aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/serial/nwpserial.c
blob: e1ab8ec0a4a64f86326494ee14112da85dc2d69b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
/*
 *  Serial Port driver for a NWP uart device
 *
 *    Copyright (C) 2008 IBM Corp., Benjamin Krill <ben@codiert.org>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */
#include <linux/init.h>
#include <linux/console.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
#include <linux/serial_core.h>
#include <linux/tty.h>
#include <linux/irqreturn.h>
#include <linux/mutex.h>
#include <linux/of_platform.h>
#include <linux/of_device.h>
#include <linux/nwpserial.h>
#include <asm/prom.h>
#include <asm/dcr.h>

#define NWPSERIAL_NR               2

#define NWPSERIAL_STATUS_RXVALID 0x1
#define NWPSERIAL_STATUS_TXFULL  0x2

struct nwpserial_port {
	struct uart_port port;
	dcr_host_t dcr_host;
	unsigned int ier;
	unsigned int mcr;
};

static DEFINE_MUTEX(nwpserial_mutex);
static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR];

static void wait_for_bits(struct nwpserial_port *up, int bits)
{
	unsigned int status, tmout = 10000;

	/* Wait up to 10ms for the character(s) to be sent. */
	do {
		status = dcr_read(up->dcr_host, UART_LSR);

		if (--tmout == 0)
			break;
		udelay(1);
	} while ((status & bits) != bits);
}

#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
static void nwpserial_console_putchar(struct uart_port *port, int c)
{
	struct nwpserial_port *up;
	up = container_of(port, struct nwpserial_port, port);
	/* check if tx buffer is full */
	wait_for_bits(up, UART_LSR_THRE);
	dcr_write(up->dcr_host, UART_TX, c);
	up->port.icount.tx++;
}

static void
nwpserial_console_write(struct console *co, const char *s, unsigned int count)
{
	struct nwpserial_port *up = &nwpserial_ports[co->index];
	unsigned long flags;
	int locked = 1;

	if (oops_in_progress)
		locked = spin_trylock_irqsave(&up->port.lock, flags);
	else
		spin_lock_irqsave(&up->port.lock, flags);

	/* save and disable interrupt */
	up->ier = dcr_read(up->dcr_host, UART_IER);
	dcr_write(up->dcr_host, UART_IER, up->ier & ~UART_IER_RDI);

	uart_console_write(&up->port, s, count, nwpserial_console_putchar);

	/* wait for transmitter to become emtpy */
	while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
		cpu_relax();

	/* restore interrupt state */
	dcr_write(up->dcr_host, UART_IER, up->ier);

	if (locked)
		spin_unlock_irqrestore(&up->port.lock, flags);
}

static struct uart_driver nwpserial_reg;
static struct console nwpserial_console = {
	.name		= "ttySQ",
	.write		= nwpserial_console_write,
	.device		= uart_console_device,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &nwpserial_reg,
};
#define NWPSERIAL_CONSOLE	(&nwpserial_console)
#else
#define NWPSERIAL_CONSOLE	NULL
#endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */

/**************************************************************************/

static int nwpserial_request_port(struct uart_port *port)
{
	return 0;
}

static void nwpserial_release_port(struct uart_port *port)
{
	/* N/A */
}

static void nwpserial_config_port(struct uart_port *port, int flags)
{
	port->type = PORT_NWPSERIAL;
}

static irqreturn_t nwpserial_interrupt(int irq, void *dev_id)
{
	struct nwpserial_port *up = dev_id;
	struct tty_struct *tty = up->port.state->port.tty;
	irqreturn_t ret;
	unsigned int iir;
	unsigned char ch;

	spin_lock(&up->port.lock);

	/* check if the uart was the interrupt source. */
	iir = dcr_read(up->dcr_host, UART_IIR);
	if (!iir) {
		ret = IRQ_NONE;
		goto out;
	}

	do {
		up->port.icount.rx++;
		ch = dcr_read(up->dcr_host, UART_RX);
		if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID)
			tty_insert_flip_char(tty, ch, TTY_NORMAL);
	} while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR);

	tty_flip_buffer_push(tty);
	ret = IRQ_HANDLED;

	/* clear interrupt */
	dcr_write(up->dcr_host, UART_IIR, 1);
out:
	spin_unlock(&up->port.lock);
	return ret;
}

static int nwpserial_startup(struct uart_port *port)
{
	struct nwpserial_port *up;
	int err;

	up = container_of(port, struct nwpserial_port, port);

