1 // SPDX-License-Identifier: GPL-2.0
3 * Atheros AR933X SoC built-in UART driver
5 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
7 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
10 #include <linux/module.h>
11 #include <linux/ioport.h>
12 #include <linux/init.h>
13 #include <linux/console.h>
14 #include <linux/sysrq.h>
15 #include <linux/delay.h>
16 #include <linux/platform_device.h>
18 #include <linux/of_platform.h>
19 #include <linux/tty.h>
20 #include <linux/tty_flip.h>
21 #include <linux/serial_core.h>
22 #include <linux/serial.h>
23 #include <linux/slab.h>
25 #include <linux/irq.h>
26 #include <linux/clk.h>
28 #include <asm/div64.h>
30 #include <asm/mach-ath79/ar933x_uart.h>
32 #define DRIVER_NAME "ar933x-uart"
34 #define AR933X_UART_MAX_SCALE 0xff
35 #define AR933X_UART_MAX_STEP 0xffff
37 #define AR933X_UART_MIN_BAUD 300
38 #define AR933X_UART_MAX_BAUD 3000000
40 #define AR933X_DUMMY_STATUS_RD 0x01
42 static struct uart_driver ar933x_uart_driver
;
44 struct ar933x_uart_port
{
45 struct uart_port port
;
46 unsigned int ier
; /* shadow Interrupt Enable Register */
47 unsigned int min_baud
;
48 unsigned int max_baud
;
52 static inline bool ar933x_uart_console_enabled(void)
54 return IS_ENABLED(CONFIG_SERIAL_AR933X_CONSOLE
);
57 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port
*up
,
60 return readl(up
->port
.membase
+ offset
);
63 static inline void ar933x_uart_write(struct ar933x_uart_port
*up
,
64 int offset
, unsigned int value
)
66 writel(value
, up
->port
.membase
+ offset
);
69 static inline void ar933x_uart_rmw(struct ar933x_uart_port
*up
,
76 t
= ar933x_uart_read(up
, offset
);
79 ar933x_uart_write(up
, offset
, t
);
82 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port
*up
,
86 ar933x_uart_rmw(up
, offset
, 0, val
);
89 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port
*up
,
93 ar933x_uart_rmw(up
, offset
, val
, 0);
96 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port
*up
)
98 up
->ier
|= AR933X_UART_INT_TX_EMPTY
;
99 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, up
->ier
);
102 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port
*up
)
104 up
->ier
&= ~AR933X_UART_INT_TX_EMPTY
;
105 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, up
->ier
);
108 static inline void ar933x_uart_putc(struct ar933x_uart_port
*up
, int ch
)
112 rdata
= ch
& AR933X_UART_DATA_TX_RX_MASK
;
113 rdata
|= AR933X_UART_DATA_TX_CSR
;
114 ar933x_uart_write(up
, AR933X_UART_DATA_REG
, rdata
);
117 static unsigned int ar933x_uart_tx_empty(struct uart_port
*port
)
119 struct ar933x_uart_port
*up
=
120 container_of(port
, struct ar933x_uart_port
, port
);
124 spin_lock_irqsave(&up
->port
.lock
, flags
);
125 rdata
= ar933x_uart_read(up
, AR933X_UART_DATA_REG
