xref: /openbmc/linux/drivers/tty/serial/sprd_serial.c (revision 979ac5ef) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
4  */
5 
6 #include <linux/clk.h>
7 #include <linux/console.h>
8 #include <linux/delay.h>
9 #include <linux/dmaengine.h>
10 #include <linux/dma-mapping.h>
11 #include <linux/dma/sprd-dma.h>
12 #include <linux/io.h>
13 #include <linux/ioport.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/serial_core.h>
19 #include <linux/serial.h>
20 #include <linux/slab.h>
21 #include <linux/tty.h>
22 #include <linux/tty_flip.h>
23 
24 /* device name */
25 #define UART_NR_MAX		8
26 #define SPRD_TTY_NAME		"ttyS"
27 #define SPRD_FIFO_SIZE		128
28 #define SPRD_DEF_RATE		26000000
29 #define SPRD_BAUD_IO_LIMIT	3000000
30 #define SPRD_TIMEOUT		256000
31 
32 /* the offset of serial registers and BITs for them */
33 /* data registers */
34 #define SPRD_TXD		0x0000
35 #define SPRD_RXD		0x0004
36 
37 /* line status register and its BITs  */
38 #define SPRD_LSR		0x0008
39 #define SPRD_LSR_OE		BIT(4)
40 #define SPRD_LSR_FE		BIT(3)
41 #define SPRD_LSR_PE		BIT(2)
42 #define SPRD_LSR_BI		BIT(7)
43 #define SPRD_LSR_TX_OVER	BIT(15)
44 
45 /* data number in TX and RX fifo */
46 #define SPRD_STS1		0x000C
47 #define SPRD_RX_FIFO_CNT_MASK	GENMASK(7, 0)
48 #define SPRD_TX_FIFO_CNT_MASK	GENMASK(15, 8)
49 
50 /* interrupt enable register and its BITs */
51 #define SPRD_IEN		0x0010
52 #define SPRD_IEN_RX_FULL	BIT(0)
53 #define SPRD_IEN_TX_EMPTY	BIT(1)
54 #define SPRD_IEN_BREAK_DETECT	BIT(7)
55 #define SPRD_IEN_TIMEOUT	BIT(13)
56 
57 /* interrupt clear register */
58 #define SPRD_ICLR		0x0014
59 #define SPRD_ICLR_TIMEOUT	BIT(13)
60 
61 /* line control register */
62 #define SPRD_LCR		0x0018
63 #define SPRD_LCR_STOP_1BIT	0x10
64 #define SPRD_LCR_STOP_2BIT	0x30
65 #define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
66 #define SPRD_LCR_DATA_LEN5	0x0
67 #define SPRD_LCR_DATA_LEN6	0x4
68 #define SPRD_LCR_DATA_LEN7	0x8
69 #define SPRD_LCR_DATA_LEN8	0xc
70 #define SPRD_LCR_PARITY		(BIT(0) | BIT(1))
71 #define SPRD_LCR_PARITY_EN	0x2
72 #define SPRD_LCR_EVEN_PAR	0x0
73 #define SPRD_LCR_ODD_PAR	0x1
74 
75 /* control register 1 */
76 #define SPRD_CTL1		0x001C
77 #define SPRD_DMA_EN		BIT(15)
78 #define SPRD_LOOPBACK_EN	BIT(14)
79 #define RX_HW_FLOW_CTL_THLD	BIT(6)
80 #define RX_HW_FLOW_CTL_EN	BIT(7)
81 #define TX_HW_FLOW_CTL_EN	BIT(8)
82 #define RX_TOUT_THLD_DEF	0x3E00
83 #define RX_HFC_THLD_DEF		0x40
84 
85 /* fifo threshold register */
86 #define SPRD_CTL2		0x0020
87 #define THLD_TX_EMPTY		0x40
88 #define THLD_TX_EMPTY_SHIFT	8
89 #define THLD_RX_FULL		0x40
90 #define THLD_RX_FULL_MASK	GENMASK(6, 0)
91 
92 /* config baud rate register */
93 #define SPRD_CLKD0		0x0024
94 #define SPRD_CLKD0_MASK		GENMASK(15, 0)
95 #define SPRD_CLKD1		0x0028
96 #define SPRD_CLKD1_MASK		GENMASK(20, 16)
97 #define SPRD_CLKD1_SHIFT	16
98 
99 /* interrupt mask status register */
100 #define SPRD_IMSR		0x002C
101 #define SPRD_IMSR_RX_FIFO_FULL	BIT(0)
102 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
103 #define SPRD_IMSR_BREAK_DETECT	BIT(7)
104 #define SPRD_IMSR_TIMEOUT	BIT(13)
105 #define SPRD_DEFAULT_SOURCE_CLK	26000000
106 
107 #define SPRD_RX_DMA_STEP	1
108 #define SPRD_RX_FIFO_FULL	1
109 #define SPRD_TX_FIFO_FULL	0x20
110 #define SPRD_UART_RX_SIZE	(UART_XMIT_SIZE / 4)
111 
112 struct sprd_uart_dma {
113 	struct dma_chan *chn;
114 	unsigned char *virt;
115 	dma_addr_t phys_addr;
116 	dma_cookie_t cookie;
117 	u32 trans_len;
118 	bool enable;
119 };
120 
121 struct sprd_uart_port {
122 	struct uart_port port;
123 	char name[16];
124 	struct clk *clk;
125 	struct sprd_uart_dma tx_dma;
126 	struct sprd_uart_dma rx_dma;
127 	dma_addr_t pos;
128 	unsigned char *rx_buf_tail;
129 };
130 
131 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
132 static int sprd_ports_num;
133 
134 static int sprd_start_dma_rx(struct uart_port *port);
135 static int sprd_tx_dma_config(struct uart_port *port);
136 
137 static inline unsigned int serial_in(struct uart_port *port,
138 				     unsigned int offset)
139 {
140 	return readl_relaxed(port->membase + offset);
141 }
142 
143 static inline void serial_out(struct uart_port *port, unsigned int offset,
144 			      int value)
145 {
146 	writel_relaxed(value, port->membase + offset);
147 }
148 
149 static unsigned int sprd_tx_empty(struct uart_port *port)
150 {
