xref: /linux/drivers/tty/serial/21285.c (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732) 
1 /*
2  * Driver for the serial port on the 21285 StrongArm-110 core logic chip.
3  *
4  * Based on drivers/char/serial.c
5  */
6 #include <linux/module.h>
7 #include <linux/tty.h>
8 #include <linux/ioport.h>
9 #include <linux/init.h>
10 #include <linux/console.h>
11 #include <linux/device.h>
12 #include <linux/tty_flip.h>
13 #include <linux/serial_core.h>
14 #include <linux/serial.h>
15 #include <linux/io.h>
16 
17 #include <asm/irq.h>
18 #include <asm/mach-types.h>
19 #include <asm/system_info.h>
20 #include <asm/hardware/dec21285.h>
21 #include <mach/hardware.h>
22 
23 #define BAUD_BASE		(mem_fclk_21285/64)
24 
25 #define SERIAL_21285_NAME	"ttyFB"
26 #define SERIAL_21285_MAJOR	204
27 #define SERIAL_21285_MINOR	4
28 
29 #define RXSTAT_DUMMY_READ	0x80000000
30 #define RXSTAT_FRAME		(1 << 0)
31 #define RXSTAT_PARITY		(1 << 1)
32 #define RXSTAT_OVERRUN		(1 << 2)
33 #define RXSTAT_ANYERR		(RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
34 
35 #define H_UBRLCR_BREAK		(1 << 0)
36 #define H_UBRLCR_PARENB		(1 << 1)
37 #define H_UBRLCR_PAREVN		(1 << 2)
38 #define H_UBRLCR_STOPB		(1 << 3)
39 #define H_UBRLCR_FIFO		(1 << 4)
40 
41 static const char serial21285_name[] = "Footbridge UART";
42 
43 #define tx_enabled(port)	((port)->unused[0])
44 #define rx_enabled(port)	((port)->unused[1])
45 
46 /*
47  * The documented expression for selecting the divisor is:
48  *  BAUD_BASE / baud - 1
49  * However, typically BAUD_BASE is not divisible by baud, so
50  * we want to select the divisor that gives us the minimum
51  * error.  Therefore, we want:
52  *  int(BAUD_BASE / baud - 0.5) ->
53  *  int(BAUD_BASE / baud - (baud >> 1) / baud) ->
54  *  int((BAUD_BASE - (baud >> 1)) / baud)
55  */
56 
57 static void serial21285_stop_tx(struct uart_port *port)
58 {
59 	if (tx_enabled(port)) {
60 		disable_irq_nosync(IRQ_CONTX);
61 		tx_enabled(port) = 0;
62 	}
63 }
64 
65 static void serial21285_start_tx(struct uart_port *port)
66 {
67 	if (!tx_enabled(port)) {
68 		enable_irq(IRQ_CONTX);
69 		tx_enabled(port) = 1;
70 	}
71 }
72 
73 static void serial21285_stop_rx(struct uart_port *port)
74 {
75 	if (rx_enabled(port)) {
76 		disable_irq_nosync(IRQ_CONRX);
77 		rx_enabled(port) = 0;
78 	}
79 }
80 
81 static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
82 {
83 	struct uart_port *port = dev_id;
84 	unsigned int status, ch, flag, rxs, max_count = 256;
85 
86 	status = *CSR_UARTFLG;
87 	while (!(status & 0x10) && max_count--) {
88 		ch = *CSR_UARTDR;
89 		flag = TTY_NORMAL;
90 		port->icount.rx++;
91 
92 		rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
93 		if (unlikely(rxs & RXSTAT_ANYERR)) {
94 			if (rxs & RXSTAT_PARITY)
95 				port->icount.parity++;
96 			else if (rxs & RXSTAT_FRAME)
97 				port->icount.frame++;
98 			if (rxs & RXSTAT_OVERRUN)
99 				port->icount.overrun++;
100 
101 			rxs &= port->read_status_mask;
102 
103 			if (rxs & RXSTAT_PARITY)
104 				flag = TTY_PARITY;
105 			else if (rxs & RXSTAT_FRAME)
106 				flag = TTY_FRAME;
107 		}
108 
109 		uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
110 
111 		status = *CSR_UARTFLG;
112 	}
113 	tty_flip_buffer_push(&port->state->port);
114 
115 	return IRQ_HANDLED;
116 }
117 
118 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
119 {
120 	struct uart_port *port = dev_id;
121 	struct circ_buf *xmit = &port->state->xmit;
122 	int count = 256;
