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Linux/drivers/tty/serial/timbuart.c

  1 /*
  2  * timbuart.c timberdale FPGA UART driver
  3  * Copyright (c) 2009 Intel Corporation
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, write to the Free Software
 16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 17  */
 18 
 19 /* Supports:
 20  * Timberdale FPGA UART
 21  */
 22 
 23 #include <linux/pci.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/serial_core.h>
 26 #include <linux/tty.h>
 27 #include <linux/tty_flip.h>
 28 #include <linux/kernel.h>
 29 #include <linux/platform_device.h>
 30 #include <linux/ioport.h>
 31 #include <linux/slab.h>
 32 #include <linux/module.h>
 33 
 34 #include "timbuart.h"
 35 
 36 struct timbuart_port {
 37         struct uart_port        port;
 38         struct tasklet_struct   tasklet;
 39         int                     usedma;
 40         u32                     last_ier;
 41         struct platform_device  *dev;
 42 };
 43 
 44 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
 45         921600, 1843200, 3250000};
 46 
 47 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
 48 
 49 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
 50 
 51 static void timbuart_stop_rx(struct uart_port *port)
 52 {
 53         /* spin lock held by upper layer, disable all RX interrupts */
 54         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
 55         iowrite32(ier, port->membase + TIMBUART_IER);
 56 }
 57 
 58 static void timbuart_stop_tx(struct uart_port *port)
 59 {
 60         /* spinlock held by upper layer, disable TX interrupt */
 61         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
 62         iowrite32(ier, port->membase + TIMBUART_IER);
 63 }
 64 
 65 static void timbuart_start_tx(struct uart_port *port)
 66 {
 67         struct timbuart_port *uart =
 68                 container_of(port, struct timbuart_port, port);
 69 
 70         /* do not transfer anything here -> fire off the tasklet */
 71         tasklet_schedule(&uart->tasklet);
 72 }
 73 
 74 static unsigned int timbuart_tx_empty(struct uart_port *port)
 75 {
 76         u32 isr = ioread32(port->membase + TIMBUART_ISR);
 77 
 78         return (isr & TXBE) ? TIOCSER_TEMT : 0;
 79 }
 80 
 81 static void timbuart_flush_buffer(struct uart_port *port)
 82 {
 83         if (!timbuart_tx_empty(port)) {
 84                 u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
 85                         TIMBUART_CTRL_FLSHTX;
 86 
 87                 iowrite8(ctl, port->membase + TIMBUART_CTRL);
 88                 iowrite32(TXBF, port->membase + TIMBUART_ISR);
 89         }
 90 }
 91 
 92 static void timbuart_rx_chars(struct uart_port *port)
 93 {
 94         struct tty_port *tport = &port->state->port;
 95 
 96         while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
 97                 u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
 98                 port->icount.rx++;
 99                 tty_insert_flip_char(tport, ch, TTY_NORMAL);
100         }
101 
102         spin_unlock(&port->lock);
103         tty_flip_buffer_push(tport);
104         spin_lock(&port->lock);
105 
106         dev_dbg(port->dev, "%s - total read %d bytes\n",
107                 __func__, port->icount.rx);
108 }
109 
110 static void timbuart_tx_chars(struct uart_port *port)
111 {
112         struct circ_buf *xmit = &port->state->xmit;
113 
114         while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
115                 !uart_circ_empty(xmit)) {
116                 iowrite8(xmit->buf[xmit->tail],
117                         port->membase + TIMBUART_TXFIFO);
118                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
119                 port->icount.tx++;
120         }
121 
122         dev_dbg(port->dev,
123                 "%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
124                  __func__,
125                 port->icount.tx,
126                 ioread8(port->membase + TIMBUART_CTRL),
127                 port->mctrl & TIOCM_RTS,
128                 ioread8(port->membase + TIMBUART_BAUDRATE));
129 }
130 
131 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
132 {
133         struct timbuart_port *uart =
134                 container_of(port, struct timbuart_port, port);
135         struct circ_buf *xmit = &port->state->xmit;
136 
137         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
138                 return;
139 
140         if (port->x_char)
141                 return;
142 
143         if (isr & TXFLAGS) {
144                 timbuart_tx_chars(port);
145                 /* clear all TX interrupts */
146                 iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
147 
148                 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
149                         uart_write_wakeup(port);
150         } else
151                 /* Re-enable any tx interrupt */
152                 *ier |= uart->last_ier & TXFLAGS;
153 
154         /* enable interrupts if there are chars in the transmit buffer,
155          * Or if we delivered some bytes and want the almost empty interrupt
156          * we wake up the upper layer later when we got the interrupt
157          * to give it some time to go out...
