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
42 static const char serial21285_name[] = "Footbridge UART";
43
44 #define tx_enabled(port) ((port)->unused[0])
45 #define rx_enabled(port) ((port)->unused[1])
46
47 /*
48 * The documented expression for selecting the divisor is:
49 * BAUD_BASE / baud - 1
50 * However, typically BAUD_BASE is not divisible by baud, so
51 * we want to select the divisor that gives us the minimum
52 * error. Therefore, we want:
53 * int(BAUD_BASE / baud - 0.5) ->
54 * int(BAUD_BASE / baud - (baud >> 1) / baud) ->
55 * int((BAUD_BASE - (baud >> 1)) / baud)
56 */
57
serial21285_stop_tx(struct uart_port * port)58 static void serial21285_stop_tx(struct uart_port *port)
59 {
60 if (tx_enabled(port)) {
61 disable_irq_nosync(IRQ_CONTX);
62 tx_enabled(port) = 0;
63 }
64 }
65
serial21285_start_tx(struct uart_port * port)66 static void serial21285_start_tx(struct uart_port *port)
67 {
68 if (!tx_enabled(port)) {
69 enable_irq(IRQ_CONTX);
70 tx_enabled(port) = 1;
71 }
72 }
73
serial21285_stop_rx(struct uart_port * port)74 static void serial21285_stop_rx(struct uart_port *port)
75 {
76 if (rx_enabled(port)) {
77 disable_irq_nosync(IRQ_CONRX);
78 rx_enabled(port) = 0;
79 }
80 }
81
serial21285_rx_chars(int irq,void * dev_id)82 static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
83 {
84 struct uart_port *port = dev_id;
85 unsigned int status, ch, flag, rxs, max_count = 256;
86
87 status = *CSR_UARTFLG;
88 while (!(status & 0x10) && max_count--) {
89 ch = *CSR_UARTDR;
90 flag = TTY_NORMAL;
91 port->icount.rx++;
92
93 rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
94 if (unlikely(rxs & RXSTAT_ANYERR)) {
95 if (rxs & RXSTAT_PARITY)
96 port->icount.parity++;
97 else if (rxs & RXSTAT_FRAME)
98 port->icount.frame++;
99 if (rxs & RXSTAT_OVERRUN)
100 port->icount.overrun++;
101
102 rxs &= port->read_status_mask;
103
104 if (rxs & RXSTAT_PARITY)
105 flag = TTY_PARITY;
106 else if (rxs & RXSTAT_FRAME)
107 flag = TTY_FRAME;
108 }
109
110 uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
111
112 status = *CSR_UARTFLG;
113 }
114 tty_flip_buffer_push(&port->state->port);
115
116 return IRQ_HANDLED;
117 }
118
serial21285_tx_chars(int irq,void * dev_id)119 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
120 {
121 struct uart_port *port = dev_id;
122 struct circ_buf *xmit = &port->state->xmit;
123 int count = 256;
124
125 if (port->x_char) {
126 *CSR_UARTDR = port->x_char;
127 port->icount.tx++;
128 port->x_char = 0;
129 goto out;
130 }
131 if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
132 serial21285_stop_tx(port);
133 goto out;
134 }
135
136 do {
137 *CSR_UARTDR = xmit->buf[xmit->tail];
138 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
139 port->icount.tx++;
140 if (uart_circ_empty(xmit))
141 break;
142 } while (--count > 0 && !(*CSR_UARTFLG & 0x20));
143
144 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
145 uart_write_wakeup(port);
146
147 if (uart_circ_empty(xmit))
148 serial21285_stop_tx(port);
149
150 out:
151 return IRQ_HANDLED;
152 }
153
serial21285_tx_empty(struct uart_port * port)154 static unsigned int serial21285_tx_empty(struct uart_port *port)
155 {
156 return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
157 }
158
159 /* no modem control lines */
serial21285_get_mctrl(struct uart_port * port)160 static unsigned int serial21285_get_mctrl(struct uart_port *port)
161 {
162 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
163 }
164
serial21285_set_mctrl(struct uart_port * port,unsigned int mctrl)165 static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
166 {
167 }
168
serial21285_break_ctl(struct uart_port * port,int break_state)169 static void serial21285_break_ctl(struct uart_port *port, int break_state)
170 {
171 unsigned long flags;
172 unsigned int h_lcr;
173
174 spin_lock_irqsave(&port->lock, flags);
175 h_lcr = *CSR_H_UBRLCR;
176 if (break_state)
177 h_lcr |= H_UBRLCR_BREAK;
178 else
179 h_lcr &= ~H_UBRLCR_BREAK;
180 *CSR_H_UBRLCR = h_lcr;
181 spin_unlock_irqrestore(&port->lock, flags);
182 }
183
serial21285_startup(struct uart_port * port)184 static int serial21285_startup(struct uart_port *port)
185 {
186 int ret;
187
188 tx_enabled(port) = 1;
189 rx_enabled(port) = 1;
190
191 ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
192 serial21285_name, port);
193 if (ret == 0) {
194 ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
195 serial21285_name, port);
196 if (ret)
197 free_irq(IRQ_CONRX, port);
198 }
199
200 return ret;
201 }
202
serial21285_shutdown(struct uart_port * port)203 static void serial21285_shutdown(struct uart_port *port)
204 {
205 free_irq(IRQ_CONTX, port);
206 free_irq(IRQ_CONRX, port);
207 }
208
209 static void
serial21285_set_termios(struct uart_port * port,struct ktermios * termios,struct ktermios * old)210 serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
211 struct ktermios *old)
212 {
213 unsigned long flags;
214 unsigned int baud, quot, h_lcr, b;
215
216 /*
217 * We don't support modem control lines.
