1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * altera_jtaguart.c -- Altera JTAG UART driver |
4 | * |
5 | * Based on mcf.c -- Freescale ColdFire UART driver |
6 | * |
7 | * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com> |
8 | * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw> |
9 | * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch> |
10 | */ |
11 | |
12 | #include <linux/bitfield.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/init.h> |
15 | #include <linux/interrupt.h> |
16 | #include <linux/module.h> |
17 | #include <linux/console.h> |
18 | #include <linux/of.h> |
19 | #include <linux/tty.h> |
20 | #include <linux/tty_flip.h> |
21 | #include <linux/serial.h> |
22 | #include <linux/serial_core.h> |
23 | #include <linux/platform_device.h> |
24 | #include <linux/io.h> |
25 | #include <linux/altera_jtaguart.h> |
26 | |
27 | #define DRV_NAME "altera_jtaguart" |
28 | |
29 | /* |
30 | * Altera JTAG UART register definitions according to the Altera JTAG UART |
31 | * datasheet: https://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf |
32 | */ |
33 | |
34 | #define ALTERA_JTAGUART_SIZE 8 |
35 | |
36 | #define ALTERA_JTAGUART_DATA_REG 0 |
37 | |
38 | #define ALTERA_JTAGUART_DATA_DATA_MSK 0x000000FF |
39 | #define ALTERA_JTAGUART_DATA_RVALID_MSK 0x00008000 |
40 | #define ALTERA_JTAGUART_DATA_RAVAIL_MSK 0xFFFF0000 |
41 | #define ALTERA_JTAGUART_DATA_RAVAIL_OFF 16 |
42 | |
43 | #define ALTERA_JTAGUART_CONTROL_REG 4 |
44 | |
45 | #define ALTERA_JTAGUART_CONTROL_RE_MSK 0x00000001 |
46 | #define ALTERA_JTAGUART_CONTROL_WE_MSK 0x00000002 |
47 | #define ALTERA_JTAGUART_CONTROL_RI_MSK 0x00000100 |
48 | #define ALTERA_JTAGUART_CONTROL_RI_OFF 8 |
49 | #define ALTERA_JTAGUART_CONTROL_WI_MSK 0x00000200 |
50 | #define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400 |
51 | #define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000 |
52 | |
53 | static unsigned int altera_jtaguart_tx_space(struct uart_port *port, u32 *ctlp) |
54 | { |
55 | u32 ctl = readl(addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
56 | |
57 | if (ctlp) |
58 | *ctlp = ctl; |
59 | |
60 | return FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ctl); |
61 | } |
62 | |
63 | static unsigned int altera_jtaguart_tx_empty(struct uart_port *port) |
64 | { |
65 | return altera_jtaguart_tx_space(port, NULL) ? TIOCSER_TEMT : 0; |
66 | } |
67 | |
68 | static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port) |
69 | { |
70 | return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; |
71 | } |
72 | |
73 | static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs) |
74 | { |
75 | } |
76 | |
77 | static void altera_jtaguart_start_tx(struct uart_port *port) |
78 | { |
79 | port->read_status_mask |= ALTERA_JTAGUART_CONTROL_WE_MSK; |
80 | writel(val: port->read_status_mask, |
81 | addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
82 | } |
83 | |
84 | static void altera_jtaguart_stop_tx(struct uart_port *port) |
85 | { |
86 | port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_WE_MSK; |
87 | writel(val: port->read_status_mask, |
88 | addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
89 | } |
90 | |
91 | static void altera_jtaguart_stop_rx(struct uart_port *port) |
92 | { |
93 | port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_RE_MSK; |
94 | writel(val: port->read_status_mask, |
95 | addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
96 | } |
97 | |
98 | static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state) |
99 | { |
100 | } |
101 | |
102 | static void altera_jtaguart_set_termios(struct uart_port *port, |
103 | struct ktermios *termios, |
104 | const struct ktermios *old) |
105 | { |
106 | /* Just copy the old termios settings back */ |
107 | if (old) |
108 | tty_termios_copy_hw(new: termios, old); |
109 | } |
110 | |
111 | static void altera_jtaguart_rx_chars(struct uart_port *port) |
112 | { |
113 | u32 status; |
114 | u8 ch; |
115 | |
