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1/*
2 * Copyright (C) 2012 - 2014 Allwinner Tech
3 * Pan Nan <pannan@allwinnertech.com>
4 *
5 * Copyright (C) 2014 Maxime Ripard
6 * Maxime Ripard <maxime.ripard@free-electrons.com>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 */
13
14#include <linux/clk.h>
15#include <linux/delay.h>
16#include <linux/device.h>
17#include <linux/interrupt.h>
18#include <linux/io.h>
19#include <linux/module.h>
20#include <linux/platform_device.h>
21#include <linux/pm_runtime.h>
22#include <linux/reset.h>
23
24#include <linux/spi/spi.h>
25
26#define SUN6I_FIFO_DEPTH 128
27
28#define SUN6I_GBL_CTL_REG 0x04
29#define SUN6I_GBL_CTL_BUS_ENABLE BIT(0)
30#define SUN6I_GBL_CTL_MASTER BIT(1)
31#define SUN6I_GBL_CTL_TP BIT(7)
32#define SUN6I_GBL_CTL_RST BIT(31)
33
34#define SUN6I_TFR_CTL_REG 0x08
35#define SUN6I_TFR_CTL_CPHA BIT(0)
36#define SUN6I_TFR_CTL_CPOL BIT(1)
37#define SUN6I_TFR_CTL_SPOL BIT(2)
38#define SUN6I_TFR_CTL_CS_MASK 0x30
39#define SUN6I_TFR_CTL_CS(cs) (((cs) << 4) & SUN6I_TFR_CTL_CS_MASK)
40#define SUN6I_TFR_CTL_CS_MANUAL BIT(6)
41#define SUN6I_TFR_CTL_CS_LEVEL BIT(7)
42#define SUN6I_TFR_CTL_DHB BIT(8)
43#define SUN6I_TFR_CTL_FBS BIT(12)
44#define SUN6I_TFR_CTL_XCH BIT(31)
45
46#define SUN6I_INT_CTL_REG 0x10
47#define SUN6I_INT_CTL_RF_OVF BIT(8)
48#define SUN6I_INT_CTL_TC BIT(12)
49
50#define SUN6I_INT_STA_REG 0x14
51
52#define SUN6I_FIFO_CTL_REG 0x18
53#define SUN6I_FIFO_CTL_RF_RST BIT(15)
54#define SUN6I_FIFO_CTL_TF_RST BIT(31)
55
56#define SUN6I_FIFO_STA_REG 0x1c
57#define SUN6I_FIFO_STA_RF_CNT_MASK 0x7f
58#define SUN6I_FIFO_STA_RF_CNT_BITS 0
59#define SUN6I_FIFO_STA_TF_CNT_MASK 0x7f
60#define SUN6I_FIFO_STA_TF_CNT_BITS 16
61
62#define SUN6I_CLK_CTL_REG 0x24
63#define SUN6I_CLK_CTL_CDR2_MASK 0xff
64#define SUN6I_CLK_CTL_CDR2(div) (((div) & SUN6I_CLK_CTL_CDR2_MASK) << 0)
65#define SUN6I_CLK_CTL_CDR1_MASK 0xf
66#define SUN6I_CLK_CTL_CDR1(div) (((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
67#define SUN6I_CLK_CTL_DRS BIT(12)
68
69#define SUN6I_BURST_CNT_REG 0x30
70#define SUN6I_BURST_CNT(cnt) ((cnt) & 0xffffff)
71
72#define SUN6I_XMIT_CNT_REG 0x34
73#define SUN6I_XMIT_CNT(cnt) ((cnt) & 0xffffff)
74
75#define SUN6I_BURST_CTL_CNT_REG 0x38
76#define SUN6I_BURST_CTL_CNT_STC(cnt) ((cnt) & 0xffffff)
77
78#define SUN6I_TXDATA_REG 0x200
79#define SUN6I_RXDATA_REG 0x300
80
81struct sun6i_spi {
82 struct spi_master *master;
83 void __iomem *base_addr;
84 struct clk *hclk;
85 struct clk *mclk;
86 struct reset_control *rstc;
87
88 struct completion done;
89
90 const u8 *tx_buf;
91 u8 *rx_buf;
92 int len;
93};
94
95static inline u32 sun6i_spi_read(struct sun6i_spi *sspi, u32 reg)
96{
97 return readl(sspi->base_addr + reg);
98}
99
100static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
101{
102 writel(value, sspi->base_addr + reg);
103}
104
105static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
106{
107 u32 reg, cnt;
108 u8 byte;
109
110 /* See how much data is available */
