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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_struct *tty = up->port.state->port.tty;
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(tty, ch, TTY_NORMAL);
150 } while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR);
151
152 tty_flip_buffer_push(tty);
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 */