1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2008-2014 STMicroelectronics Limited
4 *
5 * Author: Angus Clark <Angus.Clark@st.com>
6 * Patrice Chotard <patrice.chotard@st.com>
7 * Lee Jones <lee.jones@linaro.org>
8 *
9 * SPI host mode controller driver, used in STMicroelectronics devices.
10 */
11
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/interrupt.h>
15 #include <linux/io.h>
16 #include <linux/module.h>
17 #include <linux/pinctrl/consumer.h>
18 #include <linux/platform_device.h>
19 #include <linux/of.h>
20 #include <linux/of_irq.h>
21 #include <linux/pm_runtime.h>
22 #include <linux/spi/spi.h>
23 #include <linux/spi/spi_bitbang.h>
24
25 /* SSC registers */
26 #define SSC_BRG 0x000
27 #define SSC_TBUF 0x004
28 #define SSC_RBUF 0x008
29 #define SSC_CTL 0x00C
30 #define SSC_IEN 0x010
31 #define SSC_I2C 0x018
32
33 /* SSC Control */
34 #define SSC_CTL_DATA_WIDTH_9 0x8
35 #define SSC_CTL_DATA_WIDTH_MSK 0xf
36 #define SSC_CTL_BM 0xf
37 #define SSC_CTL_HB BIT(4)
38 #define SSC_CTL_PH BIT(5)
39 #define SSC_CTL_PO BIT(6)
40 #define SSC_CTL_SR BIT(7)
41 #define SSC_CTL_MS BIT(8)
42 #define SSC_CTL_EN BIT(9)
43 #define SSC_CTL_LPB BIT(10)
44 #define SSC_CTL_EN_TX_FIFO BIT(11)
45 #define SSC_CTL_EN_RX_FIFO BIT(12)
46 #define SSC_CTL_EN_CLST_RX BIT(13)
47
48 /* SSC Interrupt Enable */
49 #define SSC_IEN_TEEN BIT(2)
50
51 #define FIFO_SIZE 8
52
53 struct spi_st {
54 /* SSC SPI Controller */
55 void __iomem *base;
56 struct clk *clk;
57 struct device *dev;
58
59 /* SSC SPI current transaction */
60 const u8 *tx_ptr;
61 u8 *rx_ptr;
62 u16 bytes_per_word;
63 unsigned int words_remaining;
64 unsigned int baud;
65 struct completion done;
66 };
67
68 /* Load the TX FIFO */
ssc_write_tx_fifo(struct spi_st * spi_st)69 static void ssc_write_tx_fifo(struct spi_st *spi_st)
70 {
71 unsigned int count, i;
72 uint32_t word = 0;
73
74 if (spi_st->words_remaining > FIFO_SIZE)
75 count = FIFO_SIZE;
76 else
77 count = spi_st->words_remaining;
78
79 for (i = 0; i < count; i++) {
80 if (spi_st->tx_ptr) {
81 if (spi_st->bytes_per_word == 1) {
82 word = *spi_st->tx_ptr++;
83 } else {
84 word = *spi_st->tx_ptr++;
85 word = *spi_st->tx_ptr++ | (word << 8);
86 }
87 }
88 writel_relaxed(word, spi_st->base + SSC_TBUF);
89 }
90 }
91
92 /* Read the RX FIFO */
ssc_read_rx_fifo(struct spi_st * spi_st)93 static void ssc_read_rx_fifo(struct spi_st *spi_st)
94 {
95 unsigned int count, i;
96 uint32_t word = 0;
97
98 if (spi_st->words_remaining > FIFO_SIZE)
99 count = FIFO_SIZE;
100 else
101 count = spi_st->words_remaining;
102
103 for (i = 0; i < count; i++) {
104 word = readl_relaxed(spi_st->base + SSC_RBUF);
105
106 if (spi_st->rx_ptr) {
107 if (spi_st->bytes_per_word == 1) {
108 *spi_st->rx_ptr++ = (uint8_t)word;
109 } else {
110 *spi_st->rx_ptr++ = (word >> 8);
111 *spi_st->rx_ptr++ = word & 0xff;
112 }
113 }
114 }
115 spi_st->words_remaining -= count;
116 }
117
spi_st_transfer_one(struct spi_controller * host,struct spi_device * spi,struct spi_transfer * t)118 static int spi_st_transfer_one(struct spi_controller *host,
