xref: /openbmc/linux/drivers/tty/serial/rda-uart.c (revision 2f164822) 
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * RDA8810PL serial device driver
4  *
5  * Copyright RDA Microelectronics Company Limited
6  * Copyright (c) 2017 Andreas Färber
7  * Copyright (c) 2018 Manivannan Sadhasivam
8  */
9 
10 #include <linux/clk.h>
11 #include <linux/console.h>
12 #include <linux/delay.h>
13 #include <linux/io.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.h>
17 #include <linux/serial.h>
18 #include <linux/serial_core.h>
19 #include <linux/tty.h>
20 #include <linux/tty_flip.h>
21 
22 #define RDA_UART_PORT_NUM 3
23 #define RDA_UART_DEV_NAME "ttyRDA"
24 
25 #define RDA_UART_CTRL		0x00
26 #define RDA_UART_STATUS		0x04
27 #define RDA_UART_RXTX_BUFFER	0x08
28 #define RDA_UART_IRQ_MASK	0x0c
29 #define RDA_UART_IRQ_CAUSE	0x10
30 #define RDA_UART_IRQ_TRIGGERS	0x14
31 #define RDA_UART_CMD_SET	0x18
32 #define RDA_UART_CMD_CLR	0x1c
33 
34 /* UART_CTRL Bits */
35 #define RDA_UART_ENABLE			BIT(0)
36 #define RDA_UART_DBITS_8		BIT(1)
37 #define RDA_UART_TX_SBITS_2		BIT(2)
38 #define RDA_UART_PARITY_EN		BIT(3)
39 #define RDA_UART_PARITY(x)		(((x) & 0x3) << 4)
40 #define RDA_UART_PARITY_ODD		RDA_UART_PARITY(0)
41 #define RDA_UART_PARITY_EVEN		RDA_UART_PARITY(1)
42 #define RDA_UART_PARITY_SPACE		RDA_UART_PARITY(2)
43 #define RDA_UART_PARITY_MARK		RDA_UART_PARITY(3)
44 #define RDA_UART_DIV_MODE		BIT(20)
45 #define RDA_UART_IRDA_EN		BIT(21)
46 #define RDA_UART_DMA_EN			BIT(22)
47 #define RDA_UART_FLOW_CNT_EN		BIT(23)
48 #define RDA_UART_LOOP_BACK_EN		BIT(24)
49 #define RDA_UART_RX_LOCK_ERR		BIT(25)
50 #define RDA_UART_RX_BREAK_LEN(x)	(((x) & 0xf) << 28)
51 
52 /* UART_STATUS Bits */
53 #define RDA_UART_RX_FIFO(x)		(((x) & 0x7f) << 0)
54 #define RDA_UART_RX_FIFO_MASK		(0x7f << 0)
55 #define RDA_UART_TX_FIFO(x)		(((x) & 0x1f) << 8)
56 #define RDA_UART_TX_FIFO_MASK		(0x1f << 8)
57 #define RDA_UART_TX_ACTIVE		BIT(14)
58 #define RDA_UART_RX_ACTIVE		BIT(15)
59 #define RDA_UART_RX_OVERFLOW_ERR	BIT(16)
60 #define RDA_UART_TX_OVERFLOW_ERR	BIT(17)
61 #define RDA_UART_RX_PARITY_ERR		BIT(18)
62 #define RDA_UART_RX_FRAMING_ERR		BIT(19)
63 #define RDA_UART_RX_BREAK_INT		BIT(20)
64 #define RDA_UART_DCTS			BIT(24)
65 #define RDA_UART_CTS			BIT(25)
66 #define RDA_UART_DTR			BIT(28)
67 #define RDA_UART_CLK_ENABLED		BIT(31)
68 
69 /* UART_RXTX_BUFFER Bits */
70 #define RDA_UART_RX_DATA(x)		(((x) & 0xff) << 0)
71 #define RDA_UART_TX_DATA(x)		(((x) & 0xff) << 0)
72 
73 /* UART_IRQ_MASK Bits */
74 #define RDA_UART_TX_MODEM_STATUS	BIT(0)
75 #define RDA_UART_RX_DATA_AVAILABLE	BIT(1)
76 #define RDA_UART_TX_DATA_NEEDED		BIT(2)
77 #define RDA_UART_RX_TIMEOUT		BIT(3)
78 #define RDA_UART_RX_LINE_ERR		BIT(4)
79 #define RDA_UART_TX_DMA_DONE		BIT(5)
80 #define RDA_UART_RX_DMA_DONE		BIT(6)
81 #define RDA_UART_RX_DMA_TIMEOUT		BIT(7)
82 #define RDA_UART_DTR_RISE		BIT(8)
83 #define RDA_UART_DTR_FALL		BIT(9)
84 
85 /* UART_IRQ_CAUSE Bits */
86 #define RDA_UART_TX_MODEM_STATUS_U	BIT(16)
