2 * Atheros AR933X SoC built-in UART driver
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
6 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/ioport.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/sysrq.h>
18 #include <linux/delay.h>
19 #include <linux/platform_device.h>
20 #include <linux/tty.h>
21 #include <linux/tty_flip.h>
22 #include <linux/serial_core.h>
23 #include <linux/serial.h>
24 #include <linux/slab.h>
26 #include <linux/irq.h>
28 #include <asm/div64.h>
30 #include <asm/mach-ath79/ar933x_uart.h>
31 #include <asm/mach-ath79/ar933x_uart_platform.h>
33 #define DRIVER_NAME "ar933x-uart"
35 #define AR933X_UART_MAX_SCALE 0xff
36 #define AR933X_UART_MAX_STEP 0xffff
38 #define AR933X_UART_MIN_BAUD 300
39 #define AR933X_UART_MAX_BAUD 3000000
41 #define AR933X_DUMMY_STATUS_RD 0x01
43 static struct uart_driver ar933x_uart_driver;
45 struct ar933x_uart_port {
46 struct uart_port port;
47 unsigned int ier; /* shadow Interrupt Enable Register */
48 unsigned int min_baud;
49 unsigned int max_baud;
52 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
55 return readl(up->port.membase + offset);
58 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
59 int offset, unsigned int value)
61 writel(value, up->port.membase + offset);
64 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
71 t = ar933x_uart_read(up, offset);
74 ar933x_uart_write(up, offset, t);
77 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
81 ar933x_uart_rmw(up, offset, 0, val);
84 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
88 ar933x_uart_rmw(up, offset, val, 0);
91 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
93 up->ier |= AR933X_UART_INT_TX_EMPTY;
94 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
97 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
99 up->ier &= ~AR933X_UART_INT_TX_EMPTY;
100 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
103 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
107 rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
108 rdata |= AR933X_UART_DATA_TX_CSR;
109 ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
112 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
114 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
118 spin_lock_irqsave(&up->port.lock, flags);
119 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
120 spin_unlock_irqrestore(&up->port.lock, flags);
122 return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
125 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
130 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
134 static void ar933x_uart_start_tx(struct uart_port *port)
136 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
138 ar933x_uart_start_tx_interrupt(up);
141 static void ar933x_uart_stop_tx(struct uart_port *port)
143 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
145 ar933x_uart_stop_tx_interrupt(up);
148 static void ar933x_uart_stop_rx(struct uart_port *port)
150 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
152 up->ier &= ~AR933X_UART_INT_RX_VALID;
153 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
156 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
158 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
161 spin_lock_irqsave(&up->port.lock, flags);
162 if (break_state == -1)
163 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
164 AR933X_UART_CS_TX_BREAK);
166 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
167 AR933X_UART_CS_TX_BREAK);
168 spin_unlock_irqrestore(&up->port.lock, flags);
171 static void ar933x_uart_enable_ms(struct uart_port *port)
176 * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
178 static unsigned long ar933x_uart_get_baud(unsigned int clk,
185 div = (2 << 16) * (scale + 1);
194 static void ar933x_uart_get_scale_step(unsigned int clk,
206 for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
210 tstep = baud * (tscale + 1);
214 if (tstep > AR933X_UART_MAX_STEP)
217 diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
218 if (diff < min_diff) {
226 static void ar933x_uart_set_termios(struct uart_port *port,
227 struct ktermios *new,
228 struct ktermios *old)
230 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
233 unsigned int baud, scale, step;
235 /* Only CS8 is supported */
236 new->c_cflag &= ~CSIZE;
239 /* Only one stop bit is supported */
240 new->c_cflag &= ~CSTOPB;
243 if (new->c_cflag & PARENB) {
244 if (!(new->c_cflag & PARODD))
245 cs |= AR933X_UART_CS_PARITY_EVEN;
247 cs |= AR933X_UART_CS_PARITY_ODD;
249 cs |= AR933X_UART_CS_PARITY_NONE;
252 /* Mark/space parity is not supported */
253 new->c_cflag &= ~CMSPAR;
255 baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
256 ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
259 * Ok, we're now changing the port state. Do it with
260 * interrupts disabled.