111 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
112 reg &= SUN6I_FIFO_STA_RF_CNT_MASK;
113 cnt = reg >> SUN6I_FIFO_STA_RF_CNT_BITS;
114
115 if (len > cnt)
116 len = cnt;
117
118 while (len--) {
119 byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
120 if (sspi->rx_buf)
121 *sspi->rx_buf++ = byte;
122 }
123}
124
125static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
126{
127 u8 byte;
128
129 if (len > sspi->len)
130 len = sspi->len;
131
132 while (len--) {
133 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
134 writeb(byte, sspi->base_addr + SUN6I_TXDATA_REG);
135 sspi->len--;
136 }
137}
138
139static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
140{
141 struct sun6i_spi *sspi = spi_master_get_devdata(spi->master);
142 u32 reg;
143
144 reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
145 reg &= ~SUN6I_TFR_CTL_CS_MASK;
146 reg |= SUN6I_TFR_CTL_CS(spi->chip_select);
147
148 if (enable)
149 reg |= SUN6I_TFR_CTL_CS_LEVEL;
150 else
151 reg &= ~SUN6I_TFR_CTL_CS_LEVEL;
152
153 sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
154}
155
156
157static int sun6i_spi_transfer_one(struct spi_master *master,
158 struct spi_device *spi,
159 struct spi_transfer *tfr)
160{
161 struct sun6i_spi *sspi = spi_master_get_devdata(master);
162 unsigned int mclk_rate, div, timeout;
163 unsigned int tx_len = 0;
164 int ret = 0;
165 u32 reg;
166
167 /* We don't support transfer larger than the FIFO */
168 if (tfr->len > SUN6I_FIFO_DEPTH)
169 return -EINVAL;
170
171 reinit_completion(&sspi->done);
172 sspi->tx_buf = tfr->tx_buf;
173 sspi->rx_buf = tfr->rx_buf;
174 sspi->len = tfr->len;
175
176 /* Clear pending interrupts */
177 sun6i_spi_write(sspi, SUN6I_INT_STA_REG, ~0);
178
179 /* Reset FIFO */
180 sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
181 SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);
182
183 /*
184 * Setup the transfer control register: Chip Select,
185 * polarities, etc.
186 */
187 reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
188
189 if (spi->mode & SPI_CPOL)
190 reg |= SUN6I_TFR_CTL_CPOL;
191 else
192 reg &= ~SUN6I_TFR_CTL_CPOL;
193
194 if (spi->mode & SPI_CPHA)
195 reg |= SUN6I_TFR_CTL_CPHA;
196 else
197 reg &= ~SUN6I_TFR_CTL_CPHA;
198
199 if (spi->mode & SPI_LSB_FIRST)
200 reg |= SUN6I_TFR_CTL_FBS;
201 else
202 reg &= ~SUN6I_TFR_CTL_FBS;
203
204 /*
205 * If it's a TX only transfer, we don't want to fill the RX
206 * FIFO with bogus data
207 */
208 if (sspi->rx_buf)
209 reg &= ~SUN6I_TFR_CTL_DHB;
210 else
211 reg |= SUN6I_TFR_CTL_DHB;
212
213 /* We want to control the chip select manually */
214 reg |= SUN6I_TFR_CTL_CS_MANUAL;
215
216 sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
217
218 /* Ensure that we have a parent clock fast enough */
219 mclk_rate = clk_get_rate(sspi->mclk);
220 if (mclk_rate < (2 * tfr->speed_hz)) {
221 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
222 mclk_rate = clk_get_rate(sspi->mclk);
223 }
224
225 /*
226 * Setup clock divider.
