIRY_TERMINATION);
     if (ret)
         return ret;
 
     if (!wait_for_completion_timeout(&mod->termination_comp, HZ)) {
         netdev_info(mod->ndev, "%s timed out\n", __func__);
         return -ETIMEDOUT;
     }
 
     return sysfs_emit(buf, "%u\n", mod->termination_enabled);
 }
 
 static ssize_t termination_store(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
 {
     struct ican3_dev *mod = netdev_priv(to_net_dev(dev));
     unsigned long enable;
     int ret;
 
     if (kstrtoul(buf, 0, &enable))
         return -EINVAL;
 
     ret = ican3_set_termination(mod, enable);
     if (ret)
         return ret;
 
     return count;
 }
 
 static ssize_t fwinfo_show(struct device *dev,
                struct device_attribute *attr,
                char *buf)
 {
     struct ican3_dev *mod = netdev_priv(to_net_dev(dev));
 
     return scnprintf(buf, PAGE_SIZE, "%s\n", mod->fwinfo);
 }
 
 static DEVICE_ATTR_RW(termination);
 static DEVICE_ATTR_RO(fwinfo);
 
 static struct attribute *ican3_sysfs_attrs[] = {
     &dev_attr_termination.attr,
     &dev_attr_fwinfo.attr,
     NULL,
 };
 
 static const struct attribute_group ican3_sysfs_attr_group = {
     .attrs = ican3_sysfs_attrs,
 };
 
 /*
  * PCI Subsystem
  */
 
 static int ican3_probe(struct platform_device *pdev)
 {
     struct janz_platform_data *pdata;
     struct net_device *ndev;
     struct ican3_dev *mod;
     struct resource *res;
     struct device *dev;
     int ret;
 
     pdata = dev_get_platdata(&pdev->dev);
     if (!pdata)
         return -ENXIO;
 
     dev_dbg(&pdev->dev, "probe: module number %d\n", pdata->modno);
 
     /* save the struct device for printing */
     dev = &pdev->dev;
 
     /* allocate the CAN device and private data */
     ndev = alloc_candev(sizeof(*mod), 0);
     if (!ndev) {
         dev_err(dev, "unable to allocate CANdev\n");
         ret = -ENOMEM;
         goto out_return;
     }
 
     platform_set_drvdata(pdev, ndev);
     mod = netdev_priv(ndev);
     mod->ndev = ndev;
     mod->num = pdata->modno;
     netif_napi_add_weight(ndev, &mod->napi, ican3_napi, ICAN3_RX_BUFFERS);
     skb_queue_head_init(&mod->echoq);
     spin_lock_init(&mod->lock);
     init_completion(&mod->termination_comp);
     init_completion(&mod->buserror_comp);
 
     /* setup device-specific sysfs attributes */
     ndev->sysfs_groups[0] = &ican3_sysfs_attr_group;
 
     /* the first unallocated page in the DPM is 9 */
     mod->free_page = DPM_FREE_START;
 
     ndev->netdev_ops = &ican3_netdev_ops;
     ndev->ethtool_ops = &ican3_ethtool_ops;
     ndev->flags |= IFF_ECHO;
     SET_NETDEV_DEV(ndev, &pdev->dev);
 
     mod->can.clock.freq = ICAN3_CAN_CLOCK;
     mod->can.bittiming_const = &ican3_bittiming_const;
     mod->can.do_set_mode = ican3_set_mode;
     mod->can.do_get_berr_counter = ican3_get_berr_counter;
     mod->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES
                     | CAN_CTRLMODE_BERR_REPORTING
                     | CAN_CTRLMODE_ONE_SHOT;
 
     /* find our IRQ number */
     mod->irq = platform_get_irq(pdev, 0);
     if (mod->irq < 0) {
         ret = -ENODEV;
         goto out_free_ndev;
     }
 
     ndev->irq = mod->irq;
 
     /* get access to the MODULbus registers for this module */
     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
     if (!res) {
         dev_err(dev, "MODULbus registers not found\n");
         ret = -ENODEV;
         goto out_free_ndev;
     }
 
     mod->dpm = ioremap(res->start, resource_size(res));
     if (!mod->dpm) {
         dev_err(dev, "MODULbus registers not ioremap\n");
         ret = -ENOMEM;
         goto out_free_ndev;
     }
 
     mod->dpmctrl = mod->dpm + DPM_PAGE_SIZE;
 
     /* get access to the control registers for this module */
     res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
     if (!res) {
         dev_err(dev, "CONTROL registers not found\n");
         ret = -ENODEV;
         goto out_iounmap_dpm;
     }
 
     mod->ctrl = ioremap(res->start, resource_size(res));
     if (!mod->ctrl) {
         dev_err(dev, "CONTROL registers not ioremap\n");
         ret = -ENOMEM;
         goto out_iounmap_dpm;
     }
 
     /* disable our IRQ, then hookup the IRQ handler */
     iowrite8(1 << mod->num, &mod->ctrl->int_disable);
     ret = request_irq(mod->irq, ican3_irq, IRQF_SHARED, DRV_NAME, mod);
     if (ret) {
         dev_err(dev, "unable to request IRQ\n");
         goto out_iounmap_ctrl;
     }
 
     /* reset and initialize the CAN controller into fast mode */
     napi_enable(&mod->napi);
     ret = ican3_startup_module(mod);
     if (ret) {
         dev_err(dev, "%s: unable to start CANdev\n", __func__);
         goto out_free_irq;
     }
 
     /* register with the Linux CAN layer */
     ret = register_candev(ndev);
     if (ret) {
         dev_err(dev, "%s: unable to register CANdev\n", __func__);
         goto out_free_irq;
     }
 
     netdev_info(mod->ndev, "module %d: registered CAN device\n", pdata->modno);
     return 0;
 
 out_free_irq:
     napi_disable(&mod->napi);
     iowrite8(1 << mod->num, &mod->ctrl->int_disable);
     free_irq(mod->irq, mod);
 out_iounmap_ctrl:
     iounmap(mod->ctrl);
 out_iounmap_dpm:
     iounmap(mod->dpm);
 out_free_ndev:
     free_candev(ndev);
 out_return:
     return ret;
 }
 
 static int ican3_remove(struct platform_device *pdev)
 {
     struct net_device *ndev = platform_get_drvdata(pdev);
     struct ican3_dev *mod = netdev_priv(ndev);
 
     /* unregister the netdevice, stop interrupts */
     unregister_netdev(ndev);
     napi_disable(&mod->napi);
     iowrite8(1 << mod->num, &mod->ctrl->int_disable);
     free_irq(mod->irq, mod);
 
     /* put the module into reset */
     ican3_shutdown_module(mod);
 
     /* unmap all registers */
     iounmap(mod->ctrl);
     iounmap(mod->dpm);
 
     free_candev(ndev);
 
     return 0;
 }
 
 static struct platform_driver ican3_driver = {
     .driver     = {
         .name   = DRV_NAME,
     },
     .probe      = ican3_probe,
     .remove     = ican3_remove,
 };
 
 module_platform_driver(ican3_driver);
 
 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 MODULE_DESCRIPTION("Janz MODULbus VMOD-ICAN3 Driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:janz-ican3");

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