87 #define RDA_UART_RX_DATA_AVAILABLE_U	BIT(17)
88 #define RDA_UART_TX_DATA_NEEDED_U	BIT(18)
89 #define RDA_UART_RX_TIMEOUT_U		BIT(19)
90 #define RDA_UART_RX_LINE_ERR_U		BIT(20)
91 #define RDA_UART_TX_DMA_DONE_U		BIT(21)
92 #define RDA_UART_RX_DMA_DONE_U		BIT(22)
93 #define RDA_UART_RX_DMA_TIMEOUT_U	BIT(23)
94 #define RDA_UART_DTR_RISE_U		BIT(24)
95 #define RDA_UART_DTR_FALL_U		BIT(25)
96 
97 /* UART_TRIGGERS Bits */
98 #define RDA_UART_RX_TRIGGER(x)		(((x) & 0x1f) << 0)
99 #define RDA_UART_TX_TRIGGER(x)		(((x) & 0xf) << 8)
100 #define RDA_UART_AFC_LEVEL(x)		(((x) & 0x1f) << 16)
101 
102 /* UART_CMD_SET Bits */
103 #define RDA_UART_RI			BIT(0)
104 #define RDA_UART_DCD			BIT(1)
105 #define RDA_UART_DSR			BIT(2)
106 #define RDA_UART_TX_BREAK_CONTROL	BIT(3)
107 #define RDA_UART_TX_FINISH_N_WAIT	BIT(4)
108 #define RDA_UART_RTS			BIT(5)
109 #define RDA_UART_RX_FIFO_RESET		BIT(6)
110 #define RDA_UART_TX_FIFO_RESET		BIT(7)
111 
112 #define RDA_UART_TX_FIFO_SIZE	16
113 
114 static struct uart_driver rda_uart_driver;
115 
116 struct rda_uart_port {
117 	struct uart_port port;
118 	struct clk *clk;
119 };
120 
121 #define to_rda_uart_port(port) container_of(port, struct rda_uart_port, port)
122 
123 static struct rda_uart_port *rda_uart_ports[RDA_UART_PORT_NUM];
124 
125 static inline void rda_uart_write(struct uart_port *port, u32 val,
126 				  unsigned int off)
127 {
128 	writel(val, port->membase + off);
129 }
130 
131 static inline u32 rda_uart_read(struct uart_port *port, unsigned int off)
132 {
133 	return readl(port->membase + off);
134 }
135 
136 static unsigned int rda_uart_tx_empty(struct uart_port *port)
137 {
138 	unsigned long flags;
139 	unsigned int ret;
140 	u32 val;
141 
142 	spin_lock_irqsave(&port->lock, flags);
143 
144 	val = rda_uart_read(port, RDA_UART_STATUS);
145 	ret = (val & RDA_UART_TX_FIFO_MASK) ? TIOCSER_TEMT : 0;
146 
147 	spin_unlock_irqrestore(&port->lock, flags);
148 
149 	return ret;
150 }
151 
152 static unsigned int rda_uart_get_mctrl(struct uart_port *port)
153 {
154 	unsigned int mctrl = 0;
155 	u32 cmd_set, status;
156 
157 	cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
158 	status = rda_uart_read(port, RDA_UART_STATUS);
159 	if (cmd_set & RDA_UART_RTS)
160 		mctrl |= TIOCM_RTS;
161 	if (!(status & RDA_UART_CTS))
162 		mctrl |= TIOCM_CTS;
163 
164 	return mctrl;
165 }
166 
167 static void rda_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
168 {
169 	u32 val;
170 
171 	if (mctrl & TIOCM_RTS) {
172 		val = rda_uart_read(port, RDA_UART_CMD_SET);
173 		rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_SET);
174 	} else {
175 		/* Clear RTS to stop to receive. */
176 		val = rda_uart_read(port, RDA_UART_CMD_CLR);
177 		rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_CLR);
178 	}
179 
180 	val = rda_uart_read(port, RDA_UART_CTRL);
181 
182 	if (mctrl & TIOCM_LOOP)
183 		val |= RDA_UART_LOOP_BACK_EN;
184 	else
185 		val &= ~RDA_UART_LOOP_BACK_EN;
186 