218 */
219 termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
220 termios->c_cflag |= CLOCAL;
221
222 /*
223 * We don't support BREAK character recognition.
224 */
225 termios->c_iflag &= ~(IGNBRK | BRKINT);
226
227 /*
228 * Ask the core to calculate the divisor for us.
229 */
230 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
231 quot = uart_get_divisor(port, baud);
232 b = port->uartclk / (16 * quot);
233 tty_termios_encode_baud_rate(termios, b, b);
234
235 switch (termios->c_cflag & CSIZE) {
236 case CS5:
237 h_lcr = 0x00;
238 break;
239 case CS6:
240 h_lcr = 0x20;
241 break;
242 case CS7:
243 h_lcr = 0x40;
244 break;
245 default: /* CS8 */
246 h_lcr = 0x60;
247 break;
248 }
249
250 if (termios->c_cflag & CSTOPB)
251 h_lcr |= H_UBRLCR_STOPB;
252 if (termios->c_cflag & PARENB) {
253 h_lcr |= H_UBRLCR_PARENB;
254 if (!(termios->c_cflag & PARODD))
255 h_lcr |= H_UBRLCR_PAREVN;
256 }
257
258 if (port->fifosize)
259 h_lcr |= H_UBRLCR_FIFO;
260
261 spin_lock_irqsave(&port->lock, flags);
262
263 /*
264 * Update the per-port timeout.
265 */
266 uart_update_timeout(port, termios->c_cflag, baud);
267
268 /*
269 * Which character status flags are we interested in?
270 */
271 port->read_status_mask = RXSTAT_OVERRUN;
272 if (termios->c_iflag & INPCK)
273 port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
274
275 /*
276 * Which character status flags should we ignore?
277 */
278 port->ignore_status_mask = 0;
279 if (termios->c_iflag & IGNPAR)
280 port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
281 if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
282 port->ignore_status_mask |= RXSTAT_OVERRUN;
283
284 /*
285 * Ignore all characters if CREAD is not set.
286 */
287 if ((termios->c_cflag & CREAD) == 0)
288 port->ignore_status_mask |= RXSTAT_DUMMY_READ;
289
290 quot -= 1;
291
292 *CSR_UARTCON = 0;
293 *CSR_L_UBRLCR = quot & 0xff;
294 *CSR_M_UBRLCR = (quot >> 8) & 0x0f;
295 *CSR_H_UBRLCR = h_lcr;
296 *CSR_UARTCON = 1;
297
298 spin_unlock_irqrestore(&port->lock, flags);
299 }
300
serial21285_type(struct uart_port * port)301 static const char *serial21285_type(struct uart_port *port)
302 {
303 return port->type == PORT_21285 ? "DC21285" : NULL;
304 }
305
serial21285_release_port(struct uart_port * port)306 static void serial21285_release_port(struct uart_port *port)
307 {
308 release_mem_region(port->mapbase, 32);
309 }
310
serial21285_request_port(struct uart_port * port)311 static int serial21285_request_port(struct uart_port *port)
312 {
313 return request_mem_region(port->mapbase, 32, serial21285_name)
314 != NULL ? 0 : -EBUSY;
315 }
316
serial21285_config_port(struct uart_port * port,int flags)317 static void serial21285_config_port(struct uart_port *port, int flags)
318 {
319 if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
320 port->type = PORT_21285;
321 }
322
323 /*
324 * verify the new serial_struct (for TIOCSSERIAL).
