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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  Driver for GRLIB serial ports (APBUART)
0004  *
0005  *  Based on linux/drivers/serial/amba.c
0006  *
0007  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
0008  *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
0009  *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
0010  *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
0011  *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
0012  */
0013 
0014 #include <linux/module.h>
0015 #include <linux/tty.h>
0016 #include <linux/tty_flip.h>
0017 #include <linux/ioport.h>
0018 #include <linux/init.h>
0019 #include <linux/serial.h>
0020 #include <linux/console.h>
0021 #include <linux/sysrq.h>
0022 #include <linux/kthread.h>
0023 #include <linux/device.h>
0024 #include <linux/of.h>
0025 #include <linux/of_device.h>
0026 #include <linux/of_platform.h>
0027 #include <linux/of_irq.h>
0028 #include <linux/platform_device.h>
0029 #include <linux/io.h>
0030 #include <linux/serial_core.h>
0031 #include <asm/irq.h>
0032 
0033 #include "apbuart.h"
0034 
0035 #define SERIAL_APBUART_MAJOR    TTY_MAJOR
0036 #define SERIAL_APBUART_MINOR    64
0037 #define UART_DUMMY_RSR_RX   0x8000  /* for ignore all read */
0038 
0039 static void apbuart_tx_chars(struct uart_port *port);
0040 
0041 static void apbuart_stop_tx(struct uart_port *port)
0042 {
0043     unsigned int cr;
0044 
0045     cr = UART_GET_CTRL(port);
0046     cr &= ~UART_CTRL_TI;
0047     UART_PUT_CTRL(port, cr);
0048 }
0049 
0050 static void apbuart_start_tx(struct uart_port *port)
0051 {
0052     unsigned int cr;
0053 
0054     cr = UART_GET_CTRL(port);
0055     cr |= UART_CTRL_TI;
0056     UART_PUT_CTRL(port, cr);
0057 
0058     if (UART_GET_STATUS(port) & UART_STATUS_THE)
0059         apbuart_tx_chars(port);
0060 }
0061 
0062 static void apbuart_stop_rx(struct uart_port *port)
0063 {
0064     unsigned int cr;
0065 
0066     cr = UART_GET_CTRL(port);
0067     cr &= ~(UART_CTRL_RI);
0068     UART_PUT_CTRL(port, cr);
0069 }
0070 
0071 static void apbuart_rx_chars(struct uart_port *port)
0072 {
0073     unsigned int status, ch, rsr, flag;
0074     unsigned int max_chars = port->fifosize;
0075 
0076     status = UART_GET_STATUS(port);
0077 
0078     while (UART_RX_DATA(status) && (max_chars--)) {
0079 
0080         ch = UART_GET_CHAR(port);
0081         flag = TTY_NORMAL;
0082 
0083         port->icount.rx++;
0084 
0085         rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
0086         UART_PUT_STATUS(port, 0);
0087         if (rsr & UART_STATUS_ERR) {
0088 
0089             if (rsr & UART_STATUS_BR) {
0090                 rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
0091                 port->icount.brk++;
0092                 if (uart_handle_break(port))
0093                     goto ignore_char;
0094             } else if (rsr & UART_STATUS_PE) {
0095                 port->icount.parity++;
0096             } else if (rsr & UART_STATUS_FE) {
0097                 port->icount.frame++;
0098             }
0099             if (rsr & UART_STATUS_OE)
0100                 port->icount.overrun++;
0101 
0102             rsr &= port->read_status_mask;
0103 
0104             if (rsr & UART_STATUS_PE)
0105                 flag = TTY_PARITY;
0106             else if (rsr & UART_STATUS_FE)
0107                 flag = TTY_FRAME;
0108         }
0109 
0110         if (uart_handle_sysrq_char(port, ch))
0111             goto ignore_char;
0112 
0113         uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
0114 
0115 
0116           ignore_char:
0117         status = UART_GET_STATUS(port);
0118     }
0119 
0120     tty_flip_buffer_push(&port->state->port);
0121 }
0122 
0123 static void apbuart_tx_chars(struct uart_port *port)
0124 {
0125     struct circ_buf *xmit = &port->state->xmit;
0126     int count;
0127 
0128     if (port->x_char) {
0129         UART_PUT_CHAR(port, port->x_char);