187 	rda_uart_write(port, val, RDA_UART_CTRL);
188 }
189 
190 static void rda_uart_stop_tx(struct uart_port *port)
191 {
192 	u32 val;
193 
194 	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
195 	val &= ~RDA_UART_TX_DATA_NEEDED;
196 	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
197 
198 	val = rda_uart_read(port, RDA_UART_CMD_SET);
199 	val |= RDA_UART_TX_FIFO_RESET;
200 	rda_uart_write(port, val, RDA_UART_CMD_SET);
201 }
202 
203 static void rda_uart_stop_rx(struct uart_port *port)
204 {
205 	u32 val;
206 
207 	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
208 	val &= ~(RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
209 	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
210 
211 	/* Read Rx buffer before reset to avoid Rx timeout interrupt */
212 	val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);
213 
214 	val = rda_uart_read(port, RDA_UART_CMD_SET);
215 	val |= RDA_UART_RX_FIFO_RESET;
216 	rda_uart_write(port, val, RDA_UART_CMD_SET);
217 }
218 
219 static void rda_uart_start_tx(struct uart_port *port)
220 {
221 	u32 val;
222 
223 	if (uart_tx_stopped(port)) {
224 		rda_uart_stop_tx(port);
225 		return;
226 	}
227 
228 	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
229 	val |= RDA_UART_TX_DATA_NEEDED;
230 	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
231 }
232 
233 static void rda_uart_change_baudrate(struct rda_uart_port *rda_port,
234 				     unsigned long baud)
235 {
236 	clk_set_rate(rda_port->clk, baud * 8);
237 }
238 
239 static void rda_uart_set_termios(struct uart_port *port,
240 				 struct ktermios *termios,
241 				 const struct ktermios *old)
242 {
243 	struct rda_uart_port *rda_port = to_rda_uart_port(port);
244 	unsigned long flags;
245 	unsigned int ctrl, cmd_set, cmd_clr, triggers;
246 	unsigned int baud;
247 	u32 irq_mask;
248 
249 	spin_lock_irqsave(&port->lock, flags);
250 
251 	baud = uart_get_baud_rate(port, termios, old, 9600, port->uartclk / 4);
252 	rda_uart_change_baudrate(rda_port, baud);
253 
254 	ctrl = rda_uart_read(port, RDA_UART_CTRL);
255 	cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
256 	cmd_clr = rda_uart_read(port, RDA_UART_CMD_CLR);
257 
258 	switch (termios->c_cflag & CSIZE) {
259 	case CS5:
260 	case CS6:
261 		dev_warn(port->dev, "bit size not supported, using 7 bits\n");
262 		fallthrough;
263 	case CS7:
264 		ctrl &= ~RDA_UART_DBITS_8;
265 		termios->c_cflag &= ~CSIZE;
266 		termios->c_cflag |= CS7;
267 		break;
268 	default:
269 		ctrl |= RDA_UART_DBITS_8;
270 		break;
271 	}
272 
273 	/* stop bits */
274 	if (termios->c_cflag & CSTOPB)
275 		ctrl |= RDA_UART_TX_SBITS_2;
276 	else
277 		ctrl &= ~RDA_UART_TX_SBITS_2;
278 
279 	/* parity check */
280 	if (termios->c_cflag & PARENB) {
281 		ctrl |= RDA_UART_PARITY_EN;
282 
283 		/* Mark or Space parity */
284 		if (termios->c_cflag & CMSPAR) {
285 			if (termios->c_cflag & PARODD)
286 				ctrl |= RDA_UART_PARITY_MARK;
287 			else
288 				ctrl |= RDA_UART_PARITY_SPACE;
