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0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
0004  */
0005 
0006 /* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
0007  * and the service processor on IBM pSeries servers. On these servers, there
0008  * are no serial ports under the OS's control, and sometimes there is no other
0009  * console available either. However, the service processor has two standard
0010  * serial ports, so this over-complicated protocol allows the OS to control
0011  * those ports by proxy.
0012  *
0013  * Besides data, the procotol supports the reading/writing of the serial
0014  * port's DTR line, and the reading of the CD line. This is to allow the OS to
0015  * control a modem attached to the service processor's serial port. Note that
0016  * the OS cannot change the speed of the port through this protocol.
0017  */
0018 
0019 #undef DEBUG
0020 
0021 #include <linux/console.h>
0022 #include <linux/ctype.h>
0023 #include <linux/delay.h>
0024 #include <linux/init.h>
0025 #include <linux/interrupt.h>
0026 #include <linux/module.h>
0027 #include <linux/major.h>
0028 #include <linux/kernel.h>
0029 #include <linux/of_irq.h>
0030 #include <linux/spinlock.h>
0031 #include <linux/sysrq.h>
0032 #include <linux/tty.h>
0033 #include <linux/tty_flip.h>
0034 #include <asm/hvcall.h>
0035 #include <asm/hvconsole.h>
0036 #include <linux/uaccess.h>
0037 #include <asm/vio.h>
0038 #include <asm/param.h>
0039 #include <asm/hvsi.h>
0040 
0041 #define HVSI_MAJOR  229
0042 #define HVSI_MINOR  128
0043 #define MAX_NR_HVSI_CONSOLES 4
0044 
0045 #define HVSI_TIMEOUT (5*HZ)
0046 #define HVSI_VERSION 1
0047 #define HVSI_MAX_PACKET 256
0048 #define HVSI_MAX_READ 16
0049 #define HVSI_MAX_OUTGOING_DATA 12
0050 #define N_OUTBUF 12
0051 
0052 /*
0053  * we pass data via two 8-byte registers, so we would like our char arrays
0054  * properly aligned for those loads.
0055  */
0056 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
0057 
0058 struct hvsi_struct {
0059     struct tty_port port;
0060     struct delayed_work writer;
0061     struct work_struct handshaker;
0062     wait_queue_head_t emptyq; /* woken when outbuf is emptied */
0063     wait_queue_head_t stateq; /* woken when HVSI state changes */
0064     spinlock_t lock;
0065     int index;
0066     uint8_t throttle_buf[128];
0067     uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
0068     /* inbuf is for packet reassembly. leave a little room for leftovers. */
0069     uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
0070     uint8_t *inbuf_end;
0071     int n_throttle;
0072     int n_outbuf;
0073     uint32_t vtermno;
0074     uint32_t virq;
0075     atomic_t seqno; /* HVSI packet sequence number */
0076     uint16_t mctrl;
0077     uint8_t state;  /* HVSI protocol state */
0078     uint8_t flags;
0079 #ifdef CONFIG_MAGIC_SYSRQ
0080     uint8_t sysrq;
0081 #endif /* CONFIG_MAGIC_SYSRQ */
0082 };
0083 static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];
0084 
0085 static struct tty_driver *hvsi_driver;
0086 static int hvsi_count;
0087 static int (*hvsi_wait)(struct hvsi_struct *hp, int state);
0088 
0089 enum HVSI_PROTOCOL_STATE {
0090     HVSI_CLOSED,
0091     HVSI_WAIT_FOR_VER_RESPONSE,
0092     HVSI_WAIT_FOR_VER_QUERY,
0093     HVSI_OPEN,
0094     HVSI_WAIT_FOR_MCTRL_RESPONSE,
0095     HVSI_FSP_DIED,
0096 };
0097 #define HVSI_CONSOLE 0x1
0098 
0099 static inline int is_console(struct hvsi_struct *hp)
0100 {
0101     return hp->flags & HVSI_CONSOLE;
0102 }
0103 
0104 static inline int is_open(struct hvsi_struct *hp)
0105 {
0106     /* if we're waiting for an mctrl then we're already open */
0107     return (hp->state == HVSI_OPEN)
0108             || (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
0109 }
0110 
0111 static inline void print_state(struct hvsi_struct *hp)
0112 {
0113 #ifdef DEBUG
0114     static const char *state_names[] = {
0115         "HVSI_CLOSED",
0116         "HVSI_WAIT_FOR_VER_RESPONSE",
0117         "HVSI_WAIT_FOR_VER_QUERY",
0118         "HVSI_OPEN",
0119         "HVSI_WAIT_FOR_MCTRL_RESPONSE",
0120         "HVSI_FSP_DIED",
0121     };
0122     const char *name = (hp->state < ARRAY_SIZE(state_names))
0123         ? state_names[hp->state] : "UNKNOWN";
0124 
0125     pr_debug("hvsi%i: state = %s\n", hp->index, name);
0126 #endif /* DEBUG */
0127 }
0128 
0129 static inline void __set_state(struct hvsi_struct *hp, int state)
0130 {
0131     hp->state = state;
0132     print_state(hp);
0133     wake_up_all(&hp->stateq);
0134 }
0135 
0136 static inline void set_state(struct hvsi_struct *hp, int state)
0137 {
0138     unsigned long flags;
0139 
0140     spin_lock_irqsave(&hp->lock, flags);
0141     __set_state(hp, state);
0142     spin_unlock_irqrestore(&hp->lock, flags);
0143 }
0144 
0145 static inline int len_packet(const uint8_t *packet)
0146 {
0147     return (int)((struct hvsi_header *)packet)->len;
0148 }
0149 
0150 static inline int is_header(const uint8_t *packet)
0151 {
0152     struct hvsi_header *header = (struct hvsi_header *)packet;
0153     return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
0154 }
0155 
0156 static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
0157 {
0158     if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
