1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2018 Nuvoton Technology corporation.
3
4 #include <linux/kernel.h>
5 #include <linux/bitfield.h>
6 #include <linux/bitops.h>
7 #include <linux/clk.h>
8 #include <linux/interrupt.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/platform_device.h>
12 #include <linux/spi/spi.h>
13 #include <linux/reset.h>
14
15 #include <asm/unaligned.h>
16
17 #include <linux/regmap.h>
18 #include <linux/mfd/syscon.h>
19
20 struct npcm_pspi {
21 struct completion xfer_done;
22 struct reset_control *reset;
23 struct spi_master *master;
24 unsigned int tx_bytes;
25 unsigned int rx_bytes;
26 void __iomem *base;
27 bool is_save_param;
28 u8 bits_per_word;
29 const u8 *tx_buf;
30 struct clk *clk;
31 u32 speed_hz;
32 u8 *rx_buf;
33 u16 mode;
34 u32 id;
35 };
36
37 #define DRIVER_NAME "npcm-pspi"
38
39 #define NPCM_PSPI_DATA 0x00
40 #define NPCM_PSPI_CTL1 0x02
41 #define NPCM_PSPI_STAT 0x04
42
43 /* definitions for control and status register */
44 #define NPCM_PSPI_CTL1_SPIEN BIT(0)
45 #define NPCM_PSPI_CTL1_MOD BIT(2)
46 #define NPCM_PSPI_CTL1_EIR BIT(5)
47 #define NPCM_PSPI_CTL1_EIW BIT(6)
48 #define NPCM_PSPI_CTL1_SCM BIT(7)
49 #define NPCM_PSPI_CTL1_SCIDL BIT(8)
50 #define NPCM_PSPI_CTL1_SCDV6_0 GENMASK(15, 9)
51
52 #define NPCM_PSPI_STAT_BSY BIT(0)
53 #define NPCM_PSPI_STAT_RBF BIT(1)
54
55 /* general definitions */
56 #define NPCM_PSPI_TIMEOUT_MS 2000
57 #define NPCM_PSPI_MAX_CLK_DIVIDER 256
58 #define NPCM_PSPI_MIN_CLK_DIVIDER 4
59 #define NPCM_PSPI_DEFAULT_CLK 25000000
60
bytes_per_word(unsigned int bits)61 static inline unsigned int bytes_per_word(unsigned int bits)
62 {
63 return bits <= 8 ? 1 : 2;
64 }
65
npcm_pspi_irq_enable(struct npcm_pspi * priv,u16 mask)66 static inline void npcm_pspi_irq_enable(struct npcm_pspi *priv, u16 mask)
67 {
68 u16 val;
69
70 val = ioread16(priv->base + NPCM_PSPI_CTL1);
71 val |= mask;
72 iowrite16(val, priv->base + NPCM_PSPI_CTL1);
73 }
74
npcm_pspi_irq_disable(struct npcm_pspi * priv,u16 mask)75 static inline void npcm_pspi_irq_disable(struct npcm_pspi *priv, u16 mask)
76 {
77 u16 val;
78
79 val = ioread16(priv->base + NPCM_PSPI_CTL1);
80 val &= ~mask;
81 iowrite16(val, priv->base + NPCM_PSPI_CTL1);
82 }
83
npcm_pspi_enable(struct npcm_pspi * priv)84 static inline void npcm_pspi_enable(struct npcm_pspi *priv)
85 {
86 u16 val;
87
88 val = ioread16(priv->base + NPCM_PSPI_CTL1);
89 val |= NPCM_PSPI_CTL1_SPIEN;
90 iowrite16(val, priv->base + NPCM_PSPI_CTL1);
91 }
92
npcm_pspi_disable(struct npcm_pspi * priv)93 static inline void npcm_pspi_disable(struct npcm_pspi *priv)
94 {
95 u16 val;
96
97 val = ioread16(priv->base + NPCM_PSPI_CTL1);
98 val &= ~NPCM_PSPI_CTL1_SPIEN;
99 iowrite16(val, priv->base + NPCM_PSPI_CTL1);
100 }
101
npcm_pspi_set_mode(struct spi_device * spi)102 static void npcm_pspi_set_mode(struct spi_device *spi)
103 {
104 struct npcm_pspi *priv = spi_master_get_devdata(spi->master);
105 u16 regtemp;
106 u16 mode_val;
107
108 switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
109 case SPI_MODE_0:
110 mode_val = 0;
111 break;
112 case SPI_MODE_1:
113 mode_val = NPCM_PSPI_CTL1_SCIDL;
114 break;
115 case SPI_MODE_2:
