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9e862375 LJ |
1 | /* |
2 | * Copyright (c) 2008-2014 STMicroelectronics Limited | |
3 | * | |
4 | * Author: Angus Clark <Angus.Clark@st.com> | |
5 | * Patrice Chotard <patrice.chotard@st.com> | |
6 | * Lee Jones <lee.jones@linaro.org> | |
7 | * | |
8 | * SPI master mode controller driver, used in STMicroelectronics devices. | |
9 | * | |
10 | * May be copied or modified under the terms of the GNU General Public | |
11 | * License Version 2.0 only. See linux/COPYING for more information. | |
12 | */ | |
13 | ||
14 | #include <linux/clk.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/interrupt.h> | |
17 | #include <linux/io.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/pinctrl/consumer.h> | |
20 | #include <linux/platform_device.h> | |
21 | #include <linux/of.h> | |
22 | #include <linux/of_gpio.h> | |
23 | #include <linux/of_irq.h> | |
24 | #include <linux/pm_runtime.h> | |
25 | #include <linux/spi/spi.h> | |
26 | #include <linux/spi/spi_bitbang.h> | |
27 | ||
28 | /* SSC registers */ | |
29 | #define SSC_BRG 0x000 | |
30 | #define SSC_TBUF 0x004 | |
31 | #define SSC_RBUF 0x008 | |
32 | #define SSC_CTL 0x00C | |
33 | #define SSC_IEN 0x010 | |
34 | #define SSC_I2C 0x018 | |
35 | ||
36 | /* SSC Control */ | |
37 | #define SSC_CTL_DATA_WIDTH_9 0x8 | |
38 | #define SSC_CTL_DATA_WIDTH_MSK 0xf | |
39 | #define SSC_CTL_BM 0xf | |
40 | #define SSC_CTL_HB BIT(4) | |
41 | #define SSC_CTL_PH BIT(5) | |
42 | #define SSC_CTL_PO BIT(6) | |
43 | #define SSC_CTL_SR BIT(7) | |
44 | #define SSC_CTL_MS BIT(8) | |
45 | #define SSC_CTL_EN BIT(9) | |
46 | #define SSC_CTL_LPB BIT(10) | |
47 | #define SSC_CTL_EN_TX_FIFO BIT(11) | |
48 | #define SSC_CTL_EN_RX_FIFO BIT(12) | |
49 | #define SSC_CTL_EN_CLST_RX BIT(13) | |
50 | ||
51 | /* SSC Interrupt Enable */ | |
52 | #define SSC_IEN_TEEN BIT(2) | |
53 | ||
54 | #define FIFO_SIZE 8 | |
55 | ||
56 | struct spi_st { | |
57 | /* SSC SPI Controller */ | |
58 | void __iomem *base; | |
59 | struct clk *clk; | |
60 | struct device *dev; | |
61 | ||
62 | /* SSC SPI current transaction */ | |
63 | const u8 *tx_ptr; | |
64 | u8 *rx_ptr; | |
65 | u16 bytes_per_word; | |
66 | unsigned int words_remaining; | |
67 | unsigned int baud; | |
68 | struct completion done; | |
69 | }; | |
70 | ||
9e862375 LJ |
71 | /* Load the TX FIFO */ |
72 | static void ssc_write_tx_fifo(struct spi_st *spi_st) | |
73 | { | |
74 | unsigned int count, i; | |
75 | uint32_t word = 0; | |
76 | ||
77 | if (spi_st->words_remaining > FIFO_SIZE) | |
78 | count = FIFO_SIZE; | |
79 | else | |
80 | count = spi_st->words_remaining; | |
81 | ||
82 | for (i = 0; i < count; i++) { | |
83 | if (spi_st->tx_ptr) { | |
84 | if (spi_st->bytes_per_word == 1) { | |
85 | word = *spi_st->tx_ptr++; | |
86 | } else { | |
87 | word = *spi_st->tx_ptr++; | |
88 | word = *spi_st->tx_ptr++ | (word << 8); | |
89 | } | |
90 | } | |
91 | writel_relaxed(word, spi_st->base + SSC_TBUF); | |
92 | } | |
93 | } | |
94 | ||
95 | /* Read the RX FIFO */ | |
96 | static void ssc_read_rx_fifo(struct spi_st *spi_st) | |
