1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * timbuart.c timberdale FPGA UART driver
4 * Copyright (c) 2009 Intel Corporation
5 */
6
7 /* Supports:
8 * Timberdale FPGA UART
9 */
10
11 #include <linux/pci.h>
12 #include <linux/interrupt.h>
13 #include <linux/serial_core.h>
14 #include <linux/tty.h>
15 #include <linux/tty_flip.h>
16 #include <linux/kernel.h>
17 #include <linux/platform_device.h>
18 #include <linux/ioport.h>
19 #include <linux/slab.h>
20 #include <linux/module.h>
21
22 #include "timbuart.h"
23
24 struct timbuart_port {
25 struct uart_port port;
26 struct tasklet_struct tasklet;
27 int usedma;
28 u32 last_ier;
29 struct platform_device *dev;
30 };
31
32 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
33 921600, 1843200, 3250000};
34
35 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
36
37 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
38
timbuart_stop_rx(struct uart_port * port)39 static void timbuart_stop_rx(struct uart_port *port)
40 {
41 /* spin lock held by upper layer, disable all RX interrupts */
42 u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
43 iowrite32(ier, port->membase + TIMBUART_IER);
44 }
45
timbuart_stop_tx(struct uart_port * port)46 static void timbuart_stop_tx(struct uart_port *port)
47 {
48 /* spinlock held by upper layer, disable TX interrupt */
49 u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
50 iowrite32(ier, port->membase + TIMBUART_IER);
51 }
52
timbuart_start_tx(struct uart_port * port)53 static void timbuart_start_tx(struct uart_port *port)
54 {
55 struct timbuart_port *uart =
56 container_of(port, struct timbuart_port, port);
57
58 /* do not transfer anything here -> fire off the tasklet */
59 tasklet_schedule(&uart->tasklet);
60 }
61
timbuart_tx_empty(struct uart_port * port)62 static unsigned int timbuart_tx_empty(struct uart_port *port)
63 {
64 u32 isr = ioread32(port->membase + TIMBUART_ISR);
65
66 return (isr & TXBE) ? TIOCSER_TEMT : 0;
67 }
68
timbuart_flush_buffer(struct uart_port * port)69 static void timbuart_flush_buffer(struct uart_port *port)
70 {
71 if (!timbuart_tx_empty(port)) {
72 u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
73 TIMBUART_CTRL_FLSHTX;
74
75 iowrite8(ctl, port->membase + TIMBUART_CTRL);
76 iowrite32(TXBF, port->membase + TIMBUART_ISR);
77 }
78 }
79
timbuart_rx_chars(struct uart_port * port)80 static void timbuart_rx_chars(struct uart_port *port)
81 {
82 struct tty_port *tport = &port->state->port;
83
84 while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
85 u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
86 port->icount.rx++;
87 tty_insert_flip_char(tport, ch, TTY_NORMAL);
88 }
89
90 tty_flip_buffer_push(tport);
91
92 dev_dbg(port->dev, "%s - total read %d bytes\n",
93 __func__, port->icount.rx);
94 }
95
timbuart_tx_chars(struct uart_port * port)96 static void timbuart_tx_chars(struct uart_port *port)
97 {
98 unsigned char ch;
99
100 while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
101 uart_fifo_get(port, &ch))
102 iowrite8(ch, port->membase + TIMBUART_TXFIFO);
103
104 dev_dbg(port->dev,
105 "%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
106 __func__,
107 port->icount.tx,
108 ioread8(port->membase + TIMBUART_CTRL),
109 port->mctrl & TIOCM_RTS,
110 ioread8(port->membase + TIMBUART_BAUDRATE));
111 }
112
timbuart_handle_tx_port(struct uart_port * port,u32 isr,u32 * ier)113 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
114 {
115 struct timbuart_port *uart =
116 container_of(port, struct timbuart_port, port);
117 struct tty_port *tport = &port->state->port;
118
119 if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
120 return;
121
122 if (port->x_char)
123 return;
124
125 if (isr & TXFLAGS) {
126 timbuart_tx_chars(port);
127 /* clear all TX interrupts */
128 iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
129
130 if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
131 uart_write_wakeup(port);
132 } else
133 /* Re-enable any tx interrupt */
134 *ier |= uart->last_ier & TXFLAGS;
135
136 /* enable interrupts if there are chars in the transmit buffer,
137 * Or if we delivered some bytes and want the almost empty interrupt
138 * we wake up the upper layer later when we got the interrupt
139 * to give it some time to go out...
