Root/target/linux/ar71xx/files/drivers/tty/serial/ar933x_uart.c

1/*
2 * Atheros AR933X SoC built-in UART driver
3 *
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5 *
6 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
7 *
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.
11 */
12
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>
25#include <linux/io.h>
26#include <linux/irq.h>
27
28#include <asm/mach-ar71xx/ar933x_uart.h>
29#include <asm/mach-ar71xx/ar933x_uart_platform.h>
30
31#define DRIVER_NAME "ar933x-uart"
32
33#define AR933X_DUMMY_STATUS_RD 0x01
34
35static struct uart_driver ar933x_uart_driver;
36
37struct ar933x_uart_port {
38    struct uart_port port;
39    unsigned int ier; /* shadow Interrupt Enable Register */
40};
41
42static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
43                        int offset)
44{
45    return readl(up->port.membase + offset);
46}
47
48static inline void ar933x_uart_write(struct ar933x_uart_port *up,
49                     int offset, unsigned int value)
50{
51    writel(value, up->port.membase + offset);
52}
53
54static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
55                  unsigned int offset,
56                  unsigned int mask,
57                  unsigned int val)
58{
59    unsigned int t;
60
61    t = ar933x_uart_read(up, offset);
62    t &= ~mask;
63    t |= val;
64    ar933x_uart_write(up, offset, t);
65}
66
67static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
68                       unsigned int offset,
69                       unsigned int val)
70{
71    ar933x_uart_rmw(up, offset, 0, val);
72}
73
74static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
75                     unsigned int offset,
76                     unsigned int val)
77{
78    ar933x_uart_rmw(up, offset, val, 0);
79}
80
81static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
82{
83    up->ier |= AR933X_UART_INT_TX_EMPTY;
84    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
85}
86
87static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
88{
89    up->ier &= ~AR933X_UART_INT_TX_EMPTY;
90    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
91}
92
93static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
94{
95    unsigned int rdata;
96
97    rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
98    rdata |= AR933X_UART_DATA_TX_CSR;
99    ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
100}
101
102static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
103{
104    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
105    unsigned long flags;
106    unsigned int rdata;
107
108    spin_lock_irqsave(&up->port.lock, flags);
109    rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
110    spin_unlock_irqrestore(&up->port.lock, flags);
111
112    return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
113}
114
115static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
116{
117    return TIOCM_CAR;
118}
119
120static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
121{
122}
123
124static void ar933x_uart_start_tx(struct uart_port *port)
125{
126    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
127
128    ar933x_uart_start_tx_interrupt(up);
129}
130
131static void ar933x_uart_stop_tx(struct uart_port *port)
132{
133    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
134
135    ar933x_uart_stop_tx_interrupt(up);
136}
137
138static void ar933x_uart_stop_rx(struct uart_port *port)
139{
140    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
141
142    up->ier &= ~AR933X_UART_INT_RX_VALID;
143    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
144}
145
146static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
147{
148    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
149    unsigned long flags;
150
151    spin_lock_irqsave(&up->port.lock, flags);
152    if (break_state == -1)
153        ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
154                    AR933X_UART_CS_TX_BREAK);
155    else
156        ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
157                      AR933X_UART_CS_TX_BREAK);
158    spin_unlock_irqrestore(&up->port.lock, flags);
159}
160
161static void ar933x_uart_enable_ms(struct uart_port *port)
162{
163}
164
165static void ar933x_uart_set_termios(struct uart_port *port,
166                    struct ktermios *new,
167                    struct ktermios *old)
168{
169    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
170    unsigned int cs;
171    unsigned long flags;
172    unsigned int baud, scale;
173
174    /* Only CS8 is supported */
175    new->c_cflag &= ~CSIZE;
176    new->c_cflag |= CS8;
177
178    /* Only one stop bit is supported */
179    new->c_cflag &= ~CSTOPB;
180
181    cs = 0;
182    if (new->c_cflag & PARENB) {
183        if (!(new->c_cflag & PARODD))
184            cs |= AR933X_UART_CS_PARITY_EVEN;
185        else
186            cs |= AR933X_UART_CS_PARITY_ODD;
187    } else {
188        cs |= AR933X_UART_CS_PARITY_NONE;
189    }
190
191    /* Mark/space parity is not supported */
192    new->c_cflag &= ~CMSPAR;
193
194    baud = uart_get_baud_rate(port, new, old, 0, port->uartclk / 16);
195    scale = (port->uartclk / (16 * baud)) - 1;
196
197    /*
198     * Ok, we're now changing the port state. Do it with
199     * interrupts disabled.