97 | { | |
98 | unsigned int count, i; | |
99 | uint32_t word = 0; | |
100 | ||
101 | if (spi_st->words_remaining > FIFO_SIZE) | |
102 | count = FIFO_SIZE; | |
103 | else | |
104 | count = spi_st->words_remaining; | |
105 | ||
106 | for (i = 0; i < count; i++) { | |
107 | word = readl_relaxed(spi_st->base + SSC_RBUF); | |
108 | ||
109 | if (spi_st->rx_ptr) { | |
110 | if (spi_st->bytes_per_word == 1) { | |
111 | *spi_st->rx_ptr++ = (uint8_t)word; | |
112 | } else { | |
113 | *spi_st->rx_ptr++ = (word >> 8); | |
114 | *spi_st->rx_ptr++ = word & 0xff; | |
115 | } | |
116 | } | |
117 | } | |
118 | spi_st->words_remaining -= count; | |
119 | } | |
120 | ||
121 | static int spi_st_transfer_one(struct spi_master *master, | |
122 | struct spi_device *spi, struct spi_transfer *t) | |
123 | { | |
124 | struct spi_st *spi_st = spi_master_get_devdata(master); | |
125 | uint32_t ctl = 0; | |
126 | ||
127 | /* Setup transfer */ | |
128 | spi_st->tx_ptr = t->tx_buf; | |
129 | spi_st->rx_ptr = t->rx_buf; | |
130 | ||
131 | if (spi->bits_per_word > 8) { | |
132 | /* | |
133 | * Anything greater than 8 bits-per-word requires 2 | |
134 | * bytes-per-word in the RX/TX buffers | |
135 | */ | |
136 | spi_st->bytes_per_word = 2; | |
137 | spi_st->words_remaining = t->len / 2; | |
138 | ||
139 | } else if (spi->bits_per_word == 8 && !(t->len & 0x1)) { | |
140 | /* | |
141 | * If transfer is even-length, and 8 bits-per-word, then | |
142 | * implement as half-length 16 bits-per-word transfer | |
143 | */ | |
144 | spi_st->bytes_per_word = 2; | |
145 | spi_st->words_remaining = t->len / 2; | |
146 | ||
147 | /* Set SSC_CTL to 16 bits-per-word */ | |
148 | ctl = readl_relaxed(spi_st->base + SSC_CTL); | |
149 | writel_relaxed((ctl | 0xf), spi_st->base + SSC_CTL); | |
150 | ||
151 | readl_relaxed(spi_st->base + SSC_RBUF); | |
152 | ||
153 | } else { | |
154 | spi_st->bytes_per_word = 1; | |
155 | spi_st->words_remaining = t->len; | |
156 | } | |
157 | ||
158 | reinit_completion(&spi_st->done); | |
159 | ||
160 | /* Start transfer by writing to the TX FIFO */ | |
161 | ssc_write_tx_fifo(spi_st); | |
162 | writel_relaxed(SSC_IEN_TEEN, spi_st->base + SSC_IEN); | |
163 | ||
164 | /* Wait for transfer to complete */ | |
165 | wait_for_completion(&spi_st->done); | |
166 | ||
167 | /* Restore SSC_CTL if necessary */ | |
168 | if (ctl) | |
169 | writel_relaxed(ctl, spi_st->base + SSC_CTL); | |
170 | ||
171 | spi_finalize_current_transfer(spi->master); | |
172 | ||
173 | return t->len; | |
174 | } | |
175 | ||
176 | static void spi_st_cleanup(struct spi_device *spi) | |
177 | { | |
178 | int cs = spi->cs_gpio; | |
179 | ||
180 | if (gpio_is_valid(cs)) | |
181 | devm_gpio_free(&spi->dev, cs); | |
182 | } | |
183 | ||
184 | /* the spi->mode bits understood by this driver: */ | |
185 | #define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH) | |
186 | static int spi_st_setup(struct spi_device *spi) | |
187 | { | |
188 | struct spi_st *spi_st = spi_master_get_devdata(spi->master); | |
189 | u32 spi_st_clk, sscbrg, var; | |
190 | u32 hz = spi->max_speed_hz; | |