);
126 spin_unlock_irqrestore(&up
->port
.lock
, flags
);
128 return (rdata
& AR933X_UART_DATA_TX_CSR
) ? 0 : TIOCSER_TEMT
;
131 static unsigned int ar933x_uart_get_mctrl(struct uart_port
*port
)
136 static void ar933x_uart_set_mctrl(struct uart_port
*port
, unsigned int mctrl
)
140 static void ar933x_uart_start_tx(struct uart_port
*port
)
142 struct ar933x_uart_port
*up
=
143 container_of(port
, struct ar933x_uart_port
, port
);
145 ar933x_uart_start_tx_interrupt(up
);
148 static void ar933x_uart_stop_tx(struct uart_port
*port
)
150 struct ar933x_uart_port
*up
=
151 container_of(port
, struct ar933x_uart_port
, port
);
153 ar933x_uart_stop_tx_interrupt(up
);
156 static void ar933x_uart_stop_rx(struct uart_port
*port
)
158 struct ar933x_uart_port
*up
=
159 container_of(port
, struct ar933x_uart_port
, port
);
161 up
->ier
&= ~AR933X_UART_INT_RX_VALID
;
162 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, up
->ier
);
165 static void ar933x_uart_break_ctl(struct uart_port
*port
, int break_state
)
167 struct ar933x_uart_port
*up
=
168 container_of(port
, struct ar933x_uart_port
, port
);
171 spin_lock_irqsave(&up
->port
.lock
, flags
);
172 if (break_state
== -1)
173 ar933x_uart_rmw_set(up
, AR933X_UART_CS_REG
,
174 AR933X_UART_CS_TX_BREAK
);
176 ar933x_uart_rmw_clear(up
, AR933X_UART_CS_REG
,
177 AR933X_UART_CS_TX_BREAK
);
178 spin_unlock_irqrestore(&up
->port
.lock
, flags
);
182 * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
184 static unsigned long ar933x_uart_get_baud(unsigned int clk
,
191 div
= (2 << 16) * (scale
+ 1);
200 static void ar933x_uart_get_scale_step(unsigned int clk
,
212 for (tscale
= 0; tscale
< AR933X_UART_MAX_SCALE
; tscale
++) {
216 tstep
= baud
* (tscale
+ 1);
220 if (tstep
> AR933X_UART_MAX_STEP
)
223 diff
= abs(ar933x_uart_get_baud(clk
, tscale
, tstep
) - baud
);
224 if (diff
< min_diff
) {
232 static void ar933x_uart_set_termios(struct uart_port
*port
,
233 struct ktermios
*new,
234 struct ktermios
*old
)
236 struct ar933x_uart_port
*up
=
237 container_of(port
, struct ar933x_uart_port
, port
);
240 unsigned int baud
, scale
, step
;
242 /* Only CS8 is supported */
243 new->c_cflag
&= ~CSIZE
;
246 /* Only one stop bit is supported */
247 new->c_cflag
&= ~CSTOPB
;
250 if (new->c_cflag
& PARENB
) {
251 if (!(new->c_cflag
& PARODD
))
252 cs
|= AR933X_UART_CS_PARITY_EVEN
;
254 cs
|= AR933X_UART_CS_PARITY_ODD
;
256 cs
|= AR933X_UART_CS_PARITY_NONE
;
259 /* Mark/space parity is not supported */
260 new->c_cflag
&= ~CMSPAR
;
262 baud
= uart_get_baud_rate(port
, new, old
, up
->min_baud
, up
->max_baud
);
263 ar933x_uart_get_scale_step(port
->uartclk
, baud
, &scale
, &step
);
266 * Ok, we're now changing the port state. Do it with
267 * interrupts disabled.