289 		} else if (termios->c_cflag & PARODD) {
290 			ctrl |= RDA_UART_PARITY_ODD;
291 		} else {
292 			ctrl |= RDA_UART_PARITY_EVEN;
293 		}
294 	} else {
295 		ctrl &= ~RDA_UART_PARITY_EN;
296 	}
297 
298 	/* Hardware handshake (RTS/CTS) */
299 	if (termios->c_cflag & CRTSCTS) {
300 		ctrl   |= RDA_UART_FLOW_CNT_EN;
301 		cmd_set |= RDA_UART_RTS;
302 	} else {
303 		ctrl   &= ~RDA_UART_FLOW_CNT_EN;
304 		cmd_clr |= RDA_UART_RTS;
305 	}
306 
307 	ctrl |= RDA_UART_ENABLE;
308 	ctrl &= ~RDA_UART_DMA_EN;
309 
310 	triggers  = (RDA_UART_AFC_LEVEL(20) | RDA_UART_RX_TRIGGER(16));
311 	irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
312 	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
313 
314 	rda_uart_write(port, triggers, RDA_UART_IRQ_TRIGGERS);
315 	rda_uart_write(port, ctrl, RDA_UART_CTRL);
316 	rda_uart_write(port, cmd_set, RDA_UART_CMD_SET);
317 	rda_uart_write(port, cmd_clr, RDA_UART_CMD_CLR);
318 
319 	rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);
320 
321 	/* Don't rewrite B0 */
322 	if (tty_termios_baud_rate(termios))
323 		tty_termios_encode_baud_rate(termios, baud, baud);
324 
325 	/* update the per-port timeout */
326 	uart_update_timeout(port, termios->c_cflag, baud);
327 
328 	spin_unlock_irqrestore(&port->lock, flags);
329 }
330 
331 static void rda_uart_send_chars(struct uart_port *port)
332 {
333 	struct circ_buf *xmit = &port->state->xmit;
334 	unsigned int ch;
335 	u32 val;
336 
337 	if (uart_tx_stopped(port))
338 		return;
339 
340 	if (port->x_char) {
341 		while (!(rda_uart_read(port, RDA_UART_STATUS) &
342 			 RDA_UART_TX_FIFO_MASK))
343 			cpu_relax();
344 
345 		rda_uart_write(port, port->x_char, RDA_UART_RXTX_BUFFER);
346 		port->icount.tx++;
347 		port->x_char = 0;
348 	}
349 
350 	while (rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK) {
351 		if (uart_circ_empty(xmit))
352 			break;
353 
354 		ch = xmit->buf[xmit->tail];
355 		rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
356 		uart_xmit_advance(port, 1);
357 	}
358 
359 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
360 		uart_write_wakeup(port);
361 
362 	if (!uart_circ_empty(xmit)) {
363 		/* Re-enable Tx FIFO interrupt */
364 		val = rda_uart_read(port, RDA_UART_IRQ_MASK);
365 		val |= RDA_UART_TX_DATA_NEEDED;
366 		rda_uart_write(port, val, RDA_UART_IRQ_MASK);
367 	}
368 }
369 
370 static void rda_uart_receive_chars(struct uart_port *port)
371 {
372 	u32 status, val;
373 
374 	status = rda_uart_read(port, RDA_UART_STATUS);
375 	while ((status & RDA_UART_RX_FIFO_MASK)) {
376 		char flag = TTY_NORMAL;
377 
378 		if (status & RDA_UART_RX_PARITY_ERR) {
379 			port->icount.parity++;
380 			flag = TTY_PARITY;
381 		}
382 
383 		if (status & RDA_UART_RX_FRAMING_ERR) {
384 			port->icount.frame++;
385 			flag = TTY_FRAME;
386 		}
387 
388 		if (status & RDA_UART_RX_OVERFLOW_ERR) {
389 			port->icount.overrun++;
390 			flag = TTY_OVERRUN;
391 		}
392 
393 		val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);
