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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
77struct sun4i_spi {
78 struct spi_master *master;
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
90static inline u32 sun4i_spi_read(struct sun4i_spi *sspi, u32 reg)
91{
92 return readl(sspi->base_addr + reg);
93}
94
95static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value)
96{
97 writel(value, sspi->base_addr + reg);
98}
99
100static 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
109static 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
117static 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
125static 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
145static 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
162static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
163{
164 struct sun4i_spi *sspi = spi_master_get_devdata(spi->master);
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->chip_select);
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
199static size_t sun4i_spi_max_transfer_size(struct spi_device *spi)
200{
201 return SUN4I_MAX_XFER_SIZE - 1;
202}
203
204static int sun4i_spi_transfer_one(struct spi_master *master,
205 struct spi_device *spi,
206 struct spi_transfer *tfr)
207{
208 struct sun4i_spi *sspi = spi_master_get_devdata(master);
209 unsigned int mclk_rate, div, timeout;
210 unsigned int start, end, tx_time;
211 unsigned int tx_len = 0;
212 int ret = 0;
213 u32 reg;
214
215 /* We don't support transfer larger than the FIFO */
216 if (tfr->len > SUN4I_MAX_XFER_SIZE)
217 return -EMSGSIZE;
218
219 if (tfr->tx_buf && tfr->len >= SUN4I_MAX_XFER_SIZE)
220 return -EMSGSIZE;
221
222 reinit_completion(&sspi->done);
223 sspi->tx_buf = tfr->tx_buf;
224 sspi->rx_buf = tfr->rx_buf;
225 sspi->len = tfr->len;
226
227 /* Clear pending interrupts */
228 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);
229
230
231 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
232
233 /* Reset FIFOs */
234 sun4i_spi_write(sspi, SUN4I_CTL_REG,
235 reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST);
236
237 /*
238 * Setup the transfer control register: Chip Select,
239 * polarities, etc.
240 */
241 if (spi->mode & SPI_CPOL)
242 reg |= SUN4I_CTL_CPOL;
243 else
244 reg &= ~SUN4I_CTL_CPOL;
245
246 if (spi->mode & SPI_CPHA)
247 reg |= SUN4I_CTL_CPHA;
248 else
249 reg &= ~SUN4I_CTL_CPHA;
250
251 if (spi->mode & SPI_LSB_FIRST)
252 reg |= SUN4I_CTL_LMTF;
253 else
254 reg &= ~SUN4I_CTL_LMTF;
255
256
257 /*
258 * If it's a TX only transfer, we don't want to fill the RX
259 * FIFO with bogus data
260 */
261 if (sspi->rx_buf)
262 reg &= ~SUN4I_CTL_DHB;
263 else
264 reg |= SUN4I_CTL_DHB;
265
266 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
267
268 /* Ensure that we have a parent clock fast enough */
269 mclk_rate = clk_get_rate(sspi->mclk);
270 if (mclk_rate < (2 * tfr->speed_hz)) {
271 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
272 mclk_rate = clk_get_rate(sspi->mclk);
273 }
274
275 /*
276 * Setup clock divider.
277 *
278 * We have two choices there. Either we can use the clock
279 * divide rate 1, which is calculated thanks to this formula:
280 * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
281 * Or we can use CDR2, which is calculated with the formula:
282 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
283 * Whether we use the former or the latter is set through the
284 * DRS bit.
285 *
286 * First try CDR2, and if we can't reach the expected
287 * frequency, fall back to CDR1.