269 spin_lock_irqsave(&up
->port
.lock
, flags
);
271 /* disable the UART */
272 ar933x_uart_rmw_clear(up
, AR933X_UART_CS_REG
,
273 AR933X_UART_CS_IF_MODE_M
<< AR933X_UART_CS_IF_MODE_S
);
275 /* Update the per-port timeout. */
276 uart_update_timeout(port
, new->c_cflag
, baud
);
278 up
->port
.ignore_status_mask
= 0;
280 /* ignore all characters if CREAD is not set */
281 if ((new->c_cflag
& CREAD
) == 0)
282 up
->port
.ignore_status_mask
|= AR933X_DUMMY_STATUS_RD
;
284 ar933x_uart_write(up
, AR933X_UART_CLOCK_REG
,
285 scale
<< AR933X_UART_CLOCK_SCALE_S
| step
);
287 /* setup configuration register */
288 ar933x_uart_rmw(up
, AR933X_UART_CS_REG
, AR933X_UART_CS_PARITY_M
, cs
);
290 /* enable host interrupt */
291 ar933x_uart_rmw_set(up
, AR933X_UART_CS_REG
,
292 AR933X_UART_CS_HOST_INT_EN
);
294 /* reenable the UART */
295 ar933x_uart_rmw(up
, AR933X_UART_CS_REG
,
296 AR933X_UART_CS_IF_MODE_M
<< AR933X_UART_CS_IF_MODE_S
,
297 AR933X_UART_CS_IF_MODE_DCE
<< AR933X_UART_CS_IF_MODE_S
);
299 spin_unlock_irqrestore(&up
->port
.lock
, flags
);
301 if (tty_termios_baud_rate(new))
302 tty_termios_encode_baud_rate(new, baud
, baud
);
305 static void ar933x_uart_rx_chars(struct ar933x_uart_port
*up
)
307 struct tty_port
*port
= &up
->port
.state
->port
;
314 rdata
= ar933x_uart_read(up
, AR933X_UART_DATA_REG
);
315 if ((rdata
& AR933X_UART_DATA_RX_CSR
) == 0)
318 /* remove the character from the FIFO */
319 ar933x_uart_write(up
, AR933X_UART_DATA_REG
,
320 AR933X_UART_DATA_RX_CSR
);
322 up
->port
.icount
.rx
++;
323 ch
= rdata
& AR933X_UART_DATA_TX_RX_MASK
;
325 if (uart_handle_sysrq_char(&up
->port
, ch
))
328 if ((up
->port
.ignore_status_mask
& AR933X_DUMMY_STATUS_RD
) == 0)
329 tty_insert_flip_char(port
, ch
, TTY_NORMAL
);
330 } while (max_count
-- > 0);
332 spin_unlock(&up
->port
.lock
);
333 tty_flip_buffer_push(port
);
334 spin_lock(&up
->port
.lock
);
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
=
411 container_of(port
, struct ar933x_uart_port
, port
);
415 ret
= request_irq(up
->port
.irq
, ar933x_uart_interrupt
,
416 up
->port
.irqflags
, dev_name(up
->port
.dev
), up
);
420 spin_lock_irqsave(&up
->port
.lock
, flags
);
422 /* Enable HOST interrupts */
423 ar933x_uart_rmw_set(up
, AR933X_UART_CS_REG
,
424 AR933X_UART_CS_HOST_INT_EN
);
426 /* Enable RX interrupts */
427 up
->ier
= AR933X_UART_INT_RX_VALID
;
428 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, up
->ier
);
430 spin_unlock_irqrestore(&up
->port
.lock
, flags
);
435 static void ar933x_uart_shutdown(struct uart_port
*port
)
437 struct ar933x_uart_port
*up
=
438 container_of(port
, struct ar933x_uart_port
, port
);
440 /* Disable all interrupts */
442 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, up
->ier
);
444 /* Disable break condition */
445 ar933x_uart_rmw_clear(up
, AR933X_UART_CS_REG
,
446 AR933X_UART_CS_TX_BREAK
);
448 free_irq(up
->port
.irq
, up
);
451 static const char *ar933x_uart_type(struct uart_port
*port
)
453 return (port
->type
== PORT_AR933X
) ? "AR933X UART" : NULL
;
456 static void ar933x_uart_release_port(struct uart_port
*port
)
458 /* Nothing to release ... */
461 static int ar933x_uart_request_port(struct uart_port
*port
)
463 /* UARTs always present */