0159         return 0; /* don't even have the packet header */
0160 
0161     if (hp->inbuf_end < (packet + len_packet(packet)))
0162         return 0; /* don't have the rest of the packet */
0163 
0164     return 1;
0165 }
0166 
0167 /* shift remaining bytes in packetbuf down */
0168 static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
0169 {
0170     int remaining = (int)(hp->inbuf_end - read_to);
0171 
0172     pr_debug("%s: %i chars remain\n", __func__, remaining);
0173 
0174     if (read_to != hp->inbuf)
0175         memmove(hp->inbuf, read_to, remaining);
0176 
0177     hp->inbuf_end = hp->inbuf + remaining;
0178 }
0179 
0180 #ifdef DEBUG
0181 #define dbg_dump_packet(packet) dump_packet(packet)
0182 #define dbg_dump_hex(data, len) dump_hex(data, len)
0183 #else
0184 #define dbg_dump_packet(packet) do { } while (0)
0185 #define dbg_dump_hex(data, len) do { } while (0)
0186 #endif
0187 
0188 static void dump_hex(const uint8_t *data, int len)
0189 {
0190     int i;
0191 
0192     printk("    ");
0193     for (i=0; i < len; i++)
0194         printk("%.2x", data[i]);
0195 
0196     printk("\n    ");
0197     for (i=0; i < len; i++) {
0198         if (isprint(data[i]))
0199             printk("%c", data[i]);
0200         else
0201             printk(".");
0202     }
0203     printk("\n");
0204 }
0205 
0206 static void dump_packet(uint8_t *packet)
0207 {
0208     struct hvsi_header *header = (struct hvsi_header *)packet;
0209 
0210     printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
0211             header->seqno);
0212 
0213     dump_hex(packet, header->len);
0214 }
0215 
0216 static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
0217 {
0218     unsigned long got;
0219 
0220     got = hvc_get_chars(hp->vtermno, buf, count);
0221 
0222     return got;
0223 }
0224 
0225 static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
0226     struct tty_struct *tty, struct hvsi_struct **to_handshake)
0227 {
0228     struct hvsi_control *header = (struct hvsi_control *)packet;
0229 
0230     switch (be16_to_cpu(header->verb)) {
0231         case VSV_MODEM_CTL_UPDATE:
0232             if ((be32_to_cpu(header->word) & HVSI_TSCD) == 0) {
0233                 /* CD went away; no more connection */
0234                 pr_debug("hvsi%i: CD dropped\n", hp->index);
0235                 hp->mctrl &= TIOCM_CD;
0236                 if (tty && !C_CLOCAL(tty))
0237                     tty_hangup(tty);
0238             }
0239             break;
0240         case VSV_CLOSE_PROTOCOL:
0241             pr_debug("hvsi%i: service processor came back\n", hp->index);
0242             if (hp->state != HVSI_CLOSED) {
0243                 *to_handshake = hp;
0244             }
0245             break;
0246         default:
0247             printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
0248                 hp->index);
0249             dump_packet(packet);
0250             break;
0251     }
0252 }
0253 
0254 static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
0255 {
0256     struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;
0257     uint32_t mctrl_word;
0258 
0259     switch (hp->state) {
0260         case HVSI_WAIT_FOR_VER_RESPONSE:
0261             __set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
0262             break;
0263         case HVSI_WAIT_FOR_MCTRL_RESPONSE:
0264             hp->mctrl = 0;
0265             mctrl_word = be32_to_cpu(resp->u.mctrl_word);
0266             if (mctrl_word & HVSI_TSDTR)
0267                 hp->mctrl |= TIOCM_DTR;
0268             if (mctrl_word & HVSI_TSCD)
0269                 hp->mctrl |= TIOCM_CD;
0270             __set_state(hp, HVSI_OPEN);
0271             break;
0272         default:
0273             printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
0274             dump_packet(packet);
0275             break;
0276     }
0277 }
0278 
0279 /* respond to service processor's version query */
0280 static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
0281 {
0282     struct hvsi_query_response packet __ALIGNED__;
0283     int wrote;
0284 
0285     packet.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
0286     packet.hdr.len = sizeof(struct hvsi_query_response);
0287     packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
0288     packet.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
0289     packet.u.version = HVSI_VERSION;
0290     packet.query_seqno = cpu_to_be16(query_seqno+1);
0291 
0292     pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
0293     dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
0294 
0295     wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
0296     if (wrote != packet.hdr.len) {
0297         printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
0298             hp->index);
0299         return -EIO;
0300     }
0301 
0302     return 0;
0303 }
0304 
0305 static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
0306 {
0307     struct hvsi_query *query = (struct hvsi_query *)packet;
0308 
0309     switch (hp->state) {
0310         case HVSI_WAIT_FOR_VER_QUERY:
0311             hvsi_version_respond(hp, be16_to_cpu(query->hdr.seqno));
0312             __set_state(hp, HVSI_OPEN);
0313             break;
0314         default:
0315             printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
0316             dump_packet(packet);
0317             break;
0318     }
0319 }
0320 
0321 static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
0322 {
0323     int i;
0324 
0325     for (i=0; i < len; i++) {
0326         char c = buf[i];
0327 #ifdef CONFIG_MAGIC_SYSRQ
0328         if (c == '\0') {
0329             hp->sysrq = 1;
0330             continue;
0331         } else if (hp->sysrq) {
0332             handle_sysrq(c);
0333             hp->sysrq = 0;
0334             continue;
0335         }
0336 #endif /* CONFIG_MAGIC_SYSRQ */
0337         tty_insert_flip_char(&hp->port, c, 0);
0338     }
0339 }
0340 
0341 /*
0342  * We could get 252 bytes of data at once here. But the tty layer only
0343  * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
0344  * it. Accordingly we won't send more than 128 bytes at a time to the flip
0345  * buffer, which will give the tty buffer a chance to throttle us. Should the
0346  * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
0347  * revisited.
0348  */
0349 #define TTY_THRESHOLD_THROTTLE 128
0350 static bool hvsi_recv_data(struct hvsi_struct *hp, const uint8_t *packet)
0351 {
0352     const struct hvsi_header *header = (const struct hvsi_header *)packet;
0353     const uint8_t *data = packet + sizeof(struct hvsi_header);
0354     int datalen = header->len - sizeof(struct hvsi_header);
0355     int overflow = datalen - TTY_THRESHOLD_THROTTLE;
0356 
0357     pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);
0358 
0359     if (datalen == 0)
0360         return false;
0361 
0362     if (overflow > 0) {
0363         pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
0364         datalen = TTY_THRESHOLD_THROTTLE;
0365     }
0366 
0367     hvsi_insert_chars(hp, data, datalen);
0368 
0369     if (overflow > 0) {
0370         /*
0371          * we still have more data to deliver, so we need to save off the
0372          * overflow and send it later
0373          */
0374         pr_debug("%s: deferring overflow\n", __func__);
0375         memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
0376         hp->n_throttle = overflow;
0377     }
0378 
0379     return true;
0380 }
0381 
0382 /*
0383  * Returns true/false indicating data successfully read from hypervisor.
0384  * Used both to get packets for tty connections and to advance the state
0385  * machine during console handshaking (in which case tty = NULL and we ignore
0386  * incoming data).
0387  */
0388 static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct *tty,
0389         struct hvsi_struct **handshake)
0390 {
0391     uint8_t *packet = hp->inbuf;
0392     int chunklen;
0393     bool flip = false;
0394 
0395     *handshake = NULL;
0396 
0397     chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
0398     if (chunklen == 0) {
0399         pr_debug("%s: 0-length read\n", __func__);
0400         return 0;
0401     }
0402 
0403     pr_debug("%s: got %i bytes\n", __func__, chunklen);
0404     dbg_dump_hex(hp->inbuf_end, chunklen);
0405 
0406     hp->inbuf_end += chunklen;
0407 
0408     /* handle all completed packets */
0409     while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
0410         struct hvsi_header *header = (struct hvsi_header *)packet;
0411 
0412         if (!is_header(packet)) {
0413             printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
0414             /* skip bytes until we find a header or run out of data */
0415             while ((packet < hp->inbuf_end) && (!is_header(packet)))
0416                 packet++;
0417             continue;
0418         }
0419 
0420         pr_debug("%s: handling %i-byte packet\n", __func__,
0421                 len_packet(packet));
0422         dbg_dump_packet(packet);
0423 
0424         switch (header->type) {
0425             case VS_DATA_PACKET_HEADER:
0426                 if (!is_open(hp))
0427                     break;
0428                 flip = hvsi_recv_data(hp, packet);
0429                 break;
0430             case VS_CONTROL_PACKET_HEADER:
0431                 hvsi_recv_control(hp, packet, tty, handshake);
0432                 break;
0433             case VS_QUERY_RESPONSE_PACKET_HEADER:
0434                 hvsi_recv_response(hp, packet);
0435                 break;
0436             case VS_QUERY_PACKET_HEADER:
0437                 hvsi_recv_query(hp, packet);
0438                 break;
0439             default:
0440                 printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
0441                         hp->index, header->type);
0442                 dump_packet(packet);
0443                 break;
0444         }
0445 
0446         packet += len_packet(packet);
0447 
0448         if (*handshake) {
0449             pr_debug("%s: handshake\n", __func__);
0450             break;
0451         }
0452     }
0453 
0454     compact_inbuf(hp, packet);
0455 
0456     if (flip)
0457         tty_flip_buffer_push(&hp->port);
0458 
0459     return 1;
0460 }
0461 
0462 static void hvsi_send_overflow(struct hvsi_struct *hp)
0463 {
0464     pr_debug("%s: delivering %i bytes overflow\n", __func__,
0465             hp->n_throttle);
0466 
0467     hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
