Root/drivers/tty/serial/nwpserial.c

1/*
2 * Serial Port driver for a NWP uart device
3 *
4 * Copyright (C) 2008 IBM Corp., Benjamin Krill <ben@codiert.org>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 */
12#include <linux/init.h>
13#include <linux/export.h>
14#include <linux/console.h>
15#include <linux/serial.h>
16#include <linux/serial_reg.h>
17#include <linux/serial_core.h>
18#include <linux/tty.h>
19#include <linux/tty_flip.h>
20#include <linux/irqreturn.h>
21#include <linux/mutex.h>
22#include <linux/of_platform.h>
23#include <linux/of_device.h>
24#include <linux/nwpserial.h>
25#include <asm/prom.h>
26#include <asm/dcr.h>
27
28#define NWPSERIAL_NR 2
29
30#define NWPSERIAL_STATUS_RXVALID 0x1
31#define NWPSERIAL_STATUS_TXFULL 0x2
32
33struct nwpserial_port {
34    struct uart_port port;
35    dcr_host_t dcr_host;
36    unsigned int ier;
37    unsigned int mcr;
38};
39
40static DEFINE_MUTEX(nwpserial_mutex);
41static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR];
42
43static void wait_for_bits(struct nwpserial_port *up, int bits)
44{
45    unsigned int status, tmout = 10000;
46
47    /* Wait up to 10ms for the character(s) to be sent. */
48    do {
49        status = dcr_read(up->dcr_host, UART_LSR);
50
51        if (--tmout == 0)
52            break;
53        udelay(1);
54    } while ((status & bits) != bits);
55}
56
57#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
58static void nwpserial_console_putchar(struct uart_port *port, int c)
59{
60    struct nwpserial_port *up;
61    up = container_of(port, struct nwpserial_port, port);
62    /* check if tx buffer is full */
63    wait_for_bits(up, UART_LSR_THRE);
64    dcr_write(up->dcr_host, UART_TX, c);
65    up->port.icount.tx++;
66}
67
68static void
69nwpserial_console_write(struct console *co, const char *s, unsigned int count)
70{
71    struct nwpserial_port *up = &nwpserial_ports[co->index];
72    unsigned long flags;
73    int locked = 1;
74
75    if (oops_in_progress)
76        locked = spin_trylock_irqsave(&up->port.lock, flags);
77    else
78        spin_lock_irqsave(&up->port.lock, flags);
79
80    /* save and disable interrupt */
81    up->ier = dcr_read(up->dcr_host, UART_IER);
82    dcr_write(up->dcr_host, UART_IER, up->ier & ~UART_IER_RDI);
83
84    uart_console_write(&up->port, s, count, nwpserial_console_putchar);
85
86    /* wait for transmitter to become empty */
87    while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
88        cpu_relax();
89
90    /* restore interrupt state */
91    dcr_write(up->dcr_host, UART_IER, up->ier);
92
93    if (locked)
94        spin_unlock_irqrestore(&up->port.lock, flags);
95}
96
97static struct uart_driver nwpserial_reg;
98static struct console nwpserial_console = {
99    .name = "ttySQ",
100    .write = nwpserial_console_write,
101    .device = uart_console_device,
102    .flags = CON_PRINTBUFFER,
103    .index = -1,
104    .data = &nwpserial_reg,
105};
106#define NWPSERIAL_CONSOLE (&nwpserial_console)
107#else
108#define NWPSERIAL_CONSOLE NULL
109#endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */
110
111/**************************************************************************/
112
113static int nwpserial_request_port(struct uart_port *port)
114{
115    return 0;
116}
117
118static void nwpserial_release_port(struct uart_port *port)
119{
120    /* N/A */
121}
122
123static void nwpserial_config_port(struct uart_port *port, int flags)
124{
125    port->type = PORT_NWPSERIAL;
126}
127
128static irqreturn_t nwpserial_interrupt(int irq, void *dev_id)
129{
130    struct nwpserial_port *up = dev_id;
131    struct tty_port *port = &up->port.state->port;
132    irqreturn_t ret;
133    unsigned int iir;
134    unsigned char ch;
135
136    spin_lock(&up->port.lock);
137
138    /* check if the uart was the interrupt source. */
139    iir = dcr_read(up->dcr_host, UART_IIR);
140    if (!iir) {
141        ret = IRQ_NONE;
142        goto out;
143    }
144
145    do {
146        up->port.icount.rx++;
147        ch = dcr_read(up->dcr_host, UART_RX);
148        if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID)
149            tty_insert_flip_char(port, ch, TTY_NORMAL);
150    } while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR);
151
152    tty_flip_buffer_push(port);
153    ret = IRQ_HANDLED;
154
155    /* clear interrupt */
156    dcr_write(up->dcr_host, UART_IIR, 1);
157out:
158    spin_unlock(&up->port.lock);
159    return ret;
160}
161
162static int nwpserial_startup(struct uart_port *port)
163{
164    struct nwpserial_port *up;
165    int err;
