tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for the serial port on the 21285 StrongArm-110 core logic chip.
4 *
5 * Based on drivers/char/serial.c
6 */
7#include <linux/module.h>
8#include <linux/tty.h>
9#include <linux/ioport.h>
10#include <linux/init.h>
11#include <linux/console.h>
12#include <linux/device.h>
13#include <linux/tty_flip.h>
14#include <linux/serial_core.h>
15#include <linux/serial.h>
16#include <linux/io.h>
17
18#include <asm/irq.h>
19#include <asm/mach-types.h>
20#include <asm/system_info.h>
21#include <asm/hardware/dec21285.h>
22#include <mach/hardware.h>
23
24#define BAUD_BASE (mem_fclk_21285/64)
25
26#define SERIAL_21285_NAME "ttyFB"
27#define SERIAL_21285_MAJOR 204
28#define SERIAL_21285_MINOR 4
29
30#define RXSTAT_DUMMY_READ 0x80000000
31#define RXSTAT_FRAME (1 << 0)
32#define RXSTAT_PARITY (1 << 1)
33#define RXSTAT_OVERRUN (1 << 2)
34#define RXSTAT_ANYERR (RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
35
36#define H_UBRLCR_BREAK (1 << 0)
37#define H_UBRLCR_PARENB (1 << 1)
38#define H_UBRLCR_PAREVN (1 << 2)
39#define H_UBRLCR_STOPB (1 << 3)
40#define H_UBRLCR_FIFO (1 << 4)
41
42static const char serial21285_name[] = "Footbridge UART";
43
44/*
45 * We only need 2 bits of data, so instead of creating a whole structure for
46 * this, use bits of the private_data pointer of the uart port structure.
47 */
48#define tx_enabled_bit 0
49#define rx_enabled_bit 1
50
51static bool is_enabled(struct uart_port *port, int bit)
52{
53 unsigned long *private_data = (unsigned long *)&port->private_data;
54
55 if (test_bit(bit, private_data))
56 return true;
57 return false;
58}
59
60static void enable(struct uart_port *port, int bit)
61{
62 unsigned long *private_data = (unsigned long *)&port->private_data;
63
64 set_bit(bit, private_data);
65}
66
67static void disable(struct uart_port *port, int bit)
68{
69 unsigned long *private_data = (unsigned long *)&port->private_data;
70
71 clear_bit(bit, private_data);
72}
73
74#define is_tx_enabled(port) is_enabled(port, tx_enabled_bit)
75#define tx_enable(port) enable(port, tx_enabled_bit)
76#define tx_disable(port) disable(port, tx_enabled_bit)
77
78#define is_rx_enabled(port) is_enabled(port, rx_enabled_bit)
79#define rx_enable(port) enable(port, rx_enabled_bit)
80#define rx_disable(port) disable(port, rx_enabled_bit)
81
82/*
83 * The documented expression for selecting the divisor is:
84 * BAUD_BASE / baud - 1
85 * However, typically BAUD_BASE is not divisible by baud, so
86 * we want to select the divisor that gives us the minimum
87 * error. Therefore, we want:
88 * int(BAUD_BASE / baud - 0.5) ->
89 * int(BAUD_BASE / baud - (baud >> 1) / baud) ->
90 * int((BAUD_BASE - (baud >> 1)) / baud)
91 */
92
93static void serial21285_stop_tx(struct uart_port *port)
94{
95 if (is_tx_enabled(port)) {
96 disable_irq_nosync(IRQ_CONTX);
97 tx_disable(port);
98 }
99}
100
101static void serial21285_start_tx(struct uart_port *port)
102{
103 if (!is_tx_enabled(port)) {
104 enable_irq(IRQ_CONTX);
105 tx_enable(port);
106 }
107}
108
109static void serial21285_stop_rx(struct uart_port *port)
110{
111 if (is_rx_enabled(port)) {
112 disable_irq_nosync(IRQ_CONRX);
113 rx_disable(port);
114 }
115}
116
117static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
118{
119 struct uart_port *port = dev_id;
120 unsigned int status, ch, flag, rxs, max_count = 256;
121
122 status = *CSR_UARTFLG;
123 while (!(status & 0x10) && max_count--) {
124 ch = *CSR_UARTDR;
125 flag = TTY_NORMAL;
126 port->icount.rx++;
127
128 rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
129 if (unlikely(rxs & RXSTAT_ANYERR)) {
130 if (rxs & RXSTAT_PARITY)
131 port->icount.parity++;
132 else if (rxs & RXSTAT_FRAME)
133 port->icount.frame++;
134 if (rxs & RXSTAT_OVERRUN)
135 port->icount.overrun++;
136
137 rxs &= port->read_status_mask;
138
139 if (rxs & RXSTAT_PARITY)
140 flag = TTY_PARITY;
141 else if (rxs & RXSTAT_FRAME)
142 flag = TTY_FRAME;
143 }
144
145 uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
146
147 status = *CSR_UARTFLG;
148 }
149 tty_flip_buffer_push(&port->state->port);
150
151 return IRQ_HANDLED;
152}
153
154static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
155{
156 struct uart_port *port = dev_id;
157 u8 ch;
158
159 uart_port_tx_limited(port, ch, 256,
160 !(*CSR_UARTFLG & 0x20),