140 */
141 if (!kfifo_is_empty(&tport->xmit_fifo))
142 *ier |= TXBAE;
143
144 dev_dbg(port->dev, "%s - leaving\n", __func__);
145 }
146
timbuart_handle_rx_port(struct uart_port * port,u32 isr,u32 * ier)147 static void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
148 {
149 if (isr & RXFLAGS) {
150 /* Some RX status is set */
151 if (isr & RXBF) {
152 u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
153 TIMBUART_CTRL_FLSHRX;
154 iowrite8(ctl, port->membase + TIMBUART_CTRL);
155 port->icount.overrun++;
156 } else if (isr & (RXDP))
157 timbuart_rx_chars(port);
158
159 /* ack all RX interrupts */
160 iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
161 }
162
163 /* always have the RX interrupts enabled */
164 *ier |= RXBAF | RXBF | RXTT;
165
166 dev_dbg(port->dev, "%s - leaving\n", __func__);
167 }
168
timbuart_tasklet(struct tasklet_struct * t)169 static void timbuart_tasklet(struct tasklet_struct *t)
170 {
171 struct timbuart_port *uart = from_tasklet(uart, t, tasklet);
172 u32 isr, ier = 0;
173
174 uart_port_lock(&uart->port);
175
176 isr = ioread32(uart->port.membase + TIMBUART_ISR);
177 dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
178
179 if (!uart->usedma)
180 timbuart_handle_tx_port(&uart->port, isr, &ier);
181
182 timbuart_mctrl_check(&uart->port, isr, &ier);
183
184 if (!uart->usedma)
185 timbuart_handle_rx_port(&uart->port, isr, &ier);
186
187 iowrite32(ier, uart->port.membase + TIMBUART_IER);
188
189 uart_port_unlock(&uart->port);
190 dev_dbg(uart->port.dev, "%s leaving\n", __func__);
191 }
192
timbuart_get_mctrl(struct uart_port * port)193 static unsigned int timbuart_get_mctrl(struct uart_port *port)
194 {
195 u8 cts = ioread8(port->membase + TIMBUART_CTRL);
196 dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
197
198 if (cts & TIMBUART_CTRL_CTS)
199 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
200 else
201 return TIOCM_DSR | TIOCM_CAR;
202 }
203
timbuart_set_mctrl(struct uart_port * port,unsigned int mctrl)204 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
205 {
206 dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
207
208 if (mctrl & TIOCM_RTS)
209 iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
210 else
211 iowrite8(0, port->membase + TIMBUART_CTRL);
212 }
213
timbuart_mctrl_check(struct uart_port * port,u32 isr,u32 * ier)214 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
215 {
216 unsigned int cts;
217
218 if (isr & CTS_DELTA) {
219 /* ack */
220 iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
221 cts = timbuart_get_mctrl(port);
222 uart_handle_cts_change(port, cts & TIOCM_CTS);
223 wake_up_interruptible(&port->state->port.delta_msr_wait);
224 }
225
226 *ier |= CTS_DELTA;
227 }
228
timbuart_break_ctl(struct uart_port * port,int ctl)229 static void timbuart_break_ctl(struct uart_port *port, int ctl)
230 {
231 /* N/A */
232 }
233
timbuart_startup(struct uart_port * port)234 static int timbuart_startup(struct uart_port *port)
235 {
236 struct timbuart_port *uart =
237 container_of(port, struct timbuart_port, port);
238
239 dev_dbg(port->dev, "%s\n", __func__);
240
241 iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
242 iowrite32(0x1ff, port->membase + TIMBUART_ISR);
243 /* Enable all but TX interrupts */
244 iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
245 port->membase + TIMBUART_IER);
246
247 return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