0130         port->icount.tx++;
0131         port->x_char = 0;
0132         return;
0133     }
0134 
0135     if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
0136         apbuart_stop_tx(port);
0137         return;
0138     }
0139 
0140     /* amba: fill FIFO */
0141     count = port->fifosize >> 1;
0142     do {
0143         UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
0144         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
0145         port->icount.tx++;
0146         if (uart_circ_empty(xmit))
0147             break;
0148     } while (--count > 0);
0149 
0150     if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
0151         uart_write_wakeup(port);
0152 
0153     if (uart_circ_empty(xmit))
0154         apbuart_stop_tx(port);
0155 }
0156 
0157 static irqreturn_t apbuart_int(int irq, void *dev_id)
0158 {
0159     struct uart_port *port = dev_id;
0160     unsigned int status;
0161 
0162     spin_lock(&port->lock);
0163 
0164     status = UART_GET_STATUS(port);
0165     if (status & UART_STATUS_DR)
0166         apbuart_rx_chars(port);
0167     if (status & UART_STATUS_THE)
0168         apbuart_tx_chars(port);
0169 
0170     spin_unlock(&port->lock);
0171 
0172     return IRQ_HANDLED;
0173 }
0174 
0175 static unsigned int apbuart_tx_empty(struct uart_port *port)
0176 {
0177     unsigned int status = UART_GET_STATUS(port);
0178     return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
0179 }
0180 
0181 static unsigned int apbuart_get_mctrl(struct uart_port *port)
0182 {
0183     /* The GRLIB APBUART handles flow control in hardware */
0184     return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
0185 }
0186 
0187 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
0188 {
0189     /* The GRLIB APBUART handles flow control in hardware */
0190 }
0191 
0192 static void apbuart_break_ctl(struct uart_port *port, int break_state)
0193 {
0194     /* We don't support sending break */
0195 }
0196 
0197 static int apbuart_startup(struct uart_port *port)
0198 {
0199     int retval;
0200     unsigned int cr;
0201 
0202     /* Allocate the IRQ */
0203     retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
0204     if (retval)
0205         return retval;
0206 
0207     /* Finally, enable interrupts */
0208     cr = UART_GET_CTRL(port);
0209     UART_PUT_CTRL(port,
0210               cr | UART_CTRL_RE | UART_CTRL_TE |
0211               UART_CTRL_RI | UART_CTRL_TI);
0212 
0213     return 0;
0214 }
0215 
0216 static void apbuart_shutdown(struct uart_port *port)
0217 {
0218     unsigned int cr;
0219 
0220     /* disable all interrupts, disable the port */
0221     cr = UART_GET_CTRL(port);
0222     UART_PUT_CTRL(port,
0223               cr & ~(UART_CTRL_RE | UART_CTRL_TE |
0224                  UART_CTRL_RI | UART_CTRL_TI));
0225 
0226     /* Free the interrupt */
0227     free_irq(port->irq, port);
0228 }
0229 
0230 static void apbuart_set_termios(struct uart_port *port,
0231                 struct ktermios *termios, struct ktermios *old)
0232 {
0233     unsigned int cr;
0234     unsigned long flags;
0235     unsigned int baud, quot;
0236 
0237     /* Ask the core to calculate the divisor for us. */
0238     baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
0239     if (baud == 0)
0240         panic("invalid baudrate %i\n", port->uartclk / 16);
0241 
0242     /* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
0243     quot = (uart_get_divisor(port, baud)) * 2;
0244     cr = UART_GET_CTRL(port);
0245     cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
0246 
0247     if (termios->c_cflag & PARENB) {
0248         cr |= UART_CTRL_PE;
0249         if ((termios->c_cflag & PARODD))
0250             cr |= UART_CTRL_PS;
0251     }
0252 
0253     /* Enable flow control. */
0254     if (termios->c_cflag & CRTSCTS)
0255         cr |= UART_CTRL_FL;
0256 
0257     spin_lock_irqsave(&port->lock, flags);
0258 
0259     /* Update the per-port timeout. */