161 *CSR_UARTDR = ch,
162 ({}));
163
164 return IRQ_HANDLED;
165}
166
167static unsigned int serial21285_tx_empty(struct uart_port *port)
168{
169 return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
170}
171
172/* no modem control lines */
173static unsigned int serial21285_get_mctrl(struct uart_port *port)
174{
175 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
176}
177
178static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
179{
180}
181
182static void serial21285_break_ctl(struct uart_port *port, int break_state)
183{
184 unsigned long flags;
185 unsigned int h_lcr;
186
187 spin_lock_irqsave(&port->lock, flags);
188 h_lcr = *CSR_H_UBRLCR;
189 if (break_state)
190 h_lcr |= H_UBRLCR_BREAK;
191 else
192 h_lcr &= ~H_UBRLCR_BREAK;
193 *CSR_H_UBRLCR = h_lcr;
194 spin_unlock_irqrestore(&port->lock, flags);
195}
196
197static int serial21285_startup(struct uart_port *port)
198{
199 int ret;
200
201 tx_enable(port);
202 rx_enable(port);
203
204 ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
205 serial21285_name, port);
206 if (ret == 0) {
207 ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
208 serial21285_name, port);
209 if (ret)
210 free_irq(IRQ_CONRX, port);
211 }
212
213 return ret;
214}
215
216static void serial21285_shutdown(struct uart_port *port)
217{
218 free_irq(IRQ_CONTX, port);
219 free_irq(IRQ_CONRX, port);
220}
221
222static void
223serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
224 const struct ktermios *old)
225{
226 unsigned long flags;
227 unsigned int baud, quot, h_lcr, b;
228
229 /*
230 * We don't support modem control lines.
231 */
232 termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
233 termios->c_cflag |= CLOCAL;
234
235 /*
236 * We don't support BREAK character recognition.
237 */
238 termios->c_iflag &= ~(IGNBRK | BRKINT);
239
240 /*
241 * Ask the core to calculate the divisor for us.
242 */
243 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
244 quot = uart_get_divisor(port, baud);
245 b = port->uartclk / (16 * quot);
246 tty_termios_encode_baud_rate(termios, b, b);
247
248 switch (termios->c_cflag & CSIZE) {
249 case CS5:
250 h_lcr = 0x00;
251 break;
252 case CS6:
253 h_lcr = 0x20;
254 break;
255 case CS7:
256 h_lcr = 0x40;
257 break;
258 default: /* CS8 */
259 h_lcr = 0x60;
260 break;
261 }
262
263 if (termios->c_cflag & CSTOPB)
264 h_lcr |= H_UBRLCR_STOPB;
265 if (termios->c_cflag & PARENB) {
266 h_lcr |= H_UBRLCR_PARENB;
267 if (!(termios->c_cflag & PARODD))
268 h_lcr |= H_UBRLCR_PAREVN;
269 }
270
271 if (port->fifosize)
272 h_lcr |= H_UBRLCR_FIFO;
273
274 spin_lock_irqsave(&port->lock, flags);
275
276 /*
277 * Update the per-port timeout.
278 */
279 uart_update_timeout(port, termios->c_cflag, baud);
280
281 /*
282 * Which character status flags are we interested in?
283 */
284 port->read_status_mask = RXSTAT_OVERRUN;
285 if (termios->c_iflag & INPCK)
286 port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
287
288 /*
289 * Which character status flags should we ignore?
290 */
291 port->ignore_status_mask = 0;
292 if (termios->c_iflag & IGNPAR)
293 port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
294 if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
295 port->ignore_status_mask |= RXSTAT_OVERRUN;
296
297 /*
298 * Ignore all characters if CREAD is not set.
299 */
300 if ((termios->c_cflag & CREAD) == 0)
301 port->ignore_status_mask |= RXSTAT_DUMMY_READ;
302
303 quot -= 1;
304
305 *CSR_UARTCON = 0;
306 *CSR_L_UBRLCR = quot & 0xff;
307 *CSR_M_UBRLCR = (quot >> 8) & 0x0f;
308 *CSR_H_UBRLCR = h_lcr;
309 *CSR_UARTCON = 1;
310
311 spin_unlock_irqrestore(&port->lock, flags);
312}
313
314static const char *serial21285_type(struct uart_port *port)
315{
316 return port->type == PORT_21285 ? "DC21285" : NULL;
317}
318
319static void serial21285_release_port(struct uart_port *port)
320{
321 release_mem_region(port->mapbase, 32);
322}
323
324static int serial21285_request_port(struct uart_port *port)
325{
326 return request_mem_region(port->mapbase, 32, serial21285_name)
327 != NULL ? 0 : -EBUSY;
328}
329
330static void serial21285_config_port(struct uart_port *port, int flags)
331{
332 if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
333 port->type = PORT_21285;
334}
335
336/*
337 * verify the new serial_struct (for TIOCSSERIAL).