151 	if (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
152 		return 0;
153 	else
154 		return TIOCSER_TEMT;
155 }
156 
157 static unsigned int sprd_get_mctrl(struct uart_port *port)
158 {
159 	return TIOCM_DSR | TIOCM_CTS;
160 }
161 
162 static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
163 {
164 	u32 val = serial_in(port, SPRD_CTL1);
165 
166 	if (mctrl & TIOCM_LOOP)
167 		val |= SPRD_LOOPBACK_EN;
168 	else
169 		val &= ~SPRD_LOOPBACK_EN;
170 
171 	serial_out(port, SPRD_CTL1, val);
172 }
173 
174 static void sprd_stop_rx(struct uart_port *port)
175 {
176 	struct sprd_uart_port *sp =
177 		container_of(port, struct sprd_uart_port, port);
178 	unsigned int ien, iclr;
179 
180 	if (sp->rx_dma.enable)
181 		dmaengine_terminate_all(sp->rx_dma.chn);
182 
183 	iclr = serial_in(port, SPRD_ICLR);
184 	ien = serial_in(port, SPRD_IEN);
185 
186 	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
187 	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
188 
189 	serial_out(port, SPRD_IEN, ien);
190 	serial_out(port, SPRD_ICLR, iclr);
191 }
192 
193 static void sprd_uart_dma_enable(struct uart_port *port, bool enable)
194 {
195 	u32 val = serial_in(port, SPRD_CTL1);
196 
197 	if (enable)
198 		val |= SPRD_DMA_EN;
199 	else
200 		val &= ~SPRD_DMA_EN;
201 
202 	serial_out(port, SPRD_CTL1, val);
203 }
204 
205 static void sprd_stop_tx_dma(struct uart_port *port)
206 {
207 	struct sprd_uart_port *sp =
208 		container_of(port, struct sprd_uart_port, port);
209 	struct dma_tx_state state;
210 	u32 trans_len;
211 
212 	dmaengine_pause(sp->tx_dma.chn);
213 
214 	dmaengine_tx_status(sp->tx_dma.chn, sp->tx_dma.cookie, &state);
215 	if (state.residue) {
216 		trans_len = state.residue - sp->tx_dma.phys_addr;
217 		uart_xmit_advance(port, trans_len);
218 		dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
219 				 sp->tx_dma.trans_len, DMA_TO_DEVICE);
220 	}
221 
222 	dmaengine_terminate_all(sp->tx_dma.chn);
223 	sp->tx_dma.trans_len = 0;
224 }
225 
226 static int sprd_tx_buf_remap(struct uart_port *port)
227 {
228 	struct sprd_uart_port *sp =
229 		container_of(port, struct sprd_uart_port, port);
230 	struct circ_buf *xmit = &port->state->xmit;
231 
232 	sp->tx_dma.trans_len =
233 		CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
234 
235 	sp->tx_dma.phys_addr = dma_map_single(port->dev,
236 					      (void *)&(xmit->buf[xmit->tail]),
237 					      sp->tx_dma.trans_len,
238 					      DMA_TO_DEVICE);
239 	return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
240 }
241 
242 static void sprd_complete_tx_dma(void *data)
243 {
244 	struct uart_port *port = (struct uart_port *)data;
245 	struct sprd_uart_port *sp =
246 		container_of(port, struct sprd_uart_port, port);
247 	struct circ_buf *xmit = &port->state->xmit;
248 	unsigned long flags;
249 
250 	spin_lock_irqsave(&port->lock, flags);
251 	dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
252 			 sp->tx_dma.trans_len, DMA_TO_DEVICE);
253 
254 	uart_xmit_advance(port, sp->tx_dma.trans_len);
255 
256 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
257 		uart_write_wakeup(port);
258 
259 	if (uart_circ_empty(xmit) || sprd_tx_buf_remap(port) ||
260 	    sprd_tx_dma_config(port))
261 		sp->tx_dma.trans_len = 0;
262 
263 	spin_unlock_irqrestore(&port->lock, flags);
264 }
265 
266 static int sprd_uart_dma_submit(struct uart_port *port,
267 				struct sprd_uart_dma *ud, u32 trans_len,
268 				enum dma_transfer_direction direction,
269 				dma_async_tx_callback callback)
270 {
271 	struct dma_async_tx_descriptor *dma_des;
272 	unsigned long flags;
273 
274 	flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE,
275 			       SPRD_DMA_NO_TRG,
276 			       SPRD_DMA_FRAG_REQ,
277 			       SPRD_DMA_TRANS_INT);
278 
279 	dma_des = dmaengine_prep_slave_single(ud->chn, ud->phys_addr, trans_len,
280 					      direction, flags);
281 	if (!dma_des)
282 		return -ENODEV;
283 
284 	dma_des->callback = callback;
285 	dma_des->callback_param = port;
286 
287 	ud->cookie = dmaengine_submit(dma_des);
288 	if (dma_submit_error(ud->cookie))
289 		return dma_submit_error(ud->cookie);
290 
291 	dma_async_issue_pending(ud->chn);
292 
293 	return 0;
294 }
295 
296 static int sprd_tx_dma_config(struct uart_port *port)
297 {
298 	struct sprd_uart_port *sp =
299 		container_of(port, struct sprd_uart_port, port);
300 	u32 burst = sp->tx_dma.trans_len > SPRD_TX_FIFO_FULL ?