116 mode_val = NPCM_PSPI_CTL1_SCM;
117 break;
118 case SPI_MODE_3:
119 mode_val = NPCM_PSPI_CTL1_SCIDL | NPCM_PSPI_CTL1_SCM;
120 break;
121 }
122
123 regtemp = ioread16(priv->base + NPCM_PSPI_CTL1);
124 regtemp &= ~(NPCM_PSPI_CTL1_SCM | NPCM_PSPI_CTL1_SCIDL);
125 iowrite16(regtemp | mode_val, priv->base + NPCM_PSPI_CTL1);
126 }
127
npcm_pspi_set_transfer_size(struct npcm_pspi * priv,int size)128 static void npcm_pspi_set_transfer_size(struct npcm_pspi *priv, int size)
129 {
130 u16 regtemp;
131
132 regtemp = ioread16(NPCM_PSPI_CTL1 + priv->base);
133
134 switch (size) {
135 case 8:
136 regtemp &= ~NPCM_PSPI_CTL1_MOD;
137 break;
138 case 16:
139 regtemp |= NPCM_PSPI_CTL1_MOD;
140 break;
141 }
142
143 iowrite16(regtemp, NPCM_PSPI_CTL1 + priv->base);
144 }
145
npcm_pspi_set_baudrate(struct npcm_pspi * priv,unsigned int speed)146 static void npcm_pspi_set_baudrate(struct npcm_pspi *priv, unsigned int speed)
147 {
148 u32 ckdiv;
149 u16 regtemp;
150
151 /* the supported rates are numbers from 4 to 256. */
152 ckdiv = DIV_ROUND_CLOSEST(clk_get_rate(priv->clk), (2 * speed)) - 1;
153
154 regtemp = ioread16(NPCM_PSPI_CTL1 + priv->base);
155 regtemp &= ~NPCM_PSPI_CTL1_SCDV6_0;
156 iowrite16(regtemp | (ckdiv << 9), NPCM_PSPI_CTL1 + priv->base);
157 }
158
npcm_pspi_setup_transfer(struct spi_device * spi,struct spi_transfer * t)159 static void npcm_pspi_setup_transfer(struct spi_device *spi,
160 struct spi_transfer *t)
161 {
162 struct npcm_pspi *priv = spi_master_get_devdata(spi->master);
163
164 priv->tx_buf = t->tx_buf;
165 priv->rx_buf = t->rx_buf;
166 priv->tx_bytes = t->len;
167 priv->rx_bytes = t->len;
168
169 if (!priv->is_save_param || priv->mode != spi->mode) {
170 npcm_pspi_set_mode(spi);
171 priv->mode = spi->mode;
172 }
173
174 /*
175 * If transfer is even length, and 8 bits per word transfer,
176 * then implement 16 bits-per-word transfer.
177 */
178 if (priv->bits_per_word == 8 && !(t->len & 0x1))
179 t->bits_per_word = 16;
180
181 if (!priv->is_save_param || priv->bits_per_word != t->bits_per_word) {
182 npcm_pspi_set_transfer_size(priv, t->bits_per_word);
183 priv->bits_per_word = t->bits_per_word;
184 }
185
186 if (!priv->is_save_param || priv->speed_hz != t->speed_hz) {
187 npcm_pspi_set_baudrate(priv, t->speed_hz);
188 priv->speed_hz = t->speed_hz;
189 }
190
191 if (!priv->is_save_param)
192 priv->is_save_param = true;
193 }
194
npcm_pspi_send(struct npcm_pspi * priv)195 static void npcm_pspi_send(struct npcm_pspi *priv)
196 {
197 int wsize;
198 u16 val;
199
200 wsize = min(bytes_per_word(priv->bits_per_word), priv->tx_bytes);
201 priv->tx_bytes -= wsize;
202
203 if (!priv->tx_buf)
204 return;
205
206 switch (wsize) {
207 case 1:
208 val = *priv->tx_buf++;
209 iowrite8(val, NPCM_PSPI_DATA + priv->base);
210 break;
211 case 2:
212 val = *priv->tx_buf++;
213 val = *priv->tx_buf++ | (val << 8);
214 iowrite16(val, NPCM_PSPI_DATA + priv->base);
215 break;
216 default:
217 WARN_ON_ONCE(1);
218 return;
219 }
220 }
221
npcm_pspi_recv(struct npcm_pspi * priv)222 static void npcm_pspi_recv(struct npcm_pspi *priv)
223 {
224 int rsize;
225 u16 val;
226
227 rsize = min(bytes_per_word(priv->bits_per_word), priv->rx_bytes);