338 */
339static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
340{
341 int ret = 0;
342 if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
343 ret = -EINVAL;
344 if (ser->irq <= 0)
345 ret = -EINVAL;
346 if (ser->baud_base != port->uartclk / 16)
347 ret = -EINVAL;
348 return ret;
349}
350
351static const struct uart_ops serial21285_ops = {
352 .tx_empty = serial21285_tx_empty,
353 .get_mctrl = serial21285_get_mctrl,
354 .set_mctrl = serial21285_set_mctrl,
355 .stop_tx = serial21285_stop_tx,
356 .start_tx = serial21285_start_tx,
357 .stop_rx = serial21285_stop_rx,
358 .break_ctl = serial21285_break_ctl,
359 .startup = serial21285_startup,
360 .shutdown = serial21285_shutdown,
361 .set_termios = serial21285_set_termios,
362 .type = serial21285_type,
363 .release_port = serial21285_release_port,
364 .request_port = serial21285_request_port,
365 .config_port = serial21285_config_port,
366 .verify_port = serial21285_verify_port,
367};
368
369static struct uart_port serial21285_port = {
370 .mapbase = 0x42000160,
371 .iotype = UPIO_MEM,
372 .irq = 0,
373 .fifosize = 16,
374 .ops = &serial21285_ops,
375 .flags = UPF_BOOT_AUTOCONF,
376};
377
378static void serial21285_setup_ports(void)
379{
380 serial21285_port.uartclk = mem_fclk_21285 / 4;
381}
382
383#ifdef CONFIG_SERIAL_21285_CONSOLE
384static void serial21285_console_putchar(struct uart_port *port, unsigned char ch)
385{
386 while (*CSR_UARTFLG & 0x20)
387 barrier();
388 *CSR_UARTDR = ch;
389}
390
391static void
392serial21285_console_write(struct console *co, const char *s,
393 unsigned int count)
394{
395 uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
396}
397
398static void __init
399serial21285_get_options(struct uart_port *port, int *baud,
400 int *parity, int *bits)
401{
402 if (*CSR_UARTCON == 1) {
403 unsigned int tmp;
404
405 tmp = *CSR_H_UBRLCR;
406 switch (tmp & 0x60) {
407 case 0x00:
408 *bits = 5;
409 break;
410 case 0x20:
411 *bits = 6;
412 break;
413 case 0x40:
414 *bits = 7;
415 break;
416 default:
417 case 0x60:
418 *bits = 8;
419 break;
420 }
421
422 if (tmp & H_UBRLCR_PARENB) {
423 *parity = 'o';
424 if (tmp & H_UBRLCR_PAREVN)
425 *parity = 'e';
426 }
427
428 tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
429
430 *baud = port->uartclk / (16 * (tmp + 1));
431 }
432}
433
434static int __init serial21285_console_setup(struct console *co, char *options)
435{
436 struct uart_port *port = &serial21285_port;
437 int baud = 9600;
438 int bits = 8;
439 int parity = 'n';
440 int flow = 'n';
441
442 /*
443 * Check whether an invalid uart number has been specified, and
444 * if so, search for the first available port that does have
445 * console support.
446 */
447 if (options)
448 uart_parse_options(options, &baud, &parity, &bits, &flow);
449 else
450 serial21285_get_options(port, &baud, &parity, &bits);
451
452 return uart_set_options(port, co, baud, parity, bits, flow);
453}
454
455static struct uart_driver serial21285_reg;
456
457static struct console serial21285_console =
458{
459 .name = SERIAL_21285_NAME,
460 .write = serial21285_console_write,
461 .device = uart_console_device,
462 .setup = serial21285_console_setup,
463 .flags = CON_PRINTBUFFER,
464 .index = -1,
465 .data = &serial21285_reg,
466};
467
468static int __init rs285_console_init(void)
469{
470 serial21285_setup_ports();
471 register_console(&serial21285_console);
472 return 0;
473}
474console_initcall(rs285_console_init);
475
476#define SERIAL_21285_CONSOLE &serial21285_console
477#else
478#define SERIAL_21285_CONSOLE NULL
479#endif
480
481static struct uart_driver serial21285_reg = {
482 .owner = THIS_MODULE,
483 .driver_name = "ttyFB",
484 .dev_name = "ttyFB",
485 .major = SERIAL_21285_MAJOR,
486 .minor = SERIAL_21285_MINOR,
487 .nr = 1,
488 .cons = SERIAL_21285_CONSOLE,
489};
490
491static int __init serial21285_init(void)
492{
493 int ret;
494
495 printk(KERN_INFO "Serial: 21285 driver\n");
496
497 serial21285_setup_ports();
498
499 ret = uart_register_driver(&serial21285_reg);
500 if (ret == 0)
501 uart_add_one_port(&serial21285_reg, &serial21285_port);
502
503 return ret;
504}
505
506static void __exit serial21285_exit(void)
507{
508 uart_remove_one_port(&serial21285_reg, &serial21285_port);
509 uart_unregister_driver(&serial21285_reg);
510}
511
512module_init(serial21285_init);
513module_exit(serial21285_exit);
514
515MODULE_LICENSE("GPL");
516MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver");
517MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);