0260     uart_update_timeout(port, termios->c_cflag, baud);
0261 
0262     port->read_status_mask = UART_STATUS_OE;
0263     if (termios->c_iflag & INPCK)
0264         port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
0265 
0266     /* Characters to ignore */
0267     port->ignore_status_mask = 0;
0268     if (termios->c_iflag & IGNPAR)
0269         port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
0270 
0271     /* Ignore all characters if CREAD is not set. */
0272     if ((termios->c_cflag & CREAD) == 0)
0273         port->ignore_status_mask |= UART_DUMMY_RSR_RX;
0274 
0275     /* Set baud rate */
0276     quot -= 1;
0277     UART_PUT_SCAL(port, quot);
0278     UART_PUT_CTRL(port, cr);
0279 
0280     spin_unlock_irqrestore(&port->lock, flags);
0281 }
0282 
0283 static const char *apbuart_type(struct uart_port *port)
0284 {
0285     return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
0286 }
0287 
0288 static void apbuart_release_port(struct uart_port *port)
0289 {
0290     release_mem_region(port->mapbase, 0x100);
0291 }
0292 
0293 static int apbuart_request_port(struct uart_port *port)
0294 {
0295     return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
0296         != NULL ? 0 : -EBUSY;
0297     return 0;
0298 }
0299 
0300 /* Configure/autoconfigure the port */
0301 static void apbuart_config_port(struct uart_port *port, int flags)
0302 {
0303     if (flags & UART_CONFIG_TYPE) {
0304         port->type = PORT_APBUART;
0305         apbuart_request_port(port);
0306     }
0307 }
0308 
0309 /* Verify the new serial_struct (for TIOCSSERIAL) */
0310 static int apbuart_verify_port(struct uart_port *port,
0311                    struct serial_struct *ser)
0312 {
0313     int ret = 0;
0314     if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
0315         ret = -EINVAL;
0316     if (ser->irq < 0 || ser->irq >= NR_IRQS)
0317         ret = -EINVAL;
0318     if (ser->baud_base < 9600)
0319         ret = -EINVAL;
0320     return ret;
0321 }
0322 
0323 static const struct uart_ops grlib_apbuart_ops = {
0324     .tx_empty = apbuart_tx_empty,
0325     .set_mctrl = apbuart_set_mctrl,
0326     .get_mctrl = apbuart_get_mctrl,
0327     .stop_tx = apbuart_stop_tx,
0328     .start_tx = apbuart_start_tx,
0329     .stop_rx = apbuart_stop_rx,
0330     .break_ctl = apbuart_break_ctl,
0331     .startup = apbuart_startup,
0332     .shutdown = apbuart_shutdown,
0333     .set_termios = apbuart_set_termios,
0334     .type = apbuart_type,
0335     .release_port = apbuart_release_port,
0336     .request_port = apbuart_request_port,
0337     .config_port = apbuart_config_port,
0338     .verify_port = apbuart_verify_port,
0339 };
0340 
0341 static struct uart_port grlib_apbuart_ports[UART_NR];
0342 static struct device_node *grlib_apbuart_nodes[UART_NR];
0343 
0344 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
0345 {
0346     int ctrl, loop = 0;
0347     int status;
0348     int fifosize;
0349     unsigned long flags;
0350 
0351     ctrl = UART_GET_CTRL(port);
0352 
0353     /*
0354      * Enable the transceiver and wait for it to be ready to send data.
0355      * Clear interrupts so that this process will not be externally
0356      * interrupted in the middle (which can cause the transceiver to
0357      * drain prematurely).
0358      */
0359 
0360     local_irq_save(flags);
0361 
0362     UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
0363 
0364     while (!UART_TX_READY(UART_GET_STATUS(port)))
0365         loop++;
0366 
0367     /*
0368      * Disable the transceiver so data isn't actually sent during the
0369      * actual test.
0370      */
0371 
0372     UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
0373 
0374     fifosize = 1;
0375     UART_PUT_CHAR(port, 0);
0376 
0377     /*
0378      * So long as transmitting a character increments the tranceivier FIFO
0379      * length the FIFO must be at least that big. These bytes will
0380      * automatically drain off of the FIFO.