158          */
159         if (!uart_circ_empty(xmit))
160                 *ier |= TXBAE;
161 
162         dev_dbg(port->dev, "%s - leaving\n", __func__);
163 }
164 
165 static void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
166 {
167         if (isr & RXFLAGS) {
168                 /* Some RX status is set */
169                 if (isr & RXBF) {
170                         u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
171                                 TIMBUART_CTRL_FLSHRX;
172                         iowrite8(ctl, port->membase + TIMBUART_CTRL);
173                         port->icount.overrun++;
174                 } else if (isr & (RXDP))
175                         timbuart_rx_chars(port);
176 
177                 /* ack all RX interrupts */
178                 iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
179         }
180 
181         /* always have the RX interrupts enabled */
182         *ier |= RXBAF | RXBF | RXTT;
183 
184         dev_dbg(port->dev, "%s - leaving\n", __func__);
185 }
186 
187 static void timbuart_tasklet(unsigned long arg)
188 {
189         struct timbuart_port *uart = (struct timbuart_port *)arg;
190         u32 isr, ier = 0;
191 
192         spin_lock(&uart->port.lock);
193 
194         isr = ioread32(uart->port.membase + TIMBUART_ISR);
195         dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
196 
197         if (!uart->usedma)
198                 timbuart_handle_tx_port(&uart->port, isr, &ier);
199 
200         timbuart_mctrl_check(&uart->port, isr, &ier);
201 
202         if (!uart->usedma)
203                 timbuart_handle_rx_port(&uart->port, isr, &ier);
204 
205         iowrite32(ier, uart->port.membase + TIMBUART_IER);
206 
207         spin_unlock(&uart->port.lock);
208         dev_dbg(uart->port.dev, "%s leaving\n", __func__);
209 }
210 
211 static unsigned int timbuart_get_mctrl(struct uart_port *port)
212 {
213         u8 cts = ioread8(port->membase + TIMBUART_CTRL);
214         dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
215 
216         if (cts & TIMBUART_CTRL_CTS)
217                 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
218         else
219                 return TIOCM_DSR | TIOCM_CAR;
220 }
221 
222 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
223 {
224         dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
225 
226         if (mctrl & TIOCM_RTS)
227                 iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
228         else
229                 iowrite8(0, port->membase + TIMBUART_CTRL);
230 }
231 
232 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
233 {
234         unsigned int cts;
235 
236         if (isr & CTS_DELTA) {
237                 /* ack */
238                 iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
239                 cts = timbuart_get_mctrl(port);
240                 uart_handle_cts_change(port, cts & TIOCM_CTS);
241                 wake_up_interruptible(&port->state->port.delta_msr_wait);
242         }
243 
244         *ier |= CTS_DELTA;
245 }
246 
247 static void timbuart_enable_ms(struct uart_port *port)
248 {
249         /* N/A */
250 }
251 
252 static void timbuart_break_ctl(struct uart_port *port, int ctl)
253 {
254         /* N/A */
255 }
256 
257 static int timbuart_startup(struct uart_port *port)
258 {
259         struct timbuart_port *uart =
260                 container_of(port, struct timbuart_port, port);
261 
262         dev_dbg(port->dev, "%s\n", __func__);
263 
264         iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
265         iowrite32(0x1ff, port->membase + TIMBUART_ISR);
266         /* Enable all but TX interrupts */
267         iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
268                 port->membase + TIMBUART_IER);
269 
