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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_break_ctl(struct uart_port *port, int ctl)
248 {
249         /* N/A */
250 }
251 
252 static int timbuart_startup(struct uart_port *port)
253 {
254         struct timbuart_port *uart =
255                 container_of(port, struct timbuart_port, port);
256 
257         dev_dbg(port->dev, "%s\n", __func__);
258 
259         iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
260         iowrite32(0x1ff, port->membase + TIMBUART_ISR);
261         /* Enable all but TX interrupts */
262         iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
263                 port->membase + TIMBUART_IER);
264 
265         return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
266                 "timb-uart", uart);
267 }
268 
269 static void timbuart_shutdown(struct uart_port *port)
270 {
271         struct timbuart_port *uart =
272                 container_of(port, struct timbuart_port, port);
273         dev_dbg(port->dev, "%s\n", __func__);
274         free_irq(port->irq, uart);
275         iowrite32(0, port->membase + TIMBUART_IER);
276 }
277 
278 static int get_bindex(int baud)
279 {
280         int i;
281 
282         for (i = 0; i < ARRAY_SIZE(baudrates); i++)
283                 if (baud <= baudrates[i])
284                         return i;
285 
286         return -1;
287 }
288 
289 static void timbuart_set_termios(struct uart_port *port,
290         struct ktermios *termios,
291         struct ktermios *old)
292 {
293         unsigned int baud;
294         short bindex;
295         unsigned long flags;
296 
297         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
298         bindex = get_bindex(baud);
299         dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
300 
301         if (bindex < 0)
302                 bindex = 0;
303         baud = baudrates[bindex];
304 
305         /* The serial layer calls into this once with old = NULL when setting
306            up initially */
307         if (old)
308                 tty_termios_copy_hw(termios, old);
309         tty_termios_encode_baud_rate(termios, baud, baud);
310 
311         spin_lock_irqsave(&port->lock, flags);
312         iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
313         uart_update_timeout(port, termios->c_cflag, baud);
314         spin_unlock_irqrestore(&port->lock, flags);
315 }
316 
317 static const char *timbuart_type(struct uart_port *port)
318 {
319         return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
320 }
321 
322 /* We do not request/release mappings of the registers here,
323  * currently it's done in the proble function.
324  */
325 static void timbuart_release_port(struct uart_port *port)
326 {
327         struct platform_device *pdev = to_platform_device(port->dev);
328         int size =
329                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
330 
331         if (port->flags & UPF_IOREMAP) {
332                 iounmap(port->membase);
333                 port->membase = NULL;
334         }
335 
336         release_mem_region(port->mapbase, size);
337 }
338 
339 static int timbuart_request_port(struct uart_port *port)
340 {
341         struct platform_device *pdev = to_platform_device(port->dev);
342         int size =
343                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
344 
345         if (!request_mem_region(port->mapbase, size, "timb-uart"))
346                 return -EBUSY;
347 
348         if (port->flags & UPF_IOREMAP) {
349                 port->membase = ioremap(port->mapbase, size);
350                 if (port->membase == NULL) {
351                         release_mem_region(port->mapbase, size);
352                         return -ENOMEM;
353                 }
354         }
355 
356         return 0;
357 }
358 
359 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
360 {
361         struct timbuart_port *uart = (struct timbuart_port *)devid;
362 
363         if (ioread8(uart->port.membase + TIMBUART_IPR)) {
364                 uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
365 
366                 /* disable interrupts, the tasklet enables them again */
367                 iowrite32(0, uart->port.membase + TIMBUART_IER);
368 
369                 /* fire off bottom half */
370                 tasklet_schedule(&uart->tasklet);
371 
372                 return IRQ_HANDLED;
373         } else
374                 return IRQ_NONE;
375 }
376 
377 /*
378  * Configure/autoconfigure the port.