0468     hp->n_throttle = 0;
0469 }
0470 
0471 /*
0472  * must get all pending data because we only get an irq on empty->non-empty
0473  * transition
0474  */
0475 static irqreturn_t hvsi_interrupt(int irq, void *arg)
0476 {
0477     struct hvsi_struct *hp = (struct hvsi_struct *)arg;
0478     struct hvsi_struct *handshake;
0479     struct tty_struct *tty;
0480     unsigned long flags;
0481     int again = 1;
0482 
0483     pr_debug("%s\n", __func__);
0484 
0485     tty = tty_port_tty_get(&hp->port);
0486 
0487     while (again) {
0488         spin_lock_irqsave(&hp->lock, flags);
0489         again = hvsi_load_chunk(hp, tty, &handshake);
0490         spin_unlock_irqrestore(&hp->lock, flags);
0491 
0492         if (handshake) {
0493             pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
0494             schedule_work(&handshake->handshaker);
0495         }
0496     }
0497 
0498     spin_lock_irqsave(&hp->lock, flags);
0499     if (tty && hp->n_throttle && !tty_throttled(tty)) {
0500         /* we weren't hung up and we weren't throttled, so we can
0501          * deliver the rest now */
0502         hvsi_send_overflow(hp);
0503         tty_flip_buffer_push(&hp->port);
0504     }
0505     spin_unlock_irqrestore(&hp->lock, flags);
0506 
0507     tty_kref_put(tty);
0508 
0509     return IRQ_HANDLED;
0510 }
0511 
0512 /* for boot console, before the irq handler is running */
0513 static int __init poll_for_state(struct hvsi_struct *hp, int state)
0514 {
0515     unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
0516 
0517     for (;;) {
0518         hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
0519 
0520         if (hp->state == state)
0521             return 0;
0522 
0523         mdelay(5);
0524         if (time_after(jiffies, end_jiffies))
0525             return -EIO;
0526     }
0527 }
0528 
0529 /* wait for irq handler to change our state */
0530 static int wait_for_state(struct hvsi_struct *hp, int state)
0531 {
0532     int ret = 0;
0533 
0534     if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
0535         ret = -EIO;
0536 
0537     return ret;
0538 }
0539 
0540 static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
0541 {
0542     struct hvsi_query packet __ALIGNED__;
0543     int wrote;
0544 
0545     packet.hdr.type = VS_QUERY_PACKET_HEADER;
0546     packet.hdr.len = sizeof(struct hvsi_query);
0547     packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
0548     packet.verb = cpu_to_be16(verb);
0549 
0550     pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
0551     dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
0552 
0553     wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
0554     if (wrote != packet.hdr.len) {
0555         printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
0556             wrote);
0557         return -EIO;
0558     }
0559 
0560     return 0;
0561 }
0562 
0563 static int hvsi_get_mctrl(struct hvsi_struct *hp)
0564 {
0565     int ret;
0566 
0567     set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
0568     hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
0569 
0570     ret = hvsi_wait(hp, HVSI_OPEN);
0571     if (ret < 0) {
0572         printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
0573         set_state(hp, HVSI_OPEN);
0574         return ret;
0575     }
0576 
0577     pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
0578 
0579     return 0;
0580 }
0581 
0582 /* note that we can only set DTR */
0583 static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
0584 {
0585     struct hvsi_control packet __ALIGNED__;
0586     int wrote;
0587 
0588     packet.hdr.type = VS_CONTROL_PACKET_HEADER;
0589     packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
0590     packet.hdr.len = sizeof(struct hvsi_control);
0591     packet.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
0592     packet.mask = cpu_to_be32(HVSI_TSDTR);
0593 
0594     if (mctrl & TIOCM_DTR)
0595         packet.word = cpu_to_be32(HVSI_TSDTR);
0596 
0597     pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
0598     dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
0599 
0600     wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
0601     if (wrote != packet.hdr.len) {
0602         printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
0603         return -EIO;
0604     }
0605 
0606     return 0;
0607 }
0608 
0609 static void hvsi_drain_input(struct hvsi_struct *hp)
0610 {
0611     uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
0612     unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
0613 
0614     while (time_before(end_jiffies, jiffies))
0615         if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
0616             break;
0617 }
0618 
0619 static int hvsi_handshake(struct hvsi_struct *hp)
0620 {
0621     int ret;
0622 
0623     /*
0624      * We could have a CLOSE or other data waiting for us before we even try
0625      * to open; try to throw it all away so we don't get confused. (CLOSE
0626      * is the first message sent up the pipe when the FSP comes online. We
0627      * need to distinguish between "it came up a while ago and we're the first
0628      * user" and "it was just reset before it saw our handshake packet".)