123 
124 	if (port->x_char) {
125 		*CSR_UARTDR = port->x_char;
126 		port->icount.tx++;
127 		port->x_char = 0;
128 		goto out;
129 	}
130 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
131 		serial21285_stop_tx(port);
132 		goto out;
133 	}
134 
135 	do {
136 		*CSR_UARTDR = xmit->buf[xmit->tail];
137 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
138 		port->icount.tx++;
139 		if (uart_circ_empty(xmit))
140 			break;
141 	} while (--count > 0 && !(*CSR_UARTFLG & 0x20));
142 
143 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
144 		uart_write_wakeup(port);
145 
146 	if (uart_circ_empty(xmit))
147 		serial21285_stop_tx(port);
148 
149  out:
150 	return IRQ_HANDLED;
151 }
152 
153 static unsigned int serial21285_tx_empty(struct uart_port *port)
154 {
155 	return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
156 }
157 
158 /* no modem control lines */
159 static unsigned int serial21285_get_mctrl(struct uart_port *port)
160 {
161 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
162 }
163 
164 static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
165 {
166 }
167 
168 static void serial21285_break_ctl(struct uart_port *port, int break_state)
169 {
170 	unsigned long flags;
171 	unsigned int h_lcr;
172 
173 	spin_lock_irqsave(&port->lock, flags);
174 	h_lcr = *CSR_H_UBRLCR;
175 	if (break_state)
176 		h_lcr |= H_UBRLCR_BREAK;
177 	else
178 		h_lcr &= ~H_UBRLCR_BREAK;
179 	*CSR_H_UBRLCR = h_lcr;
180 	spin_unlock_irqrestore(&port->lock, flags);
181 }
182 
183 static int serial21285_startup(struct uart_port *port)
184 {
185 	int ret;
186 
187 	tx_enabled(port) = 1;
188 	rx_enabled(port) = 1;
189 
190 	ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
191 			  serial21285_name, port);
192 	if (ret == 0) {
193 		ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
194 				  serial21285_name, port);
195 		if (ret)
196 			free_irq(IRQ_CONRX, port);
197 	}
198 
199 	return ret;
200 }
201 
202 static void serial21285_shutdown(struct uart_port *port)
203 {
204 	free_irq(IRQ_CONTX, port);
205 	free_irq(IRQ_CONRX, port);
206 }
207 
208 static void
209 serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
210 			struct ktermios *old)
211 {
212 	unsigned long flags;
213 	unsigned int baud, quot, h_lcr, b;
214 
215 	/*
216 	 * We don't support modem control lines.
217 	 */
218 	termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
219 	termios->c_cflag |= CLOCAL;
220 
221 	/*
222 	 * We don't support BREAK character recognition.
223 	 */
224 	termios->c_iflag &= ~(IGNBRK | BRKINT);
225 
226 	/*
227 	 * Ask the core to calculate the divisor for us.
228 	 */
229 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
230 	quot = uart_get_divisor(port, baud);
231 	b = port->uartclk / (16 * quot);
232 	tty_termios_encode_baud_rate(termios, b, b);
233 
234 	switch (termios->c_cflag & CSIZE) {
235 	case CS5:
236 		h_lcr = 0x00;
237 		break;
238 	case CS6:
239 		h_lcr = 0x20;
240 		break;
241 	case CS7:
242 		h_lcr = 0x40;
243 		break;
244 	default: /* CS8 */
245 		h_lcr = 0x60;
246 		break;
247 	}
248 
249 	if (termios->c_cflag & CSTOPB)
250 		h_lcr |= H_UBRLCR_STOPB;
251 	if (termios->c_cflag & PARENB) {
252 		h_lcr |= H_UBRLCR_PARENB;
253 		if (!(termios->c_cflag & PARODD))
254 			h_lcr |= H_UBRLCR_PAREVN;
255 	}
256 
257 	if (port->fifosize)
258 		h_lcr |= H_UBRLCR_FIFO;
259 
260 	spin_lock_irqsave(&port->lock, flags);
261 
262 	/*
263 	 * Update the per-port timeout.