	/* disable flow control by default */
	up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE;
	dcr_write(up->dcr_host, UART_MCR, up->mcr);

	/* register interrupt handler */
	err = request_irq(up->port.irq, nwpserial_interrupt,
			IRQF_SHARED, "nwpserial", up);
	if (err)
		return err;

	/* enable interrupts */
	up->ier = UART_IER_RDI;
	dcr_write(up->dcr_host, UART_IER, up->ier);

	/* enable receiving */
	up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID;

	return 0;
}

static void nwpserial_shutdown(struct uart_port *port)
{
	struct nwpserial_port *up;
	up = container_of(port, struct nwpserial_port, port);

	/* disable receiving */
	up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;

	/* disable interrupts from this port */
	up->ier = 0;
	dcr_write(up->dcr_host, UART_IER, up->ier);

	/* free irq */
	free_irq(up->port.irq, port);
}

static int nwpserial_verify_port(struct uart_port *port,
			struct serial_struct *ser)
{
	return -EINVAL;
}

static const char *nwpserial_type(struct uart_port *port)
{
	return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL;
}

static void nwpserial_set_termios(struct uart_port *port,
			struct ktermios *termios, struct ktermios *old)
{
	struct nwpserial_port *up;
	up = container_of(port, struct nwpserial_port, port);

	up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID
				| NWPSERIAL_STATUS_TXFULL;

	up->port.ignore_status_mask = 0;
	/* ignore all characters if CREAD is not set */
	if ((termios->c_cflag & CREAD) == 0)
		up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;

	/* Copy back the old hardware settings */
	if (old)
		tty_termios_copy_hw(termios, old);
}

static void nwpserial_break_ctl(struct uart_port *port, int ctl)
{
	/* N/A */
}

static void nwpserial_enable_ms(struct uart_port *port)
{
	/* N/A */
}

static void nwpserial_stop_rx(struct uart_port *port)
{
	struct nwpserial_port *up;
	up = container_of(port, struct nwpserial_port, port);
	/* don't forward any more data (like !CREAD) */
	up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID;
}

static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c)
{
	/* check if tx buffer is full */
	wait_for_bits(up, UART_LSR_THRE);
	dcr_write(up->dcr_host, UART_TX, c);
	up->port.icount.tx++;
}

static void nwpserial_start_tx(struct uart_port *port)
{
	struct nwpserial_port *up;
	struct circ_buf *xmit;
	up = container_of(port, struct nwpserial_port, port);
	xmit  = &up->port.state->xmit;

	if (port->x_char) {
		nwpserial_putchar(up, up->port.x_char);
		port->x_char = 0;
	}

	while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) {
		nwpserial_putchar(up, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
	}
}

static unsigned int nwpserial_get_mctrl(struct uart_port *port)
{
	return 0;
}

static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	/* N/A */
}

static void nwpserial_stop_tx(struct uart_port *port)
{
	/* N/A */
}

static unsigned int nwpserial_tx_empty(struct uart_port *port)
{
	struct nwpserial_port *up;
	unsigned long flags;
	int ret;
	up = container_of(port, struct nwpserial_port, port);

	spin_lock_irqsave(&up->port.lock, flags);
	ret = dcr_read(up->dcr_host, UART_LSR);
	spin_unlock_irqrestore(&up->port.lock, flags);

	return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
}

static struct uart_ops nwpserial_pops = {
	.tx_empty     = nwpserial_tx_empty,
	.set_mctrl    = nwpserial_set_mctrl,
	.get_mctrl    = nwpserial_get_mctrl,
	.stop_tx      = nwpserial_stop_tx,
	.start_tx     = nwpserial_start_tx,
	.stop_rx      = nwpserial_stop_rx,
	.enable_ms    = nwpserial_enable_ms,
	.break_ctl    = nwpserial_break_ctl,
	.startup      = nwpserial_startup,
	.shutdown     = nwpserial_shutdown,
	.set_termios  = nwpserial_set_termios,
	.type         = nwpserial_type,
	.release_port = nwpserial_release_port,
	.request_port = nwpserial_request_port,
	.config_port  = nwpserial_config_port,
	.verify_port  = nwpserial_verify_port,
};