301 		SPRD_TX_FIFO_FULL : sp->tx_dma.trans_len;
302 	int ret;
303 	struct dma_slave_config cfg = {
304 		.dst_addr = port->mapbase + SPRD_TXD,
305 		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
306 		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
307 		.src_maxburst = burst,
308 	};
309 
310 	ret = dmaengine_slave_config(sp->tx_dma.chn, &cfg);
311 	if (ret < 0)
312 		return ret;
313 
314 	return sprd_uart_dma_submit(port, &sp->tx_dma, sp->tx_dma.trans_len,
315 				    DMA_MEM_TO_DEV, sprd_complete_tx_dma);
316 }
317 
318 static void sprd_start_tx_dma(struct uart_port *port)
319 {
320 	struct sprd_uart_port *sp =
321 		container_of(port, struct sprd_uart_port, port);
322 	struct circ_buf *xmit = &port->state->xmit;
323 
324 	if (port->x_char) {
325 		serial_out(port, SPRD_TXD, port->x_char);
326 		port->icount.tx++;
327 		port->x_char = 0;
328 		return;
329 	}
330 
331 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
332 		sprd_stop_tx_dma(port);
333 		return;
334 	}
335 
336 	if (sp->tx_dma.trans_len)
337 		return;
338 
339 	if (sprd_tx_buf_remap(port) || sprd_tx_dma_config(port))
340 		sp->tx_dma.trans_len = 0;
341 }
342 
343 static void sprd_rx_full_thld(struct uart_port *port, u32 thld)
344 {
345 	u32 val = serial_in(port, SPRD_CTL2);
346 
347 	val &= ~THLD_RX_FULL_MASK;
348 	val |= thld & THLD_RX_FULL_MASK;
349 	serial_out(port, SPRD_CTL2, val);
350 }
351 
352 static int sprd_rx_alloc_buf(struct sprd_uart_port *sp)
353 {
354 	sp->rx_dma.virt = dma_alloc_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
355 					     &sp->rx_dma.phys_addr, GFP_KERNEL);
356 	if (!sp->rx_dma.virt)
357 		return -ENOMEM;
358 
359 	return 0;
360 }
361 
362 static void sprd_rx_free_buf(struct sprd_uart_port *sp)
363 {
364 	if (sp->rx_dma.virt)
365 		dma_free_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
366 				  sp->rx_dma.virt, sp->rx_dma.phys_addr);
367 
368 }
369 
370 static int sprd_rx_dma_config(struct uart_port *port, u32 burst)
371 {
372 	struct sprd_uart_port *sp =
373 		container_of(port, struct sprd_uart_port, port);
374 	struct dma_slave_config cfg = {
375 		.src_addr = port->mapbase + SPRD_RXD,
376 		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
377 		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
378 		.src_maxburst = burst,
379 	};
380 
381 	return dmaengine_slave_config(sp->rx_dma.chn, &cfg);
382 }
383 
384 static void sprd_uart_dma_rx(struct uart_port *port)
385 {
386 	struct sprd_uart_port *sp =
387 		container_of(port, struct sprd_uart_port, port);
388 	struct tty_port *tty = &port->state->port;
389 
390 	port->icount.rx += sp->rx_dma.trans_len;
391 	tty_insert_flip_string(tty, sp->rx_buf_tail, sp->rx_dma.trans_len);
392 	tty_flip_buffer_push(tty);
393 }
394 
395 static void sprd_uart_dma_irq(struct uart_port *port)
396 {
397 	struct sprd_uart_port *sp =
398 		container_of(port, struct sprd_uart_port, port);
399 	struct dma_tx_state state;
400 	enum dma_status status;
401 
402 	status = dmaengine_tx_status(sp->rx_dma.chn,
403 				     sp->rx_dma.cookie, &state);
404 	if (status == DMA_ERROR)
405 		sprd_stop_rx(port);
406 
407 	if (!state.residue && sp->pos == sp->rx_dma.phys_addr)
408 		return;
409 
410 	if (!state.residue) {
411 		sp->rx_dma.trans_len = SPRD_UART_RX_SIZE +
412 			sp->rx_dma.phys_addr - sp->pos;
413 		sp->pos = sp->rx_dma.phys_addr;
414 	} else {
415 		sp->rx_dma.trans_len = state.residue - sp->pos;
416 		sp->pos = state.residue;
417 	}
418 
419 	sprd_uart_dma_rx(port);
420 	sp->rx_buf_tail += sp->rx_dma.trans_len;
421 }
422 
423 static void sprd_complete_rx_dma(void *data)
424 {
425 	struct uart_port *port = (struct uart_port *)data;
426 	struct sprd_uart_port *sp =
427 		container_of(port, struct sprd_uart_port, port);
428 	struct dma_tx_state state;
429 	enum dma_status status;
430 	unsigned long flags;
431 
432 	spin_lock_irqsave(&port->lock, flags);
433 
434 	status = dmaengine_tx_status(sp->rx_dma.chn,
435 				     sp->rx_dma.cookie, &state);
436 	if (status != DMA_COMPLETE) {
437 		sprd_stop_rx(port);
438 		spin_unlock_irqrestore(&port->lock, flags);
439 		return;
440 	}
441 
442 	if (sp->pos != sp->rx_dma.phys_addr) {
443 		sp->rx_dma.trans_len =  SPRD_UART_RX_SIZE +
444 			sp->rx_dma.phys_addr - sp->pos;
445 		sprd_uart_dma_rx(port);
446 		sp->rx_buf_tail += sp->rx_dma.trans_len;
447 	}
448 
449 	if (sprd_start_dma_rx(port))
450 		sprd_stop_rx(port);
451 
452 	spin_unlock_irqrestore(&port->lock, flags);
453 }
454 
455 static int sprd_start_dma_rx(struct uart_port *port)
456 {
457 	struct sprd_uart_port *sp =
458 		container_of(port, struct sprd_uart_port, port);
459 	int ret;
460 
461 	if (!sp->rx_dma.enable)
462 		return 0;
463 
464 	sp->pos = sp->rx_dma.phys_addr;
465 	sp->rx_buf_tail = sp->rx_dma.virt;