0629      */
0630     hvsi_drain_input(hp);
0631 
0632     set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
0633     ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
0634     if (ret < 0) {
0635         printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
0636         return ret;
0637     }
0638 
0639     ret = hvsi_wait(hp, HVSI_OPEN);
0640     if (ret < 0)
0641         return ret;
0642 
0643     return 0;
0644 }
0645 
0646 static void hvsi_handshaker(struct work_struct *work)
0647 {
0648     struct hvsi_struct *hp =
0649         container_of(work, struct hvsi_struct, handshaker);
0650 
0651     if (hvsi_handshake(hp) >= 0)
0652         return;
0653 
0654     printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
0655     if (is_console(hp)) {
0656         /*
0657          * ttys will re-attempt the handshake via hvsi_open, but
0658          * the console will not.
0659          */
0660         printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
0661     }
0662 }
0663 
0664 static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
0665 {
0666     struct hvsi_data packet __ALIGNED__;
0667     int ret;
0668 
0669     BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
0670 
0671     packet.hdr.type = VS_DATA_PACKET_HEADER;
0672     packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
0673     packet.hdr.len = count + sizeof(struct hvsi_header);
0674     memcpy(&packet.data, buf, count);
0675 
0676     ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
0677     if (ret == packet.hdr.len) {
0678         /* return the number of chars written, not the packet length */
0679         return count;
0680     }
0681     return ret; /* return any errors */
0682 }
0683 
0684 static void hvsi_close_protocol(struct hvsi_struct *hp)
0685 {
0686     struct hvsi_control packet __ALIGNED__;
0687 
0688     packet.hdr.type = VS_CONTROL_PACKET_HEADER;
0689     packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
0690     packet.hdr.len = 6;
0691     packet.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
0692 
0693     pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
0694     dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
0695 
0696     hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
0697 }
0698 
0699 static int hvsi_open(struct tty_struct *tty, struct file *filp)
0700 {
0701     struct hvsi_struct *hp;
0702     unsigned long flags;
0703     int ret;
0704 
0705     pr_debug("%s\n", __func__);
0706 
0707     hp = &hvsi_ports[tty->index];
0708 
0709     tty->driver_data = hp;
0710 
0711     mb();
0712     if (hp->state == HVSI_FSP_DIED)
0713         return -EIO;
0714 
0715     tty_port_tty_set(&hp->port, tty);
0716     spin_lock_irqsave(&hp->lock, flags);
0717     hp->port.count++;
0718     atomic_set(&hp->seqno, 0);
0719     h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
0720     spin_unlock_irqrestore(&hp->lock, flags);
0721 
0722     if (is_console(hp))
0723         return 0; /* this has already been handshaked as the console */
0724 
0725     ret = hvsi_handshake(hp);
0726     if (ret < 0) {
0727         printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
0728         return ret;
0729     }
0730 
0731     ret = hvsi_get_mctrl(hp);
0732     if (ret < 0) {
0733         printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
0734         return ret;
0735     }
0736 
0737     ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
0738     if (ret < 0) {
0739         printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
0740         return ret;
0741     }
0742 
0743     return 0;
0744 }
0745 
0746 /* wait for hvsi_write_worker to empty hp->outbuf */
0747 static void hvsi_flush_output(struct hvsi_struct *hp)
0748 {
0749     wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
0750 
0751     /* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
0752     cancel_delayed_work_sync(&hp->writer);
0753     flush_work(&hp->handshaker);
0754 
0755     /*
0756      * it's also possible that our timeout expired and hvsi_write_worker
0757      * didn't manage to push outbuf. poof.