288 */
289 div = mclk_rate / (2 * tfr->speed_hz);
290 if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
291 if (div > 0)
292 div--;
293
294 reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
295 } else {
296 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz);
297 reg = SUN4I_CLK_CTL_CDR1(div);
298 }
299
300 sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg);
301
302 /* Setup the transfer now... */
303 if (sspi->tx_buf)
304 tx_len = tfr->len;
305
306 /* Setup the counters */
307 sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
308 sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
309
310 /*
311 * Fill the TX FIFO
312 * Filling the FIFO fully causes timeout for some reason
313 * at least on spi2 on A10s
314 */
315 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
316
317 /* Enable the interrupts */
318 sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TC |
319 SUN4I_INT_CTL_RF_F34);
320 /* Only enable Tx FIFO interrupt if we really need it */
321 if (tx_len > SUN4I_FIFO_DEPTH)
322 sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
323
324 /* Start the transfer */
325 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
326 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
327
328 tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
329 start = jiffies;
330 timeout = wait_for_completion_timeout(&sspi->done,
331 msecs_to_jiffies(tx_time));
332 end = jiffies;
333 if (!timeout) {
334 dev_warn(&master->dev,
335 "%s: timeout transferring %u bytes@%iHz for %i(%i)ms",
336 dev_name(&spi->dev), tfr->len, tfr->speed_hz,
337 jiffies_to_msecs(end - start), tx_time);
338 ret = -ETIMEDOUT;
339 goto out;
340 }
341
342
343out:
344 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
345
346 return ret;
347}
348
349static irqreturn_t sun4i_spi_handler(int irq, void *dev_id)
350{
351 struct sun4i_spi *sspi = dev_id;
352 u32 status = sun4i_spi_read(sspi, SUN4I_INT_STA_REG);
353
354 /* Transfer complete */
355 if (status & SUN4I_INT_CTL_TC) {
356 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC);
357 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
358 complete(&sspi->done);
359 return IRQ_HANDLED;
360 }
361
362 /* Receive FIFO 3/4 full */
363 if (status & SUN4I_INT_CTL_RF_F34) {
364 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
365 /* Only clear the interrupt _after_ draining the FIFO */
366 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_RF_F34);
367 return IRQ_HANDLED;
368 }
369
370 /* Transmit FIFO 3/4 empty */
371 if (status & SUN4I_INT_CTL_TF_E34) {
372 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
373
374 if (!sspi->len)
375 /* nothing left to transmit */
376 sun4i_spi_disable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
377
378 /* Only clear the interrupt _after_ re-seeding the FIFO */
379 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TF_E34);
380
381 return IRQ_HANDLED;
382 }
383
384 return IRQ_NONE;
385}
386
387static int sun4i_spi_runtime_resume(struct device *dev)
388{
389 struct spi_master *master = dev_get_drvdata(dev);
390 struct sun4i_spi *sspi = spi_master_get_devdata(master);
391 int ret;
392
393 ret = clk_prepare_enable(sspi->hclk);
394 if (ret) {
395 dev_err(dev, "Couldn't enable AHB clock\n");
396 goto out;
397 }
398
399 ret = clk_prepare_enable(sspi->mclk);
400 if (ret) {
401 dev_err(dev, "Couldn't enable module clock\n");
402 goto err;
403 }
404
405 sun4i_spi_write(sspi, SUN4I_CTL_REG,
406 SUN4I_CTL_ENABLE | SUN4I_CTL_MASTER | SUN4I_CTL_TP);
407
408 return 0;
409
410err:
411 clk_disable_unprepare(sspi->hclk);
412out:
413 return ret;
414}
415
416static int sun4i_spi_runtime_suspend(struct device *dev)
417{
418 struct spi_master *master = dev_get_drvdata(dev);
