1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // spi-mt7621.c -- MediaTek MT7621 SPI controller driver
4 //
5 // Copyright (C) 2011 Sergiy <piratfm@gmail.com>
6 // Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
7 // Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
8 //
9 // Some parts are based on spi-orion.c:
10 // Author: Shadi Ammouri <shadi@marvell.com>
11 // Copyright (C) 2007-2008 Marvell Ltd.
12
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/io.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/platform_device.h>
20 #include <linux/reset.h>
21 #include <linux/spi/spi.h>
22
23 #define DRIVER_NAME "spi-mt7621"
24
25 /* in usec */
26 #define RALINK_SPI_WAIT_MAX_LOOP 2000
27
28 /* SPISTAT register bit field */
29 #define SPISTAT_BUSY BIT(0)
30
31 #define MT7621_SPI_TRANS 0x00
32 #define SPITRANS_BUSY BIT(16)
33
34 #define MT7621_SPI_OPCODE 0x04
35 #define MT7621_SPI_DATA0 0x08
36 #define MT7621_SPI_DATA4 0x18
37 #define SPI_CTL_TX_RX_CNT_MASK 0xff
38 #define SPI_CTL_START BIT(8)
39
40 #define MT7621_SPI_MASTER 0x28
41 #define MASTER_MORE_BUFMODE BIT(2)
42 #define MASTER_FULL_DUPLEX BIT(10)
43 #define MASTER_RS_CLK_SEL GENMASK(27, 16)
44 #define MASTER_RS_CLK_SEL_SHIFT 16
45 #define MASTER_RS_SLAVE_SEL GENMASK(31, 29)
46
47 #define MT7621_SPI_MOREBUF 0x2c
48 #define MT7621_SPI_POLAR 0x38
49 #define MT7621_SPI_SPACE 0x3c
50
51 #define MT7621_CPHA BIT(5)
52 #define MT7621_CPOL BIT(4)
53 #define MT7621_LSB_FIRST BIT(3)
54
55 struct mt7621_spi {
56 struct spi_controller *master;
57 void __iomem *base;
58 unsigned int sys_freq;
59 unsigned int speed;
60 int pending_write;
61 };
62
spidev_to_mt7621_spi(struct spi_device * spi)63 static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi)
64 {
65 return spi_controller_get_devdata(spi->master);
66 }
67
mt7621_spi_read(struct mt7621_spi * rs,u32 reg)68 static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
69 {
70 return ioread32(rs->base + reg);
71 }
72
mt7621_spi_write(struct mt7621_spi * rs,u32 reg,u32 val)73 static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
74 {
75 iowrite32(val, rs->base + reg);
76 }
77
mt7621_spi_set_cs(struct spi_device * spi,int enable)78 static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
79 {
80 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
81 int cs = spi_get_chipselect(spi, 0);
82 u32 polar = 0;
83 u32 master;
84
85 /*
86 * Select SPI device 7, enable "more buffer mode" and disable
87 * full-duplex (only half-duplex really works on this chip
88 * reliably)
89 */
90 master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
91 master |= MASTER_RS_SLAVE_SEL | MASTER_MORE_BUFMODE;
92 master &= ~MASTER_FULL_DUPLEX;
93 mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
94
95 rs->pending_write = 0;
96
97 if (enable)
98 polar = BIT(cs);
99 mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
100 }
101
mt7621_spi_prepare(struct spi_device * spi,unsigned int speed)102 static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
103 {
104 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
105 u32 rate;
106 u32 reg;
107
108 dev_dbg(&spi->dev, "speed:%u\n", speed);
109
110 rate = DIV_ROUND_UP(rs->sys_freq, speed);
111 dev_dbg(&spi->dev, "rate-1:%u\n", rate);
112
113 if (rate > 4097)
114 return -EINVAL;
115
116 if (rate < 2)
117 rate = 2;
118
119 reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
120 reg &= ~MASTER_RS_CLK_SEL;
121 reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
122 rs->speed = speed;
123
124 reg &= ~MT7621_LSB_FIRST;
125 if (spi->mode & SPI_LSB_FIRST)
126 reg |= MT7621_LSB_FIRST;
127
128 /*
129 * This SPI controller seems to be tested on SPI flash only and some
130 * bits are swizzled under other SPI modes probably due to incorrect
131 * wiring inside the silicon. Only mode 0 works correctly.
132 */
133 reg &= ~(MT7621_CPHA | MT7621_CPOL);
134
135 mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
136
137 return 0;
138 }
139
mt7621_spi_wait_till_ready(struct mt7621_spi * rs)140 static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
141 {
142 int i;
143
144 for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
145 u32 status;
146
147 status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
148 if ((status & SPITRANS_BUSY) == 0)
149 return 0;
150 cpu_relax();
151 udelay(1);
152 }
153
154 return -ETIMEDOUT;
155 }
156
mt7621_spi_read_half_duplex(struct mt7621_spi * rs,int rx_len,u8 * buf)157 static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs,
158 int rx_len, u8 *buf)
159 {
160 int tx_len;
161
162 /*
163 * Combine with any pending write, and perform one or more half-duplex
164 * transactions reading 'len' bytes. Data to be written is already in
165 * MT7621_SPI_DATA.