227 *
228 * We have two choices there. Either we can use the clock
229 * divide rate 1, which is calculated thanks to this formula:
230 * SPI_CLK = MOD_CLK / (2 ^ cdr)
231 * Or we can use CDR2, which is calculated with the formula:
232 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
233 * Wether we use the former or the latter is set through the
234 * DRS bit.
235 *
236 * First try CDR2, and if we can't reach the expected
237 * frequency, fall back to CDR1.
238 */
239 div = mclk_rate / (2 * tfr->speed_hz);
240 if (div <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) {
241 if (div > 0)
242 div--;
243
244 reg = SUN6I_CLK_CTL_CDR2(div) | SUN6I_CLK_CTL_DRS;
245 } else {
246 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz);
247 reg = SUN6I_CLK_CTL_CDR1(div);
248 }
249
250 sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg);
251
252 /* Setup the transfer now... */
253 if (sspi->tx_buf)
254 tx_len = tfr->len;
255
256 /* Setup the counters */
257 sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, SUN6I_BURST_CNT(tfr->len));
258 sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, SUN6I_XMIT_CNT(tx_len));
259 sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG,
260 SUN6I_BURST_CTL_CNT_STC(tx_len));
261
262 /* Fill the TX FIFO */
263 sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
264
265 /* Enable the interrupts */
266 sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
267
268 /* Start the transfer */
269 reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
270 sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);
271
272 timeout = wait_for_completion_timeout(&sspi->done,
273 msecs_to_jiffies(1000));
274 if (!timeout) {
275 ret = -ETIMEDOUT;
276 goto out;
277 }
278
279 sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
280
281out:
282 sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);
283
284 return ret;
285}
286
287static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
288{
289 struct sun6i_spi *sspi = dev_id;
290 u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);
291
292 /* Transfer complete */
293 if (status & SUN6I_INT_CTL_TC) {
294 sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
295 complete(&sspi->done);
296 return IRQ_HANDLED;
297 }
298
299 return IRQ_NONE;
300}
301
302static int sun6i_spi_runtime_resume(struct device *dev)
303{
304 struct spi_master *master = dev_get_drvdata(dev);
305 struct sun6i_spi *sspi = spi_master_get_devdata(master);
306 int ret;
307
308 ret = clk_prepare_enable(sspi->hclk);
309 if (ret) {
310 dev_err(dev, "Couldn't enable AHB clock\n");
311 goto out;
312 }
313
314 ret = clk_prepare_enable(sspi->mclk);
315 if (ret) {
316 dev_err(dev, "Couldn't enable module clock\n");
317 goto err;
318 }
319
320 ret = reset_control_deassert(sspi->rstc);
321 if (ret) {
322 dev_err(dev, "Couldn't deassert the device from reset\n");
323 goto err2;
324 }
325
326 sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG,
327 SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP);
328
329 return 0;
330
331err2:
332 clk_disable_unprepare(sspi->mclk);
333err:
334 clk_disable_unprepare(sspi->hclk);
335out:
336 return ret;
337}
338
339static int sun6i_spi_runtime_suspend(struct device *dev)
340{
341 struct spi_master *master = dev_get_drvdata(dev);
342 struct sun6i_spi *sspi = spi_master_get_devdata(master);
343
344 reset_control_assert(sspi->rstc);
345 clk_disable_unprepare(sspi->mclk);
346 clk_disable_unprepare(sspi->hclk);
347
348 return 0;
349}
350
351static int sun6i_spi_probe(struct platform_device *pdev)
352{
353 struct spi_master *master;
354 struct sun6i_spi *sspi;