166
167    up = container_of(port, struct nwpserial_port, port);
168
169    /* disable flow control by default */
170    up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE;
171    dcr_write(up->dcr_host, UART_MCR, up->mcr);
172
173    /* register interrupt handler */
174    err = request_irq(up->port.irq, nwpserial_interrupt,
175            IRQF_SHARED, "nwpserial", up);
176    if (err)
177        return err;
178
179    /* enable interrupts */
180    up->ier = UART_IER_RDI;
181    dcr_write(up->dcr_host, UART_IER, up->ier);
182
183    /* enable receiving */
184    up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID;
185
186    return 0;
187}
188
189static void nwpserial_shutdown(struct uart_port *port)
190{
191    struct nwpserial_port *up;
192    up = container_of(port, struct nwpserial_port, port);
193
194    /* disable receiving */
195    up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
196
197    /* disable interrupts from this port */
198    up->ier = 0;
199    dcr_write(up->dcr_host, UART_IER, up->ier);
200
201    /* free irq */
202    free_irq(up->port.irq, port);
203}
204
205static int nwpserial_verify_port(struct uart_port *port,
206            struct serial_struct *ser)
207{
208    return -EINVAL;
209}
210
211static const char *nwpserial_type(struct uart_port *port)
212{
213    return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL;
214}
215
216static void nwpserial_set_termios(struct uart_port *port,
217            struct ktermios *termios, struct ktermios *old)
218{
219    struct nwpserial_port *up;
220    up = container_of(port, struct nwpserial_port, port);
221
222    up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID
223                | NWPSERIAL_STATUS_TXFULL;
224
225    up->port.ignore_status_mask = 0;
226    /* ignore all characters if CREAD is not set */
227    if ((termios->c_cflag & CREAD) == 0)
228        up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
229
230    /* Copy back the old hardware settings */
231    if (old)
232        tty_termios_copy_hw(termios, old);
233}
234
235static void nwpserial_break_ctl(struct uart_port *port, int ctl)
236{
237    /* N/A */
238}
239
240static void nwpserial_enable_ms(struct uart_port *port)
241{
242    /* N/A */
243}
244
245static void nwpserial_stop_rx(struct uart_port *port)
246{
247    struct nwpserial_port *up;
248    up = container_of(port, struct nwpserial_port, port);
249    /* don't forward any more data (like !CREAD) */
250    up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID;
251}
252
253static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c)
254{
255    /* check if tx buffer is full */
256    wait_for_bits(up, UART_LSR_THRE);
257    dcr_write(up->dcr_host, UART_TX, c);
258    up->port.icount.tx++;
259}
260
261static void nwpserial_start_tx(struct uart_port *port)
262{
263    struct nwpserial_port *up;
264    struct circ_buf *xmit;
265    up = container_of(port, struct nwpserial_port, port);
266    xmit = &up->port.state->xmit;
267
268    if (port->x_char) {
269        nwpserial_putchar(up, up->port.x_char);
270        port->x_char = 0;
271    }
272
273    while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) {
274        nwpserial_putchar(up, xmit->buf[xmit->tail]);
275        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
276    }
277}
278
279static unsigned int nwpserial_get_mctrl(struct uart_port *port)
280{
281    return 0;
282}
283
284static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl)
285{
286    /* N/A */
287}
288
289static void nwpserial_stop_tx(struct uart_port *port)
290{
291    /* N/A */
292}
293
294static unsigned int nwpserial_tx_empty(struct uart_port *port)
295{
296    struct nwpserial_port *up;
297    unsigned long flags;
298    int ret;
299    up = container_of(port, struct nwpserial_port, port);
300
301    spin_lock_irqsave(&up->port.lock, flags);
302    ret = dcr_read(up->dcr_host, UART_LSR);
303    spin_unlock_irqrestore(&up->port.lock, flags);
304
305    return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
306}
307
308static struct uart_ops nwpserial_pops = {
309    .tx_empty = nwpserial_tx_empty,
310    .set_mctrl = nwpserial_set_mctrl,
311    .get_mctrl = nwpserial_get_mctrl,
312    .stop_tx = nwpserial_stop_tx,
313    .start_tx = nwpserial_start_tx,
314    .stop_rx = nwpserial_stop_rx,
315    .enable_ms = nwpserial_enable_ms,
316    .break_ctl = nwpserial_break_ctl,
317    .startup = nwpserial_startup,
318    .shutdown = nwpserial_shutdown,
319    .set_termios = nwpserial_set_termios,
320    .type = nwpserial_type,