0381      */
0382 
0383     status = UART_GET_STATUS(port);
0384     while (((status >> 20) & 0x3F) == fifosize) {
0385         fifosize++;
0386         UART_PUT_CHAR(port, 0);
0387         status = UART_GET_STATUS(port);
0388     }
0389 
0390     fifosize--;
0391 
0392     UART_PUT_CTRL(port, ctrl);
0393     local_irq_restore(flags);
0394 
0395     if (fifosize == 0)
0396         fifosize = 1;
0397 
0398     return fifosize;
0399 }
0400 
0401 static void apbuart_flush_fifo(struct uart_port *port)
0402 {
0403     int i;
0404 
0405     for (i = 0; i < port->fifosize; i++)
0406         UART_GET_CHAR(port);
0407 }
0408 
0409 
0410 /* ======================================================================== */
0411 /* Console driver, if enabled                                               */
0412 /* ======================================================================== */
0413 
0414 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
0415 
0416 static void apbuart_console_putchar(struct uart_port *port, unsigned char ch)
0417 {
0418     unsigned int status;
0419     do {
0420         status = UART_GET_STATUS(port);
0421     } while (!UART_TX_READY(status));
0422     UART_PUT_CHAR(port, ch);
0423 }
0424 
0425 static void
0426 apbuart_console_write(struct console *co, const char *s, unsigned int count)
0427 {
0428     struct uart_port *port = &grlib_apbuart_ports[co->index];
0429     unsigned int status, old_cr, new_cr;
0430 
0431     /* First save the CR then disable the interrupts */
0432     old_cr = UART_GET_CTRL(port);
0433     new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
0434     UART_PUT_CTRL(port, new_cr);
0435 
0436     uart_console_write(port, s, count, apbuart_console_putchar);
0437 
0438     /*
0439      *      Finally, wait for transmitter to become empty
0440      *      and restore the TCR
0441      */
0442     do {
0443         status = UART_GET_STATUS(port);
0444     } while (!UART_TX_READY(status));
0445     UART_PUT_CTRL(port, old_cr);
0446 }
0447 
0448 static void __init
0449 apbuart_console_get_options(struct uart_port *port, int *baud,
0450                 int *parity, int *bits)
0451 {
0452     if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
0453 
0454         unsigned int quot, status;
0455         status = UART_GET_STATUS(port);
0456 
0457         *parity = 'n';
0458         if (status & UART_CTRL_PE) {
0459             if ((status & UART_CTRL_PS) == 0)
0460                 *parity = 'e';
0461             else
0462                 *parity = 'o';
0463         }
0464 
0465         *bits = 8;
0466         quot = UART_GET_SCAL(port) / 8;
0467         *baud = port->uartclk / (16 * (quot + 1));
0468     }
0469 }
0470 
0471 static int __init apbuart_console_setup(struct console *co, char *options)
0472 {
0473     struct uart_port *port;
0474     int baud = 38400;
0475     int bits = 8;
0476     int parity = 'n';
0477     int flow = 'n';
0478 
0479     pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
0480          co, co->index, options);
0481 
0482     /*
0483      * Check whether an invalid uart number has been specified, and
0484      * if so, search for the first available port that does have
0485      * console support.
0486      */
0487     if (co->index >= grlib_apbuart_port_nr)
0488         co->index = 0;
0489 
0490     port = &grlib_apbuart_ports[co->index];
0491 
0492     spin_lock_init(&port->lock);
0493 
0494     if (options)
0495         uart_parse_options(options, &baud, &parity, &bits, &flow);
0496     else
0497         apbuart_console_get_options(port, &baud, &parity, &bits);
0498 
0499     return uart_set_options(port, co, baud, parity, bits, flow);
0500 }
0501 
0502 static struct uart_driver grlib_apbuart_driver;
0503 
0504 static struct console grlib_apbuart_console = {
0505     .name = "ttyS",
0506     .write = apbuart_console_write,
0507     .device = uart_console_device,
0508     .setup = apbuart_console_setup,
0509     .flags = CON_PRINTBUFFER,
0510     .index = -1,
0511     .data = &grlib_apbuart_driver,
0512 };
0513 
0514 
0515 static int grlib_apbuart_configure(void);
0516 
0517 static int __init apbuart_console_init(void)
0518 {
0519     if (grlib_apbuart_configure())
0520         return -ENODEV;
0521     register_console(&grlib_apbuart_console);
0522     return 0;
0523 }
0524 
0525 console_initcall(apbuart_console_init);
0526 
0527 #define APBUART_CONSOLE (&grlib_apbuart_console)
0528 #else
0529 #define APBUART_CONSOLE NULL
0530 #endif
0531 
0532 static struct uart_driver grlib_apbuart_driver = {
0533     .owner = THIS_MODULE,
0534     .driver_name = "serial",
0535     .dev_name = "ttyS",
0536     .major = SERIAL_APBUART_MAJOR,
0537     .minor = SERIAL_APBUART_MINOR,
0538     .nr = UART_NR,
0539     .cons = APBUART_CONSOLE,
0540 };
0541 
0542 
0543 /* ======================================================================== */
0544 /* OF Platform Driver                                                       */
0545 /* ======================================================================== */
0546 
0547 static int apbuart_probe(struct platform_device *op)
0548 {
0549     int i;
0550     struct uart_port *port = NULL;
0551 
0552     for (i = 0; i < grlib_apbuart_port_nr; i++) {
0553         if (op->dev.of_node == grlib_apbuart_nodes[i])
0554             break;
0555     }
0556 
0557     port = &grlib_apbuart_ports[i];
0558     port->dev = &op->dev;
0559     port->irq = op->archdata.irqs[0];
0560 
0561     uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
0562 
0563     apbuart_flush_fifo((struct uart_port *) port);
0564 
0565     printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
0566            (unsigned long long) port->mapbase, port->irq);
0567     return 0;
0568 }
0569 
0570 static const struct of_device_id apbuart_match[] = {
0571     {
0572      .name = "GAISLER_APBUART",
0573      },
0574     {
0575      .name = "01_00c",
0576      },
0577     {},
0578 };
0579 MODULE_DEVICE_TABLE(of, apbuart_match);
0580 
0581 static struct platform_driver grlib_apbuart_of_driver = {
0582     .probe = apbuart_probe,
0583     .driver = {
0584         .name = "grlib-apbuart",
0585         .of_match_table = apbuart_match,
0586     },
0587 };
0588 
0589 
0590 static int __init grlib_apbuart_configure(void)
0591 {
0592     struct device_node *np;
0593     int line = 0;
0594 
0595     for_each_matching_node(np, apbuart_match) {
0596         const int *ampopts;
0597         const u32 *freq_hz;
0598         const struct amba_prom_registers *regs;
0599         struct uart_port *port;
0600         unsigned long addr;
0601 
0602         ampopts = of_get_property(np, "ampopts", NULL);
0603         if (ampopts && (*ampopts == 0))
0604             continue; /* Ignore if used by another OS instance */
0605         regs = of_get_property(np, "reg", NULL);
0606         /* Frequency of APB Bus is frequency of UART */
0607         freq_hz = of_get_property(np, "freq", NULL);
0608 
0609         if (!regs || !freq_hz || (*freq_hz == 0))
0610             continue;
0611 
0612         grlib_apbuart_nodes[line] = np;
0613 
0614         addr = regs->phys_addr;
0615 
0616         port = &grlib_apbuart_ports[line];
0617 
0618         port->mapbase = addr;
0619         port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
0620         port->irq = 0;
0621         port->iotype = UPIO_MEM;
0622         port->ops = &grlib_apbuart_ops;
0623         port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
0624         port->flags = UPF_BOOT_AUTOCONF;
0625         port->line = line;
0626         port->uartclk = *freq_hz;
0627         port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
0628         line++;
0629 
0630         /* We support maximum UART_NR uarts ... */
0631         if (line == UART_NR)
0632             break;
0633     }
0634 
0635     grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
0636     return line ? 0 : -ENODEV;
0637 }
0638 
0639 static int __init grlib_apbuart_init(void)
0640 {
0641     int ret;
0642 
0643     /* Find all APBUARTS in device the tree and initialize their ports */
0644     ret = grlib_apbuart_configure();
0645     if (ret)
0646         return ret;
0647 
0648     printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
0649 
0650     ret = uart_register_driver(&grlib_apbuart_driver);
0651 
0652     if (ret) {
0653         printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
0654                __FILE__, ret);
0655         return ret;
0656     }
0657 
0658     ret = platform_driver_register(&grlib_apbuart_of_driver);
0659     if (ret) {
0660         printk(KERN_ERR
0661                "%s: platform_driver_register failed (%i)\n",
0662                __FILE__, ret);
0663         uart_unregister_driver(&grlib_apbuart_driver);
0664         return ret;
0665     }
0666 
0667     return ret;
0668 }
0669 
0670 static void __exit grlib_apbuart_exit(void)
0671 {
0672     int i;
0673 
0674     for (i = 0; i < grlib_apbuart_port_nr; i++)
0675         uart_remove_one_port(&grlib_apbuart_driver,
0676                      &grlib_apbuart_ports[i]);
0677 
0678     uart_unregister_driver(&grlib_apbuart_driver);
0679     platform_driver_unregister(&grlib_apbuart_of_driver);
0680 }
0681 
0682 module_init(grlib_apbuart_init);
0683 module_exit(grlib_apbuart_exit);
0684 
0685 MODULE_AUTHOR("Aeroflex Gaisler AB");
0686 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
0687 MODULE_VERSION("2.1");
0688 MODULE_LICENSE("GPL");
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