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Linux/drivers/tty/serial/altera_jtaguart.c

  1 /*
  2  * altera_jtaguart.c -- Altera JTAG UART driver
  3  *
  4  * Based on mcf.c -- Freescale ColdFire UART driver
  5  *
  6  * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
  7  * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
  8  * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
  9  *
 10  * This program is free software; you can redistribute it and/or modify
 11  * it under the terms of the GNU General Public License as published by
 12  * the Free Software Foundation; either version 2 of the License, or
 13  * (at your option) any later version.
 14  */
 15 
 16 #include <linux/kernel.h>
 17 #include <linux/init.h>
 18 #include <linux/interrupt.h>
 19 #include <linux/module.h>
 20 #include <linux/console.h>
 21 #include <linux/of.h>
 22 #include <linux/tty.h>
 23 #include <linux/tty_flip.h>
 24 #include <linux/serial.h>
 25 #include <linux/serial_core.h>
 26 #include <linux/platform_device.h>
 27 #include <linux/io.h>
 28 #include <linux/altera_jtaguart.h>
 29 
 30 #define DRV_NAME "altera_jtaguart"
 31 
 32 /*
 33  * Altera JTAG UART register definitions according to the Altera JTAG UART
 34  * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
 35  */
 36 
 37 #define ALTERA_JTAGUART_SIZE                    8
 38 
 39 #define ALTERA_JTAGUART_DATA_REG                0
 40 
 41 #define ALTERA_JTAGUART_DATA_DATA_MSK           0x000000FF
 42 #define ALTERA_JTAGUART_DATA_RVALID_MSK         0x00008000
 43 #define ALTERA_JTAGUART_DATA_RAVAIL_MSK         0xFFFF0000
 44 #define ALTERA_JTAGUART_DATA_RAVAIL_OFF         16
 45 
 46 #define ALTERA_JTAGUART_CONTROL_REG             4
 47 
 48 #define ALTERA_JTAGUART_CONTROL_RE_MSK          0x00000001
 49 #define ALTERA_JTAGUART_CONTROL_WE_MSK          0x00000002
 50 #define ALTERA_JTAGUART_CONTROL_RI_MSK          0x00000100
 51 #define ALTERA_JTAGUART_CONTROL_RI_OFF          8
 52 #define ALTERA_JTAGUART_CONTROL_WI_MSK          0x00000200
 53 #define ALTERA_JTAGUART_CONTROL_AC_MSK          0x00000400
 54 #define ALTERA_JTAGUART_CONTROL_WSPACE_MSK      0xFFFF0000
 55 #define ALTERA_JTAGUART_CONTROL_WSPACE_OFF      16
 56 
 57 /*
 58  * Local per-uart structure.
 59  */
 60 struct altera_jtaguart {
 61         struct uart_port port;
 62         unsigned int sigs;      /* Local copy of line sigs */
 63         unsigned long imr;      /* Local IMR mirror */
 64 };
 65 
 66 static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
 67 {
 68         return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
 69                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
 70 }
 71 
 72 static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
 73 {
 74         return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 75 }
 76 
 77 static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
 78 {
 79 }
 80 
 81 static void altera_jtaguart_start_tx(struct uart_port *port)
 82 {
 83         struct altera_jtaguart *pp =
 84             container_of(port, struct altera_jtaguart, port);
 85 
 86         pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
 87         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 88 }
 89 
 90 static void altera_jtaguart_stop_tx(struct uart_port *port)
 91 {
 92         struct altera_jtaguart *pp =
 93             container_of(port, struct altera_jtaguart, port);
 94 
 95         pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
 96         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 97 }
 98 
 99 static void altera_jtaguart_stop_rx(struct uart_port *port)
100 {
101         struct altera_jtaguart *pp =
102             container_of(port, struct altera_jtaguart, port);
103 
104         pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
105         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
106 }
107 
108 static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
109 {
110 }
111 
112 static void altera_jtaguart_set_termios(struct uart_port *port,
113                                         struct ktermios *termios,
114                                         struct ktermios *old)
115 {
116         /* Just copy the old termios settings back */
117         if (old)
118                 tty_termios_copy_hw(termios, old);
119 }
120 
121 static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
122 {
123         struct uart_port *port = &pp->port;
124         unsigned char ch, flag;
125         unsigned long status;
126 
127         while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
128                ALTERA_JTAGUART_DATA_RVALID_MSK) {
129                 ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
130                 flag = TTY_NORMAL;
131                 port->icount.rx++;
132 
133                 if (uart_handle_sysrq_char(port, ch))
134                         continue;
135                 uart_insert_char(port, 0, 0, ch, flag);
136         }
137 
138         spin_unlock(&port->lock);
139         tty_flip_buffer_push(&port->state->port);