191 | int cs = spi->cs_gpio; | |
192 | int ret; | |
193 | ||
9e862375 LJ |
194 | if (!hz) { |
195 | dev_err(&spi->dev, "max_speed_hz unspecified\n"); | |
196 | return -EINVAL; | |
197 | } | |
198 | ||
199 | if (!gpio_is_valid(cs)) { | |
200 | dev_err(&spi->dev, "%d is not a valid gpio\n", cs); | |
201 | return -EINVAL; | |
202 | } | |
203 | ||
204 | if (devm_gpio_request(&spi->dev, cs, dev_name(&spi->dev))) { | |
205 | dev_err(&spi->dev, "could not request gpio:%d\n", cs); | |
206 | return -EINVAL; | |
207 | } | |
208 | ||
209 | ret = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH); | |
210 | if (ret) | |
211 | return ret; | |
212 | ||
213 | spi_st_clk = clk_get_rate(spi_st->clk); | |
214 | ||
215 | /* Set SSC_BRF */ | |
216 | sscbrg = spi_st_clk / (2 * hz); | |
217 | if (sscbrg < 0x07 || sscbrg > BIT(16)) { | |
218 | dev_err(&spi->dev, | |
219 | "baudrate %d outside valid range %d\n", sscbrg, hz); | |
220 | return -EINVAL; | |
221 | } | |
222 | ||
223 | spi_st->baud = spi_st_clk / (2 * sscbrg); | |
224 | if (sscbrg == BIT(16)) /* 16-bit counter wraps */ | |
225 | sscbrg = 0x0; | |
226 | ||
227 | writel_relaxed(sscbrg, spi_st->base + SSC_BRG); | |
228 | ||
229 | dev_dbg(&spi->dev, | |
230 | "setting baudrate:target= %u hz, actual= %u hz, sscbrg= %u\n", | |
231 | hz, spi_st->baud, sscbrg); | |
232 | ||
233 | /* Set SSC_CTL and enable SSC */ | |
234 | var = readl_relaxed(spi_st->base + SSC_CTL); | |
235 | var |= SSC_CTL_MS; | |
236 | ||
237 | if (spi->mode & SPI_CPOL) | |
238 | var |= SSC_CTL_PO; | |
239 | else | |
240 | var &= ~SSC_CTL_PO; | |
241 | ||
242 | if (spi->mode & SPI_CPHA) | |
243 | var |= SSC_CTL_PH; | |
244 | else | |
245 | var &= ~SSC_CTL_PH; | |
246 | ||
247 | if ((spi->mode & SPI_LSB_FIRST) == 0) | |
248 | var |= SSC_CTL_HB; | |
249 | else | |
250 | var &= ~SSC_CTL_HB; | |
251 | ||
252 | if (spi->mode & SPI_LOOP) | |
253 | var |= SSC_CTL_LPB; | |
254 | else | |
255 | var &= ~SSC_CTL_LPB; | |
256 | ||
257 | var &= ~SSC_CTL_DATA_WIDTH_MSK; | |
258 | var |= (spi->bits_per_word - 1); | |
259 | ||
260 | var |= SSC_CTL_EN_TX_FIFO | SSC_CTL_EN_RX_FIFO; | |
261 | var |= SSC_CTL_EN; | |
262 | ||
263 | writel_relaxed(var, spi_st->base + SSC_CTL); | |
264 | ||
265 | /* Clear the status register */ | |
266 | readl_relaxed(spi_st->base + SSC_RBUF); | |
267 | ||
268 | return 0; | |
269 | } | |
270 | ||
271 | /* Interrupt fired when TX shift register becomes empty */ | |
272 | static irqreturn_t spi_st_irq(int irq, void *dev_id) | |
273 | { | |
274 | struct spi_st *spi_st = (struct spi_st *)dev_id; | |
275 | ||
276 | /* Read RX FIFO */ | |
277 | ssc_read_rx_fifo(spi_st); | |
278 | ||
279 | /* Fill TX FIFO */ | |
280 | if (spi_st->words_remaining) { | |
281 | ssc_write_tx_fifo(spi_st); | |
282 | } else { | |
283 | /* TX/RX complete */ | |
284 | writel_relaxed(0x0, spi_st->base + SSC_IEN); | |
285 | /* | |
286 | * read SSC_IEN to ensure that this bit is set | |
287 | * before re-enabling interrupt | |
288 | */ | |
289 | readl(spi_st->base + SSC_IEN); | |
290 | complete(&spi_st->done); | |
291 | } | |
292 | ||
293 | return IRQ_HANDLED; | |