116 | while ((status = readl(addr: port->membase + ALTERA_JTAGUART_DATA_REG)) & |
117 | ALTERA_JTAGUART_DATA_RVALID_MSK) { |
118 | ch = status & ALTERA_JTAGUART_DATA_DATA_MSK; |
119 | port->icount.rx++; |
120 | |
121 | if (uart_handle_sysrq_char(port, ch)) |
122 | continue; |
123 | uart_insert_char(port, status: 0, overrun: 0, ch, TTY_NORMAL); |
124 | } |
125 | |
126 | tty_flip_buffer_push(port: &port->state->port); |
127 | } |
128 | |
129 | static void altera_jtaguart_tx_chars(struct uart_port *port) |
130 | { |
131 | unsigned int count; |
132 | u8 ch; |
133 | |
134 | count = altera_jtaguart_tx_space(port, NULL); |
135 | |
136 | uart_port_tx_limited(port, ch, count, |
137 | true, |
138 | writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG), |
139 | ({})); |
140 | } |
141 | |
142 | static irqreturn_t altera_jtaguart_interrupt(int irq, void *data) |
143 | { |
144 | struct uart_port *port = data; |
145 | unsigned int isr; |
146 | |
147 | isr = (readl(addr: port->membase + ALTERA_JTAGUART_CONTROL_REG) >> |
148 | ALTERA_JTAGUART_CONTROL_RI_OFF) & port->read_status_mask; |
149 | |
150 | uart_port_lock(up: port); |
151 | |
152 | if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK) |
153 | altera_jtaguart_rx_chars(port); |
154 | if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK) |
155 | altera_jtaguart_tx_chars(port); |
156 | |
157 | uart_port_unlock(up: port); |
158 | |
159 | return IRQ_RETVAL(isr); |
160 | } |
161 | |
162 | static void altera_jtaguart_config_port(struct uart_port *port, int flags) |
163 | { |
164 | port->type = PORT_ALTERA_JTAGUART; |
165 | |
166 | /* Clear mask, so no surprise interrupts. */ |
167 | writel(val: 0, addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
168 | } |
169 | |
170 | static int altera_jtaguart_startup(struct uart_port *port) |
171 | { |
172 | unsigned long flags; |
173 | int ret; |
174 | |
175 | ret = request_irq(irq: port->irq, handler: altera_jtaguart_interrupt, flags: 0, |
176 | DRV_NAME, dev: port); |
177 | if (ret) { |
178 | pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d " |
179 | "interrupt vector=%d\n" , port->line, port->irq); |
180 | return ret; |
181 | } |
182 | |
183 | uart_port_lock_irqsave(up: port, flags: &flags); |
184 | |
185 | /* Enable RX interrupts now */ |
186 | port->read_status_mask = ALTERA_JTAGUART_CONTROL_RE_MSK; |
187 | writel(val: port->read_status_mask, |
188 | addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
189 | |
190 | uart_port_unlock_irqrestore(up: port, flags); |
191 | |
192 | return 0; |
193 | } |
194 | |
195 | static void altera_jtaguart_shutdown(struct uart_port *port) |
196 | { |
197 | unsigned long flags; |
198 | |
199 | uart_port_lock_irqsave(up: port, flags: &flags); |
200 | |
201 | /* Disable all interrupts now */ |
202 | port->read_status_mask = 0; |
203 | writel(val: port->read_status_mask, |
204 | addr: port->membase + ALTERA_JTAGUART_CONTROL_REG); |
205 | |
206 | uart_port_unlock_irqrestore(up: port, flags); |
207 | |
208 | free_irq(port->irq, port); |
209 | } |
210 | |
211 | static const char *altera_jtaguart_type(struct uart_port *port) |
212 | { |
213 | return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL; |
214 | } |
215 | |
216 | static int altera_jtaguart_request_port(struct uart_port *port) |
217 | { |
218 | /* UARTs always present */ |
219 | return 0; |
220 | } |
221 | |
222 | static void altera_jtaguart_release_port(struct uart_port *port) |
223 | { |
224 | /* Nothing to release... */ |
225 | } |
226 | |
227 | static int altera_jtaguart_verify_port(struct uart_port *port, |
228 | struct serial_struct *ser) |
229 | { |
230 | if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART) |
231 | return -EINVAL; |
232 | return 0; |
233 | } |
234 | |
235 | /* |
236 | * Define the basic serial functions we support. |
237 | */ |
238 | static const struct uart_ops altera_jtaguart_ops = { |
239 | .tx_empty = altera_jtaguart_tx_empty, |
240 | .get_mctrl = altera_jtaguart_get_mctrl, |
241 | .set_mctrl = altera_jtaguart_set_mctrl, |