248 "timb-uart", uart);
249 }
250
timbuart_shutdown(struct uart_port * port)251 static void timbuart_shutdown(struct uart_port *port)
252 {
253 struct timbuart_port *uart =
254 container_of(port, struct timbuart_port, port);
255 dev_dbg(port->dev, "%s\n", __func__);
256 free_irq(port->irq, uart);
257 iowrite32(0, port->membase + TIMBUART_IER);
258
259 timbuart_flush_buffer(port);
260 }
261
get_bindex(int baud)262 static int get_bindex(int baud)
263 {
264 int i;
265
266 for (i = 0; i < ARRAY_SIZE(baudrates); i++)
267 if (baud <= baudrates[i])
268 return i;
269
270 return -1;
271 }
272
timbuart_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old)273 static void timbuart_set_termios(struct uart_port *port,
274 struct ktermios *termios,
275 const struct ktermios *old)
276 {
277 unsigned int baud;
278 short bindex;
279 unsigned long flags;
280
281 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
282 bindex = get_bindex(baud);
283 dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
284
285 if (bindex < 0)
286 bindex = 0;
287 baud = baudrates[bindex];
288
289 /* The serial layer calls into this once with old = NULL when setting
290 up initially */
291 if (old)
292 tty_termios_copy_hw(termios, old);
293 tty_termios_encode_baud_rate(termios, baud, baud);
294
295 uart_port_lock_irqsave(port, &flags);
296 iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
297 uart_update_timeout(port, termios->c_cflag, baud);
298 uart_port_unlock_irqrestore(port, flags);
299 }
300
timbuart_type(struct uart_port * port)301 static const char *timbuart_type(struct uart_port *port)
302 {
303 return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
304 }
305
306 /* We do not request/release mappings of the registers here,
307 * currently it's done in the proble function.
308 */
timbuart_release_port(struct uart_port * port)309 static void timbuart_release_port(struct uart_port *port)
310 {
311 struct platform_device *pdev = to_platform_device(port->dev);
312 int size =
313 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
314
315 if (port->flags & UPF_IOREMAP) {
316 iounmap(port->membase);
317 port->membase = NULL;
318 }
319
320 release_mem_region(port->mapbase, size);
321 }
322
timbuart_request_port(struct uart_port * port)323 static int timbuart_request_port(struct uart_port *port)
324 {
325 struct platform_device *pdev = to_platform_device(port->dev);
326 int size =
327 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
328
329 if (!request_mem_region(port->mapbase, size, "timb-uart"))
330 return -EBUSY;
331
332 if (port->flags & UPF_IOREMAP) {
333 port->membase = ioremap(port->mapbase, size);
334 if (port->membase == NULL) {
335 release_mem_region(port->mapbase, size);
336 return -ENOMEM;
337 }
338 }
339
340 return 0;
341 }
342
timbuart_handleinterrupt(int irq,void * devid)343 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
344 {
345 struct timbuart_port *uart = (struct timbuart_port *)devid;
346
347 if (ioread8(uart->port.membase + TIMBUART_IPR)) {
348 uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
349
350 /* disable interrupts, the tasklet enables them again */
351 iowrite32(0, uart->port.membase + TIMBUART_IER);
352
353 /* fire off bottom half */
354 tasklet_schedule(&uart->tasklet);
355
356 return IRQ_HANDLED;
357 } else
358 return IRQ_NONE;
359 }
360
361 /*
362 * Configure/autoconfigure the port.