200     */
201    spin_lock_irqsave(&up->port.lock, flags);
202
203    /* Update the per-port timeout. */
204    uart_update_timeout(port, new->c_cflag, baud);
205
206    up->port.ignore_status_mask = 0;
207
208    /* ignore all characters if CREAD is not set */
209    if ((new->c_cflag & CREAD) == 0)
210        up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
211
212    ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
213              scale << AR933X_UART_CLOCK_SCALE_S | 8192);
214
215    /* setup configuration register */
216    ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
217
218    /* enable host interrupt */
219    ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
220                AR933X_UART_CS_HOST_INT_EN);
221
222    spin_unlock_irqrestore(&up->port.lock, flags);
223
224    if (tty_termios_baud_rate(new))
225        tty_termios_encode_baud_rate(new, baud, baud);
226}
227
228static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
229{
230    struct tty_struct *tty;
231    int max_count = 256;
232
233    tty = tty_port_tty_get(&up->port.state->port);
234    do {
235        unsigned int rdata;
236        unsigned char ch;
237
238        rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
239        if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
240            break;
241
242        /* remove the character from the FIFO */
243        ar933x_uart_write(up, AR933X_UART_DATA_REG,
244                  AR933X_UART_DATA_RX_CSR);
245
246        if (!tty) {
247            /* discard the data if no tty available */
248            continue;
249        }
250
251        up->port.icount.rx++;
252        ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
253
254        if (uart_handle_sysrq_char(&up->port, ch))
255            continue;
256
257        if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
258            tty_insert_flip_char(tty, ch, TTY_NORMAL);
259    } while (max_count-- > 0);
260
261    if (tty) {
262        tty_flip_buffer_push(tty);
263        tty_kref_put(tty);
264    }
265}
266
267static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
268{
269    struct circ_buf *xmit = &up->port.state->xmit;
270    int count;
271
272    if (uart_tx_stopped(&up->port))
273        return;
274
275    count = up->port.fifosize;
276    do {
277        unsigned int rdata;
278
279        rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
280        if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
281            break;
282
283        if (up->port.x_char) {
284            ar933x_uart_putc(up, up->port.x_char);
285            up->port.icount.tx++;
286            up->port.x_char = 0;
287            continue;
288        }
289
290        if (uart_circ_empty(xmit))
291            break;
292
293        ar933x_uart_putc(up, xmit->buf[xmit->tail]);
294
295        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
296        up->port.icount.tx++;
297    } while (--count > 0);
298
299    if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
300        uart_write_wakeup(&up->port);
301
302    if (!uart_circ_empty(xmit))
303        ar933x_uart_start_tx_interrupt(up);
304}
305
306static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
307{
308    struct ar933x_uart_port *up = dev_id;
309    unsigned int status;
310
311    status = ar933x_uart_read(up, AR933X_UART_CS_REG);
312    if ((status & AR933X_UART_CS_HOST_INT) == 0)
313        return IRQ_NONE;
314
315    spin_lock(&up->port.lock);
316
317    status = ar933x_uart_read(up, AR933X_UART_INT_REG);
318    status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
319
320    if (status & AR933X_UART_INT_RX_VALID) {
321        ar933x_uart_write(up, AR933X_UART_INT_REG,
322                  AR933X_UART_INT_RX_VALID);
323        ar933x_uart_rx_chars(up);
324    }
325
326    if (status & AR933X_UART_INT_TX_EMPTY) {
327        ar933x_uart_write(up, AR933X_UART_INT_REG,
328                  AR933X_UART_INT_TX_EMPTY);
329        ar933x_uart_stop_tx_interrupt(up);
330        ar933x_uart_tx_chars(up);
331    }
332
333    spin_unlock(&up->port.lock);
334
335    return IRQ_HANDLED;
336}
337
338static int ar933x_uart_startup(struct uart_port *port)
339{
340    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
341    unsigned long flags;
342    int ret;
343
344    ret = request_irq(up->port.irq, ar933x_uart_interrupt,
345              up->port.irqflags, dev_name(up->port.dev), up);
346    if (ret)
347        return ret;
348
349    spin_lock_irqsave(&up->port.lock, flags);
350
351    /* Enable HOST interrupts */
352    ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