467 static void ar933x_uart_config_port(struct uart_port
*port
, int flags
)
469 if (flags
& UART_CONFIG_TYPE
)
470 port
->type
= PORT_AR933X
;
473 static int ar933x_uart_verify_port(struct uart_port
*port
,
474 struct serial_struct
*ser
)
476 struct ar933x_uart_port
*up
=
477 container_of(port
, struct ar933x_uart_port
, port
);
479 if (ser
->type
!= PORT_UNKNOWN
&&
480 ser
->type
!= PORT_AR933X
)
483 if (ser
->irq
< 0 || ser
->irq
>= NR_IRQS
)
486 if (ser
->baud_base
< up
->min_baud
||
487 ser
->baud_base
> up
->max_baud
)
493 static const struct uart_ops ar933x_uart_ops
= {
494 .tx_empty
= ar933x_uart_tx_empty
,
495 .set_mctrl
= ar933x_uart_set_mctrl
,
496 .get_mctrl
= ar933x_uart_get_mctrl
,
497 .stop_tx
= ar933x_uart_stop_tx
,
498 .start_tx
= ar933x_uart_start_tx
,
499 .stop_rx
= ar933x_uart_stop_rx
,
500 .break_ctl
= ar933x_uart_break_ctl
,
501 .startup
= ar933x_uart_startup
,
502 .shutdown
= ar933x_uart_shutdown
,
503 .set_termios
= ar933x_uart_set_termios
,
504 .type
= ar933x_uart_type
,
505 .release_port
= ar933x_uart_release_port
,
506 .request_port
= ar933x_uart_request_port
,
507 .config_port
= ar933x_uart_config_port
,
508 .verify_port
= ar933x_uart_verify_port
,
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
=
531 container_of(port
, struct ar933x_uart_port
, port
);
533 ar933x_uart_wait_xmitr(up
);
534 ar933x_uart_putc(up
, ch
);
537 static void ar933x_uart_console_write(struct console
*co
, const char *s
,
540 struct ar933x_uart_port
*up
= ar933x_console_ports
[co
->index
];
545 local_irq_save(flags
);
549 else if (oops_in_progress
)
550 locked
= spin_trylock(&up
->port
.lock
);
552 spin_lock(&up
->port
.lock
);
555 * First save the IER then disable the interrupts
557 int_en
= ar933x_uart_read(up
, AR933X_UART_INT_EN_REG
);
558 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, 0);
560 uart_console_write(&up
->port
, s
, count
, ar933x_uart_console_putchar
);
563 * Finally, wait for transmitter to become empty
564 * and restore the IER
566 ar933x_uart_wait_xmitr(up
);
567 ar933x_uart_write(up
, AR933X_UART_INT_EN_REG
, int_en
);
569 ar933x_uart_write(up
, AR933X_UART_INT_REG
, AR933X_UART_INT_ALLINTS
);
572 spin_unlock(&up
->port
.lock
);
574 local_irq_restore(flags
);
577 static int ar933x_uart_console_setup(struct console
*co
, char *options
)
579 struct ar933x_uart_port
*up
;
585 if (co
->index
< 0 || co
->index
>= CONFIG_SERIAL_AR933X_NR_UARTS
)
588 up
= ar933x_console_ports
[co
->index
];
593 uart_parse_options(options
, &baud
, &parity
, &bits
, &flow
);
595 return uart_set_options(&up
->port
, co
, baud
, parity
, bits
, flow
);
598 static struct console ar933x_uart_console
= {
600 .write
= ar933x_uart_console_write
,
601 .device
= uart_console_device
,
602 .setup
= ar933x_uart_console_setup
,
603 .flags
= CON_PRINTBUFFER
,
605 .data
= &ar933x_uart_driver
,
608 static void ar933x_uart_add_console_port(struct ar933x_uart_port
*up
)
610 if (!ar933x_uart_console_enabled())
613 ar933x_console_ports
[up
->port
.line
] = up
;
616 static struct uart_driver ar933x_uart_driver
= {
617 .owner
= THIS_MODULE
,
618 .driver_name
= DRIVER_NAME
,
619 .dev_name
= "ttyATH",
620 .nr
= CONFIG_SERIAL_AR933X_NR_UARTS
,
621 .cons
= NULL
, /* filled in runtime */