394 		val &= 0xff;
395 
396 		port->icount.rx++;
397 		tty_insert_flip_char(&port->state->port, val, flag);
398 
399 		status = rda_uart_read(port, RDA_UART_STATUS);
400 	}
401 
402 	tty_flip_buffer_push(&port->state->port);
403 }
404 
405 static irqreturn_t rda_interrupt(int irq, void *dev_id)
406 {
407 	struct uart_port *port = dev_id;
408 	unsigned long flags;
409 	u32 val, irq_mask;
410 
411 	spin_lock_irqsave(&port->lock, flags);
412 
413 	/* Clear IRQ cause */
414 	val = rda_uart_read(port, RDA_UART_IRQ_CAUSE);
415 	rda_uart_write(port, val, RDA_UART_IRQ_CAUSE);
416 
417 	if (val & (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT))
418 		rda_uart_receive_chars(port);
419 
420 	if (val & (RDA_UART_TX_DATA_NEEDED)) {
421 		irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
422 		irq_mask &= ~RDA_UART_TX_DATA_NEEDED;
423 		rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);
424 
425 		rda_uart_send_chars(port);
426 	}
427 
428 	spin_unlock_irqrestore(&port->lock, flags);
429 
430 	return IRQ_HANDLED;
431 }
432 
433 static int rda_uart_startup(struct uart_port *port)
434 {
435 	unsigned long flags;
436 	int ret;
437 	u32 val;
438 
439 	spin_lock_irqsave(&port->lock, flags);
440 	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
441 	spin_unlock_irqrestore(&port->lock, flags);
442 
443 	ret = request_irq(port->irq, rda_interrupt, IRQF_NO_SUSPEND,
444 			  "rda-uart", port);
445 	if (ret)
446 		return ret;
447 
448 	spin_lock_irqsave(&port->lock, flags);
449 
450 	val = rda_uart_read(port, RDA_UART_CTRL);
451 	val |= RDA_UART_ENABLE;
452 	rda_uart_write(port, val, RDA_UART_CTRL);
453 
454 	/* enable rx interrupt */
455 	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
456 	val |= (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
457 	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
458 
459 	spin_unlock_irqrestore(&port->lock, flags);
460 
461 	return 0;
462 }
463 
464 static void rda_uart_shutdown(struct uart_port *port)
465 {
466 	unsigned long flags;
467 	u32 val;
468 
469 	spin_lock_irqsave(&port->lock, flags);
470 
471 	rda_uart_stop_tx(port);
472 	rda_uart_stop_rx(port);
473 
474 	val = rda_uart_read(port, RDA_UART_CTRL);
475 	val &= ~RDA_UART_ENABLE;
476 	rda_uart_write(port, val, RDA_UART_CTRL);
477 
478 	spin_unlock_irqrestore(&port->lock, flags);
479 }
480 
481 static const char *rda_uart_type(struct uart_port *port)
482 {
483 	return (port->type == PORT_RDA) ? "rda-uart" : NULL;
484 }
485 
486 static int rda_uart_request_port(struct uart_port *port)
487 {
488 	struct platform_device *pdev = to_platform_device(port->dev);
489 	struct resource *res;
490 
491 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
492 	if (!res)
493 		return -ENXIO;
494 
495 	if (!devm_request_mem_region(port->dev, port->mapbase,
496 				     resource_size(res), dev_name(port->dev)))
497 		return -EBUSY;
498 
499 	if (port->flags & UPF_IOREMAP) {
500 		port->membase = devm_ioremap(port->dev, port->mapbase,