294 | } | |
295 | ||
296 | static int spi_st_probe(struct platform_device *pdev) | |
297 | { | |
298 | struct device_node *np = pdev->dev.of_node; | |
299 | struct spi_master *master; | |
300 | struct resource *res; | |
301 | struct spi_st *spi_st; | |
302 | int irq, ret = 0; | |
303 | u32 var; | |
304 | ||
305 | master = spi_alloc_master(&pdev->dev, sizeof(*spi_st)); | |
306 | if (!master) | |
307 | return -ENOMEM; | |
308 | ||
309 | master->dev.of_node = np; | |
310 | master->mode_bits = MODEBITS; | |
311 | master->setup = spi_st_setup; | |
312 | master->cleanup = spi_st_cleanup; | |
313 | master->transfer_one = spi_st_transfer_one; | |
314 | master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16); | |
315 | master->auto_runtime_pm = true; | |
316 | master->bus_num = pdev->id; | |
317 | spi_st = spi_master_get_devdata(master); | |
318 | ||
319 | spi_st->clk = devm_clk_get(&pdev->dev, "ssc"); | |
320 | if (IS_ERR(spi_st->clk)) { | |
321 | dev_err(&pdev->dev, "Unable to request clock\n"); | |
1051550e AL |
322 | ret = PTR_ERR(spi_st->clk); |
323 | goto put_master; | |
9e862375 LJ |
324 | } |
325 | ||
cf4b5ceb | 326 | ret = clk_prepare_enable(spi_st->clk); |
9e862375 | 327 | if (ret) |
1051550e | 328 | goto put_master; |
9e862375 LJ |
329 | |
330 | init_completion(&spi_st->done); | |
331 | ||
332 | /* Get resources */ | |
333 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
334 | spi_st->base = devm_ioremap_resource(&pdev->dev, res); | |
335 | if (IS_ERR(spi_st->base)) { | |
336 | ret = PTR_ERR(spi_st->base); | |
337 | goto clk_disable; | |
338 | } | |
339 | ||
340 | /* Disable I2C and Reset SSC */ | |
341 | writel_relaxed(0x0, spi_st->base + SSC_I2C); | |
342 | var = readw_relaxed(spi_st->base + SSC_CTL); | |
343 | var |= SSC_CTL_SR; | |
344 | writel_relaxed(var, spi_st->base + SSC_CTL); | |
345 | ||
346 | udelay(1); | |
347 | var = readl_relaxed(spi_st->base + SSC_CTL); | |
348 | var &= ~SSC_CTL_SR; | |
349 | writel_relaxed(var, spi_st->base + SSC_CTL); | |
350 | ||
351 | /* Set SSC into slave mode before reconfiguring PIO pins */ | |
352 | var = readl_relaxed(spi_st->base + SSC_CTL); | |
353 | var &= ~SSC_CTL_MS; | |
354 | writel_relaxed(var, spi_st->base + SSC_CTL); | |
355 | ||
356 | irq = irq_of_parse_and_map(np, 0); | |
357 | if (!irq) { | |
358 | dev_err(&pdev->dev, "IRQ missing or invalid\n"); | |
359 | ret = -EINVAL; | |
360 | goto clk_disable; | |
361 | } | |
362 | ||
363 | ret = devm_request_irq(&pdev->dev, irq, spi_st_irq, 0, | |
364 | pdev->name, spi_st); | |
365 | if (ret) { | |
366 | dev_err(&pdev->dev, "Failed to request irq %d\n", irq); | |
367 | goto clk_disable; | |
368 | } | |
369 | ||
370 | /* by default the device is on */ | |
371 | pm_runtime_set_active(&pdev->dev); | |
372 | pm_runtime_enable(&pdev->dev); | |
373 | ||
374 | platform_set_drvdata(pdev, master); | |
375 | ||
376 | ret = devm_spi_register_master(&pdev->dev, master); | |
377 | if (ret) { | |
378 | dev_err(&pdev->dev, "Failed to register master\n"); | |
379 | goto clk_disable; | |
380 | } | |
381 | ||
382 | return 0; | |
383 | ||