419 struct sun4i_spi *sspi = spi_master_get_devdata(master);
420
421 clk_disable_unprepare(sspi->mclk);
422 clk_disable_unprepare(sspi->hclk);
423
424 return 0;
425}
426
427static int sun4i_spi_probe(struct platform_device *pdev)
428{
429 struct spi_master *master;
430 struct sun4i_spi *sspi;
431 int ret = 0, irq;
432
433 master = spi_alloc_master(&pdev->dev, sizeof(struct sun4i_spi));
434 if (!master) {
435 dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
436 return -ENOMEM;
437 }
438
439 platform_set_drvdata(pdev, master);
440 sspi = spi_master_get_devdata(master);
441
442 sspi->base_addr = devm_platform_ioremap_resource(pdev, 0);
443 if (IS_ERR(sspi->base_addr)) {
444 ret = PTR_ERR(sspi->base_addr);
445 goto err_free_master;
446 }
447
448 irq = platform_get_irq(pdev, 0);
449 if (irq < 0) {
450 ret = -ENXIO;
451 goto err_free_master;
452 }
453
454 ret = devm_request_irq(&pdev->dev, irq, sun4i_spi_handler,
455 0, "sun4i-spi", sspi);
456 if (ret) {
457 dev_err(&pdev->dev, "Cannot request IRQ\n");
458 goto err_free_master;
459 }
460
461 sspi->master = master;
462 master->max_speed_hz = 100 * 1000 * 1000;
463 master->min_speed_hz = 3 * 1000;
464 master->set_cs = sun4i_spi_set_cs;
465 master->transfer_one = sun4i_spi_transfer_one;
466 master->num_chipselect = 4;
467 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
468 master->bits_per_word_mask = SPI_BPW_MASK(8);
469 master->dev.of_node = pdev->dev.of_node;
470 master->auto_runtime_pm = true;
471 master->max_transfer_size = sun4i_spi_max_transfer_size;
472
473 sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
474 if (IS_ERR(sspi->hclk)) {
475 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
476 ret = PTR_ERR(sspi->hclk);
477 goto err_free_master;
478 }
479
480 sspi->mclk = devm_clk_get(&pdev->dev, "mod");
481 if (IS_ERR(sspi->mclk)) {
482 dev_err(&pdev->dev, "Unable to acquire module clock\n");
483 ret = PTR_ERR(sspi->mclk);
484 goto err_free_master;
485 }
486
487 init_completion(&sspi->done);
488
489 /*
490 * This wake-up/shutdown pattern is to be able to have the
491 * device woken up, even if runtime_pm is disabled
492 */
493 ret = sun4i_spi_runtime_resume(&pdev->dev);
494 if (ret) {
495 dev_err(&pdev->dev, "Couldn't resume the device\n");
496 goto err_free_master;
497 }
498
499 pm_runtime_set_active(&pdev->dev);
500 pm_runtime_enable(&pdev->dev);
501 pm_runtime_idle(&pdev->dev);
502
503 ret = devm_spi_register_master(&pdev->dev, master);
504 if (ret) {
505 dev_err(&pdev->dev, "cannot register SPI master\n");
506 goto err_pm_disable;
507 }
508
509 return 0;
510
511err_pm_disable:
512 pm_runtime_disable(&pdev->dev);
513 sun4i_spi_runtime_suspend(&pdev->dev);
514err_free_master:
515 spi_master_put(master);
516 return ret;
517}
518
519static int sun4i_spi_remove(struct platform_device *pdev)
520{
521 pm_runtime_force_suspend(&pdev->dev);
522
523 return 0;
524}
525
526static const struct of_device_id sun4i_spi_match[] = {
527 { .compatible = "allwinner,sun4i-a10-spi", },
528 {}
529};
530MODULE_DEVICE_TABLE(of, sun4i_spi_match);
531
532static const struct dev_pm_ops sun4i_spi_pm_ops = {
533 .runtime_resume = sun4i_spi_runtime_resume,
534 .runtime_suspend = sun4i_spi_runtime_suspend,
535};
536
537static struct platform_driver sun4i_spi_driver = {
538 .probe = sun4i_spi_probe,
539 .remove = sun4i_spi_remove,
540 .driver = {
541 .name = "sun4i-spi",
542 .of_match_table = sun4i_spi_match,
543 .pm = &sun4i_spi_pm_ops,
544 },
545};
546module_platform_driver(sun4i_spi_driver);
547
548MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
549MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
550MODULE_DESCRIPTION("Allwinner A1X/A20 SPI controller driver");
551MODULE_LICENSE("GPL");