270         return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
271                 "timb-uart", uart);
272 }
273 
274 static void timbuart_shutdown(struct uart_port *port)
275 {
276         struct timbuart_port *uart =
277                 container_of(port, struct timbuart_port, port);
278         dev_dbg(port->dev, "%s\n", __func__);
279         free_irq(port->irq, uart);
280         iowrite32(0, port->membase + TIMBUART_IER);
281 }
282 
283 static int get_bindex(int baud)
284 {
285         int i;
286 
287         for (i = 0; i < ARRAY_SIZE(baudrates); i++)
288                 if (baud <= baudrates[i])
289                         return i;
290 
291         return -1;
292 }
293 
294 static void timbuart_set_termios(struct uart_port *port,
295         struct ktermios *termios,
296         struct ktermios *old)
297 {
298         unsigned int baud;
299         short bindex;
300         unsigned long flags;
301 
302         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
303         bindex = get_bindex(baud);
304         dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
305 
306         if (bindex < 0)
307                 bindex = 0;
308         baud = baudrates[bindex];
309 
310         /* The serial layer calls into this once with old = NULL when setting
311            up initially */
312         if (old)
313                 tty_termios_copy_hw(termios, old);
314         tty_termios_encode_baud_rate(termios, baud, baud);
315 
316         spin_lock_irqsave(&port->lock, flags);
317         iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
318         uart_update_timeout(port, termios->c_cflag, baud);
319         spin_unlock_irqrestore(&port->lock, flags);
320 }
321 
322 static const char *timbuart_type(struct uart_port *port)
323 {
324         return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
325 }
326 
327 /* We do not request/release mappings of the registers here,
328  * currently it's done in the proble function.
329  */
330 static void timbuart_release_port(struct uart_port *port)
331 {
332         struct platform_device *pdev = to_platform_device(port->dev);
333         int size =
334                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
335 
336         if (port->flags & UPF_IOREMAP) {
337                 iounmap(port->membase);
338                 port->membase = NULL;
339         }
340 
341         release_mem_region(port->mapbase, size);
342 }
343 
344 static int timbuart_request_port(struct uart_port *port)
345 {
346         struct platform_device *pdev = to_platform_device(port->dev);
347         int size =
348                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
349 
350         if (!request_mem_region(port->mapbase, size, "timb-uart"))
351                 return -EBUSY;
352 
353         if (port->flags & UPF_IOREMAP) {
354                 port->membase = ioremap(port->mapbase, size);
355                 if (port->membase == NULL) {
356                         release_mem_region(port->mapbase, size);
357                         return -ENOMEM;
358                 }
359         }
360 
361         return 0;
362 }
363 
364 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
365 {
366         struct timbuart_port *uart = (struct timbuart_port *)devid;
367 
368         if (ioread8(uart->port.membase + TIMBUART_IPR)) {
369                 uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
370 
371                 /* disable interrupts, the tasklet enables them again */
372                 iowrite32(0, uart->port.membase + TIMBUART_IER);
373 
374                 /* fire off bottom half */
375                 tasklet_schedule(&uart->tasklet);
376 
377                 return IRQ_HANDLED;
378         } else
379                 return IRQ_NONE;
380 }
381 
382 /*
383  * Configure/autoconfigure the port.