0758      */
0759     hp->n_outbuf = 0;
0760 }
0761 
0762 static void hvsi_close(struct tty_struct *tty, struct file *filp)
0763 {
0764     struct hvsi_struct *hp = tty->driver_data;
0765     unsigned long flags;
0766 
0767     pr_debug("%s\n", __func__);
0768 
0769     if (tty_hung_up_p(filp))
0770         return;
0771 
0772     spin_lock_irqsave(&hp->lock, flags);
0773 
0774     if (--hp->port.count == 0) {
0775         tty_port_tty_set(&hp->port, NULL);
0776         hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
0777 
0778         /* only close down connection if it is not the console */
0779         if (!is_console(hp)) {
0780             h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
0781             __set_state(hp, HVSI_CLOSED);
0782             /*
0783              * any data delivered to the tty layer after this will be
0784              * discarded (except for XON/XOFF)
0785              */
0786             tty->closing = 1;
0787 
0788             spin_unlock_irqrestore(&hp->lock, flags);
0789 
0790             /* let any existing irq handlers finish. no more will start. */
0791             synchronize_irq(hp->virq);
0792 
0793             /* hvsi_write_worker will re-schedule until outbuf is empty. */
0794             hvsi_flush_output(hp);
0795 
0796             /* tell FSP to stop sending data */
0797             hvsi_close_protocol(hp);
0798 
0799             /*
0800              * drain anything FSP is still in the middle of sending, and let
0801              * hvsi_handshake drain the rest on the next open.
0802              */
0803             hvsi_drain_input(hp);
0804 
0805             spin_lock_irqsave(&hp->lock, flags);
0806         }
0807     } else if (hp->port.count < 0)
0808         printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
0809                hp - hvsi_ports, hp->port.count);
0810 
0811     spin_unlock_irqrestore(&hp->lock, flags);
0812 }
0813 
0814 static void hvsi_hangup(struct tty_struct *tty)
0815 {
0816     struct hvsi_struct *hp = tty->driver_data;
0817     unsigned long flags;
0818 
0819     pr_debug("%s\n", __func__);
0820 
0821     tty_port_tty_set(&hp->port, NULL);
0822 
0823     spin_lock_irqsave(&hp->lock, flags);
0824     hp->port.count = 0;
0825     hp->n_outbuf = 0;
0826     spin_unlock_irqrestore(&hp->lock, flags);
0827 }
0828 
0829 /* called with hp->lock held */
0830 static void hvsi_push(struct hvsi_struct *hp)
0831 {
0832     int n;
0833 
0834     if (hp->n_outbuf <= 0)
0835         return;
0836 
0837     n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
0838     if (n > 0) {
0839         /* success */
0840         pr_debug("%s: wrote %i chars\n", __func__, n);
0841         hp->n_outbuf = 0;
0842     } else if (n == -EIO) {
0843         __set_state(hp, HVSI_FSP_DIED);
0844         printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
0845     }
0846 }
0847 
0848 /* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
0849 static void hvsi_write_worker(struct work_struct *work)
0850 {
0851     struct hvsi_struct *hp =
0852         container_of(work, struct hvsi_struct, writer.work);
0853     unsigned long flags;
0854 #ifdef DEBUG
0855     static long start_j = 0;
0856 
0857     if (start_j == 0)
0858         start_j = jiffies;
0859 #endif /* DEBUG */
0860 
0861     spin_lock_irqsave(&hp->lock, flags);
0862 
0863     pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
0864 
0865     if (!is_open(hp)) {
0866         /*
0867          * We could have a non-open connection if the service processor died
0868          * while we were busily scheduling ourselves. In that case, it could
0869          * be minutes before the service processor comes back, so only try
0870          * again once a second.
0871          */
0872         schedule_delayed_work(&hp->writer, HZ);
0873         goto out;
0874     }
0875 
0876     hvsi_push(hp);
0877     if (hp->n_outbuf > 0)
0878         schedule_delayed_work(&hp->writer, 10);
0879     else {
0880 #ifdef DEBUG
0881         pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
0882                 jiffies - start_j);
0883         start_j = 0;
0884 #endif /* DEBUG */
0885         wake_up_all(&hp->emptyq);
0886         tty_port_tty_wakeup(&hp->port);
0887     }
0888 
0889 out:
0890     spin_unlock_irqrestore(&hp->lock, flags);
0891 }
0892 
0893 static unsigned int hvsi_write_room(struct tty_struct *tty)
0894 {
0895     struct hvsi_struct *hp = tty->driver_data;
0896 
0897     return N_OUTBUF - hp->n_outbuf;
0898 }
0899 
0900 static unsigned int hvsi_chars_in_buffer(struct tty_struct *tty)
0901 {
0902     struct hvsi_struct *hp = tty->driver_data;
0903 
0904     return hp->n_outbuf;
0905 }
0906 
0907 static int hvsi_write(struct tty_struct *tty,
0908              const unsigned char *buf, int count)
0909 {
0910     struct hvsi_struct *hp = tty->driver_data;
0911     const char *source = buf;
0912     unsigned long flags;
0913     int total = 0;
0914     int origcount = count;
0915 
0916     spin_lock_irqsave(&hp->lock, flags);
0917 
0918     pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
0919 
0920     if (!is_open(hp)) {
0921         /* we're either closing or not yet open; don't accept data */
0922         pr_debug("%s: not open\n", __func__);
0923         goto out;
0924     }
0925 
0926     /*
0927      * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
0928      * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
0929      * will see there is no room in outbuf and return.