466 	sprd_rx_full_thld(port, SPRD_RX_FIFO_FULL);
467 	ret = sprd_rx_dma_config(port, SPRD_RX_DMA_STEP);
468 	if (ret)
469 		return ret;
470 
471 	return sprd_uart_dma_submit(port, &sp->rx_dma, SPRD_UART_RX_SIZE,
472 				    DMA_DEV_TO_MEM, sprd_complete_rx_dma);
473 }
474 
475 static void sprd_release_dma(struct uart_port *port)
476 {
477 	struct sprd_uart_port *sp =
478 		container_of(port, struct sprd_uart_port, port);
479 
480 	sprd_uart_dma_enable(port, false);
481 
482 	if (sp->rx_dma.enable)
483 		dma_release_channel(sp->rx_dma.chn);
484 
485 	if (sp->tx_dma.enable)
486 		dma_release_channel(sp->tx_dma.chn);
487 
488 	sp->tx_dma.enable = false;
489 	sp->rx_dma.enable = false;
490 }
491 
492 static void sprd_request_dma(struct uart_port *port)
493 {
494 	struct sprd_uart_port *sp =
495 		container_of(port, struct sprd_uart_port, port);
496 
497 	sp->tx_dma.enable = true;
498 	sp->rx_dma.enable = true;
499 
500 	sp->tx_dma.chn = dma_request_chan(port->dev, "tx");
501 	if (IS_ERR(sp->tx_dma.chn)) {
502 		dev_err(port->dev, "request TX DMA channel failed, ret = %ld\n",
503 			PTR_ERR(sp->tx_dma.chn));
504 		sp->tx_dma.enable = false;
505 	}
506 
507 	sp->rx_dma.chn = dma_request_chan(port->dev, "rx");
508 	if (IS_ERR(sp->rx_dma.chn)) {
509 		dev_err(port->dev, "request RX DMA channel failed, ret = %ld\n",
510 			PTR_ERR(sp->rx_dma.chn));
511 		sp->rx_dma.enable = false;
512 	}
513 }
514 
515 static void sprd_stop_tx(struct uart_port *port)
516 {
517 	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
518 						 port);
519 	unsigned int ien, iclr;
520 
521 	if (sp->tx_dma.enable) {
522 		sprd_stop_tx_dma(port);
523 		return;
524 	}
525 
526 	iclr = serial_in(port, SPRD_ICLR);
527 	ien = serial_in(port, SPRD_IEN);
528 
529 	iclr |= SPRD_IEN_TX_EMPTY;
530 	ien &= ~SPRD_IEN_TX_EMPTY;
531 
532 	serial_out(port, SPRD_IEN, ien);
533 	serial_out(port, SPRD_ICLR, iclr);
534 }
535 
536 static void sprd_start_tx(struct uart_port *port)
537 {
538 	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
539 						 port);
540 	unsigned int ien;
541 
542 	if (sp->tx_dma.enable) {
543 		sprd_start_tx_dma(port);
544 		return;
545 	}
546 
547 	ien = serial_in(port, SPRD_IEN);
548 	if (!(ien & SPRD_IEN_TX_EMPTY)) {
549 		ien |= SPRD_IEN_TX_EMPTY;
550 		serial_out(port, SPRD_IEN, ien);
551 	}
552 }
553 
554 /* The Sprd serial does not support this function. */
555 static void sprd_break_ctl(struct uart_port *port, int break_state)
556 {
557 	/* nothing to do */
558 }
559 
560 static int handle_lsr_errors(struct uart_port *port,
561 			     unsigned int *flag,
562 			     unsigned int *lsr)
563 {
564 	int ret = 0;
565 
566 	/* statistics */
567 	if (*lsr & SPRD_LSR_BI) {
568 		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
569 		port->icount.brk++;
570 		ret = uart_handle_break(port);
571 		if (ret)
572 			return ret;
573 	} else if (*lsr & SPRD_LSR_PE)
574 		port->icount.parity++;
575 	else if (*lsr & SPRD_LSR_FE)
576 		port->icount.frame++;
577 	if (*lsr & SPRD_LSR_OE)
578 		port->icount.overrun++;
579 
580 	/* mask off conditions which should be ignored */
581 	*lsr &= port->read_status_mask;
582 	if (*lsr & SPRD_LSR_BI)
583 		*flag = TTY_BREAK;
584 	else if (*lsr & SPRD_LSR_PE)
585 		*flag = TTY_PARITY;
586 	else if (*lsr & SPRD_LSR_FE)
587 		*flag = TTY_FRAME;
588 
589 	return ret;
590 }
591 
592 static inline void sprd_rx(struct uart_port *port)
593 {
594 	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
595 						 port);
596 	struct tty_port *tty = &port->state->port;
597 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
598 
599 	if (sp->rx_dma.enable) {
600 		sprd_uart_dma_irq(port);
601 		return;
602 	}
603 
604 	while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
605 	       max_count--) {
606 		lsr = serial_in(port, SPRD_LSR);
607 		ch = serial_in(port, SPRD_RXD);
608 		flag = TTY_NORMAL;
609 		port->icount.rx++;
610 
611 		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
612 			   SPRD_LSR_FE | SPRD_LSR_OE))
613 			if (handle_lsr_errors(port, &flag, &lsr))
614 				continue;
615 		if (uart_handle_sysrq_char(port, ch))
616 			continue;
617 
618 		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
619 	}
620 
621 	tty_flip_buffer_push(tty);
622 }
623 
624 static inline void sprd_tx(struct uart_port *port)
625 {
626 	u8 ch;
627 
628 	uart_port_tx_limited(port, ch, THLD_TX_EMPTY,
629 		true,
630 		serial_out(port, SPRD_TXD, ch),
631 		({}));
632 }
633 
634 /* this handles the interrupt from one port */
635 static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
636 {
637 	struct uart_port *port = dev_id;
638 	unsigned int ims;
639 
640 	spin_lock(&port->lock);
641 
642 	ims = serial_in(port, SPRD_IMSR);
643 
644 	if (!ims) {
645 		spin_unlock(&port->lock);
646 		return IRQ_NONE;
647 	}
648 