242 | .start_tx = altera_jtaguart_start_tx, |
243 | .stop_tx = altera_jtaguart_stop_tx, |
244 | .stop_rx = altera_jtaguart_stop_rx, |
245 | .break_ctl = altera_jtaguart_break_ctl, |
246 | .startup = altera_jtaguart_startup, |
247 | .shutdown = altera_jtaguart_shutdown, |
248 | .set_termios = altera_jtaguart_set_termios, |
249 | .type = altera_jtaguart_type, |
250 | .request_port = altera_jtaguart_request_port, |
251 | .release_port = altera_jtaguart_release_port, |
252 | .config_port = altera_jtaguart_config_port, |
253 | .verify_port = altera_jtaguart_verify_port, |
254 | }; |
255 | |
256 | #define ALTERA_JTAGUART_MAXPORTS 1 |
257 | static struct uart_port altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS]; |
258 | |
259 | #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) |
260 | |
261 | #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS) |
262 | static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c) |
263 | { |
264 | unsigned long flags; |
265 | u32 status; |
266 | |
267 | uart_port_lock_irqsave(up: port, flags: &flags); |
268 | while (!altera_jtaguart_tx_space(port, ctlp: &status)) { |
269 | uart_port_unlock_irqrestore(up: port, flags); |
270 | |
271 | if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) { |
272 | return; /* no connection activity */ |
273 | } |
274 | |
275 | cpu_relax(); |
276 | uart_port_lock_irqsave(up: port, flags: &flags); |
277 | } |
278 | writel(val: c, addr: port->membase + ALTERA_JTAGUART_DATA_REG); |
279 | uart_port_unlock_irqrestore(up: port, flags); |
280 | } |
281 | #else |
282 | static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c) |
283 | { |
284 | unsigned long flags; |
285 | |
286 | uart_port_lock_irqsave(port, &flags); |
287 | while (!altera_jtaguart_tx_space(port, NULL)) { |
288 | uart_port_unlock_irqrestore(port, flags); |
289 | cpu_relax(); |
290 | uart_port_lock_irqsave(port, &flags); |
291 | } |
292 | writel(c, port->membase + ALTERA_JTAGUART_DATA_REG); |
293 | uart_port_unlock_irqrestore(port, flags); |
294 | } |
295 | #endif |
296 | |
297 | static void altera_jtaguart_console_write(struct console *co, const char *s, |
298 | unsigned int count) |
299 | { |
300 | struct uart_port *port = &altera_jtaguart_ports[co->index]; |
301 | |
302 | uart_console_write(port, s, count, putchar: altera_jtaguart_console_putc); |
303 | } |
304 | |
305 | static int __init altera_jtaguart_console_setup(struct console *co, |
306 | char *options) |
307 | { |
308 | struct uart_port *port; |
309 | |
310 | if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS) |
311 | return -EINVAL; |
312 | port = &altera_jtaguart_ports[co->index]; |
313 | if (port->membase == NULL) |
314 | return -ENODEV; |
315 | return 0; |
316 | } |
317 | |
318 | static struct uart_driver altera_jtaguart_driver; |
319 | |
320 | static struct console altera_jtaguart_console = { |
321 | .name = "ttyJ" , |
322 | .write = altera_jtaguart_console_write, |
323 | .device = uart_console_device, |
324 | .setup = altera_jtaguart_console_setup, |
325 | .flags = CON_PRINTBUFFER, |
326 | .index = -1, |
327 | .data = &altera_jtaguart_driver, |
328 | }; |
329 | |
330 | static int __init altera_jtaguart_console_init(void) |
331 | { |
332 | register_console(&altera_jtaguart_console); |
333 | return 0; |
334 | } |
335 | |
336 | console_initcall(altera_jtaguart_console_init); |
337 | |
338 | #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console) |
339 | |
340 | static void altera_jtaguart_earlycon_write(struct console *co, const char *s, |
341 | unsigned int count) |
342 | { |
343 | struct earlycon_device *dev = co->data; |
344 | |
345 | uart_console_write(port: &dev->port, s, count, putchar: altera_jtaguart_console_putc); |
346 | } |
347 | |
348 | static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev, |
349 | const char *options) |
350 | { |
351 | if (!dev->port.membase) |
352 | return -ENODEV; |
353 | |
354 | dev->con->write = altera_jtaguart_earlycon_write; |
355 | return 0; |