119 struct spi_device *spi, struct spi_transfer *t)
120 {
121 struct spi_st *spi_st = spi_controller_get_devdata(host);
122 uint32_t ctl = 0;
123
124 /* Setup transfer */
125 spi_st->tx_ptr = t->tx_buf;
126 spi_st->rx_ptr = t->rx_buf;
127
128 if (spi->bits_per_word > 8) {
129 /*
130 * Anything greater than 8 bits-per-word requires 2
131 * bytes-per-word in the RX/TX buffers
132 */
133 spi_st->bytes_per_word = 2;
134 spi_st->words_remaining = t->len / 2;
135
136 } else if (spi->bits_per_word == 8 && !(t->len & 0x1)) {
137 /*
138 * If transfer is even-length, and 8 bits-per-word, then
139 * implement as half-length 16 bits-per-word transfer
140 */
141 spi_st->bytes_per_word = 2;
142 spi_st->words_remaining = t->len / 2;
143
144 /* Set SSC_CTL to 16 bits-per-word */
145 ctl = readl_relaxed(spi_st->base + SSC_CTL);
146 writel_relaxed((ctl | 0xf), spi_st->base + SSC_CTL);
147
148 readl_relaxed(spi_st->base + SSC_RBUF);
149
150 } else {
151 spi_st->bytes_per_word = 1;
152 spi_st->words_remaining = t->len;
153 }
154
155 reinit_completion(&spi_st->done);
156
157 /* Start transfer by writing to the TX FIFO */
158 ssc_write_tx_fifo(spi_st);
159 writel_relaxed(SSC_IEN_TEEN, spi_st->base + SSC_IEN);
160
161 /* Wait for transfer to complete */
162 wait_for_completion(&spi_st->done);
163
164 /* Restore SSC_CTL if necessary */
165 if (ctl)
166 writel_relaxed(ctl, spi_st->base + SSC_CTL);
167
168 spi_finalize_current_transfer(spi->controller);
169
170 return t->len;
171 }
172
173 /* the spi->mode bits understood by this driver: */
174 #define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH)
spi_st_setup(struct spi_device * spi)175 static int spi_st_setup(struct spi_device *spi)
176 {
177 struct spi_st *spi_st = spi_controller_get_devdata(spi->controller);
178 u32 spi_st_clk, sscbrg, var;
179 u32 hz = spi->max_speed_hz;
180
181 if (!hz) {
182 dev_err(&spi->dev, "max_speed_hz unspecified\n");
183 return -EINVAL;
184 }
185
186 if (!spi_get_csgpiod(spi, 0)) {
187 dev_err(&spi->dev, "no valid gpio assigned\n");
188 return -EINVAL;
189 }
190
191 spi_st_clk = clk_get_rate(spi_st->clk);
192
193 /* Set SSC_BRF */
194 sscbrg = spi_st_clk / (2 * hz);
195 if (sscbrg < 0x07 || sscbrg > BIT(16)) {
196 dev_err(&spi->dev,
197 "baudrate %d outside valid range %d\n", sscbrg, hz);
198 return -EINVAL;
199 }
200
201 spi_st->baud = spi_st_clk / (2 * sscbrg);
202 if (sscbrg == BIT(16)) /* 16-bit counter wraps */
203 sscbrg = 0x0;
204
205 writel_relaxed(sscbrg, spi_st->base + SSC_BRG);
206
207 dev_dbg(&spi->dev,
208 "setting baudrate:target= %u hz, actual= %u hz, sscbrg= %u\n",
209 hz, spi_st->baud, sscbrg);
210
211 /* Set SSC_CTL and enable SSC */
212 var = readl_relaxed(spi_st->base + SSC_CTL);
213 var |= SSC_CTL_MS;
214
215 if (spi->mode & SPI_CPOL)
216 var |= SSC_CTL_PO;
217 else
218 var &= ~SSC_CTL_PO;
219
220 if (spi->mode & SPI_CPHA)
221 var |= SSC_CTL_PH;
222 else
223 var &= ~SSC_CTL_PH;
224
225 if ((spi->mode & SPI_LSB_FIRST) == 0)
226 var |= SSC_CTL_HB;
227 else
228 var &= ~SSC_CTL_HB;
229
230 if (spi->mode & SPI_LOOP)
231 var |= SSC_CTL_LPB;
232 else