355 struct resource *res;
356 int ret = 0, irq;
357
358 master = spi_alloc_master(&pdev->dev, sizeof(struct sun6i_spi));
359 if (!master) {
360 dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
361 return -ENOMEM;
362 }
363
364 platform_set_drvdata(pdev, master);
365 sspi = spi_master_get_devdata(master);
366
367 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
368 sspi->base_addr = devm_ioremap_resource(&pdev->dev, res);
369 if (IS_ERR(sspi->base_addr)) {
370 ret = PTR_ERR(sspi->base_addr);
371 goto err_free_master;
372 }
373
374 irq = platform_get_irq(pdev, 0);
375 if (irq < 0) {
376 dev_err(&pdev->dev, "No spi IRQ specified\n");
377 ret = -ENXIO;
378 goto err_free_master;
379 }
380
381 ret = devm_request_irq(&pdev->dev, irq, sun6i_spi_handler,
382 0, "sun6i-spi", sspi);
383 if (ret) {
384 dev_err(&pdev->dev, "Cannot request IRQ\n");
385 goto err_free_master;
386 }
387
388 sspi->master = master;
389 master->set_cs = sun6i_spi_set_cs;
390 master->transfer_one = sun6i_spi_transfer_one;
391 master->num_chipselect = 4;
392 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
393 master->bits_per_word_mask = SPI_BPW_MASK(8);
394 master->dev.of_node = pdev->dev.of_node;
395 master->auto_runtime_pm = true;
396
397 sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
398 if (IS_ERR(sspi->hclk)) {
399 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
400 ret = PTR_ERR(sspi->hclk);
401 goto err_free_master;
402 }
403
404 sspi->mclk = devm_clk_get(&pdev->dev, "mod");
405 if (IS_ERR(sspi->mclk)) {
406 dev_err(&pdev->dev, "Unable to acquire module clock\n");
407 ret = PTR_ERR(sspi->mclk);
408 goto err_free_master;
409 }
410
411 init_completion(&sspi->done);
412
413 sspi->rstc = devm_reset_control_get(&pdev->dev, NULL);
414 if (IS_ERR(sspi->rstc)) {
415 dev_err(&pdev->dev, "Couldn't get reset controller\n");
416 ret = PTR_ERR(sspi->rstc);
417 goto err_free_master;
418 }
419
420 /*
421 * This wake-up/shutdown pattern is to be able to have the
422 * device woken up, even if runtime_pm is disabled
423 */
424 ret = sun6i_spi_runtime_resume(&pdev->dev);
425 if (ret) {
426 dev_err(&pdev->dev, "Couldn't resume the device\n");
427 goto err_free_master;
428 }
429
430 pm_runtime_set_active(&pdev->dev);
431 pm_runtime_enable(&pdev->dev);
432 pm_runtime_idle(&pdev->dev);
433
434 ret = devm_spi_register_master(&pdev->dev, master);
435 if (ret) {
436 dev_err(&pdev->dev, "cannot register SPI master\n");
437 goto err_pm_disable;
438 }
439
440 return 0;
441
442err_pm_disable:
443 pm_runtime_disable(&pdev->dev);
444 sun6i_spi_runtime_suspend(&pdev->dev);
445err_free_master:
446 spi_master_put(master);
447 return ret;
448}
449
450static int sun6i_spi_remove(struct platform_device *pdev)
451{
452 pm_runtime_disable(&pdev->dev);
453
454 return 0;
455}
456
457static const struct of_device_id sun6i_spi_match[] = {
458 { .compatible = "allwinner,sun6i-a31-spi", },
459 {}
460};
461MODULE_DEVICE_TABLE(of, sun6i_spi_match);
462
463static const struct dev_pm_ops sun6i_spi_pm_ops = {
464 .runtime_resume = sun6i_spi_runtime_resume,
465 .runtime_suspend = sun6i_spi_runtime_suspend,
466};
467
468static struct platform_driver sun6i_spi_driver = {
469 .probe = sun6i_spi_probe,
470 .remove = sun6i_spi_remove,
471 .driver = {
472 .name = "sun6i-spi",
473 .of_match_table = sun6i_spi_match,
474 .pm = &sun6i_spi_pm_ops,
475 },
476};
477module_platform_driver(sun6i_spi_driver);
478
479MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
480MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
481MODULE_DESCRIPTION("Allwinner A31 SPI controller driver");
482MODULE_LICENSE("GPL");