363 */
timbuart_config_port(struct uart_port * port,int flags)364 static void timbuart_config_port(struct uart_port *port, int flags)
365 {
366 if (flags & UART_CONFIG_TYPE) {
367 port->type = PORT_TIMBUART;
368 timbuart_request_port(port);
369 }
370 }
371
timbuart_verify_port(struct uart_port * port,struct serial_struct * ser)372 static int timbuart_verify_port(struct uart_port *port,
373 struct serial_struct *ser)
374 {
375 /* we don't want the core code to modify any port params */
376 return -EINVAL;
377 }
378
379 static const struct uart_ops timbuart_ops = {
380 .tx_empty = timbuart_tx_empty,
381 .set_mctrl = timbuart_set_mctrl,
382 .get_mctrl = timbuart_get_mctrl,
383 .stop_tx = timbuart_stop_tx,
384 .start_tx = timbuart_start_tx,
385 .flush_buffer = timbuart_flush_buffer,
386 .stop_rx = timbuart_stop_rx,
387 .break_ctl = timbuart_break_ctl,
388 .startup = timbuart_startup,
389 .shutdown = timbuart_shutdown,
390 .set_termios = timbuart_set_termios,
391 .type = timbuart_type,
392 .release_port = timbuart_release_port,
393 .request_port = timbuart_request_port,
394 .config_port = timbuart_config_port,
395 .verify_port = timbuart_verify_port
396 };
397
398 static struct uart_driver timbuart_driver = {
399 .owner = THIS_MODULE,
400 .driver_name = "timberdale_uart",
401 .dev_name = "ttyTU",
402 .major = TIMBUART_MAJOR,
403 .minor = TIMBUART_MINOR,
404 .nr = 1
405 };
406
timbuart_probe(struct platform_device * dev)407 static int timbuart_probe(struct platform_device *dev)
408 {
409 int err, irq;
410 struct timbuart_port *uart;
411 struct resource *iomem;
412
413 dev_dbg(&dev->dev, "%s\n", __func__);
414
415 uart = kzalloc(sizeof(*uart), GFP_KERNEL);
416 if (!uart) {
417 err = -EINVAL;
418 goto err_mem;
419 }
420
421 uart->usedma = 0;
422
423 uart->port.uartclk = 3250000 * 16;
424 uart->port.fifosize = TIMBUART_FIFO_SIZE;
425 uart->port.regshift = 2;
426 uart->port.iotype = UPIO_MEM;
427 uart->port.ops = &timbuart_ops;
428 uart->port.irq = 0;
429 uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
430 uart->port.line = 0;
431 uart->port.dev = &dev->dev;
432
433 iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
434 if (!iomem) {
435 err = -ENOMEM;
436 goto err_register;
437 }
438 uart->port.mapbase = iomem->start;
439 uart->port.membase = NULL;
440
441 irq = platform_get_irq(dev, 0);
442 if (irq < 0) {
443 err = -EINVAL;
444 goto err_register;
445 }
446 uart->port.irq = irq;
447
448 tasklet_setup(&uart->tasklet, timbuart_tasklet);
449
450 err = uart_register_driver(&timbuart_driver);
451 if (err)
452 goto err_register;
453
454 err = uart_add_one_port(&timbuart_driver, &uart->port);
455 if (err)
456 goto err_add_port;
457
458 platform_set_drvdata(dev, uart);
459
460 return 0;
461
462 err_add_port:
463 uart_unregister_driver(&timbuart_driver);
464 err_register:
465 kfree(uart);
466 err_mem:
467 printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
468 err);
469
470 return err;
471 }
472
timbuart_remove(struct platform_device * dev)473 static void timbuart_remove(struct platform_device *dev)
474 {
475 struct timbuart_port *uart = platform_get_drvdata(dev);
476
477 tasklet_kill(&uart->tasklet);
478 uart_remove_one_port(&timbuart_driver, &uart->port);
479 uart_unregister_driver(&timbuart_driver);
480 kfree(uart);
481 }
482
483 static struct platform_driver timbuart_platform_driver = {
484 .driver = {
485 .name = "timb-uart",
486 },
487 .probe = timbuart_probe,
488 .remove = timbuart_remove,
489 };
490
491 module_platform_driver(timbuart_platform_driver);
492
493 MODULE_DESCRIPTION("Timberdale UART driver");
494 MODULE_LICENSE("GPL v2");
495 MODULE_ALIAS("platform:timb-uart");
496
497