264 	 */
265 	uart_update_timeout(port, termios->c_cflag, baud);
266 
267 	/*
268 	 * Which character status flags are we interested in?
269 	 */
270 	port->read_status_mask = RXSTAT_OVERRUN;
271 	if (termios->c_iflag & INPCK)
272 		port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
273 
274 	/*
275 	 * Which character status flags should we ignore?
276 	 */
277 	port->ignore_status_mask = 0;
278 	if (termios->c_iflag & IGNPAR)
279 		port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
280 	if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
281 		port->ignore_status_mask |= RXSTAT_OVERRUN;
282 
283 	/*
284 	 * Ignore all characters if CREAD is not set.
285 	 */
286 	if ((termios->c_cflag & CREAD) == 0)
287 		port->ignore_status_mask |= RXSTAT_DUMMY_READ;
288 
289 	quot -= 1;
290 
291 	*CSR_UARTCON = 0;
292 	*CSR_L_UBRLCR = quot & 0xff;
293 	*CSR_M_UBRLCR = (quot >> 8) & 0x0f;
294 	*CSR_H_UBRLCR = h_lcr;
295 	*CSR_UARTCON = 1;
296 
297 	spin_unlock_irqrestore(&port->lock, flags);
298 }
299 
300 static const char *serial21285_type(struct uart_port *port)
301 {
302 	return port->type == PORT_21285 ? "DC21285" : NULL;
303 }
304 
305 static void serial21285_release_port(struct uart_port *port)
306 {
307 	release_mem_region(port->mapbase, 32);
308 }
309 
310 static int serial21285_request_port(struct uart_port *port)
311 {
312 	return request_mem_region(port->mapbase, 32, serial21285_name)
313 			 != NULL ? 0 : -EBUSY;
314 }
315 
316 static void serial21285_config_port(struct uart_port *port, int flags)
317 {
318 	if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
319 		port->type = PORT_21285;
320 }
321 
322 /*
323  * verify the new serial_struct (for TIOCSSERIAL).
324  */
325 static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
326 {
327 	int ret = 0;
328 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
329 		ret = -EINVAL;
330 	if (ser->irq <= 0)
331 		ret = -EINVAL;
332 	if (ser->baud_base != port->uartclk / 16)
333 		ret = -EINVAL;
334 	return ret;
335 }
336 
337 static struct uart_ops serial21285_ops = {
338 	.tx_empty	= serial21285_tx_empty,
339 	.get_mctrl	= serial21285_get_mctrl,
340 	.set_mctrl	= serial21285_set_mctrl,
341 	.stop_tx	= serial21285_stop_tx,
342 	.start_tx	= serial21285_start_tx,
343 	.stop_rx	= serial21285_stop_rx,
344 	.break_ctl	= serial21285_break_ctl,
345 	.startup	= serial21285_startup,
346 	.shutdown	= serial21285_shutdown,
347 	.set_termios	= serial21285_set_termios,
348 	.type		= serial21285_type,
349 	.release_port	= serial21285_release_port,
350 	.request_port	= serial21285_request_port,
351 	.config_port	= serial21285_config_port,
352 	.verify_port	= serial21285_verify_port,
353 };
354 
355 static struct uart_port serial21285_port = {
356 	.mapbase	= 0x42000160,
357 	.iotype		= UPIO_MEM,
358 	.irq		= 0,
359 	.fifosize	= 16,
360 	.ops		= &serial21285_ops,
361 	.flags		= UPF_BOOT_AUTOCONF,
362 };
363 
364 static void serial21285_setup_ports(void)
365 {
366 	serial21285_port.uartclk = mem_fclk_21285 / 4;
367 }
368 
369 #ifdef CONFIG_SERIAL_21285_CONSOLE
370 static void serial21285_console_putchar(struct uart_port *port, int ch)
371 {
372 	while (*CSR_UARTFLG & 0x20)
373 		barrier();
374 	*CSR_UARTDR = ch;
375 }
376 
377 static void