262 spin_lock_irqsave(&up->port.lock, flags);
264 /* disable the UART */
265 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
266 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
268 /* Update the per-port timeout. */
269 uart_update_timeout(port, new->c_cflag, baud);
271 up->port.ignore_status_mask = 0;
273 /* ignore all characters if CREAD is not set */
274 if ((new->c_cflag & CREAD) == 0)
275 up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
277 ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
278 scale << AR933X_UART_CLOCK_SCALE_S | step);
280 /* setup configuration register */
281 ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
283 /* enable host interrupt */
284 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
285 AR933X_UART_CS_HOST_INT_EN);
287 /* reenable the UART */
288 ar933x_uart_rmw(up, AR933X_UART_CS_REG,
289 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
290 AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
292 spin_unlock_irqrestore(&up->port.lock, flags);
294 if (tty_termios_baud_rate(new))
295 tty_termios_encode_baud_rate(new, baud, baud);
298 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
300 struct tty_struct *tty;
303 tty = tty_port_tty_get(&up->port.state->port);
308 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
309 if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
312 /* remove the character from the FIFO */
313 ar933x_uart_write(up, AR933X_UART_DATA_REG,
314 AR933X_UART_DATA_RX_CSR);
317 /* discard the data if no tty available */
321 up->port.icount.rx++;
322 ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
324 if (uart_handle_sysrq_char(&up->port, ch))
327 if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
328 tty_insert_flip_char(tty, ch, TTY_NORMAL);
329 } while (max_count-- > 0);
332 tty_flip_buffer_push(tty);
337 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
339 struct circ_buf *xmit = &up->port.state->xmit;
342 if (uart_tx_stopped(&up->port))
345 count = up->port.fifosize;
349 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
350 if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
353 if (up->port.x_char) {
354 ar933x_uart_putc(up, up->port.x_char);
355 up->port.icount.tx++;
360 if (uart_circ_empty(xmit))
363 ar933x_uart_putc(up, xmit->buf[xmit->tail]);
365 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
366 up->port.icount.tx++;
367 } while (--count > 0);
369 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
370 uart_write_wakeup(&up->port);
372 if (!uart_circ_empty(xmit))
373 ar933x_uart_start_tx_interrupt(up);
376 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
378 struct ar933x_uart_port *up = dev_id;
381 status = ar933x_uart_read(up, AR933X_UART_CS_REG);
382 if ((status & AR933X_UART_CS_HOST_INT) == 0)
385 spin_lock(&up->port.lock);
387 status = ar933x_uart_read(up, AR933X_UART_INT_REG);
388 status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
390 if (status & AR933X_UART_INT_RX_VALID) {
391 ar933x_uart_write(up, AR933X_UART_INT_REG,
392 AR933X_UART_INT_RX_VALID);
393 ar933x_uart_rx_chars(up);
396 if (status & AR933X_UART_INT_TX_EMPTY) {
397 ar933x_uart_write(up, AR933X_UART_INT_REG,
398 AR933X_UART_INT_TX_EMPTY);
399 ar933x_uart_stop_tx_interrupt(up);
400 ar933x_uart_tx_chars(up);
403 spin_unlock(&up->port.lock);
408 static int ar933x_uart_startup(struct uart_port *port)
410 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
414 ret = request_irq(up->port.irq, ar933x_uart_interrupt,
415 up->port.irqflags, dev_name(up->port.dev), up);
419 spin_lock_irqsave(&up->port.lock, flags);
421 /* Enable HOST interrupts */
422 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
423 AR933X_UART_CS_HOST_INT_EN);
425 /* Enable RX interrupts */
426 up->ier = AR933X_UART_INT_RX_VALID;
427 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
429 spin_unlock_irqrestore(&up->port.lock, flags);
434 static void ar933x_uart_shutdown(struct uart_port *port)
436 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
438 /* Disable all interrupts */
440 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
442 /* Disable break condition */
443 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
444 AR933X_UART_CS_TX_BREAK);
446 free_irq(up->port.irq, up);
449 static const char *ar933x_uart_type(struct uart_port *port)
451 return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
454 static void ar933x_uart_release_port(struct uart_port *port)
456 /* Nothing to release ... */
459 static int ar933x_uart_request_port(struct uart_port *port)
461 /* UARTs always present */
465 static void ar933x_uart_config_port(struct uart_port *port, int flags)
467 if (flags & UART_CONFIG_TYPE)
468 port->type = PORT_AR933X;
471 static int ar933x_uart_verify_port(struct uart_port *port,
472 struct serial_struct *ser)
474 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
476 if (ser->type != PORT_UNKNOWN &&
477 ser->type != PORT_AR933X)
480 if (ser->irq < 0 || ser->irq >= NR_IRQS)
483 if (ser->baud_base < up->min_baud ||
484 ser->baud_base > up->max_baud)
490 static struct uart_ops ar933x_uart_ops = {
491 .tx_empty = ar933x_uart_tx_empty,
492 .set_mctrl = ar933x_uart_set_mctrl,
493 .get_mctrl = ar933x_uart_get_mctrl,
494 .stop_tx = ar933x_uart_stop_tx,
495 .start_tx = ar933x_uart_start_tx,
496 .stop_rx = ar933x_uart_stop_rx,
497 .enable_ms = ar933x_uart_enable_ms,