140         spin_lock(&port->lock);
141 }
142 
143 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
144 {
145         struct uart_port *port = &pp->port;
146         struct circ_buf *xmit = &port->state->xmit;
147         unsigned int pending, count;
148 
149         if (port->x_char) {
150                 /* Send special char - probably flow control */
151                 writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
152                 port->x_char = 0;
153                 port->icount.tx++;
154                 return;
155         }
156 
157         pending = uart_circ_chars_pending(xmit);
158         if (pending > 0) {
159                 count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
160                                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
161                         ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
162                 if (count > pending)
163                         count = pending;
164                 if (count > 0) {
165                         pending -= count;
166                         while (count--) {
167                                 writel(xmit->buf[xmit->tail],
168                                        port->membase + ALTERA_JTAGUART_DATA_REG);
169                                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
170                                 port->icount.tx++;
171                         }
172                         if (pending < WAKEUP_CHARS)
173                                 uart_write_wakeup(port);
174                 }
175         }
176 
177         if (pending == 0) {
178                 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
179                 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
180         }
181 }
182 
183 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
184 {
185         struct uart_port *port = data;
186         struct altera_jtaguart *pp =
187             container_of(port, struct altera_jtaguart, port);
188         unsigned int isr;
189 
190         isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
191                ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
192 
193         spin_lock(&port->lock);
194 
195         if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
196                 altera_jtaguart_rx_chars(pp);
197         if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
198                 altera_jtaguart_tx_chars(pp);
199 
200         spin_unlock(&port->lock);
201 
202         return IRQ_RETVAL(isr);
203 }
204 
205 static void altera_jtaguart_config_port(struct uart_port *port, int flags)
206 {
207         port->type = PORT_ALTERA_JTAGUART;
208 
209         /* Clear mask, so no surprise interrupts. */
210         writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
211 }
212 
213 static int altera_jtaguart_startup(struct uart_port *port)
214 {
215         struct altera_jtaguart *pp =
216             container_of(port, struct altera_jtaguart, port);
217         unsigned long flags;
218         int ret;
219 
220         ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
221                         DRV_NAME, port);
222         if (ret) {
223                 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
224                        "interrupt vector=%d\n", port->line, port->irq);
225                 return ret;
226         }
227 
228         spin_lock_irqsave(&port->lock, flags);
229 
230         /* Enable RX interrupts now */
231         pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
232         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
233 
234         spin_unlock_irqrestore(&port->lock, flags);
235 
236         return 0;
237 }
238 
239 static void altera_jtaguart_shutdown(struct uart_port *port)
240 {
241         struct altera_jtaguart *pp =
242             container_of(port, struct altera_jtaguart, port);
243         unsigned long flags;
244 
245         spin_lock_irqsave(&port->lock, flags);
246 
247         /* Disable all interrupts now */
248         pp->imr = 0;
249         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
250 
251         spin_unlock_irqrestore(&port->lock, flags);
252 
253         free_irq(port->irq, port);
254 }
255 
256 static const char *altera_jtaguart_type(struct uart_port *port)
257 {
258         return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
259 }
260 
261 static int altera_jtaguart_request_port(struct uart_port *port)
262 {
263         /* UARTs always present */
264         return 0;
265 }
266 
267 static void altera_jtaguart_release_port(struct uart_port *port)
268 {
269         /* Nothing to release... */
270 }
271 
272 static int altera_jtaguart_verify_port(struct uart_port *port,
273                                        struct serial_struct *ser)
274 {
275         if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
276                 return -EINVAL;
277         return 0;
278 }
279 
280 /*
281  *      Define the basic serial functions we support.