233 var &= ~SSC_CTL_LPB;
234
235 var &= ~SSC_CTL_DATA_WIDTH_MSK;
236 var |= (spi->bits_per_word - 1);
237
238 var |= SSC_CTL_EN_TX_FIFO | SSC_CTL_EN_RX_FIFO;
239 var |= SSC_CTL_EN;
240
241 writel_relaxed(var, spi_st->base + SSC_CTL);
242
243 /* Clear the status register */
244 readl_relaxed(spi_st->base + SSC_RBUF);
245
246 return 0;
247 }
248
249 /* Interrupt fired when TX shift register becomes empty */
spi_st_irq(int irq,void * dev_id)250 static irqreturn_t spi_st_irq(int irq, void *dev_id)
251 {
252 struct spi_st *spi_st = (struct spi_st *)dev_id;
253
254 /* Read RX FIFO */
255 ssc_read_rx_fifo(spi_st);
256
257 /* Fill TX FIFO */
258 if (spi_st->words_remaining) {
259 ssc_write_tx_fifo(spi_st);
260 } else {
261 /* TX/RX complete */
262 writel_relaxed(0x0, spi_st->base + SSC_IEN);
263 /*
264 * read SSC_IEN to ensure that this bit is set
265 * before re-enabling interrupt
266 */
267 readl(spi_st->base + SSC_IEN);
268 complete(&spi_st->done);
269 }
270
271 return IRQ_HANDLED;
272 }
273
spi_st_probe(struct platform_device * pdev)274 static int spi_st_probe(struct platform_device *pdev)
275 {
276 struct device_node *np = pdev->dev.of_node;
277 struct spi_controller *host;
278 struct spi_st *spi_st;
279 int irq, ret = 0;
280 u32 var;
281
282 host = spi_alloc_host(&pdev->dev, sizeof(*spi_st));
283 if (!host)
284 return -ENOMEM;
285
286 host->dev.of_node = np;
287 host->mode_bits = MODEBITS;
288 host->setup = spi_st_setup;
289 host->transfer_one = spi_st_transfer_one;
290 host->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
291 host->auto_runtime_pm = true;
292 host->bus_num = pdev->id;
293 host->use_gpio_descriptors = true;
294 spi_st = spi_controller_get_devdata(host);
295
296 spi_st->clk = devm_clk_get(&pdev->dev, "ssc");
297 if (IS_ERR(spi_st->clk)) {
298 dev_err(&pdev->dev, "Unable to request clock\n");
299 ret = PTR_ERR(spi_st->clk);
300 goto put_host;
301 }
302
303 ret = clk_prepare_enable(spi_st->clk);
304 if (ret)
305 goto put_host;
306
307 init_completion(&spi_st->done);
308
309 /* Get resources */
310 spi_st->base = devm_platform_ioremap_resource(pdev, 0);
311 if (IS_ERR(spi_st->base)) {
312 ret = PTR_ERR(spi_st->base);
313 goto clk_disable;
314 }
315
316 /* Disable I2C and Reset SSC */
317 writel_relaxed(0x0, spi_st->base + SSC_I2C);
318 var = readw_relaxed(spi_st->base + SSC_CTL);
319 var |= SSC_CTL_SR;
320 writel_relaxed(var, spi_st->base + SSC_CTL);
321
322 udelay(1);
323 var = readl_relaxed(spi_st->base + SSC_CTL);
324 var &= ~SSC_CTL_SR;
325 writel_relaxed(var, spi_st->base + SSC_CTL);
326
327 /* Set SSC into target mode before reconfiguring PIO pins */
328 var = readl_relaxed(spi_st->base + SSC_CTL);
329 var &= ~SSC_CTL_MS;
330 writel_relaxed(var, spi_st->base + SSC_CTL);
331
332 irq = irq_of_parse_and_map(np, 0);
333 if (!irq) {
334 dev_err(&pdev->dev, "IRQ missing or invalid\n");
335 ret = -EINVAL;
336 goto clk_disable;
337 }
338
339 ret = devm_request_irq(&pdev->dev, irq, spi_st_irq, 0,
340 pdev->name, spi_st);
341 if (ret) {
342 dev_err(&pdev->dev, "Failed to request irq %d\n", irq);
343 goto clk_disable;