353                AR933X_UART_CS_HOST_INT_EN);
354
355    /* Enable RX interrupts */
356    up->ier = AR933X_UART_INT_RX_VALID;
357    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
358
359    spin_unlock_irqrestore(&up->port.lock, flags);
360
361    return 0;
362}
363
364static void ar933x_uart_shutdown(struct uart_port *port)
365{
366    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
367
368    /* Disable all interrupts */
369    up->ier = 0;
370    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
371
372    /* Disable break condition */
373    ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
374                  AR933X_UART_CS_TX_BREAK);
375
376    free_irq(up->port.irq, up);
377}
378
379static const char *ar933x_uart_type(struct uart_port *port)
380{
381    return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
382}
383
384static void ar933x_uart_release_port(struct uart_port *port)
385{
386    /* Nothing to release ... */
387}
388
389static int ar933x_uart_request_port(struct uart_port *port)
390{
391    /* UARTs always present */
392    return 0;
393}
394
395static void ar933x_uart_config_port(struct uart_port *port, int flags)
396{
397    if (flags & UART_CONFIG_TYPE)
398        port->type = PORT_AR933X;
399}
400
401static int ar933x_uart_verify_port(struct uart_port *port,
402                   struct serial_struct *ser)
403{
404    if (ser->type != PORT_UNKNOWN &&
405        ser->type != PORT_AR933X)
406        return -EINVAL;
407
408    if (ser->irq < 0 || ser->irq >= NR_IRQS)
409        return -EINVAL;
410
411    if (ser->baud_base < 28800)
412        return -EINVAL;
413
414    return 0;
415}
416
417static struct uart_ops ar933x_uart_ops = {
418    .tx_empty = ar933x_uart_tx_empty,
419    .set_mctrl = ar933x_uart_set_mctrl,
420    .get_mctrl = ar933x_uart_get_mctrl,
421    .stop_tx = ar933x_uart_stop_tx,
422    .start_tx = ar933x_uart_start_tx,
423    .stop_rx = ar933x_uart_stop_rx,
424    .enable_ms = ar933x_uart_enable_ms,
425    .break_ctl = ar933x_uart_break_ctl,
426    .startup = ar933x_uart_startup,
427    .shutdown = ar933x_uart_shutdown,
428    .set_termios = ar933x_uart_set_termios,
429    .type = ar933x_uart_type,
430    .release_port = ar933x_uart_release_port,
431    .request_port = ar933x_uart_request_port,
432    .config_port = ar933x_uart_config_port,
433    .verify_port = ar933x_uart_verify_port,
434};
435
436#ifdef CONFIG_SERIAL_AR933X_CONSOLE
437
438static struct ar933x_uart_port *
439ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
440
441static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
442{
443    unsigned int status;
444    unsigned int timeout = 60000;
445
446    /* Wait up to 60ms for the character(s) to be sent. */
447    do {
448        status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
449        if (--timeout == 0)
450            break;
451        udelay(1);
452    } while ((status & AR933X_UART_DATA_TX_CSR) == 0);
453}
454
455static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
456{
457    struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
458
459    ar933x_uart_wait_xmitr(up);
460    ar933x_uart_putc(up, ch);
461}
462
463static void ar933x_uart_console_write(struct console *co, const char *s,
464                      unsigned int count)
465{
466    struct ar933x_uart_port *up = ar933x_console_ports[co->index];
467    unsigned long flags;
468    unsigned int int_en;
469    int locked = 1;
470
471    local_irq_save(flags);
472
473    if (up->port.sysrq)
474        locked = 0;
475    else if (oops_in_progress)
476        locked = spin_trylock(&up->port.lock);
477    else
478        spin_lock(&up->port.lock);
479
480    /*
481     * First save the IER then disable the interrupts
482     */
483    int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
484    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
485
486    uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
487
488    /*
489     * Finally, wait for transmitter to become empty
490     * and restore the IER
491     */
492    ar933x_uart_wait_xmitr(up);
493    ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
494
495    ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
496
497    if (locked)
498        spin_unlock(&up->port.lock);
499
500    local_irq_restore(flags);
501}
502
503static int ar933x_uart_console_setup(struct console *co, char *options)
504{
505    struct ar933x_uart_port *up;
506    int baud = 115200;
507    int bits = 8;
508    int parity = 'n';
509    int flow = 'n';
510
511    if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
512        return -EINVAL;
513
514    up = ar933x_console_ports[co->index];