282  */
283 static struct uart_ops altera_jtaguart_ops = {
284         .tx_empty       = altera_jtaguart_tx_empty,
285         .get_mctrl      = altera_jtaguart_get_mctrl,
286         .set_mctrl      = altera_jtaguart_set_mctrl,
287         .start_tx       = altera_jtaguart_start_tx,
288         .stop_tx        = altera_jtaguart_stop_tx,
289         .stop_rx        = altera_jtaguart_stop_rx,
290         .break_ctl      = altera_jtaguart_break_ctl,
291         .startup        = altera_jtaguart_startup,
292         .shutdown       = altera_jtaguart_shutdown,
293         .set_termios    = altera_jtaguart_set_termios,
294         .type           = altera_jtaguart_type,
295         .request_port   = altera_jtaguart_request_port,
296         .release_port   = altera_jtaguart_release_port,
297         .config_port    = altera_jtaguart_config_port,
298         .verify_port    = altera_jtaguart_verify_port,
299 };
300 
301 #define ALTERA_JTAGUART_MAXPORTS 1
302 static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
303 
304 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
305 
306 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
307 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
308 {
309         unsigned long status;
310         unsigned long flags;
311 
312         spin_lock_irqsave(&port->lock, flags);
313         while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
314                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
315                 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
316                         spin_unlock_irqrestore(&port->lock, flags);
317                         return; /* no connection activity */
318                 }
319                 spin_unlock_irqrestore(&port->lock, flags);
320                 cpu_relax();
321                 spin_lock_irqsave(&port->lock, flags);
322         }
323         writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
324         spin_unlock_irqrestore(&port->lock, flags);
325 }
326 #else
327 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
328 {
329         unsigned long flags;
330 
331         spin_lock_irqsave(&port->lock, flags);
332         while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
333                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
334                 spin_unlock_irqrestore(&port->lock, flags);
335                 cpu_relax();
336                 spin_lock_irqsave(&port->lock, flags);
337         }
338         writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
339         spin_unlock_irqrestore(&port->lock, flags);
340 }
341 #endif
342 
343 static void altera_jtaguart_console_write(struct console *co, const char *s,
344                                           unsigned int count)
345 {
346         struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
347 
348         uart_console_write(port, s, count, altera_jtaguart_console_putc);
349 }
350 
351 static int __init altera_jtaguart_console_setup(struct console *co,
352                                                 char *options)
353 {
354         struct uart_port *port;
355 
356         if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
357                 return -EINVAL;
358         port = &altera_jtaguart_ports[co->index].port;
359         if (port->membase == NULL)
360                 return -ENODEV;
361         return 0;
362 }
363 
364 static struct uart_driver altera_jtaguart_driver;
365 
366 static struct console altera_jtaguart_console = {
367         .name   = "ttyJ",
368         .write  = altera_jtaguart_console_write,
369         .device = uart_console_device,
370         .setup  = altera_jtaguart_console_setup,
371         .flags  = CON_PRINTBUFFER,
372         .index  = -1,
373         .data   = &altera_jtaguart_driver,
374 };
375 
376 static int __init altera_jtaguart_console_init(void)
377 {
378         register_console(&altera_jtaguart_console);
379         return 0;
380 }
381 
382 console_initcall(altera_jtaguart_console_init);
383 
384 #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)