344 }
345
346 /* by default the device is on */
347 pm_runtime_set_active(&pdev->dev);
348 pm_runtime_enable(&pdev->dev);
349
350 platform_set_drvdata(pdev, host);
351
352 ret = devm_spi_register_controller(&pdev->dev, host);
353 if (ret) {
354 dev_err(&pdev->dev, "Failed to register host\n");
355 goto rpm_disable;
356 }
357
358 return 0;
359
360 rpm_disable:
361 pm_runtime_disable(&pdev->dev);
362 clk_disable:
363 clk_disable_unprepare(spi_st->clk);
364 put_host:
365 spi_controller_put(host);
366 return ret;
367 }
368
spi_st_remove(struct platform_device * pdev)369 static void spi_st_remove(struct platform_device *pdev)
370 {
371 struct spi_controller *host = platform_get_drvdata(pdev);
372 struct spi_st *spi_st = spi_controller_get_devdata(host);
373
374 pm_runtime_disable(&pdev->dev);
375
376 clk_disable_unprepare(spi_st->clk);
377
378 pinctrl_pm_select_sleep_state(&pdev->dev);
379 }
380
381 #ifdef CONFIG_PM
spi_st_runtime_suspend(struct device * dev)382 static int spi_st_runtime_suspend(struct device *dev)
383 {
384 struct spi_controller *host = dev_get_drvdata(dev);
385 struct spi_st *spi_st = spi_controller_get_devdata(host);
386
387 writel_relaxed(0, spi_st->base + SSC_IEN);
388 pinctrl_pm_select_sleep_state(dev);
389
390 clk_disable_unprepare(spi_st->clk);
391
392 return 0;
393 }
394
spi_st_runtime_resume(struct device * dev)395 static int spi_st_runtime_resume(struct device *dev)
396 {
397 struct spi_controller *host = dev_get_drvdata(dev);
398 struct spi_st *spi_st = spi_controller_get_devdata(host);
399 int ret;
400
401 ret = clk_prepare_enable(spi_st->clk);
402 pinctrl_pm_select_default_state(dev);
403
404 return ret;
405 }
406 #endif
407
408 #ifdef CONFIG_PM_SLEEP
spi_st_suspend(struct device * dev)409 static int spi_st_suspend(struct device *dev)
410 {
411 struct spi_controller *host = dev_get_drvdata(dev);
412 int ret;
413
414 ret = spi_controller_suspend(host);
415 if (ret)
416 return ret;
417
418 return pm_runtime_force_suspend(dev);
419 }
420
spi_st_resume(struct device * dev)421 static int spi_st_resume(struct device *dev)
422 {
423 struct spi_controller *host = dev_get_drvdata(dev);
424 int ret;
425
426 ret = spi_controller_resume(host);
427 if (ret)
428 return ret;
429
430 return pm_runtime_force_resume(dev);
431 }
432 #endif
433
434 static const struct dev_pm_ops spi_st_pm = {
435 SET_SYSTEM_SLEEP_PM_OPS(spi_st_suspend, spi_st_resume)
436 SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL)
437 };
438
439 static const struct of_device_id stm_spi_match[] = {
440 { .compatible = "st,comms-ssc4-spi", },
441 {},
442 };
443 MODULE_DEVICE_TABLE(of, stm_spi_match);
444
445 static struct platform_driver spi_st_driver = {
446 .driver = {
447 .name = "spi-st",
448 .pm = &spi_st_pm,
449 .of_match_table = of_match_ptr(stm_spi_match),
450 },
451 .probe = spi_st_probe,
452 .remove_new = spi_st_remove,
453 };
454 module_platform_driver(spi_st_driver);
455
456 MODULE_AUTHOR("Patrice Chotard <patrice.chotard@st.com>");
457 MODULE_DESCRIPTION("STM SSC SPI driver");
458 MODULE_LICENSE("GPL v2");
459