321    .release_port = nwpserial_release_port,
322    .request_port = nwpserial_request_port,
323    .config_port = nwpserial_config_port,
324    .verify_port = nwpserial_verify_port,
325};
326
327static struct uart_driver nwpserial_reg = {
328    .owner = THIS_MODULE,
329    .driver_name = "nwpserial",
330    .dev_name = "ttySQ",
331    .major = TTY_MAJOR,
332    .minor = 68,
333    .nr = NWPSERIAL_NR,
334    .cons = NWPSERIAL_CONSOLE,
335};
336
337int nwpserial_register_port(struct uart_port *port)
338{
339    struct nwpserial_port *up = NULL;
340    int ret = -1;
341    int i;
342    static int first = 1;
343    int dcr_len;
344    int dcr_base;
345    struct device_node *dn;
346
347    mutex_lock(&nwpserial_mutex);
348
349    dn = port->dev->of_node;
350    if (dn == NULL)
351        goto out;
352
353    /* get dcr base. */
354    dcr_base = dcr_resource_start(dn, 0);
355
356    /* find matching entry */
357    for (i = 0; i < NWPSERIAL_NR; i++)
358        if (nwpserial_ports[i].port.iobase == dcr_base) {
359            up = &nwpserial_ports[i];
360            break;
361        }
362
363    /* we didn't find a mtching entry, search for a free port */
364    if (up == NULL)
365        for (i = 0; i < NWPSERIAL_NR; i++)
366            if (nwpserial_ports[i].port.type == PORT_UNKNOWN &&
367                nwpserial_ports[i].port.iobase == 0) {
368                up = &nwpserial_ports[i];
369                break;
370            }
371
372    if (up == NULL) {
373        ret = -EBUSY;
374        goto out;
375    }
376
377    if (first)
378        uart_register_driver(&nwpserial_reg);
379    first = 0;
380
381    up->port.membase = port->membase;
382    up->port.irq = port->irq;
383    up->port.uartclk = port->uartclk;
384    up->port.fifosize = port->fifosize;
385    up->port.regshift = port->regshift;
386    up->port.iotype = port->iotype;
387    up->port.flags = port->flags;
388    up->port.mapbase = port->mapbase;
389    up->port.private_data = port->private_data;
390
391    if (port->dev)
392        up->port.dev = port->dev;
393
394    if (up->port.iobase != dcr_base) {
395        up->port.ops = &nwpserial_pops;
396        up->port.fifosize = 16;
397
398        spin_lock_init(&up->port.lock);
399
400        up->port.iobase = dcr_base;
401        dcr_len = dcr_resource_len(dn, 0);
402
403        up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
404        if (!DCR_MAP_OK(up->dcr_host)) {
405            printk(KERN_ERR "Cannot map DCR resources for NWPSERIAL");
406            goto out;
407        }
408    }
409
410    ret = uart_add_one_port(&nwpserial_reg, &up->port);
411    if (ret == 0)
412        ret = up->port.line;
413
414out:
415    mutex_unlock(&nwpserial_mutex);
416
417    return ret;
418}
419EXPORT_SYMBOL(nwpserial_register_port);
420
421void nwpserial_unregister_port(int line)
422{
423    struct nwpserial_port *up = &nwpserial_ports[line];
424    mutex_lock(&nwpserial_mutex);
425    uart_remove_one_port(&nwpserial_reg, &up->port);
426
427    up->port.type = PORT_UNKNOWN;
428
429    mutex_unlock(&nwpserial_mutex);
430}
431EXPORT_SYMBOL(nwpserial_unregister_port);
432
433#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
434static int __init nwpserial_console_init(void)
435{
436    struct nwpserial_port *up = NULL;
437    struct device_node *dn;
438    const char *name;
439    int dcr_base;
440    int dcr_len;
441    int i;
442
443    /* search for a free port */
444    for (i = 0; i < NWPSERIAL_NR; i++)
445        if (nwpserial_ports[i].port.type == PORT_UNKNOWN) {
446            up = &nwpserial_ports[i];
447            break;
448        }
449
450    if (up == NULL)
451        return -1;
452
453    name = of_get_property(of_chosen, "linux,stdout-path", NULL);
454    if (name == NULL)
455        return -1;
456
457    dn = of_find_node_by_path(name);
458    if (!dn)
459        return -1;
460
461    spin_lock_init(&up->port.lock);
462    up->port.ops = &nwpserial_pops;
463    up->port.type = PORT_NWPSERIAL;
464    up->port.fifosize = 16;
465
466    dcr_base = dcr_resource_start(dn, 0);
467    dcr_len = dcr_resource_len(dn, 0);
468    up->port.iobase = dcr_base;
469
470    up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
471    if (!DCR_MAP_OK(up->dcr_host)) {
472        printk("Cannot map DCR resources for SERIAL");
473        return -1;
474    }
475    register_console(&nwpserial_console);
476    return 0;
477}
478console_initcall(nwpserial_console_init);
479#endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */
480

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