384 | clk_disable: | |
cf4b5ceb | 385 | clk_disable_unprepare(spi_st->clk); |
1051550e AL |
386 | put_master: |
387 | spi_master_put(master); | |
9e862375 LJ |
388 | return ret; |
389 | } | |
390 | ||
391 | static int spi_st_remove(struct platform_device *pdev) | |
392 | { | |
393 | struct spi_master *master = platform_get_drvdata(pdev); | |
394 | struct spi_st *spi_st = spi_master_get_devdata(master); | |
395 | ||
cf4b5ceb | 396 | clk_disable_unprepare(spi_st->clk); |
9e862375 LJ |
397 | |
398 | pinctrl_pm_select_sleep_state(&pdev->dev); | |
399 | ||
400 | return 0; | |
401 | } | |
402 | ||
403 | #ifdef CONFIG_PM | |
404 | static int spi_st_runtime_suspend(struct device *dev) | |
405 | { | |
406 | struct spi_master *master = dev_get_drvdata(dev); | |
407 | struct spi_st *spi_st = spi_master_get_devdata(master); | |
408 | ||
409 | writel_relaxed(0, spi_st->base + SSC_IEN); | |
410 | pinctrl_pm_select_sleep_state(dev); | |
411 | ||
cf4b5ceb | 412 | clk_disable_unprepare(spi_st->clk); |
9e862375 LJ |
413 | |
414 | return 0; | |
415 | } | |
416 | ||
417 | static int spi_st_runtime_resume(struct device *dev) | |
418 | { | |
419 | struct spi_master *master = dev_get_drvdata(dev); | |
420 | struct spi_st *spi_st = spi_master_get_devdata(master); | |
421 | int ret; | |
422 | ||
cf4b5ceb | 423 | ret = clk_prepare_enable(spi_st->clk); |
9e862375 LJ |
424 | pinctrl_pm_select_default_state(dev); |
425 | ||
426 | return ret; | |
427 | } | |
428 | #endif | |
429 | ||
430 | #ifdef CONFIG_PM_SLEEP | |
431 | static int spi_st_suspend(struct device *dev) | |
432 | { | |
433 | struct spi_master *master = dev_get_drvdata(dev); | |
434 | int ret; | |
435 | ||
436 | ret = spi_master_suspend(master); | |
437 | if (ret) | |
438 | return ret; | |
439 | ||
440 | return pm_runtime_force_suspend(dev); | |
441 | } | |
442 | ||
443 | static int spi_st_resume(struct device *dev) | |
444 | { | |
445 | struct spi_master *master = dev_get_drvdata(dev); | |
446 | int ret; | |
447 | ||
448 | ret = spi_master_resume(master); | |
449 | if (ret) | |
450 | return ret; | |
451 | ||
452 | return pm_runtime_force_resume(dev); | |
453 | } | |
454 | #endif | |
455 | ||
456 | static const struct dev_pm_ops spi_st_pm = { | |
457 | SET_SYSTEM_SLEEP_PM_OPS(spi_st_suspend, spi_st_resume) | |
458 | SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL) | |
459 | }; | |
460 | ||
09355402 | 461 | static const struct of_device_id stm_spi_match[] = { |
9e862375 LJ |
462 | { .compatible = "st,comms-ssc4-spi", }, |
463 | {}, | |
464 | }; | |
465 | MODULE_DEVICE_TABLE(of, stm_spi_match); | |
466 | ||
467 | static struct platform_driver spi_st_driver = { | |
468 | .driver = { | |
469 | .name = "spi-st", | |
470 | .pm = &spi_st_pm, | |
471 | .of_match_table = of_match_ptr(stm_spi_match), | |
472 | }, | |
473 | .probe = spi_st_probe, | |
474 | .remove = spi_st_remove, | |
475 | }; | |
476 | module_platform_driver(spi_st_driver); | |
477 | ||
478 | MODULE_AUTHOR("Patrice Chotard <patrice.chotard@st.com>"); | |
479 | MODULE_DESCRIPTION("STM SSC SPI driver"); | |
480 | MODULE_LICENSE("GPL v2"); |