378 serial21285_console_write(struct console *co, const char *s,
379 			  unsigned int count)
380 {
381 	uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
382 }
383 
384 static void __init
385 serial21285_get_options(struct uart_port *port, int *baud,
386 			int *parity, int *bits)
387 {
388 	if (*CSR_UARTCON == 1) {
389 		unsigned int tmp;
390 
391 		tmp = *CSR_H_UBRLCR;
392 		switch (tmp & 0x60) {
393 		case 0x00:
394 			*bits = 5;
395 			break;
396 		case 0x20:
397 			*bits = 6;
398 			break;
399 		case 0x40:
400 			*bits = 7;
401 			break;
402 		default:
403 		case 0x60:
404 			*bits = 8;
405 			break;
406 		}
407 
408 		if (tmp & H_UBRLCR_PARENB) {
409 			*parity = 'o';
410 			if (tmp & H_UBRLCR_PAREVN)
411 				*parity = 'e';
412 		}
413 
414 		tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
415 
416 		*baud = port->uartclk / (16 * (tmp + 1));
417 	}
418 }
419 
420 static int __init serial21285_console_setup(struct console *co, char *options)
421 {
422 	struct uart_port *port = &serial21285_port;
423 	int baud = 9600;
424 	int bits = 8;
425 	int parity = 'n';
426 	int flow = 'n';
427 
428 	if (machine_is_personal_server())
429 		baud = 57600;
430 
431 	/*
432 	 * Check whether an invalid uart number has been specified, and
433 	 * if so, search for the first available port that does have
434 	 * console support.
435 	 */
436 	if (options)
437 		uart_parse_options(options, &baud, &parity, &bits, &flow);
438 	else
439 		serial21285_get_options(port, &baud, &parity, &bits);
440 
441 	return uart_set_options(port, co, baud, parity, bits, flow);
442 }
443 
444 static struct uart_driver serial21285_reg;
445 
446 static struct console serial21285_console =
447 {
448 	.name		= SERIAL_21285_NAME,
449 	.write		= serial21285_console_write,
450 	.device		= uart_console_device,
451 	.setup		= serial21285_console_setup,
452 	.flags		= CON_PRINTBUFFER,
453 	.index		= -1,
454 	.data		= &serial21285_reg,
455 };
456 
457 static int __init rs285_console_init(void)
458 {
459 	serial21285_setup_ports();
460 	register_console(&serial21285_console);
461 	return 0;
462 }
463 console_initcall(rs285_console_init);
464 
465 #define SERIAL_21285_CONSOLE	&serial21285_console
466 #else
467 #define SERIAL_21285_CONSOLE	NULL
468 #endif
469 
470 static struct uart_driver serial21285_reg = {
471 	.owner			= THIS_MODULE,
472 	.driver_name		= "ttyFB",
473 	.dev_name		= "ttyFB",
474 	.major			= SERIAL_21285_MAJOR,
475 	.minor			= SERIAL_21285_MINOR,
476 	.nr			= 1,
477 	.cons			= SERIAL_21285_CONSOLE,
478 };
479 
480 static int __init serial21285_init(void)
481 {
482 	int ret;
483 
484 	printk(KERN_INFO "Serial: 21285 driver\n");
485 
486 	serial21285_setup_ports();
487 
488 	ret = uart_register_driver(&serial21285_reg);
489 	if (ret == 0)
490 		uart_add_one_port(&serial21285_reg, &serial21285_port);
491 
492 	return ret;
493 }
494 
495 static void __exit serial21285_exit(void)
496 {
497 	uart_remove_one_port(&serial21285_reg, &serial21285_port);
498 	uart_unregister_driver(&serial21285_reg);
499 }
500 
501 module_init(serial21285_init);
502 module_exit(serial21285_exit);
503 
504 MODULE_LICENSE("GPL");
505 MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver");
506 MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);
507