501 						     resource_size(res));
502 		if (!port->membase)
503 			return -EBUSY;
504 	}
505 
506 	return 0;
507 }
508 
509 static void rda_uart_config_port(struct uart_port *port, int flags)
510 {
511 	unsigned long irq_flags;
512 
513 	if (flags & UART_CONFIG_TYPE) {
514 		port->type = PORT_RDA;
515 		rda_uart_request_port(port);
516 	}
517 
518 	spin_lock_irqsave(&port->lock, irq_flags);
519 
520 	/* Clear mask, so no surprise interrupts. */
521 	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
522 
523 	/* Clear status register */
524 	rda_uart_write(port, 0, RDA_UART_STATUS);
525 
526 	spin_unlock_irqrestore(&port->lock, irq_flags);
527 }
528 
529 static void rda_uart_release_port(struct uart_port *port)
530 {
531 	struct platform_device *pdev = to_platform_device(port->dev);
532 	struct resource *res;
533 
534 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
535 	if (!res)
536 		return;
537 
538 	if (port->flags & UPF_IOREMAP) {
539 		devm_release_mem_region(port->dev, port->mapbase,
540 					resource_size(res));
541 		devm_iounmap(port->dev, port->membase);
542 		port->membase = NULL;
543 	}
544 }
545 
546 static int rda_uart_verify_port(struct uart_port *port,
547 				struct serial_struct *ser)
548 {
549 	if (port->type != PORT_RDA)
550 		return -EINVAL;
551 
552 	if (port->irq != ser->irq)
553 		return -EINVAL;
554 
555 	return 0;
556 }
557 
558 static const struct uart_ops rda_uart_ops = {
559 	.tx_empty       = rda_uart_tx_empty,
560 	.get_mctrl      = rda_uart_get_mctrl,
561 	.set_mctrl      = rda_uart_set_mctrl,
562 	.start_tx       = rda_uart_start_tx,
563 	.stop_tx        = rda_uart_stop_tx,
564 	.stop_rx        = rda_uart_stop_rx,
565 	.startup        = rda_uart_startup,
566 	.shutdown       = rda_uart_shutdown,
567 	.set_termios    = rda_uart_set_termios,
568 	.type           = rda_uart_type,
569 	.request_port	= rda_uart_request_port,
570 	.release_port	= rda_uart_release_port,
571 	.config_port	= rda_uart_config_port,
572 	.verify_port	= rda_uart_verify_port,
573 };
574 
575 #ifdef CONFIG_SERIAL_RDA_CONSOLE
576 
577 static void rda_console_putchar(struct uart_port *port, unsigned char ch)
578 {
579 	if (!port->membase)
580 		return;
581 
582 	while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
583 		cpu_relax();
584 
585 	rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
586 }
587 
588 static void rda_uart_port_write(struct uart_port *port, const char *s,
589 				u_int count)
590 {
591 	u32 old_irq_mask;
592 	unsigned long flags;
593 	int locked;
594 
595 	local_irq_save(flags);
596 
597 	if (port->sysrq) {
598 		locked = 0;
599 	} else if (oops_in_progress) {
600 		locked = spin_trylock(&port->lock);
601 	} else {
602 		spin_lock(&port->lock);
603 		locked = 1;
604 	}
605 
606 	old_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
607 	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
608 
609 	uart_console_write(port, s, count, rda_console_putchar);
610 
