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
altera_jtaguart_tx_space(struct uart_port * port,u32 * ctlp)53 static unsigned int altera_jtaguart_tx_space(struct uart_port *port, u32 *ctlp)
54 {
55 u32 ctl = readl(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
altera_jtaguart_tx_empty(struct uart_port * port)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
altera_jtaguart_get_mctrl(struct uart_port * port)68 static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
69 {
70 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
71 }
72
altera_jtaguart_set_mctrl(struct uart_port * port,unsigned int sigs)73 static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
74 {
75 }
76
altera_jtaguart_start_tx(struct uart_port * port)77 static void altera_jtaguart_start_tx(struct uart_port *port)
78 {
79 port->read_status_mask |= ALTERA_JTAGUART_CONTROL_WE_MSK;
80 writel(port->read_status_mask,
81 port->membase + ALTERA_JTAGUART_CONTROL_REG);
82 }
83
altera_jtaguart_stop_tx(struct uart_port * port)84 static void altera_jtaguart_stop_tx(struct uart_port *port)
85 {
86 port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
87 writel(port->read_status_mask,
88 port->membase + ALTERA_JTAGUART_CONTROL_REG);
89 }
90
altera_jtaguart_stop_rx(struct uart_port * port)91 static void altera_jtaguart_stop_rx(struct uart_port *port)
92 {
93 port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
94 writel(port->read_status_mask,
95 port->membase + ALTERA_JTAGUART_CONTROL_REG);
96 }
97
altera_jtaguart_break_ctl(struct uart_port * port,int break_state)98 static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
99 {
100 }
101
altera_jtaguart_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old)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(termios, old);
109 }
110
altera_jtaguart_rx_chars(struct uart_port * port)111 static void altera_jtaguart_rx_chars(struct uart_port *port)
112 {
113 u32 status;
114 u8 ch;
115
116 while ((status = readl(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, 0, 0, ch, TTY_NORMAL);
124 }
125
126 tty_flip_buffer_push(&port->state->port);
127 }
128
altera_jtaguart_tx_chars(struct uart_port * port)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
altera_jtaguart_interrupt(int irq,void * data)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(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
148 ALTERA_JTAGUART_CONTROL_RI_OFF) & port->read_status_mask;
149
150 spin_lock(&port->lock);
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 spin_unlock(&port->lock);
158
159 return IRQ_RETVAL(isr);
160 }
161
altera_jtaguart_config_port(struct uart_port * port,int flags)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(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
168 }
169
altera_jtaguart_startup(struct uart_port * port)170 static int altera_jtaguart_startup(struct uart_port *port)
171 {
172 unsigned long flags;
173 int ret;
174
175 ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
176 DRV_NAME, 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 spin_lock_irqsave(&port->lock, flags);
184
185 /* Enable RX interrupts now */
186 port->read_status_mask = ALTERA_JTAGUART_CONTROL_RE_MSK;
187 writel(port->read_status_mask,
188 port->membase + ALTERA_JTAGUART_CONTROL_REG);
189
190 spin_unlock_irqrestore(&port->lock, flags);
191
192 return 0;
193 }
194
altera_jtaguart_shutdown(struct uart_port * port)195 static void altera_jtaguart_shutdown(struct uart_port *port)
196 {
197 unsigned long flags;
198
199 spin_lock_irqsave(&port->lock, flags);
200
201 /* Disable all interrupts now */
202 port->read_status_mask = 0;
203 writel(port->read_status_mask,
204 port->membase + ALTERA_JTAGUART_CONTROL_REG);
205
206 spin_unlock_irqrestore(&port->lock, flags);
207
208 free_irq(port->irq, port);
209 }
210
altera_jtaguart_type(struct uart_port * port)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
altera_jtaguart_request_port(struct uart_port * port)216 static int altera_jtaguart_request_port(struct uart_port *port)
217 {
218 /* UARTs always present */
219 return 0;
220 }
221
altera_jtaguart_release_port(struct uart_port * port)222 static void altera_jtaguart_release_port(struct uart_port *port)
223 {
224 /* Nothing to release... */
225 }
226
altera_jtaguart_verify_port(struct uart_port * port,struct serial_struct * ser)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)
altera_jtaguart_console_putc(struct uart_port * port,unsigned char c)262 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
263 {
264 unsigned long flags;
265 u32 status;
266
267 spin_lock_irqsave(&port->lock, flags);
268 while (!altera_jtaguart_tx_space(port, &status)) {
269 spin_unlock_irqrestore(&port->lock, flags);
270
271 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
272 return; /* no connection activity */
273 }
274
275 cpu_relax();
276 spin_lock_irqsave(&port->lock, flags);
277 }
278 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
279 spin_unlock_irqrestore(&port->lock, flags);
280 }
281 #else
altera_jtaguart_console_putc(struct uart_port * port,unsigned char c)282 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
283 {
284 unsigned long flags;
285
286 spin_lock_irqsave(&port->lock, flags);
287 while (!altera_jtaguart_tx_space(port, NULL)) {
288 spin_unlock_irqrestore(&port->lock, flags);
289 cpu_relax();
290 spin_lock_irqsave(&port->lock, flags);
291 }
292 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
293 spin_unlock_irqrestore(&port->lock, flags);
294 }
295 #endif
296
altera_jtaguart_console_write(struct console * co,const char * s,unsigned int count)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, altera_jtaguart_console_putc);
303 }
304
altera_jtaguart_console_setup(struct console * co,char * options)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
altera_jtaguart_console_init(void)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
altera_jtaguart_earlycon_write(struct console * co,const char * s,unsigned int count)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(&dev->port, s, count, altera_jtaguart_console_putc);
346 }
347
altera_jtaguart_earlycon_setup(struct earlycon_device * dev,const char * options)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
altera_jtaguart_probe(struct platform_device * pdev)376 static int altera_jtaguart_probe(struct platform_device *pdev)
377 {
378 struct altera_jtaguart_platform_uart *platp =
379 dev_get_platdata(&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(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(&altera_jtaguart_driver, port);
424
425 return 0;
426 }
427
altera_jtaguart_remove(struct platform_device * pdev)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(&altera_jtaguart_driver, port);
438 iounmap(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
altera_jtaguart_init(void)461 static int __init altera_jtaguart_init(void)
462 {
463 int rc;
464
465 rc = uart_register_driver(&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(&altera_jtaguart_driver);
471 return rc;
472 }
473
altera_jtaguart_exit(void)474 static void __exit altera_jtaguart_exit(void)
475 {
476 platform_driver_unregister(&altera_jtaguart_platform_driver);
477 uart_unregister_driver(&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