228 priv->rx_bytes -= rsize;
229
230 if (!priv->rx_buf)
231 return;
232
233 switch (rsize) {
234 case 1:
235 *priv->rx_buf++ = ioread8(priv->base + NPCM_PSPI_DATA);
236 break;
237 case 2:
238 val = ioread16(priv->base + NPCM_PSPI_DATA);
239 *priv->rx_buf++ = (val >> 8);
240 *priv->rx_buf++ = val & 0xff;
241 break;
242 default:
243 WARN_ON_ONCE(1);
244 return;
245 }
246 }
247
npcm_pspi_transfer_one(struct spi_master * master,struct spi_device * spi,struct spi_transfer * t)248 static int npcm_pspi_transfer_one(struct spi_master *master,
249 struct spi_device *spi,
250 struct spi_transfer *t)
251 {
252 struct npcm_pspi *priv = spi_master_get_devdata(master);
253 int status;
254
255 npcm_pspi_setup_transfer(spi, t);
256 reinit_completion(&priv->xfer_done);
257 npcm_pspi_enable(priv);
258 status = wait_for_completion_timeout(&priv->xfer_done,
259 msecs_to_jiffies
260 (NPCM_PSPI_TIMEOUT_MS));
261 if (status == 0) {
262 npcm_pspi_disable(priv);
263 return -ETIMEDOUT;
264 }
265
266 return 0;
267 }
268
npcm_pspi_prepare_transfer_hardware(struct spi_master * master)269 static int npcm_pspi_prepare_transfer_hardware(struct spi_master *master)
270 {
271 struct npcm_pspi *priv = spi_master_get_devdata(master);
272
273 npcm_pspi_irq_enable(priv, NPCM_PSPI_CTL1_EIR | NPCM_PSPI_CTL1_EIW);
274
275 return 0;
276 }
277
npcm_pspi_unprepare_transfer_hardware(struct spi_master * master)278 static int npcm_pspi_unprepare_transfer_hardware(struct spi_master *master)
279 {
280 struct npcm_pspi *priv = spi_master_get_devdata(master);
281
282 npcm_pspi_irq_disable(priv, NPCM_PSPI_CTL1_EIR | NPCM_PSPI_CTL1_EIW);
283
284 return 0;
285 }
286
npcm_pspi_reset_hw(struct npcm_pspi * priv)287 static void npcm_pspi_reset_hw(struct npcm_pspi *priv)
288 {
289 reset_control_assert(priv->reset);
290 udelay(5);
291 reset_control_deassert(priv->reset);
292 }
293
npcm_pspi_handler(int irq,void * dev_id)294 static irqreturn_t npcm_pspi_handler(int irq, void *dev_id)
295 {
296 struct npcm_pspi *priv = dev_id;
297 u8 stat;
298
299 stat = ioread8(priv->base + NPCM_PSPI_STAT);
300
301 if (!priv->tx_buf && !priv->rx_buf)
302 return IRQ_NONE;
303
304 if (priv->tx_buf) {
305 if (stat & NPCM_PSPI_STAT_RBF) {
306 ioread8(NPCM_PSPI_DATA + priv->base);
307 if (priv->tx_bytes == 0) {
308 npcm_pspi_disable(priv);
309 complete(&priv->xfer_done);
310 return IRQ_HANDLED;
311 }
312 }
313
314 if ((stat & NPCM_PSPI_STAT_BSY) == 0)
315 if (priv->tx_bytes)
316 npcm_pspi_send(priv);
317 }
318
319 if (priv->rx_buf) {
320 if (stat & NPCM_PSPI_STAT_RBF) {
321 if (!priv->rx_bytes)
322 return IRQ_NONE;
323
324 npcm_pspi_recv(priv);
325
326 if (!priv->rx_bytes) {
327 npcm_pspi_disable(priv);
328 complete(&priv->xfer_done);
329 return IRQ_HANDLED;
330 }
331 }
332
333 if (((stat & NPCM_PSPI_STAT_BSY) == 0) && !priv->tx_buf)
334 iowrite8(0x0, NPCM_PSPI_DATA + priv->base);
335 }
336
337 return IRQ_HANDLED;
338 }
339
npcm_pspi_probe(struct platform_device * pdev)340 static int npcm_pspi_probe(struct platform_device *pdev)
341 {
342 struct npcm_pspi *priv;
343 struct spi_master *master;
344 unsigned long clk_hz;
345 int irq;
346 int ret;
347
348 master = spi_alloc_master(&pdev->dev, sizeof(*priv));