384  */
385 static void timbuart_config_port(struct uart_port *port, int flags)
386 {
387         if (flags & UART_CONFIG_TYPE) {
388                 port->type = PORT_TIMBUART;
389                 timbuart_request_port(port);
390         }
391 }
392 
393 static int timbuart_verify_port(struct uart_port *port,
394         struct serial_struct *ser)
395 {
396         /* we don't want the core code to modify any port params */
397         return -EINVAL;
398 }
399 
400 static struct uart_ops timbuart_ops = {
401         .tx_empty = timbuart_tx_empty,
402         .set_mctrl = timbuart_set_mctrl,
403         .get_mctrl = timbuart_get_mctrl,
404         .stop_tx = timbuart_stop_tx,
405         .start_tx = timbuart_start_tx,
406         .flush_buffer = timbuart_flush_buffer,
407         .stop_rx = timbuart_stop_rx,
408         .enable_ms = timbuart_enable_ms,
409         .break_ctl = timbuart_break_ctl,
410         .startup = timbuart_startup,
411         .shutdown = timbuart_shutdown,
412         .set_termios = timbuart_set_termios,
413         .type = timbuart_type,
414         .release_port = timbuart_release_port,
415         .request_port = timbuart_request_port,
416         .config_port = timbuart_config_port,
417         .verify_port = timbuart_verify_port
418 };
419 
420 static struct uart_driver timbuart_driver = {
421         .owner = THIS_MODULE,
422         .driver_name = "timberdale_uart",
423         .dev_name = "ttyTU",
424         .major = TIMBUART_MAJOR,
425         .minor = TIMBUART_MINOR,
426         .nr = 1
427 };
428 
429 static int timbuart_probe(struct platform_device *dev)
430 {
431         int err, irq;
432         struct timbuart_port *uart;
433         struct resource *iomem;
434 
435         dev_dbg(&dev->dev, "%s\n", __func__);
436 
437         uart = kzalloc(sizeof(*uart), GFP_KERNEL);
438         if (!uart) {
439                 err = -EINVAL;
440                 goto err_mem;
441         }
442 
443         uart->usedma = 0;
444 
445         uart->port.uartclk = 3250000 * 16;
446         uart->port.fifosize  = TIMBUART_FIFO_SIZE;
447         uart->port.regshift  = 2;
448         uart->port.iotype  = UPIO_MEM;
449         uart->port.ops = &timbuart_ops;
450         uart->port.irq = 0;
451         uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
452         uart->port.line  = 0;
453         uart->port.dev  = &dev->dev;
454 
455         iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
456         if (!iomem) {
457                 err = -ENOMEM;
458                 goto err_register;
459         }
460         uart->port.mapbase = iomem->start;
461         uart->port.membase = NULL;
462 
463         irq = platform_get_irq(dev, 0);
464         if (irq < 0) {
465                 err = -EINVAL;
466                 goto err_register;
467         }
468         uart->port.irq = irq;
469 
470         tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
471 
472         err = uart_register_driver(&timbuart_driver);
473         if (err)
474                 goto err_register;
475 
476         err = uart_add_one_port(&timbuart_driver, &uart->port);
477         if (err)
478                 goto err_add_port;
479 
480         platform_set_drvdata(dev, uart);
481 
482         return 0;
483 
484 err_add_port:
485         uart_unregister_driver(&timbuart_driver);
486 err_register:
487         kfree(uart);
488 err_mem:
489         printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
490                 err);
491 
492         return err;
493 }
494 
495 static int timbuart_remove(struct platform_device *dev)
496 {
497         struct timbuart_port *uart = platform_get_drvdata(dev);
498 
499         tasklet_kill(&uart->tasklet);
500         uart_remove_one_port(&timbuart_driver, &uart->port);
501         uart_unregister_driver(&timbuart_driver);
502         kfree(uart);
503 
504         return 0;
505 }
506 
507 static struct platform_driver timbuart_platform_driver = {
508         .driver = {
509                 .name   = "timb-uart",
510                 .owner  = THIS_MODULE,
511         },
512         .probe          = timbuart_probe,
513         .remove         = timbuart_remove,
514 };
515 
516 module_platform_driver(timbuart_platform_driver);
517 
518 MODULE_DESCRIPTION("Timberdale UART driver");
519 MODULE_LICENSE("GPL v2");
520 MODULE_ALIAS("platform:timb-uart");
521 
522 

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