515    if (!up)
516        return -ENODEV;
517
518    if (options)
519        uart_parse_options(options, &baud, &parity, &bits, &flow);
520
521    return uart_set_options(&up->port, co, baud, parity, bits, flow);
522}
523
524static struct console ar933x_uart_console = {
525    .name = "ttyATH",
526    .write = ar933x_uart_console_write,
527    .device = uart_console_device,
528    .setup = ar933x_uart_console_setup,
529    .flags = CON_PRINTBUFFER,
530    .index = -1,
531    .data = &ar933x_uart_driver,
532};
533
534static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
535{
536    ar933x_console_ports[up->port.line] = up;
537}
538
539#define AR933X_SERIAL_CONSOLE (&ar933x_uart_console)
540
541#else
542
543static inline void ar933x_uart_add_console_port(struct ar933x_uart_port *up) {}
544
545#define AR933X_SERIAL_CONSOLE NULL
546
547#endif /* CONFIG_SERIAL_AR933X_CONSOLE */
548
549static struct uart_driver ar933x_uart_driver = {
550    .owner = THIS_MODULE,
551    .driver_name = DRIVER_NAME,
552    .dev_name = "ttyATH",
553    .nr = CONFIG_SERIAL_AR933X_NR_UARTS,
554    .cons = AR933X_SERIAL_CONSOLE,
555};
556
557static int __devinit ar933x_uart_probe(struct platform_device *pdev)
558{
559    struct ar933x_uart_platform_data *pdata;
560    struct ar933x_uart_port *up;
561    struct uart_port *port;
562    struct resource *mem_res;
563    struct resource *irq_res;
564    int id;
565    int ret;
566
567    pdata = pdev->dev.platform_data;
568    if (!pdata)
569        return -EINVAL;
570
571    id = pdev->id;
572    if (id == -1)
573        id = 0;
574
575    if (id > CONFIG_SERIAL_AR933X_NR_UARTS)
576        return -EINVAL;
577
578    mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
579    if (!mem_res) {
580        dev_err(&pdev->dev, "no MEM resource\n");
581        return -EINVAL;
582    }
583
584    irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
585    if (!irq_res) {
586        dev_err(&pdev->dev, "no IRQ resource\n");
587        return -EINVAL;
588    }
589
590    up = kzalloc(sizeof(struct ar933x_uart_port), GFP_KERNEL);
591    if (!up)
592        return -ENOMEM;
593
594    port = &up->port;
595    port->mapbase = mem_res->start;
596
597    port->membase = ioremap(mem_res->start, AR933X_UART_REGS_SIZE);
598    if (!port->membase) {
599        ret = -ENOMEM;
600        goto err_free_up;
601    }
602
603    port->line = id;
604    port->irq = irq_res->start;
605    port->dev = &pdev->dev;
606    port->type = PORT_AR933X;
607    port->iotype = UPIO_MEM32;
608    port->uartclk = pdata->uartclk;
609
610    port->regshift = 2;
611    port->fifosize = AR933X_UART_FIFO_SIZE;
612    port->ops = &ar933x_uart_ops;
613
614    ar933x_uart_add_console_port(up);
615
616    ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
617    if (ret)
618        goto err_unmap;
619
620    platform_set_drvdata(pdev, up);
621    return 0;
622
623err_unmap:
624    iounmap(up->port.membase);
625err_free_up:
626    kfree(up);
627    return ret;
628}
629
630static int __devexit ar933x_uart_remove(struct platform_device *pdev)
631{
632    struct ar933x_uart_port *up;
633
634    up = platform_get_drvdata(pdev);
635    platform_set_drvdata(pdev, NULL);
636
637    if (up) {
638        uart_remove_one_port(&ar933x_uart_driver, &up->port);
639        iounmap(up->port.membase);
640        kfree(up);
641    }
642
643    return 0;
644}
645
646static struct platform_driver ar933x_uart_platform_driver = {
647    .probe = ar933x_uart_probe,
648    .remove = __devexit_p(ar933x_uart_remove),
649    .driver = {
650        .name = DRIVER_NAME,
651        .owner = THIS_MODULE,
652    },
653};
654
655static int __init ar933x_uart_init(void)
656{
657    int ret;
658
659    ar933x_uart_driver.nr = CONFIG_SERIAL_AR933X_NR_UARTS;
660    ret = uart_register_driver(&ar933x_uart_driver);
661    if (ret)
662        goto err_out;
663
664    ret = platform_driver_register(&ar933x_uart_platform_driver);
665    if (ret)
666        goto err_unregister_uart_driver;
667
668    return 0;
669
670err_unregister_uart_driver:
671    uart_unregister_driver(&ar933x_uart_driver);
672err_out:
673    return ret;
674}
675
676static void __exit ar933x_uart_exit(void)
677{
678    platform_driver_unregister(&ar933x_uart_platform_driver);
679    uart_unregister_driver(&ar933x_uart_driver);
680}
681
682module_init(ar933x_uart_init);
683module_exit(ar933x_uart_exit);
684
685MODULE_DESCRIPTION("Atheros AR933X UART driver");
686MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
687MODULE_LICENSE("GPL v2");
688MODULE_ALIAS("platform:" DRIVER_NAME);
689

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