624 static int ar933x_uart_probe(struct platform_device
*pdev
)
626 struct ar933x_uart_port
*up
;
627 struct uart_port
*port
;
628 struct resource
*mem_res
;
629 struct resource
*irq_res
;
630 struct device_node
*np
;
635 np
= pdev
->dev
.of_node
;
636 if (IS_ENABLED(CONFIG_OF
) && np
) {
637 id
= of_alias_get_id(np
, "serial");
639 dev_err(&pdev
->dev
, "unable to get alias id, err=%d\n",
649 if (id
>= CONFIG_SERIAL_AR933X_NR_UARTS
)
652 irq_res
= platform_get_resource(pdev
, IORESOURCE_IRQ
, 0);
654 dev_err(&pdev
->dev
, "no IRQ resource\n");
658 up
= devm_kzalloc(&pdev
->dev
, sizeof(struct ar933x_uart_port
),
663 up
->clk
= devm_clk_get(&pdev
->dev
, "uart");
664 if (IS_ERR(up
->clk
)) {
665 dev_err(&pdev
->dev
, "unable to get UART clock\n");
666 return PTR_ERR(up
->clk
);
671 mem_res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
672 port
->membase
= devm_ioremap_resource(&pdev
->dev
, mem_res
);
673 if (IS_ERR(port
->membase
))
674 return PTR_ERR(port
->membase
);
676 ret
= clk_prepare_enable(up
->clk
);
680 port
->uartclk
= clk_get_rate(up
->clk
);
681 if (!port
->uartclk
) {
683 goto err_disable_clk
;
686 port
->mapbase
= mem_res
->start
;
688 port
->irq
= irq_res
->start
;
689 port
->dev
= &pdev
->dev
;
690 port
->type
= PORT_AR933X
;
691 port
->iotype
= UPIO_MEM32
;
694 port
->fifosize
= AR933X_UART_FIFO_SIZE
;
695 port
->ops
= &ar933x_uart_ops
;
697 baud
= ar933x_uart_get_baud(port
->uartclk
, AR933X_UART_MAX_SCALE
, 1);
698 up
->min_baud
= max_t(unsigned int, baud
, AR933X_UART_MIN_BAUD
);
700 baud
= ar933x_uart_get_baud(port
->uartclk
, 0, AR933X_UART_MAX_STEP
);
701 up
->max_baud
= min_t(unsigned int, baud
, AR933X_UART_MAX_BAUD
);
703 ar933x_uart_add_console_port(up
);
705 ret
= uart_add_one_port(&ar933x_uart_driver
, &up
->port
);
707 goto err_disable_clk
;
709 platform_set_drvdata(pdev
, up
);
713 clk_disable_unprepare(up
->clk
);
717 static int ar933x_uart_remove(struct platform_device
*pdev
)
719 struct ar933x_uart_port
*up
;
721 up
= platform_get_drvdata(pdev
);
724 uart_remove_one_port(&ar933x_uart_driver
, &up
->port
);
725 clk_disable_unprepare(up
->clk
);
732 static const struct of_device_id ar933x_uart_of_ids
[] = {
733 { .compatible
= "qca,ar9330-uart" },
736 MODULE_DEVICE_TABLE(of
, ar933x_uart_of_ids
);
739 static struct platform_driver ar933x_uart_platform_driver
= {
740 .probe
= ar933x_uart_probe
,
741 .remove
= ar933x_uart_remove
,
744 .of_match_table
= of_match_ptr(ar933x_uart_of_ids
),
748 static int __init
ar933x_uart_init(void)
752 if (ar933x_uart_console_enabled())
753 ar933x_uart_driver
.cons
= &ar933x_uart_console
;
755 ret
= uart_register_driver(&ar933x_uart_driver
);
759 ret
= platform_driver_register(&ar933x_uart_platform_driver
);
761 goto err_unregister_uart_driver
;
765 err_unregister_uart_driver
:
766 uart_unregister_driver(&ar933x_uart_driver
);
771 static void __exit
ar933x_uart_exit(void)
773 platform_driver_unregister(&ar933x_uart_platform_driver
);
774 uart_unregister_driver(&ar933x_uart_driver
);
777 module_init(ar933x_uart_init
);
778 module_exit(ar933x_uart_exit
);
780 MODULE_DESCRIPTION("Atheros AR933X UART driver");
781 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
782 MODULE_LICENSE("GPL v2");
783 MODULE_ALIAS("platform:" DRIVER_NAME
);