0930      */
0931     while ((count > 0) && (hvsi_write_room(tty) > 0)) {
0932         int chunksize = min_t(int, count, hvsi_write_room(tty));
0933 
0934         BUG_ON(hp->n_outbuf < 0);
0935         memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
0936         hp->n_outbuf += chunksize;
0937 
0938         total += chunksize;
0939         source += chunksize;
0940         count -= chunksize;
0941         hvsi_push(hp);
0942     }
0943 
0944     if (hp->n_outbuf > 0) {
0945         /*
0946          * we weren't able to write it all to the hypervisor.
0947          * schedule another push attempt.
0948          */
0949         schedule_delayed_work(&hp->writer, 10);
0950     }
0951 
0952 out:
0953     spin_unlock_irqrestore(&hp->lock, flags);
0954 
0955     if (total != origcount)
0956         pr_debug("%s: wanted %i, only wrote %i\n", __func__, origcount,
0957             total);
0958 
0959     return total;
0960 }
0961 
0962 /*
0963  * I have never seen throttle or unthrottle called, so this little throttle
0964  * buffering scheme may or may not work.
0965  */
0966 static void hvsi_throttle(struct tty_struct *tty)
0967 {
0968     struct hvsi_struct *hp = tty->driver_data;
0969 
0970     pr_debug("%s\n", __func__);
0971 
0972     h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
0973 }
0974 
0975 static void hvsi_unthrottle(struct tty_struct *tty)
0976 {
0977     struct hvsi_struct *hp = tty->driver_data;
0978     unsigned long flags;
0979 
0980     pr_debug("%s\n", __func__);
0981 
0982     spin_lock_irqsave(&hp->lock, flags);
0983     if (hp->n_throttle) {
0984         hvsi_send_overflow(hp);
0985         tty_flip_buffer_push(&hp->port);
0986     }
0987     spin_unlock_irqrestore(&hp->lock, flags);
0988 
0989 
0990     h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
0991 }
0992 
0993 static int hvsi_tiocmget(struct tty_struct *tty)
0994 {
0995     struct hvsi_struct *hp = tty->driver_data;
0996 
0997     hvsi_get_mctrl(hp);
0998     return hp->mctrl;
0999 }
1000 
1001 static int hvsi_tiocmset(struct tty_struct *tty,
1002                 unsigned int set, unsigned int clear)
1003 {
1004     struct hvsi_struct *hp = tty->driver_data;
1005     unsigned long flags;
1006     uint16_t new_mctrl;
1007 
1008     /* we can only alter DTR */
1009     clear &= TIOCM_DTR;
1010     set &= TIOCM_DTR;
1011 
1012     spin_lock_irqsave(&hp->lock, flags);
1013 
1014     new_mctrl = (hp->mctrl & ~clear) | set;
1015 
1016     if (hp->mctrl != new_mctrl) {
1017         hvsi_set_mctrl(hp, new_mctrl);
1018         hp->mctrl = new_mctrl;
1019     }
1020     spin_unlock_irqrestore(&hp->lock, flags);
1021 
1022     return 0;
1023 }
1024 
1025 
1026 static const struct tty_operations hvsi_ops = {
1027     .open = hvsi_open,
1028     .close = hvsi_close,
1029     .write = hvsi_write,
1030     .hangup = hvsi_hangup,
1031     .write_room = hvsi_write_room,
1032     .chars_in_buffer = hvsi_chars_in_buffer,
1033     .throttle = hvsi_throttle,
1034     .unthrottle = hvsi_unthrottle,
1035     .tiocmget = hvsi_tiocmget,
1036     .tiocmset = hvsi_tiocmset,
1037 };
1038 
1039 static int __init hvsi_init(void)
1040 {
1041     struct tty_driver *driver;
1042     int i, ret;
1043 
1044     driver = tty_alloc_driver(hvsi_count, TTY_DRIVER_REAL_RAW);
1045     if (IS_ERR(driver))
1046         return PTR_ERR(driver);
1047 
1048     driver->driver_name = "hvsi";
1049     driver->name = "hvsi";
1050     driver->major = HVSI_MAJOR;
1051     driver->minor_start = HVSI_MINOR;
1052     driver->type = TTY_DRIVER_TYPE_SYSTEM;
1053     driver->init_termios = tty_std_termios;
1054     driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
1055     driver->init_termios.c_ispeed = 9600;
1056     driver->init_termios.c_ospeed = 9600;
1057     tty_set_operations(driver, &hvsi_ops);
1058 
1059     for (i=0; i < hvsi_count; i++) {
1060         struct hvsi_struct *hp = &hvsi_ports[i];
1061         int ret = 1;
1062 
1063         tty_port_link_device(&hp->port, driver, i);
1064 
1065         ret = request_irq(hp->virq, hvsi_interrupt, 0, "hvsi", hp);
1066         if (ret)
1067             printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
1068                 hp->virq, ret);
1069     }
1070     hvsi_wait = wait_for_state; /* irqs active now */
1071 
1072     ret = tty_register_driver(driver);
1073     if (ret) {
1074         pr_err("Couldn't register hvsi console driver\n");
1075         goto err_free_irq;
1076     }
1077 
1078     hvsi_driver = driver;
1079 
1080     printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
1081 
1082     return 0;
1083 err_free_irq:
1084     hvsi_wait = poll_for_state;
1085     for (i = 0; i < hvsi_count; i++) {
1086         struct hvsi_struct *hp = &hvsi_ports[i];
1087 
1088         free_irq(hp->virq, hp);
1089     }
1090     tty_driver_kref_put(driver);
1091 
1092     return ret;
1093 }
1094 device_initcall(hvsi_init);
1095 
1096 /***** console (not tty) code: *****/
1097 
1098 static void hvsi_console_print(struct console *console, const char *buf,
1099         unsigned int count)
1100 {
1101     struct hvsi_struct *hp = &hvsi_ports[console->index];
1102     char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
1103     unsigned int i = 0, n = 0;
1104     int ret, donecr = 0;
1105 
1106     mb();
1107     if (!is_open(hp))
1108         return;
1109 
1110     /*
1111      * ugh, we have to translate LF -> CRLF ourselves, in place.