static struct uart_driver nwpserial_reg = {
	.owner       = THIS_MODULE,
	.driver_name = "nwpserial",
	.dev_name    = "ttySQ",
	.major       = TTY_MAJOR,
	.minor       = 68,
	.nr          = NWPSERIAL_NR,
	.cons        = NWPSERIAL_CONSOLE,
};

int nwpserial_register_port(struct uart_port *port)
{
	struct nwpserial_port *up = NULL;
	int ret = -1;
	int i;
	static int first = 1;
	int dcr_len;
	int dcr_base;
	struct device_node *dn;

	mutex_lock(&nwpserial_mutex);

	dn = to_of_device(port->dev)->node;
	if (dn == NULL)
		goto out;

	/* get dcr base. */
	dcr_base = dcr_resource_start(dn, 0);

	/* find matching entry */
	for (i = 0; i < NWPSERIAL_NR; i++)
		if (nwpserial_ports[i].port.iobase == dcr_base) {
			up = &nwpserial_ports[i];
			break;
		}

	/* we didn't find a mtching entry, search for a free port */
	if (up == NULL)
		for (i = 0; i < NWPSERIAL_NR; i++)
			if (nwpserial_ports[i].port.type == PORT_UNKNOWN &&
				nwpserial_ports[i].port.iobase == 0) {
				up = &nwpserial_ports[i];
				break;
			}

	if (up == NULL) {
		ret = -EBUSY;
		goto out;
	}

	if (first)
		uart_register_driver(&nwpserial_reg);
	first = 0;

	up->port.membase      = port->membase;
	up->port.irq          = port->irq;
	up->port.uartclk      = port->uartclk;
	up->port.fifosize     = port->fifosize;
	up->port.regshift     = port->regshift;
	up->port.iotype       = port->iotype;
	up->port.flags        = port->flags;
	up->port.mapbase      = port->mapbase;
	up->port.private_data = port->private_data;

	if (port->dev)
		up->port.dev = port->dev;

	if (up->port.iobase != dcr_base) {
		up->port.ops          = &nwpserial_pops;
		up->port.fifosize     = 16;

		spin_lock_init(&up->port.lock);

		up->port.iobase = dcr_base;
		dcr_len = dcr_resource_len(dn, 0);

		up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
		if (!DCR_MAP_OK(up->dcr_host)) {
			printk(KERN_ERR "Cannot map DCR resources for NWPSERIAL");
			goto out;
		}
	}

	ret = uart_add_one_port(&nwpserial_reg, &up->port);
	if (ret == 0)
		ret = up->port.line;

out:
	mutex_unlock(&nwpserial_mutex);

	return ret;
}
EXPORT_SYMBOL(nwpserial_register_port);

void nwpserial_unregister_port(int line)
{
	struct nwpserial_port *up = &nwpserial_ports[line];
	mutex_lock(&nwpserial_mutex);
	uart_remove_one_port(&nwpserial_reg, &up->port);

	up->port.type = PORT_UNKNOWN;

	mutex_unlock(&nwpserial_mutex);
}
EXPORT_SYMBOL(nwpserial_unregister_port);

#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
static int __init nwpserial_console_init(void)
{
	struct nwpserial_port *up = NULL;
	struct device_node *dn;
	const char *name;
	int dcr_base;
	int dcr_len;
	int i;

	/* search for a free port */
	for (i = 0; i < NWPSERIAL_NR; i++)
		if (nwpserial_ports[i].port.type == PORT_UNKNOWN) {
			up = &nwpserial_ports[i];
			break;
		}

	if (up == NULL)
		return -1;

	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
	if (name == NULL)
		return -1;

	dn = of_find_node_by_path(name);
	if (!dn)
		return -1;

	spin_lock_init(&up->port.lock);
	up->port.ops = &nwpserial_pops;
	up->port.type = PORT_NWPSERIAL;
	up->port.fifosize = 16;

	dcr_base = dcr_resource_start(dn, 0);
	dcr_len = dcr_resource_len(dn, 0);
	up->port.iobase = dcr_base;

	up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
	if (!DCR_MAP_OK(up->dcr_host)) {
		printk("Cannot map DCR resources for SERIAL");
		return -1;
	}
	register_console(&nwpserial_console);
	return 0;
}
console_initcall(nwpserial_console_init);
#endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */