1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2012 - 2014 Allwinner Tech
4 * Pan Nan <pannan@allwinnertech.com>
5 *
6 * Copyright (C) 2014 Maxime Ripard
7 * Maxime Ripard <maxime.ripard@free-electrons.com>
8 */
9
10 #include <linux/clk.h>
11 #include <linux/delay.h>
12 #include <linux/device.h>
13 #include <linux/interrupt.h>
14 #include <linux/io.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/pm_runtime.h>
18
19 #include <linux/spi/spi.h>
20
21 #define SUN4I_FIFO_DEPTH 64
22
23 #define SUN4I_RXDATA_REG 0x00
24
25 #define SUN4I_TXDATA_REG 0x04
26
27 #define SUN4I_CTL_REG 0x08
28 #define SUN4I_CTL_ENABLE BIT(0)
29 #define SUN4I_CTL_MASTER BIT(1)
30 #define SUN4I_CTL_CPHA BIT(2)
31 #define SUN4I_CTL_CPOL BIT(3)
32 #define SUN4I_CTL_CS_ACTIVE_LOW BIT(4)
33 #define SUN4I_CTL_LMTF BIT(6)
34 #define SUN4I_CTL_TF_RST BIT(8)
35 #define SUN4I_CTL_RF_RST BIT(9)
36 #define SUN4I_CTL_XCH BIT(10)
37 #define SUN4I_CTL_CS_MASK 0x3000
38 #define SUN4I_CTL_CS(cs) (((cs) << 12) & SUN4I_CTL_CS_MASK)
39 #define SUN4I_CTL_DHB BIT(15)
40 #define SUN4I_CTL_CS_MANUAL BIT(16)
41 #define SUN4I_CTL_CS_LEVEL BIT(17)
42 #define SUN4I_CTL_TP BIT(18)
43
44 #define SUN4I_INT_CTL_REG 0x0c
45 #define SUN4I_INT_CTL_RF_F34 BIT(4)
46 #define SUN4I_INT_CTL_TF_E34 BIT(12)
47 #define SUN4I_INT_CTL_TC BIT(16)
48
49 #define SUN4I_INT_STA_REG 0x10
50
51 #define SUN4I_DMA_CTL_REG 0x14
52
53 #define SUN4I_WAIT_REG 0x18
54
55 #define SUN4I_CLK_CTL_REG 0x1c
56 #define SUN4I_CLK_CTL_CDR2_MASK 0xff
57 #define SUN4I_CLK_CTL_CDR2(div) ((div) & SUN4I_CLK_CTL_CDR2_MASK)
58 #define SUN4I_CLK_CTL_CDR1_MASK 0xf
59 #define SUN4I_CLK_CTL_CDR1(div) (((div) & SUN4I_CLK_CTL_CDR1_MASK) << 8)
60 #define SUN4I_CLK_CTL_DRS BIT(12)
61
62 #define SUN4I_MAX_XFER_SIZE 0xffffff
63
64 #define SUN4I_BURST_CNT_REG 0x20
65 #define SUN4I_BURST_CNT(cnt) ((cnt) & SUN4I_MAX_XFER_SIZE)
66
67 #define SUN4I_XMIT_CNT_REG 0x24
68 #define SUN4I_XMIT_CNT(cnt) ((cnt) & SUN4I_MAX_XFER_SIZE)
69
70
71 #define SUN4I_FIFO_STA_REG 0x28
72 #define SUN4I_FIFO_STA_RF_CNT_MASK 0x7f
73 #define SUN4I_FIFO_STA_RF_CNT_BITS 0
74 #define SUN4I_FIFO_STA_TF_CNT_MASK 0x7f
75 #define SUN4I_FIFO_STA_TF_CNT_BITS 16
76
77 struct sun4i_spi {
78 struct spi_controller *host;
79 void __iomem *base_addr;
80 struct clk *hclk;
81 struct clk *mclk;
82
83 struct completion done;
84
85 const u8 *tx_buf;
86 u8 *rx_buf;
87 int len;
88 };
89
sun4i_spi_read(struct sun4i_spi * sspi,u32 reg)90 static inline u32 sun4i_spi_read(struct sun4i_spi *sspi, u32 reg)
91 {
92 return readl(sspi->base_addr + reg);
93 }
94
sun4i_spi_write(struct sun4i_spi * sspi,u32 reg,u32 value)95 static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value)
96 {
97 writel(value, sspi->base_addr + reg);
98 }
99
sun4i_spi_get_tx_fifo_count(struct sun4i_spi * sspi)100 static inline u32 sun4i_spi_get_tx_fifo_count(struct sun4i_spi *sspi)
101 {
102 u32 reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
103
104 reg >>= SUN4I_FIFO_STA_TF_CNT_BITS;
105
106 return reg & SUN4I_FIFO_STA_TF_CNT_MASK;
107 }
108
sun4i_spi_enable_interrupt(struct sun4i_spi * sspi,u32 mask)109 static inline void sun4i_spi_enable_interrupt(struct sun4i_spi *sspi, u32 mask)
110 {
111 u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
112
113 reg |= mask;
114 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
115 }
116
sun4i_spi_disable_interrupt(struct sun4i_spi * sspi,u32 mask)117 static inline void sun4i_spi_disable_interrupt(struct sun4i_spi *sspi, u32 mask)
118 {
119 u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
120
121 reg &= ~mask;
122 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
123 }
124
sun4i_spi_drain_fifo(struct sun4i_spi * sspi,int len)125 static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len)
126 {
127 u32 reg, cnt;
128 u8 byte;
129
130 /* See how much data is available */
131 reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
132 reg &= SUN4I_FIFO_STA_RF_CNT_MASK;
133 cnt = reg >> SUN4I_FIFO_STA_RF_CNT_BITS;
134
135 if (len > cnt)
136 len = cnt;
137
138 while (len--) {
139 byte = readb(sspi->base_addr + SUN4I_RXDATA_REG);
140 if (sspi->rx_buf)
141 *sspi->rx_buf++ = byte;
142 }
143 }
144
sun4i_spi_fill_fifo(struct sun4i_spi * sspi,int len)145 static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len)
146 {
147 u32 cnt;
148 u8 byte;
149
150 /* See how much data we can fit */
151 cnt = SUN4I_FIFO_DEPTH - sun4i_spi_get_tx_fifo_count(sspi);
152
153 len = min3(len, (int)cnt, sspi->len);
154
155 while (len--) {
156 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
157 writeb(byte, sspi->base_addr + SUN4I_TXDATA_REG);
158 sspi->len--;
159 }
160 }
161
sun4i_spi_set_cs(struct spi_device * spi,bool enable)162 static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
163 {
164 struct sun4i_spi *sspi = spi_controller_get_devdata(spi->controller);
165 u32 reg;
166
167 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
168
169 reg &= ~SUN4I_CTL_CS_MASK;
170 reg |= SUN4I_CTL_CS(spi_get_chipselect(spi, 0));
171
172 /* We want to control the chip select manually */
173 reg |= SUN4I_CTL_CS_MANUAL;
174
175 if (enable)
176 reg |= SUN4I_CTL_CS_LEVEL;
177 else
178 reg &= ~SUN4I_CTL_CS_LEVEL;
179
180 /*
181 * Even though this looks irrelevant since we are supposed to
182 * be controlling the chip select manually, this bit also
183 * controls the levels of the chip select for inactive
184 * devices.
185 *
186 * If we don't set it, the chip select level will go low by
187 * default when the device is idle, which is not really
188 * expected in the common case where the chip select is active
189 * low.
190 */
191 if (spi->mode & SPI_CS_HIGH)
192 reg &= ~SUN4I_CTL_CS_ACTIVE_LOW;
193 else
194 reg |= SUN4I_CTL_CS_ACTIVE_LOW;
195
196 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
197 }
198
sun4i_spi_max_transfer_size(struct spi_device * spi)199 static size_t sun4i_spi_max_transfer_size(struct spi_device *spi)
200 {
201 return SUN4I_MAX_XFER_SIZE - 1;
202 }
203
sun4i_spi_transfer_one(struct spi_controller * host,struct spi_device * spi,struct spi_transfer * tfr)204 static int sun4i_spi_transfer_one(struct spi_controller *host,
205 struct spi_device *spi,
206 struct spi_transfer *tfr)
207 {
208 struct sun4i_spi *sspi = spi_controller_get_devdata(host);
209 unsigned int mclk_rate, div;
210 unsigned long time_left;
211 unsigned int start, end, tx_time;
212 unsigned int tx_len = 0;
213 int ret = 0;
214 u32 reg;
215
216 /* We don't support transfer larger than the FIFO */
217 if (tfr->len > SUN4I_MAX_XFER_SIZE)
218 return -EMSGSIZE;
219
220 if (tfr->tx_buf && tfr->len >= SUN4I_MAX_XFER_SIZE)
221 return -EMSGSIZE;
222
223 reinit_completion(&sspi->done);
224 sspi->tx_buf = tfr->tx_buf;
225 sspi->rx_buf = tfr->rx_buf;
226 sspi->len = tfr->len;
227
228 /* Clear pending interrupts */
229 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);
230
231
232 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
233
234 /* Reset FIFOs */
235 sun4i_spi_write(sspi, SUN4I_CTL_REG,
236 reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST);
237
238 /*
239 * Setup the transfer control register: Chip Select,
240 * polarities, etc.
241 */
242 if (spi->mode & SPI_CPOL)
243 reg |= SUN4I_CTL_CPOL;
244 else
245 reg &= ~SUN4I_CTL_CPOL;
246
247 if (spi->mode & SPI_CPHA)
248 reg |= SUN4I_CTL_CPHA;
249 else
250 reg &= ~SUN4I_CTL_CPHA;
251
252 if (spi->mode & SPI_LSB_FIRST)
253 reg |= SUN4I_CTL_LMTF;
254 else
255 reg &= ~SUN4I_CTL_LMTF;
256
257
258 /*
259 * If it's a TX only transfer, we don't want to fill the RX
260 * FIFO with bogus data
261 */
262 if (sspi->rx_buf)
263 reg &= ~SUN4I_CTL_DHB;
264 else
265 reg |= SUN4I_CTL_DHB;
266
267 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
268
269 /* Ensure that we have a parent clock fast enough */
270 mclk_rate = clk_get_rate(sspi->mclk);
271 if (mclk_rate < (2 * tfr->speed_hz)) {
272 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
273 mclk_rate = clk_get_rate(sspi->mclk);
274 }
275
276 /*
277 * Setup clock divider.
278 *
279 * We have two choices there. Either we can use the clock
280 * divide rate 1, which is calculated thanks to this formula:
281 * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
282 * Or we can use CDR2, which is calculated with the formula:
283 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
284 * Whether we use the former or the latter is set through the
285 * DRS bit.
286 *
287 * First try CDR2, and if we can't reach the expected
288 * frequency, fall back to CDR1.
289 */
290 div = mclk_rate / (2 * tfr->speed_hz);
291 if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
292 if (div > 0)
293 div--;
294
295 reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
296 } else {
297 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz);
298 reg = SUN4I_CLK_CTL_CDR1(div);
299 }
300
301 sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg);
302
303 /* Setup the transfer now... */
304 if (sspi->tx_buf)
305 tx_len = tfr->len;
306
307 /* Setup the counters */
308 sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
309 sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
310
311 /*
312 * Fill the TX FIFO
313 * Filling the FIFO fully causes timeout for some reason
314 * at least on spi2 on A10s
315 */
316 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
317
318 /* Enable the interrupts */
319 sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TC |
320 SUN4I_INT_CTL_RF_F34);
321 /* Only enable Tx FIFO interrupt if we really need it */
322 if (tx_len > SUN4I_FIFO_DEPTH)
323 sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
324
325 /* Start the transfer */
326 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
327 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
328
329 tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
330 start = jiffies;
331 time_left = wait_for_completion_timeout(&sspi->done,
332 msecs_to_jiffies(tx_time));
333 end = jiffies;
334 if (!time_left) {
335 dev_warn(&host->dev,
336 "%s: timeout transferring %u bytes@%iHz for %i(%i)ms",
337 dev_name(&spi->dev), tfr->len, tfr->speed_hz,
338 jiffies_to_msecs(end - start), tx_time);
339 ret = -ETIMEDOUT;
340 goto out;
341 }
342
343
344 out:
345 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
346
347 return ret;
348 }
349
sun4i_spi_handler(int irq,void * dev_id)350 static irqreturn_t sun4i_spi_handler(int irq, void *dev_id)
351 {
352 struct sun4i_spi *sspi = dev_id;
353 u32 status = sun4i_spi_read(sspi, SUN4I_INT_STA_REG);
354
355 /* Transfer complete */
356 if (status & SUN4I_INT_CTL_TC) {
357 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC);
358 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
359 complete(&sspi->done);
360 return IRQ_HANDLED;
361 }
362
363 /* Receive FIFO 3/4 full */
364 if (status & SUN4I_INT_CTL_RF_F34) {
365 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
366 /* Only clear the interrupt _after_ draining the FIFO */
367 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_RF_F34);
368 return IRQ_HANDLED;
369 }
370
371 /* Transmit FIFO 3/4 empty */
372 if (status & SUN4I_INT_CTL_TF_E34) {
373 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
374
375 if (!sspi->len)
376 /* nothing left to transmit */
377 sun4i_spi_disable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
378
379 /* Only clear the interrupt _after_ re-seeding the FIFO */
380 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TF_E34);
381
382 return IRQ_HANDLED;
383 }
384
385 return IRQ_NONE;
386 }
387
sun4i_spi_runtime_resume(struct device * dev)388 static int sun4i_spi_runtime_resume(struct device *dev)
389 {
390 struct spi_controller *host = dev_get_drvdata(dev);
391 struct sun4i_spi *sspi = spi_controller_get_devdata(host);
392 int ret;
393
394 ret = clk_prepare_enable(sspi->hclk);
395 if (ret) {
396 dev_err(dev, "Couldn't enable AHB clock\n");
397 goto out;
398 }
399
400 ret = clk_prepare_enable(sspi->mclk);
401 if (ret) {
402 dev_err(dev, "Couldn't enable module clock\n");
403 goto err;
404 }
405
406 sun4i_spi_write(sspi, SUN4I_CTL_REG,
407 SUN4I_CTL_ENABLE | SUN4I_CTL_MASTER | SUN4I_CTL_TP);
408
409 return 0;
410
411 err:
412 clk_disable_unprepare(sspi->hclk);
413 out:
414 return ret;
415 }
416
sun4i_spi_runtime_suspend(struct device * dev)417 static int sun4i_spi_runtime_suspend(struct device *dev)
418 {
419 struct spi_controller *host = dev_get_drvdata(dev);
420 struct sun4i_spi *sspi = spi_controller_get_devdata(host);
421
422 clk_disable_unprepare(sspi->mclk);
423 clk_disable_unprepare(sspi->hclk);
424
425 return 0;
426 }
427
sun4i_spi_probe(struct platform_device * pdev)428 static int sun4i_spi_probe(struct platform_device *pdev)
429 {
430 struct spi_controller *host;
431 struct sun4i_spi *sspi;
432 int ret = 0, irq;
433
434 host = spi_alloc_host(&pdev->dev, sizeof(struct sun4i_spi));
435 if (!host) {
436 dev_err(&pdev->dev, "Unable to allocate SPI Host\n");
437 return -ENOMEM;
438 }
439
440 platform_set_drvdata(pdev, host);
441 sspi = spi_controller_get_devdata(host);
442
443 sspi->base_addr = devm_platform_ioremap_resource(pdev, 0);
444 if (IS_ERR(sspi->base_addr)) {
445 ret = PTR_ERR(sspi->base_addr);
446 goto err_free_host;
447 }
448
449 irq = platform_get_irq(pdev, 0);
450 if (irq < 0) {
451 ret = -ENXIO;
452 goto err_free_host;
453 }
454
455 ret = devm_request_irq(&pdev->dev, irq, sun4i_spi_handler,
456 0, "sun4i-spi", sspi);
457 if (ret) {
458 dev_err(&pdev->dev, "Cannot request IRQ\n");
459 goto err_free_host;
460 }
461
462 sspi->host = host;
463 host->max_speed_hz = 100 * 1000 * 1000;
464 host->min_speed_hz = 3 * 1000;
465 host->set_cs = sun4i_spi_set_cs;
466 host->transfer_one = sun4i_spi_transfer_one;
467 host->num_chipselect = 4;
468 host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
469 host->bits_per_word_mask = SPI_BPW_MASK(8);
470 host->dev.of_node = pdev->dev.of_node;
471 host->auto_runtime_pm = true;
472 host->max_transfer_size = sun4i_spi_max_transfer_size;
473
474 sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
475 if (IS_ERR(sspi->hclk)) {
476 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
477 ret = PTR_ERR(sspi->hclk);
478 goto err_free_host;
479 }
480
481 sspi->mclk = devm_clk_get(&pdev->dev, "mod");
482 if (IS_ERR(sspi->mclk)) {
483 dev_err(&pdev->dev, "Unable to acquire module clock\n");
484 ret = PTR_ERR(sspi->mclk);
485 goto err_free_host;
486 }
487
488 init_completion(&sspi->done);
489
490 /*
491 * This wake-up/shutdown pattern is to be able to have the
492 * device woken up, even if runtime_pm is disabled
493 */
494 ret = sun4i_spi_runtime_resume(&pdev->dev);
495 if (ret) {
496 dev_err(&pdev->dev, "Couldn't resume the device\n");
497 goto err_free_host;
498 }
499
500 pm_runtime_set_active(&pdev->dev);
501 pm_runtime_enable(&pdev->dev);
502 pm_runtime_idle(&pdev->dev);
503
504 ret = devm_spi_register_controller(&pdev->dev, host);
505 if (ret) {
506 dev_err(&pdev->dev, "cannot register SPI host\n");
507 goto err_pm_disable;
508 }
509
510 return 0;
511
512 err_pm_disable:
513 pm_runtime_disable(&pdev->dev);
514 sun4i_spi_runtime_suspend(&pdev->dev);
515 err_free_host:
516 spi_controller_put(host);
517 return ret;
518 }
519
sun4i_spi_remove(struct platform_device * pdev)520 static void sun4i_spi_remove(struct platform_device *pdev)
521 {
522 pm_runtime_force_suspend(&pdev->dev);
523 }
524
525 static const struct of_device_id sun4i_spi_match[] = {
526 { .compatible = "allwinner,sun4i-a10-spi", },
527 {}
528 };
529 MODULE_DEVICE_TABLE(of, sun4i_spi_match);
530
531 static const struct dev_pm_ops sun4i_spi_pm_ops = {
532 .runtime_resume = sun4i_spi_runtime_resume,
533 .runtime_suspend = sun4i_spi_runtime_suspend,
534 };
535
536 static struct platform_driver sun4i_spi_driver = {
537 .probe = sun4i_spi_probe,
538 .remove_new = sun4i_spi_remove,
539 .driver = {
540 .name = "sun4i-spi",
541 .of_match_table = sun4i_spi_match,
542 .pm = &sun4i_spi_pm_ops,
543 },
544 };
545 module_platform_driver(sun4i_spi_driver);
546
547 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
548 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
549 MODULE_DESCRIPTION("Allwinner A1X/A20 SPI controller driver");
550 MODULE_LICENSE("GPL");
551