325 */
serial21285_verify_port(struct uart_port * port,struct serial_struct * ser)326 static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
327 {
328 int ret = 0;
329 if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
330 ret = -EINVAL;
331 if (ser->irq <= 0)
332 ret = -EINVAL;
333 if (ser->baud_base != port->uartclk / 16)
334 ret = -EINVAL;
335 return ret;
336 }
337
338 static const struct uart_ops serial21285_ops = {
339 .tx_empty = serial21285_tx_empty,
340 .get_mctrl = serial21285_get_mctrl,
341 .set_mctrl = serial21285_set_mctrl,
342 .stop_tx = serial21285_stop_tx,
343 .start_tx = serial21285_start_tx,
344 .stop_rx = serial21285_stop_rx,
345 .break_ctl = serial21285_break_ctl,
346 .startup = serial21285_startup,
347 .shutdown = serial21285_shutdown,
348 .set_termios = serial21285_set_termios,
349 .type = serial21285_type,
350 .release_port = serial21285_release_port,
351 .request_port = serial21285_request_port,
352 .config_port = serial21285_config_port,
353 .verify_port = serial21285_verify_port,
354 };
355
356 static struct uart_port serial21285_port = {
357 .mapbase = 0x42000160,
358 .iotype = UPIO_MEM,
359 .irq = 0,
360 .fifosize = 16,
361 .ops = &serial21285_ops,
362 .flags = UPF_BOOT_AUTOCONF,
363 };
364
serial21285_setup_ports(void)365 static void serial21285_setup_ports(void)
366 {
367 serial21285_port.uartclk = mem_fclk_21285 / 4;
368 }
369
370 #ifdef CONFIG_SERIAL_21285_CONSOLE
serial21285_console_putchar(struct uart_port * port,int ch)371 static void serial21285_console_putchar(struct uart_port *port, int ch)
372 {
373 while (*CSR_UARTFLG & 0x20)
374 barrier();
375 *CSR_UARTDR = ch;
376 }
377
378 static void
serial21285_console_write(struct console * co,const char * s,unsigned int count)379 serial21285_console_write(struct console *co, const char *s,
380 unsigned int count)
381 {
382 uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
383 }
384
385 static void __init
serial21285_get_options(struct uart_port * port,int * baud,int * parity,int * bits)386 serial21285_get_options(struct uart_port *port, int *baud,
387 int *parity, int *bits)
388 {
389 if (*CSR_UARTCON == 1) {
390 unsigned int tmp;
391
392 tmp = *CSR_H_UBRLCR;
393 switch (tmp & 0x60) {
394 case 0x00:
395 *bits = 5;
396 break;
397 case 0x20:
398 *bits = 6;
399 break;
400 case 0x40:
401 *bits = 7;
402 break;
403 default:
404 case 0x60:
405 *bits = 8;
406 break;
407 }
408
409 if (tmp & H_UBRLCR_PARENB) {
410 *parity = 'o';
411 if (tmp & H_UBRLCR_PAREVN)
412 *parity = 'e';
413 }
414
415 tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
416
417 *baud = port->uartclk / (16 * (tmp + 1));
418 }
419 }
420
serial21285_console_setup(struct console * co,char * options)421 static int __init serial21285_console_setup(struct console *co, char *options)
422 {
423 struct uart_port *port = &serial21285_port;
424 int baud = 9600;
425 int bits = 8;
426 int parity = 'n';
427 int flow = 'n';
428
429 if (machine_is_personal_server())
430 baud = 57600;
431
432 /*
433 * Check whether an invalid uart number has been specified, and
434 * if so, search for the first available port that does have
435 * console support.
436 */
437 if (options)
438 uart_parse_options(options, &baud, &parity, &bits, &flow);
439 else
440 serial21285_get_options(port, &baud, &parity, &bits);
441
442 return uart_set_options(port, co, baud, parity, bits, flow);
443 }
444
445 static struct uart_driver serial21285_reg;
446
447 static struct console serial21285_console =
448 {
449 .name = SERIAL_21285_NAME,
450 .write = serial21285_console_write,
451 .device = uart_console_device,
452 .setup = serial21285_console_setup,
453 .flags = CON_PRINTBUFFER,
454 .index = -1,
455 .data = &serial21285_reg,
456 };
457
rs285_console_init(void)458 static int __init rs285_console_init(void)
459 {
460 serial21285_setup_ports();
461 register_console(&serial21285_console);
462 return 0;
463 }
464 console_initcall(rs285_console_init);
465
466 #define SERIAL_21285_CONSOLE &serial21285_console
467 #else
468 #define SERIAL_21285_CONSOLE NULL
469 #endif
470
471 static struct uart_driver serial21285_reg = {
472 .owner = THIS_MODULE,
473 .driver_name = "ttyFB",
474 .dev_name = "ttyFB",
475 .major = SERIAL_21285_MAJOR,
476 .minor = SERIAL_21285_MINOR,
477 .nr = 1,
478 .cons = SERIAL_21285_CONSOLE,
479 };
480
serial21285_init(void)481 static int __init serial21285_init(void)
482 {
483 int ret;
484
485 printk(KERN_INFO "Serial: 21285 driver\n");
486
487 serial21285_setup_ports();
488
489 ret = uart_register_driver(&serial21285_reg);
490 if (ret == 0)
491 uart_add_one_port(&serial21285_reg, &serial21285_port);
492
493 return ret;
494 }
495
serial21285_exit(void)496 static void __exit serial21285_exit(void)
497 {
498 uart_remove_one_port(&serial21285_reg, &serial21285_port);
499 uart_unregister_driver(&serial21285_reg);
500 }
501
502 module_init(serial21285_init);
503 module_exit(serial21285_exit);
504
505 MODULE_LICENSE("GPL");
506 MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver");
507 MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);
508