498 .break_ctl = ar933x_uart_break_ctl,
499 .startup = ar933x_uart_startup,
500 .shutdown = ar933x_uart_shutdown,
501 .set_termios = ar933x_uart_set_termios,
502 .type = ar933x_uart_type,
503 .release_port = ar933x_uart_release_port,
504 .request_port = ar933x_uart_request_port,
505 .config_port = ar933x_uart_config_port,
506 .verify_port = ar933x_uart_verify_port,
509 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
511 static struct ar933x_uart_port *
512 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
514 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
517 unsigned int timeout = 60000;
519 /* Wait up to 60ms for the character(s) to be sent. */
521 status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
525 } while ((status & AR933X_UART_DATA_TX_CSR) == 0);
528 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
530 struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
532 ar933x_uart_wait_xmitr(up);
533 ar933x_uart_putc(up, ch);
536 static void ar933x_uart_console_write(struct console *co, const char *s,
539 struct ar933x_uart_port *up = ar933x_console_ports[co->index];
544 local_irq_save(flags);
548 else if (oops_in_progress)
549 locked = spin_trylock(&up->port.lock);
551 spin_lock(&up->port.lock);
554 * First save the IER then disable the interrupts
556 int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
557 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
559 uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
562 * Finally, wait for transmitter to become empty
563 * and restore the IER
565 ar933x_uart_wait_xmitr(up);
566 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
568 ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
571 spin_unlock(&up->port.lock);
573 local_irq_restore(flags);
576 static int ar933x_uart_console_setup(struct console *co, char *options)
578 struct ar933x_uart_port *up;
584 if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
587 up = ar933x_console_ports[co->index];
592 uart_parse_options(options, &baud, &parity, &bits, &flow);
594 return uart_set_options(&up->port, co, baud, parity, bits, flow);
597 static struct console ar933x_uart_console = {
599 .write = ar933x_uart_console_write,
600 .device = uart_console_device,
601 .setup = ar933x_uart_console_setup,
602 .flags = CON_PRINTBUFFER,
604 .data = &ar933x_uart_driver,
607 static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
609 ar933x_console_ports[up->port.line] = up;
612 #define AR933X_SERIAL_CONSOLE (&ar933x_uart_console)
616 static inline void ar933x_uart_add_console_port(struct ar933x_uart_port *up) {}
618 #define AR933X_SERIAL_CONSOLE NULL
620 #endif /* CONFIG_SERIAL_AR933X_CONSOLE */
622 static struct uart_driver ar933x_uart_driver = {
623 .owner = THIS_MODULE,
624 .driver_name = DRIVER_NAME,
625 .dev_name = "ttyATH",
626 .nr = CONFIG_SERIAL_AR933X_NR_UARTS,
627 .cons = AR933X_SERIAL_CONSOLE,
630 static int ar933x_uart_probe(struct platform_device *pdev)
632 struct ar933x_uart_platform_data *pdata;
633 struct ar933x_uart_port *up;
634 struct uart_port *port;
635 struct resource *mem_res;
636 struct resource *irq_res;
641 pdata = pdev->dev.platform_data;
649 if (id > CONFIG_SERIAL_AR933X_NR_UARTS)
652 mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
654 dev_err(&pdev->dev, "no MEM resource\n");
658 irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
660 dev_err(&pdev->dev, "no IRQ resource\n");
664 up = kzalloc(sizeof(struct ar933x_uart_port), GFP_KERNEL);
669 port->mapbase = mem_res->start;
671 port->membase = ioremap(mem_res->start, AR933X_UART_REGS_SIZE);
672 if (!port->membase) {
678 port->irq = irq_res->start;
679 port->dev = &pdev->dev;
680 port->type = PORT_AR933X;
681 port->iotype = UPIO_MEM32;
682 port->uartclk = pdata->uartclk;
685 port->fifosize = AR933X_UART_FIFO_SIZE;
686 port->ops = &ar933x_uart_ops;
688 baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
689 up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
691 baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
692 up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
694 ar933x_uart_add_console_port(up);
696 ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
700 platform_set_drvdata(pdev, up);
704 iounmap(up->port.membase);
710 static int ar933x_uart_remove(struct platform_device *pdev)
712 struct ar933x_uart_port *up;
714 up = platform_get_drvdata(pdev);
715 platform_set_drvdata(pdev, NULL);
718 uart_remove_one_port(&ar933x_uart_driver, &up->port);
719 iounmap(up->port.membase);
726 static struct platform_driver ar933x_uart_platform_driver = {
727 .probe = ar933x_uart_probe,
728 .remove = ar933x_uart_remove,
731 .owner = THIS_MODULE,
735 static int __init ar933x_uart_init(void)
739 ar933x_uart_driver.nr = CONFIG_SERIAL_AR933X_NR_UARTS;
740 ret = uart_register_driver(&ar933x_uart_driver);
744 ret = platform_driver_register(&ar933x_uart_platform_driver);
746 goto err_unregister_uart_driver;
750 err_unregister_uart_driver:
751 uart_unregister_driver(&ar933x_uart_driver);
756 static void __exit ar933x_uart_exit(void)
758 platform_driver_unregister(&ar933x_uart_platform_driver);
759 uart_unregister_driver(&ar933x_uart_driver);
762 module_init(ar933x_uart_init);
763 module_exit(ar933x_uart_exit);
765 MODULE_DESCRIPTION("Atheros AR933X UART driver");
766 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
767 MODULE_LICENSE("GPL v2");
768 MODULE_ALIAS("platform:" DRIVER_NAME);