385 
386 #else
387 
388 #define ALTERA_JTAGUART_CONSOLE NULL
389 
390 #endif /* CONFIG_ALTERA_JTAGUART_CONSOLE */
391 
392 static struct uart_driver altera_jtaguart_driver = {
393         .owner          = THIS_MODULE,
394         .driver_name    = "altera_jtaguart",
395         .dev_name       = "ttyJ",
396         .major          = ALTERA_JTAGUART_MAJOR,
397         .minor          = ALTERA_JTAGUART_MINOR,
398         .nr             = ALTERA_JTAGUART_MAXPORTS,
399         .cons           = ALTERA_JTAGUART_CONSOLE,
400 };
401 
402 static int altera_jtaguart_probe(struct platform_device *pdev)
403 {
404         struct altera_jtaguart_platform_uart *platp =
405                         dev_get_platdata(&pdev->dev);
406         struct uart_port *port;
407         struct resource *res_irq, *res_mem;
408         int i = pdev->id;
409 
410         /* -1 emphasizes that the platform must have one port, no .N suffix */
411         if (i == -1)
412                 i = 0;
413 
414         if (i >= ALTERA_JTAGUART_MAXPORTS)
415                 return -EINVAL;
416 
417         port = &altera_jtaguart_ports[i].port;
418 
419         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
420         if (res_mem)
421                 port->mapbase = res_mem->start;
422         else if (platp)
423                 port->mapbase = platp->mapbase;
424         else
425                 return -ENODEV;
426 
427         res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
428         if (res_irq)
429                 port->irq = res_irq->start;
430         else if (platp)
431                 port->irq = platp->irq;
432         else
433                 return -ENODEV;
434 
435         port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
436         if (!port->membase)
437                 return -ENOMEM;
438 
439         port->line = i;
440         port->type = PORT_ALTERA_JTAGUART;
441         port->iotype = SERIAL_IO_MEM;
442         port->ops = &altera_jtaguart_ops;
443         port->flags = UPF_BOOT_AUTOCONF;
444 
445         uart_add_one_port(&altera_jtaguart_driver, port);
446 
447         return 0;
448 }
449 
450 static int altera_jtaguart_remove(struct platform_device *pdev)
451 {
452         struct uart_port *port;
453         int i = pdev->id;
454 
455         if (i == -1)
456                 i = 0;
457 
458         port = &altera_jtaguart_ports[i].port;
459         uart_remove_one_port(&altera_jtaguart_driver, port);
460 
461         return 0;
462 }
463 
464 #ifdef CONFIG_OF
465 static struct of_device_id altera_jtaguart_match[] = {
466         { .compatible = "ALTR,juart-1.0", },
467         { .compatible = "altr,juart-1.0", },
468         {},
469 };
470 MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
471 #endif /* CONFIG_OF */
472 
473 static struct platform_driver altera_jtaguart_platform_driver = {
474         .probe  = altera_jtaguart_probe,
475         .remove = altera_jtaguart_remove,
476         .driver = {
477                 .name           = DRV_NAME,
478                 .owner          = THIS_MODULE,
479                 .of_match_table = of_match_ptr(altera_jtaguart_match),
480         },
481 };
482 
483 static int __init altera_jtaguart_init(void)
484 {
485         int rc;
486 
487         rc = uart_register_driver(&altera_jtaguart_driver);
488         if (rc)
489                 return rc;
490         rc = platform_driver_register(&altera_jtaguart_platform_driver);
491         if (rc)
492                 uart_unregister_driver(&altera_jtaguart_driver);
493         return rc;
494 }
495 
496 static void __exit altera_jtaguart_exit(void)
497 {
498         platform_driver_unregister(&altera_jtaguart_platform_driver);
499         uart_unregister_driver(&altera_jtaguart_driver);
500 }
501 
502 module_init(altera_jtaguart_init);
503 module_exit(altera_jtaguart_exit);
504 
505 MODULE_DESCRIPTION("Altera JTAG UART driver");
506 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
507 MODULE_LICENSE("GPL");
508 MODULE_ALIAS("platform:" DRV_NAME);
509 

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