611 	/* wait until all contents have been sent out */
612 	while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
613 		cpu_relax();
614 
615 	rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);
616 
617 	if (locked)
618 		spin_unlock(&port->lock);
619 
620 	local_irq_restore(flags);
621 }
622 
623 static void rda_uart_console_write(struct console *co, const char *s,
624 				   u_int count)
625 {
626 	struct rda_uart_port *rda_port;
627 
628 	rda_port = rda_uart_ports[co->index];
629 	if (!rda_port)
630 		return;
631 
632 	rda_uart_port_write(&rda_port->port, s, count);
633 }
634 
635 static int rda_uart_console_setup(struct console *co, char *options)
636 {
637 	struct rda_uart_port *rda_port;
638 	int baud = 921600;
639 	int bits = 8;
640 	int parity = 'n';
641 	int flow = 'n';
642 
643 	if (co->index < 0 || co->index >= RDA_UART_PORT_NUM)
644 		return -EINVAL;
645 
646 	rda_port = rda_uart_ports[co->index];
647 	if (!rda_port || !rda_port->port.membase)
648 		return -ENODEV;
649 
650 	if (options)
651 		uart_parse_options(options, &baud, &parity, &bits, &flow);
652 
653 	return uart_set_options(&rda_port->port, co, baud, parity, bits, flow);
654 }
655 
656 static struct console rda_uart_console = {
657 	.name = RDA_UART_DEV_NAME,
658 	.write = rda_uart_console_write,
659 	.device = uart_console_device,
660 	.setup = rda_uart_console_setup,
661 	.flags = CON_PRINTBUFFER,
662 	.index = -1,
663 	.data = &rda_uart_driver,
664 };
665 
666 static int __init rda_uart_console_init(void)
667 {
668 	register_console(&rda_uart_console);
669 
670 	return 0;
671 }
672 console_initcall(rda_uart_console_init);
673 
674 static void rda_uart_early_console_write(struct console *co,
675 					 const char *s,
676 					 u_int count)
677 {
678 	struct earlycon_device *dev = co->data;
679 
680 	rda_uart_port_write(&dev->port, s, count);
681 }
682 
683 static int __init
684 rda_uart_early_console_setup(struct earlycon_device *device, const char *opt)
685 {
686 	if (!device->port.membase)
687 		return -ENODEV;
688 
689 	device->con->write = rda_uart_early_console_write;
690 
691 	return 0;
692 }
693 
694 OF_EARLYCON_DECLARE(rda, "rda,8810pl-uart",
695 		    rda_uart_early_console_setup);
696 
697 #define RDA_UART_CONSOLE (&rda_uart_console)
698 #else
699 #define RDA_UART_CONSOLE NULL
700 #endif /* CONFIG_SERIAL_RDA_CONSOLE */
701 
702 static struct uart_driver rda_uart_driver = {
703 	.owner = THIS_MODULE,
704 	.driver_name = "rda-uart",
705 	.dev_name = RDA_UART_DEV_NAME,
706 	.nr = RDA_UART_PORT_NUM,
707 	.cons = RDA_UART_CONSOLE,
708 };
709 
710 static const struct of_device_id rda_uart_dt_matches[] = {
711 	{ .compatible = "rda,8810pl-uart" },
712 	{ }
713 };
714 MODULE_DEVICE_TABLE(of, rda_uart_dt_matches);
715 
716 static int rda_uart_probe(struct platform_device *pdev)
717 {
718 	struct resource *res_mem;
719 	struct rda_uart_port *rda_port;
720 	int ret, irq;
721 
722 	if (pdev->dev.of_node)
723 		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");