1112      * copied from hvc_console.c:
1113      */
1114     while (count > 0 || i > 0) {
1115         if (count > 0 && i < sizeof(c)) {
1116             if (buf[n] == '\n' && !donecr) {
1117                 c[i++] = '\r';
1118                 donecr = 1;
1119             } else {
1120                 c[i++] = buf[n++];
1121                 donecr = 0;
1122                 --count;
1123             }
1124         } else {
1125             ret = hvsi_put_chars(hp, c, i);
1126             if (ret < 0)
1127                 i = 0;
1128             i -= ret;
1129         }
1130     }
1131 }
1132 
1133 static struct tty_driver *hvsi_console_device(struct console *console,
1134     int *index)
1135 {
1136     *index = console->index;
1137     return hvsi_driver;
1138 }
1139 
1140 static int __init hvsi_console_setup(struct console *console, char *options)
1141 {
1142     struct hvsi_struct *hp;
1143     int ret;
1144 
1145     if (console->index < 0 || console->index >= hvsi_count)
1146         return -EINVAL;
1147     hp = &hvsi_ports[console->index];
1148 
1149     /* give the FSP a chance to change the baud rate when we re-open */
1150     hvsi_close_protocol(hp);
1151 
1152     ret = hvsi_handshake(hp);
1153     if (ret < 0)
1154         return ret;
1155 
1156     ret = hvsi_get_mctrl(hp);
1157     if (ret < 0)
1158         return ret;
1159 
1160     ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
1161     if (ret < 0)
1162         return ret;
1163 
1164     hp->flags |= HVSI_CONSOLE;
1165 
1166     return 0;
1167 }
1168 
1169 static struct console hvsi_console = {
1170     .name       = "hvsi",
1171     .write      = hvsi_console_print,
1172     .device     = hvsi_console_device,
1173     .setup      = hvsi_console_setup,
1174     .flags      = CON_PRINTBUFFER,
1175     .index      = -1,
1176 };
1177 
1178 static int __init hvsi_console_init(void)
1179 {
1180     struct device_node *vty;
1181 
1182     hvsi_wait = poll_for_state; /* no irqs yet; must poll */
1183 
1184     /* search device tree for vty nodes */
1185     for_each_compatible_node(vty, "serial", "hvterm-protocol") {
1186         struct hvsi_struct *hp;
1187         const __be32 *vtermno, *irq;
1188 
1189         vtermno = of_get_property(vty, "reg", NULL);
1190         irq = of_get_property(vty, "interrupts", NULL);
1191         if (!vtermno || !irq)
1192             continue;
1193 
1194         if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
1195             of_node_put(vty);
1196             break;
1197         }
1198 
1199         hp = &hvsi_ports[hvsi_count];
1200         INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
1201         INIT_WORK(&hp->handshaker, hvsi_handshaker);
1202         init_waitqueue_head(&hp->emptyq);
1203         init_waitqueue_head(&hp->stateq);
1204         spin_lock_init(&hp->lock);
1205         tty_port_init(&hp->port);
1206         hp->index = hvsi_count;
1207         hp->inbuf_end = hp->inbuf;
1208         hp->state = HVSI_CLOSED;
1209         hp->vtermno = be32_to_cpup(vtermno);
1210         hp->virq = irq_create_mapping(NULL, be32_to_cpup(irq));
1211         if (hp->virq == 0) {
1212             printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
1213                    __func__, be32_to_cpup(irq));
1214             tty_port_destroy(&hp->port);
1215             continue;
1216         }
1217 
1218         hvsi_count++;
1219     }
1220 
1221     if (hvsi_count)
1222         register_console(&hvsi_console);
1223     return 0;
1224 }
1225 console_initcall(hvsi_console_init);
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