649 	if (ims & SPRD_IMSR_TIMEOUT)
650 		serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT);
651 
652 	if (ims & SPRD_IMSR_BREAK_DETECT)
653 		serial_out(port, SPRD_ICLR, SPRD_IMSR_BREAK_DETECT);
654 
655 	if (ims & (SPRD_IMSR_RX_FIFO_FULL | SPRD_IMSR_BREAK_DETECT |
656 		   SPRD_IMSR_TIMEOUT))
657 		sprd_rx(port);
658 
659 	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
660 		sprd_tx(port);
661 
662 	spin_unlock(&port->lock);
663 
664 	return IRQ_HANDLED;
665 }
666 
667 static void sprd_uart_dma_startup(struct uart_port *port,
668 				  struct sprd_uart_port *sp)
669 {
670 	int ret;
671 
672 	sprd_request_dma(port);
673 	if (!(sp->rx_dma.enable || sp->tx_dma.enable))
674 		return;
675 
676 	ret = sprd_start_dma_rx(port);
677 	if (ret) {
678 		sp->rx_dma.enable = false;
679 		dma_release_channel(sp->rx_dma.chn);
680 		dev_warn(port->dev, "fail to start RX dma mode\n");
681 	}
682 
683 	sprd_uart_dma_enable(port, true);
684 }
685 
686 static int sprd_startup(struct uart_port *port)
687 {
688 	int ret = 0;
689 	unsigned int ien, fc;
690 	unsigned int timeout;
691 	struct sprd_uart_port *sp;
692 	unsigned long flags;
693 
694 	serial_out(port, SPRD_CTL2,
695 		   THLD_TX_EMPTY << THLD_TX_EMPTY_SHIFT | THLD_RX_FULL);
696 
697 	/* clear rx fifo */
698 	timeout = SPRD_TIMEOUT;
699 	while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK)
700 		serial_in(port, SPRD_RXD);
701 
702 	/* clear tx fifo */
703 	timeout = SPRD_TIMEOUT;
704 	while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
705 		cpu_relax();
706 
707 	/* clear interrupt */
708 	serial_out(port, SPRD_IEN, 0);
709 	serial_out(port, SPRD_ICLR, ~0);
710 
711 	/* allocate irq */
712 	sp = container_of(port, struct sprd_uart_port, port);
713 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
714 
715 	sprd_uart_dma_startup(port, sp);
716 
717 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
718 			       IRQF_SHARED, sp->name, port);
719 	if (ret) {
720 		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
721 			port->irq, ret);
722 		return ret;
723 	}
724 	fc = serial_in(port, SPRD_CTL1);
725 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
726 	serial_out(port, SPRD_CTL1, fc);
727 
728 	/* enable interrupt */
729 	spin_lock_irqsave(&port->lock, flags);
730 	ien = serial_in(port, SPRD_IEN);
731 	ien |= SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
732 	if (!sp->rx_dma.enable)
733 		ien |= SPRD_IEN_RX_FULL;
734 	serial_out(port, SPRD_IEN, ien);
735 	spin_unlock_irqrestore(&port->lock, flags);
736 
737 	return 0;
738 }
739 
740 static void sprd_shutdown(struct uart_port *port)
741 {
742 	sprd_release_dma(port);
743 	serial_out(port, SPRD_IEN, 0);
744 	serial_out(port, SPRD_ICLR, ~0);
745 	devm_free_irq(port->dev, port->irq, port);
746 }
747 
748 static void sprd_set_termios(struct uart_port *port, struct ktermios *termios,
749 		             const struct ktermios *old)
750 {
751 	unsigned int baud, quot;
752 	unsigned int lcr = 0, fc;
753 	unsigned long flags;
754 
755 	/* ask the core to calculate the divisor for us */
756 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
757 
758 	quot = port->uartclk / baud;
759 
760 	/* set data length */
761 	switch (termios->c_cflag & CSIZE) {
762 	case CS5:
763 		lcr |= SPRD_LCR_DATA_LEN5;
764 		break;
765 	case CS6:
766 		lcr |= SPRD_LCR_DATA_LEN6;
767 		break;
768 	case CS7:
769 		lcr |= SPRD_LCR_DATA_LEN7;
770 		break;
771 	case CS8:
772 	default:
773 		lcr |= SPRD_LCR_DATA_LEN8;
774 		break;
775 	}
776 
777 	/* calculate stop bits */
778 	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
779 	if (termios->c_cflag & CSTOPB)
780 		lcr |= SPRD_LCR_STOP_2BIT;
781 	else
782 		lcr |= SPRD_LCR_STOP_1BIT;
783 
784 	/* calculate parity */
785 	lcr &= ~SPRD_LCR_PARITY;
786 	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
787 	if (termios->c_cflag & PARENB) {
788 		lcr |= SPRD_LCR_PARITY_EN;
789 		if (termios->c_cflag & PARODD)
790 			lcr |= SPRD_LCR_ODD_PAR;
791 		else
792 			lcr |= SPRD_LCR_EVEN_PAR;
793 	}
794 
795 	spin_lock_irqsave(&port->lock, flags);
796 
797 	/* update the per-port timeout */
798 	uart_update_timeout(port, termios->c_cflag, baud);
799 
800 	port->read_status_mask = SPRD_LSR_OE;
801 	if (termios->c_iflag & INPCK)
802 		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
803 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
804 		port->read_status_mask |= SPRD_LSR_BI;
805 
806 	/* characters to ignore */
807 	port->ignore_status_mask = 0;
808 	if (termios->c_iflag & IGNPAR)
809 		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
810 	if (termios->c_iflag & IGNBRK) {
811 		port->ignore_status_mask |= SPRD_LSR_BI;
812 		/*
813 		 * If we're ignoring parity and break indicators,
814 		 * ignore overruns too (for real raw support).
815 		 */
816 		if (termios->c_iflag & IGNPAR)
817 			port->ignore_status_mask |= SPRD_LSR_OE;
818 	}
819 
820 	/* flow control */
821 	fc = serial_in(port, SPRD_CTL1);
822 	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
823 	if (termios->c_cflag & CRTSCTS) {
824 		fc |= RX_HW_FLOW_CTL_THLD;
825 		fc |= RX_HW_FLOW_CTL_EN;
826 		fc |= TX_HW_FLOW_CTL_EN;
827 	}
828 
829 	/* clock divider bit0~bit15 */
830 	serial_out(port, SPRD_CLKD0, quot & SPRD_CLKD0_MASK);
831 
832 	/* clock divider bit16~bit20 */
833 	serial_out(port, SPRD_CLKD1,
834 		   (quot & SPRD_CLKD1_MASK) >> SPRD_CLKD1_SHIFT);
835 	serial_out(port, SPRD_LCR, lcr);
836 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
837 	serial_out(port, SPRD_CTL1, fc);
838 
839 	spin_unlock_irqrestore(&port->lock, flags);
840 
841 	/* Don't rewrite B0 */
842 	if (tty_termios_baud_rate(termios))
843 		tty_termios_encode_baud_rate(termios, baud, baud);
844 }
845 
846 static const char *sprd_type(struct uart_port *port)
847 {
848 	return "SPX";
849 }
850 
851 static void sprd_release_port(struct uart_port *port)
852 {
853 	/* nothing to do */
854 }
855 
856 static int sprd_request_port(struct uart_port *port)
857 {
858 	return 0;
859 }
860 
861 static void sprd_config_port(struct uart_port *port, int flags)
862 {
863 	if (flags & UART_CONFIG_TYPE)
864 		port->type = PORT_SPRD;
865 }
866 
867 static int sprd_verify_port(struct uart_port *port, struct serial_struct *ser)
868 {
869 	if (ser->type != PORT_SPRD)
870 		return -EINVAL;
871 	if (port->irq != ser->irq)
872 		return -EINVAL;
873 	if (port->iotype != ser->io_type)
874 		return -EINVAL;
875 	return 0;
876 }
877 
878 static void sprd_pm(struct uart_port *port, unsigned int state,
879 		unsigned int oldstate)
880 {
881 	struct sprd_uart_port *sup =
882 		container_of(port, struct sprd_uart_port, port);
883 
884 	switch (state) {
885 	case UART_PM_STATE_ON:
886 		clk_prepare_enable(sup->clk);
887 		break;
888 	case UART_PM_STATE_OFF:
889 		clk_disable_unprepare(sup->clk);
890 		break;
891 	}
892 }
893 
894 #ifdef CONFIG_CONSOLE_POLL
895 static int sprd_poll_init(struct uart_port *port)
896 {
897 	if (port->state->pm_state != UART_PM_STATE_ON) {
898 		sprd_pm(port, UART_PM_STATE_ON, 0);
899 		port->state->pm_state = UART_PM_STATE_ON;
900 	}
901 
902 	return 0;
903 }
904 
905 static int sprd_poll_get_char(struct uart_port *port)
906 {
907 	while (!(serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK))
908 		cpu_relax();
909 
910 	return serial_in(port, SPRD_RXD);
911 }
912 
913 static void sprd_poll_put_char(struct uart_port *port, unsigned char ch)
914 {
915 	while (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
916 		cpu_relax();
917 
918 	serial_out(port, SPRD_TXD, ch);
919 }
920 #endif
921 
922 static const struct uart_ops serial_sprd_ops = {
923 	.tx_empty = sprd_tx_empty,
924 	.get_mctrl = sprd_get_mctrl,
925 	.set_mctrl = sprd_set_mctrl,
926 	.stop_tx = sprd_stop_tx,
927 	.start_tx = sprd_start_tx,
928 	.stop_rx = sprd_stop_rx,
929 	.break_ctl = sprd_break_ctl,
930 	.startup = sprd_startup,
931 	.shutdown = sprd_shutdown,
932 	.set_termios = sprd_set_termios,
933 	.type = sprd_type,
934 	.release_port = sprd_release_port,
935 	.request_port = sprd_request_port,
936 	.config_port = sprd_config_port,
937 	.verify_port = sprd_verify_port,
938 	.pm = sprd_pm,
939 #ifdef CONFIG_CONSOLE_POLL
940 	.poll_init	= sprd_poll_init,
941 	.poll_get_char	= sprd_poll_get_char,
942 	.poll_put_char	= sprd_poll_put_char,
943 #endif
944 };
945 
946 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
947 static void wait_for_xmitr(struct uart_port *port)
948 {
949 	unsigned int status, tmout = 10000;
950 
951 	/* wait up to 10ms for the character(s) to be sent */
952 	do {
953 		status = serial_in(port, SPRD_STS1);
954 		if (--tmout == 0)
955 			break;
956 		udelay(1);
957 	} while (status & SPRD_TX_FIFO_CNT_MASK);
958 }
959 
960 static void sprd_console_putchar(struct uart_port *port, unsigned char ch)
961 {
962 	wait_for_xmitr(port);
963 	serial_out(port, SPRD_TXD, ch);
964 }
965 