349 if (!master)
350 return -ENOMEM;
351
352 platform_set_drvdata(pdev, master);
353
354 priv = spi_master_get_devdata(master);
355 priv->master = master;
356 priv->is_save_param = false;
357
358 priv->base = devm_platform_ioremap_resource(pdev, 0);
359 if (IS_ERR(priv->base)) {
360 ret = PTR_ERR(priv->base);
361 goto out_master_put;
362 }
363
364 priv->clk = devm_clk_get(&pdev->dev, NULL);
365 if (IS_ERR(priv->clk)) {
366 dev_err(&pdev->dev, "failed to get clock\n");
367 ret = PTR_ERR(priv->clk);
368 goto out_master_put;
369 }
370
371 ret = clk_prepare_enable(priv->clk);
372 if (ret)
373 goto out_master_put;
374
375 irq = platform_get_irq(pdev, 0);
376 if (irq < 0) {
377 ret = irq;
378 goto out_disable_clk;
379 }
380
381 priv->reset = devm_reset_control_get(&pdev->dev, NULL);
382 if (IS_ERR(priv->reset)) {
383 ret = PTR_ERR(priv->reset);
384 goto out_disable_clk;
385 }
386
387 /* reset SPI-HW block */
388 npcm_pspi_reset_hw(priv);
389
390 ret = devm_request_irq(&pdev->dev, irq, npcm_pspi_handler, 0,
391 "npcm-pspi", priv);
392 if (ret) {
393 dev_err(&pdev->dev, "failed to request IRQ\n");
394 goto out_disable_clk;
395 }
396
397 init_completion(&priv->xfer_done);
398
399 clk_hz = clk_get_rate(priv->clk);
400
401 master->max_speed_hz = DIV_ROUND_UP(clk_hz, NPCM_PSPI_MIN_CLK_DIVIDER);
402 master->min_speed_hz = DIV_ROUND_UP(clk_hz, NPCM_PSPI_MAX_CLK_DIVIDER);
403 master->mode_bits = SPI_CPHA | SPI_CPOL;
404 master->dev.of_node = pdev->dev.of_node;
405 master->bus_num = -1;
406 master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
407 master->transfer_one = npcm_pspi_transfer_one;
408 master->prepare_transfer_hardware =
409 npcm_pspi_prepare_transfer_hardware;
410 master->unprepare_transfer_hardware =
411 npcm_pspi_unprepare_transfer_hardware;
412 master->use_gpio_descriptors = true;
413
414 /* set to default clock rate */
415 npcm_pspi_set_baudrate(priv, NPCM_PSPI_DEFAULT_CLK);
416
417 ret = devm_spi_register_master(&pdev->dev, master);
418 if (ret)
419 goto out_disable_clk;
420
421 pr_info("NPCM Peripheral SPI %d probed\n", master->bus_num);
422
423 return 0;
424
425 out_disable_clk:
426 clk_disable_unprepare(priv->clk);
427
428 out_master_put:
429 spi_master_put(master);
430 return ret;
431 }
432
npcm_pspi_remove(struct platform_device * pdev)433 static int npcm_pspi_remove(struct platform_device *pdev)
434 {
435 struct spi_master *master = platform_get_drvdata(pdev);
436 struct npcm_pspi *priv = spi_master_get_devdata(master);
437
438 npcm_pspi_reset_hw(priv);
439 clk_disable_unprepare(priv->clk);
440
441 return 0;
442 }
443
444 static const struct of_device_id npcm_pspi_match[] = {
445 { .compatible = "nuvoton,npcm750-pspi", .data = NULL },
446 {}
447 };
448 MODULE_DEVICE_TABLE(of, npcm_pspi_match);
449
450 static struct platform_driver npcm_pspi_driver = {
451 .driver = {
452 .name = DRIVER_NAME,
453 .of_match_table = npcm_pspi_match,
454 },
455 .probe = npcm_pspi_probe,
456 .remove = npcm_pspi_remove,
457 };
458 module_platform_driver(npcm_pspi_driver);
459
460 MODULE_DESCRIPTION("NPCM peripheral SPI Controller driver");
461 MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
462 MODULE_LICENSE("GPL v2");
463
464