724 
725 	if (pdev->id < 0 || pdev->id >= RDA_UART_PORT_NUM) {
726 		dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
727 		return -EINVAL;
728 	}
729 
730 	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
731 	if (!res_mem) {
732 		dev_err(&pdev->dev, "could not get mem\n");
733 		return -ENODEV;
734 	}
735 
736 	irq = platform_get_irq(pdev, 0);
737 	if (irq < 0)
738 		return irq;
739 
740 	if (rda_uart_ports[pdev->id]) {
741 		dev_err(&pdev->dev, "port %d already allocated\n", pdev->id);
742 		return -EBUSY;
743 	}
744 
745 	rda_port = devm_kzalloc(&pdev->dev, sizeof(*rda_port), GFP_KERNEL);
746 	if (!rda_port)
747 		return -ENOMEM;
748 
749 	rda_port->clk = devm_clk_get(&pdev->dev, NULL);
750 	if (IS_ERR(rda_port->clk)) {
751 		dev_err(&pdev->dev, "could not get clk\n");
752 		return PTR_ERR(rda_port->clk);
753 	}
754 
755 	rda_port->port.dev = &pdev->dev;
756 	rda_port->port.regshift = 0;
757 	rda_port->port.line = pdev->id;
758 	rda_port->port.type = PORT_RDA;
759 	rda_port->port.iotype = UPIO_MEM;
760 	rda_port->port.mapbase = res_mem->start;
761 	rda_port->port.irq = irq;
762 	rda_port->port.uartclk = clk_get_rate(rda_port->clk);
763 	if (rda_port->port.uartclk == 0) {
764 		dev_err(&pdev->dev, "clock rate is zero\n");
765 		return -EINVAL;
766 	}
767 	rda_port->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP |
768 			       UPF_LOW_LATENCY;
769 	rda_port->port.x_char = 0;
770 	rda_port->port.fifosize = RDA_UART_TX_FIFO_SIZE;
771 	rda_port->port.ops = &rda_uart_ops;
772 
773 	rda_uart_ports[pdev->id] = rda_port;
774 	platform_set_drvdata(pdev, rda_port);
775 
776 	ret = uart_add_one_port(&rda_uart_driver, &rda_port->port);
777 	if (ret)
778 		rda_uart_ports[pdev->id] = NULL;
779 
780 	return ret;
781 }
782 
783 static int rda_uart_remove(struct platform_device *pdev)
784 {
785 	struct rda_uart_port *rda_port = platform_get_drvdata(pdev);
786 
787 	uart_remove_one_port(&rda_uart_driver, &rda_port->port);
788 	rda_uart_ports[pdev->id] = NULL;
789 
790 	return 0;
791 }
792 
793 static struct platform_driver rda_uart_platform_driver = {
794 	.probe = rda_uart_probe,
795 	.remove = rda_uart_remove,
796 	.driver = {
797 		.name = "rda-uart",
798 		.of_match_table = rda_uart_dt_matches,
799 	},
800 };
801 
802 static int __init rda_uart_init(void)
803 {
804 	int ret;
805 
806 	ret = uart_register_driver(&rda_uart_driver);
807 	if (ret)
808 		return ret;
809 
810 	ret = platform_driver_register(&rda_uart_platform_driver);
811 	if (ret)
812 		uart_unregister_driver(&rda_uart_driver);
813 
814 	return ret;
815 }
816 
817 static void __exit rda_uart_exit(void)
818 {
819 	platform_driver_unregister(&rda_uart_platform_driver);
820 	uart_unregister_driver(&rda_uart_driver);
821 }
822 
823 module_init(rda_uart_init);
824 module_exit(rda_uart_exit);
825 
826 MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
827 MODULE_DESCRIPTION("RDA8810PL serial device driver");
828 MODULE_LICENSE("GPL");
829