356 | } |
357 | |
358 | OF_EARLYCON_DECLARE(juart, "altr,juart-1.0" , altera_jtaguart_earlycon_setup); |
359 | |
360 | #else |
361 | |
362 | #define ALTERA_JTAGUART_CONSOLE NULL |
363 | |
364 | #endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */ |
365 | |
366 | static struct uart_driver altera_jtaguart_driver = { |
367 | .owner = THIS_MODULE, |
368 | .driver_name = "altera_jtaguart" , |
369 | .dev_name = "ttyJ" , |
370 | .major = ALTERA_JTAGUART_MAJOR, |
371 | .minor = ALTERA_JTAGUART_MINOR, |
372 | .nr = ALTERA_JTAGUART_MAXPORTS, |
373 | .cons = ALTERA_JTAGUART_CONSOLE, |
374 | }; |
375 | |
376 | static int altera_jtaguart_probe(struct platform_device *pdev) |
377 | { |
378 | struct altera_jtaguart_platform_uart *platp = |
379 | dev_get_platdata(dev: &pdev->dev); |
380 | struct uart_port *port; |
381 | struct resource *res_mem; |
382 | int i = pdev->id; |
383 | int irq; |
384 | |
385 | /* -1 emphasizes that the platform must have one port, no .N suffix */ |
386 | if (i == -1) |
387 | i = 0; |
388 | |
389 | if (i >= ALTERA_JTAGUART_MAXPORTS) |
390 | return -EINVAL; |
391 | |
392 | port = &altera_jtaguart_ports[i]; |
393 | |
394 | res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
395 | if (res_mem) |
396 | port->mapbase = res_mem->start; |
397 | else if (platp) |
398 | port->mapbase = platp->mapbase; |
399 | else |
400 | return -ENODEV; |
401 | |
402 | irq = platform_get_irq_optional(pdev, 0); |
403 | if (irq < 0 && irq != -ENXIO) |
404 | return irq; |
405 | if (irq > 0) |
406 | port->irq = irq; |
407 | else if (platp) |
408 | port->irq = platp->irq; |
409 | else |
410 | return -ENODEV; |
411 | |
412 | port->membase = ioremap(offset: port->mapbase, ALTERA_JTAGUART_SIZE); |
413 | if (!port->membase) |
414 | return -ENOMEM; |
415 | |
416 | port->line = i; |
417 | port->type = PORT_ALTERA_JTAGUART; |
418 | port->iotype = SERIAL_IO_MEM; |
419 | port->ops = &altera_jtaguart_ops; |
420 | port->flags = UPF_BOOT_AUTOCONF; |
421 | port->dev = &pdev->dev; |
422 | |
423 | uart_add_one_port(reg: &altera_jtaguart_driver, port); |
424 | |
425 | return 0; |
426 | } |
427 | |
428 | static int altera_jtaguart_remove(struct platform_device *pdev) |
429 | { |
430 | struct uart_port *port; |
431 | int i = pdev->id; |
432 | |
433 | if (i == -1) |
434 | i = 0; |
435 | |
436 | port = &altera_jtaguart_ports[i]; |
437 | uart_remove_one_port(reg: &altera_jtaguart_driver, port); |
438 | iounmap(addr: port->membase); |
439 | |
440 | return 0; |
441 | } |
442 | |
443 | #ifdef CONFIG_OF |
444 | static const struct of_device_id altera_jtaguart_match[] = { |
445 | { .compatible = "ALTR,juart-1.0" , }, |
446 | { .compatible = "altr,juart-1.0" , }, |
447 | {}, |
448 | }; |
449 | MODULE_DEVICE_TABLE(of, altera_jtaguart_match); |
450 | #endif /* CONFIG_OF */ |
451 | |
452 | static struct platform_driver altera_jtaguart_platform_driver = { |
453 | .probe = altera_jtaguart_probe, |
454 | .remove = altera_jtaguart_remove, |
455 | .driver = { |
456 | .name = DRV_NAME, |
457 | .of_match_table = of_match_ptr(altera_jtaguart_match), |
458 | }, |
459 | }; |
460 | |
461 | static int __init altera_jtaguart_init(void) |
462 | { |
463 | int rc; |
464 | |
465 | rc = uart_register_driver(uart: &altera_jtaguart_driver); |
466 | if (rc) |
467 | return rc; |
468 | rc = platform_driver_register(&altera_jtaguart_platform_driver); |
469 | if (rc) |
470 | uart_unregister_driver(uart: &altera_jtaguart_driver); |
471 | return rc; |
472 | } |
473 | |
474 | static void __exit altera_jtaguart_exit(void) |
475 | { |
476 | platform_driver_unregister(&altera_jtaguart_platform_driver); |
477 | uart_unregister_driver(uart: &altera_jtaguart_driver); |
478 | } |
479 | |
480 | module_init(altera_jtaguart_init); |
481 | module_exit(altera_jtaguart_exit); |
482 | |
483 | MODULE_DESCRIPTION("Altera JTAG UART driver" ); |
484 | MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>" ); |
485 | MODULE_LICENSE("GPL" ); |
486 | MODULE_ALIAS("platform:" DRV_NAME); |
487 | |