379  */
380 static void timbuart_config_port(struct uart_port *port, int flags)
381 {
382         if (flags & UART_CONFIG_TYPE) {
383                 port->type = PORT_TIMBUART;
384                 timbuart_request_port(port);
385         }
386 }
387 
388 static int timbuart_verify_port(struct uart_port *port,
389         struct serial_struct *ser)
390 {
391         /* we don't want the core code to modify any port params */
392         return -EINVAL;
393 }
394 
395 static struct uart_ops timbuart_ops = {
396         .tx_empty = timbuart_tx_empty,
397         .set_mctrl = timbuart_set_mctrl,
398         .get_mctrl = timbuart_get_mctrl,
399         .stop_tx = timbuart_stop_tx,
400         .start_tx = timbuart_start_tx,
401         .flush_buffer = timbuart_flush_buffer,
402         .stop_rx = timbuart_stop_rx,
403         .break_ctl = timbuart_break_ctl,
404         .startup = timbuart_startup,
405         .shutdown = timbuart_shutdown,
406         .set_termios = timbuart_set_termios,
407         .type = timbuart_type,
408         .release_port = timbuart_release_port,
409         .request_port = timbuart_request_port,
410         .config_port = timbuart_config_port,
411         .verify_port = timbuart_verify_port
412 };
413 
414 static struct uart_driver timbuart_driver = {
415         .owner = THIS_MODULE,
416         .driver_name = "timberdale_uart",
417         .dev_name = "ttyTU",
418         .major = TIMBUART_MAJOR,
419         .minor = TIMBUART_MINOR,
420         .nr = 1
421 };
422 
423 static int timbuart_probe(struct platform_device *dev)
424 {
425         int err, irq;
426         struct timbuart_port *uart;
427         struct resource *iomem;
428 
429         dev_dbg(&dev->dev, "%s\n", __func__);
430 
431         uart = kzalloc(sizeof(*uart), GFP_KERNEL);
432         if (!uart) {
433                 err = -EINVAL;
434                 goto err_mem;
435         }
436 
437         uart->usedma = 0;
438 
439         uart->port.uartclk = 3250000 * 16;
440         uart->port.fifosize  = TIMBUART_FIFO_SIZE;
441         uart->port.regshift  = 2;
442         uart->port.iotype  = UPIO_MEM;
443         uart->port.ops = &timbuart_ops;
444         uart->port.irq = 0;
445         uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
446         uart->port.line  = 0;
447         uart->port.dev  = &dev->dev;
448 
449         iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
450         if (!iomem) {
451                 err = -ENOMEM;
452                 goto err_register;
453         }
454         uart->port.mapbase = iomem->start;
455         uart->port.membase = NULL;
456 
457         irq = platform_get_irq(dev, 0);
458         if (irq < 0) {
459                 err = -EINVAL;
460                 goto err_register;
461         }
462         uart->port.irq = irq;
463 
464         tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
465 
466         err = uart_register_driver(&timbuart_driver);
467         if (err)
468                 goto err_register;
469 
470         err = uart_add_one_port(&timbuart_driver, &uart->port);
471         if (err)
472                 goto err_add_port;
473 
474         platform_set_drvdata(dev, uart);
475 
476         return 0;
477 
478 err_add_port:
479         uart_unregister_driver(&timbuart_driver);
480 err_register:
481         kfree(uart);
482 err_mem:
483         printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
484                 err);
485 
486         return err;
487 }
488 
489 static int timbuart_remove(struct platform_device *dev)
490 {
491         struct timbuart_port *uart = platform_get_drvdata(dev);
492 
493         tasklet_kill(&uart->tasklet);
494         uart_remove_one_port(&timbuart_driver, &uart->port);
495         uart_unregister_driver(&timbuart_driver);
496         kfree(uart);
497 
498         return 0;
499 }
500 
501 static struct platform_driver timbuart_platform_driver = {
502         .driver = {
503                 .name   = "timb-uart",
504                 .owner  = THIS_MODULE,
505         },
506         .probe          = timbuart_probe,
507         .remove         = timbuart_remove,
508 };
509 
510 module_platform_driver(timbuart_platform_driver);
511 
512 MODULE_DESCRIPTION("Timberdale UART driver");
513 MODULE_LICENSE("GPL v2");
514 MODULE_ALIAS("platform:timb-uart");
515 
516 

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