966 static void sprd_console_write(struct console *co, const char *s,
967 			       unsigned int count)
968 {
969 	struct uart_port *port = &sprd_port[co->index]->port;
970 	int locked = 1;
971 	unsigned long flags;
972 
973 	if (port->sysrq)
974 		locked = 0;
975 	else if (oops_in_progress)
976 		locked = spin_trylock_irqsave(&port->lock, flags);
977 	else
978 		spin_lock_irqsave(&port->lock, flags);
979 
980 	uart_console_write(port, s, count, sprd_console_putchar);
981 
982 	/* wait for transmitter to become empty */
983 	wait_for_xmitr(port);
984 
985 	if (locked)
986 		spin_unlock_irqrestore(&port->lock, flags);
987 }
988 
989 static int sprd_console_setup(struct console *co, char *options)
990 {
991 	struct sprd_uart_port *sprd_uart_port;
992 	int baud = 115200;
993 	int bits = 8;
994 	int parity = 'n';
995 	int flow = 'n';
996 
997 	if (co->index >= UART_NR_MAX || co->index < 0)
998 		co->index = 0;
999 
1000 	sprd_uart_port = sprd_port[co->index];
1001 	if (!sprd_uart_port || !sprd_uart_port->port.membase) {
1002 		pr_info("serial port %d not yet initialized\n", co->index);
1003 		return -ENODEV;
1004 	}
1005 
1006 	if (options)
1007 		uart_parse_options(options, &baud, &parity, &bits, &flow);
1008 
1009 	return uart_set_options(&sprd_uart_port->port, co, baud,
1010 				parity, bits, flow);
1011 }
1012 
1013 static struct uart_driver sprd_uart_driver;
1014 static struct console sprd_console = {
1015 	.name = SPRD_TTY_NAME,
1016 	.write = sprd_console_write,
1017 	.device = uart_console_device,
1018 	.setup = sprd_console_setup,
1019 	.flags = CON_PRINTBUFFER,
1020 	.index = -1,
1021 	.data = &sprd_uart_driver,
1022 };
1023 
1024 static int __init sprd_serial_console_init(void)
1025 {
1026 	register_console(&sprd_console);
1027 	return 0;
1028 }
1029 console_initcall(sprd_serial_console_init);
1030 
1031 #define SPRD_CONSOLE	(&sprd_console)
1032 
1033 /* Support for earlycon */
1034 static void sprd_putc(struct uart_port *port, unsigned char c)
1035 {
1036 	unsigned int timeout = SPRD_TIMEOUT;
1037 
1038 	while (timeout-- &&
1039 	       !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
1040 		cpu_relax();
1041 
1042 	writeb(c, port->membase + SPRD_TXD);
1043 }
1044 
1045 static void sprd_early_write(struct console *con, const char *s, unsigned int n)
1046 {
1047 	struct earlycon_device *dev = con->data;
1048 
1049 	uart_console_write(&dev->port, s, n, sprd_putc);
1050 }
1051 
1052 static int __init sprd_early_console_setup(struct earlycon_device *device,
1053 					   const char *opt)
1054 {
1055 	if (!device->port.membase)
1056 		return -ENODEV;
1057 
1058 	device->con->write = sprd_early_write;
1059 	return 0;
1060 }
1061 OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
1062 		    sprd_early_console_setup);
1063 
1064 #else /* !CONFIG_SERIAL_SPRD_CONSOLE */
1065 #define SPRD_CONSOLE		NULL
1066 #endif
1067 
1068 static struct uart_driver sprd_uart_driver = {
1069 	.owner = THIS_MODULE,
1070 	.driver_name = "sprd_serial",
1071 	.dev_name = SPRD_TTY_NAME,
1072 	.major = 0,
1073 	.minor = 0,
1074 	.nr = UART_NR_MAX,
1075 	.cons = SPRD_CONSOLE,
1076 };
1077 
1078 static int sprd_remove(struct platform_device *dev)
1079 {
1080 	struct sprd_uart_port *sup = platform_get_drvdata(dev);
1081 
1082 	if (sup) {
1083 		uart_remove_one_port(&sprd_uart_driver, &sup->port);
1084 		sprd_port[sup->port.line] = NULL;
1085 		sprd_rx_free_buf(sup);
1086 		sprd_ports_num--;
1087 	}
1088 
1089 	if (!sprd_ports_num)
1090 		uart_unregister_driver(&sprd_uart_driver);
1091 
1092 	return 0;
1093 }
1094 
1095 static bool sprd_uart_is_console(struct uart_port *uport)
1096 {
1097 	struct console *cons = sprd_uart_driver.cons;
1098 
1099 	if ((cons && cons->index >= 0 && cons->index == uport->line) ||
1100 	    of_console_check(uport->dev->of_node, SPRD_TTY_NAME, uport->line))
1101 		return true;
1102 
1103 	return false;
1104 }
1105 
1106 static int sprd_clk_init(struct uart_port *uport)
1107 {
1108 	struct clk *clk_uart, *clk_parent;
1109 	struct sprd_uart_port *u = sprd_port[uport->line];
1110 
1111 	clk_uart = devm_clk_get(uport->dev, "uart");
1112 	if (IS_ERR(clk_uart)) {
1113 		dev_warn(uport->dev, "uart%d can't get uart clock\n",
1114 			 uport->line);
1115 		clk_uart = NULL;
1116 	}
1117 
1118 	clk_parent = devm_clk_get(uport->dev, "source");
1119 	if (IS_ERR(clk_parent)) {
1120 		dev_warn(uport->dev, "uart%d can't get source clock\n",
1121 			 uport->line);
1122 		clk_parent = NULL;
1123 	}
1124 
1125 	if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
1126 		uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
1127 	else
1128 		uport->uartclk = clk_get_rate(clk_uart);
1129 
1130 	u->clk = devm_clk_get(uport->dev, "enable");
1131 	if (IS_ERR(u->clk)) {
1132 		if (PTR_ERR(u->clk) == -EPROBE_DEFER)
1133 			return -EPROBE_DEFER;
1134 
1135 		dev_warn(uport->dev, "uart%d can't get enable clock\n",
1136 			uport->line);
1137 
1138 		/* To keep console alive even if the error occurred */
1139 		if (!sprd_uart_is_console(uport))
1140 			return PTR_ERR(u->clk);
1141 
1142 		u->clk = NULL;
1143 	}
1144 
1145 	return 0;
1146 }
1147 
1148 static int sprd_probe(struct platform_device *pdev)
1149 {
1150 	struct resource *res;
1151 	struct uart_port *up;
1152 	int irq;
1153 	int index;
1154 	int ret;
1155 
1156 	index = of_alias_get_id(pdev->dev.of_node, "serial");
1157 	if (index < 0 || index >= ARRAY_SIZE(sprd_port)) {
1158 		dev_err(&pdev->dev, "got a wrong serial alias id %d\n", index);
1159 		return -EINVAL;
1160 	}
1161 
1162 	sprd_port[index] = devm_kzalloc(&pdev->dev, sizeof(*sprd_port[index]),
1163 					GFP_KERNEL);
1164 	if (!sprd_port[index])
1165 		return -ENOMEM;
1166 
1167 	up = &sprd_port[index]->port;
1168 	up->dev = &pdev->dev;
1169 	up->line = index;
1170 	up->type = PORT_SPRD;
1171 	up->iotype = UPIO_MEM;
1172 	up->uartclk = SPRD_DEF_RATE;
1173 	up->fifosize = SPRD_FIFO_SIZE;
1174 	up->ops = &serial_sprd_ops;
1175 	up->flags = UPF_BOOT_AUTOCONF;
1176 	up->has_sysrq = IS_ENABLED(CONFIG_SERIAL_SPRD_CONSOLE);
1177 
1178 	ret = sprd_clk_init(up);
1179 	if (ret)
1180 		return ret;
1181 
1182 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1183 	up->membase = devm_ioremap_resource(&pdev->dev, res);
1184 	if (IS_ERR(up->membase))
1185 		return PTR_ERR(up->membase);
1186 
1187 	up->mapbase = res->start;
1188 
1189 	irq = platform_get_irq(pdev, 0);
1190 	if (irq < 0)
1191 		return irq;
1192 	up->irq = irq;
1193 
1194 	/*
1195 	 * Allocate one dma buffer to prepare for receive transfer, in case
1196 	 * memory allocation failure at runtime.
1197 	 */
1198 	ret = sprd_rx_alloc_buf(sprd_port[index]);
1199 	if (ret)
1200 		return ret;
1201 
1202 	if (!sprd_ports_num) {
1203 		ret = uart_register_driver(&sprd_uart_driver);
1204 		if (ret < 0) {
1205 			pr_err("Failed to register SPRD-UART driver\n");
1206 			return ret;
1207 		}
1208 	}
1209 	sprd_ports_num++;
1210 
1211 	ret = uart_add_one_port(&sprd_uart_driver, up);
1212 	if (ret)
1213 		sprd_remove(pdev);
1214 
1215 	platform_set_drvdata(pdev, up);
1216 
1217 	return ret;
1218 }
1219 
1220 #ifdef CONFIG_PM_SLEEP
1221 static int sprd_suspend(struct device *dev)
1222 {
1223 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
1224 
1225 	uart_suspend_port(&sprd_uart_driver, &sup->port);
1226 
1227 	return 0;
1228 }
1229 
1230 static int sprd_resume(struct device *dev)
1231 {
1232 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
1233 
1234 	uart_resume_port(&sprd_uart_driver, &sup->port);
1235 
1236 	return 0;
1237 }
1238 #endif
1239 
1240 static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
1241 
1242 static const struct of_device_id serial_ids[] = {
1243 	{.compatible = "sprd,sc9836-uart",},
1244 	{}
1245 };
1246 MODULE_DEVICE_TABLE(of, serial_ids);
1247 
1248 static struct platform_driver sprd_platform_driver = {
1249 	.probe		= sprd_probe,
1250 	.remove		= sprd_remove,
1251 	.driver		= {
1252 		.name	= "sprd_serial",
1253 		.of_match_table = of_match_ptr(serial_ids),
1254 		.pm	= &sprd_pm_ops,
1255 	},
1256 };
1257 
1258 module_platform_driver(sprd_platform_driver);
1259 
1260 MODULE_LICENSE("GPL v2");
1261 MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");
1262