166 */
167 tx_len = rs->pending_write;
168 rs->pending_write = 0;
169
170 while (rx_len || tx_len) {
171 int i;
172 u32 val = (min(tx_len, 4) * 8) << 24;
173 int rx = min(rx_len, 32);
174
175 if (tx_len > 4)
176 val |= (tx_len - 4) * 8;
177 val |= (rx * 8) << 12;
178 mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
179
180 tx_len = 0;
181
182 val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
183 val |= SPI_CTL_START;
184 mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
185
186 mt7621_spi_wait_till_ready(rs);
187
188 for (i = 0; i < rx; i++) {
189 if ((i % 4) == 0)
190 val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
191 *buf++ = val & 0xff;
192 val >>= 8;
193 }
194
195 rx_len -= i;
196 }
197 }
198
mt7621_spi_flush(struct mt7621_spi * rs)199 static inline void mt7621_spi_flush(struct mt7621_spi *rs)
200 {
201 mt7621_spi_read_half_duplex(rs, 0, NULL);
202 }
203
mt7621_spi_write_half_duplex(struct mt7621_spi * rs,int tx_len,const u8 * buf)204 static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
205 int tx_len, const u8 *buf)
206 {
207 int len = rs->pending_write;
208 int val = 0;
209
210 if (len & 3) {
211 val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3));
212 if (len < 4) {
213 val <<= (4 - len) * 8;
214 val = swab32(val);
215 }
216 }
217
218 while (tx_len > 0) {
219 if (len >= 36) {
220 rs->pending_write = len;
221 mt7621_spi_flush(rs);
222 len = 0;
223 }
224
225 val |= *buf++ << (8 * (len & 3));
226 len++;
227 if ((len & 3) == 0) {
228 if (len == 4)
229 /* The byte-order of the opcode is weird! */
230 val = swab32(val);
231 mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val);
232 val = 0;
233 }
234 tx_len -= 1;
235 }
236
237 if (len & 3) {
238 if (len < 4) {
239 val = swab32(val);
240 val >>= (4 - len) * 8;
241 }
242 mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val);
243 }
244
245 rs->pending_write = len;
246 }
247
mt7621_spi_transfer_one_message(struct spi_controller * master,struct spi_message * m)248 static int mt7621_spi_transfer_one_message(struct spi_controller *master,
249 struct spi_message *m)
250 {
251 struct mt7621_spi *rs = spi_controller_get_devdata(master);
252 struct spi_device *spi = m->spi;
253 unsigned int speed = spi->max_speed_hz;
254 struct spi_transfer *t = NULL;
255 int status = 0;
256
257 mt7621_spi_wait_till_ready(rs);
258
259 list_for_each_entry(t, &m->transfers, transfer_list)
260 if (t->speed_hz < speed)
261 speed = t->speed_hz;
262
263 if (mt7621_spi_prepare(spi, speed)) {
264 status = -EIO;
265 goto msg_done;
266 }
267
268 /* Assert CS */
269 mt7621_spi_set_cs(spi, 1);
270
271 m->actual_length = 0;
272 list_for_each_entry(t, &m->transfers, transfer_list) {
273 if ((t->rx_buf) && (t->tx_buf)) {
274 /*
275 * This controller will shift some extra data out
276 * of spi_opcode if (mosi_bit_cnt > 0) &&
277 * (cmd_bit_cnt == 0). So the claimed full-duplex
278 * support is broken since we have no way to read
279 * the MISO value during that bit.
280 */
281 status = -EIO;
282 goto msg_done;
283 } else if (t->rx_buf) {
284 mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
285 } else if (t->tx_buf) {
286 mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
287 }
288 m->actual_length += t->len;
289 }
290
291 /* Flush data and deassert CS */
292 mt7621_spi_flush(rs);
293 mt7621_spi_set_cs(spi, 0);
294
295 msg_done:
296 m->status = status;
297 spi_finalize_current_message(master);
298
299 return 0;
300 }
301
mt7621_spi_setup(struct spi_device * spi)302 static int mt7621_spi_setup(struct spi_device *spi)
303 {
304 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
305
306 if ((spi->max_speed_hz == 0) ||
307 (spi->max_speed_hz > (rs->sys_freq / 2)))
308 spi->max_speed_hz = rs->sys_freq / 2;
309
310 if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
311 dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
312 spi->max_speed_hz);
313 return -EINVAL;
314 }
315
316 return 0;
317 }
318
319 static const struct of_device_id mt7621_spi_match[] = {
320 { .compatible = "ralink,mt7621-spi" },
321 {},
322 };
323 MODULE_DEVICE_TABLE(of, mt7621_spi_match);
324
mt7621_spi_probe(struct platform_device * pdev)325 static int mt7621_spi_probe(struct platform_device *pdev)
326 {
327 const struct of_device_id *match;
328 struct spi_controller *master;
329 struct mt7621_spi *rs;
330 void __iomem *base;
331 struct clk *clk;
332 int ret;
333
334 match = of_match_device(mt7621_spi_match, &pdev->dev);
335 if (!match)
336 return -EINVAL;
337
338 base = devm_platform_ioremap_resource(pdev, 0);
339 if (IS_ERR(base))
340 return PTR_ERR(base);
341
342 clk = devm_clk_get_enabled(&pdev->dev, NULL);
343 if (IS_ERR(clk))
344 return dev_err_probe(&pdev->dev, PTR_ERR(clk),
345 "unable to get SYS clock\n");
346
347 master = devm_spi_alloc_master(&pdev->dev, sizeof(*rs));
348 if (!master) {
349 dev_info(&pdev->dev, "master allocation failed\n");
350 return -ENOMEM;
351 }
352
353 master->mode_bits = SPI_LSB_FIRST;
354 master->flags = SPI_CONTROLLER_HALF_DUPLEX;
355 master->setup = mt7621_spi_setup;
356 master->transfer_one_message = mt7621_spi_transfer_one_message;
357 master->bits_per_word_mask = SPI_BPW_MASK(8);
358 master->dev.of_node = pdev->dev.of_node;
359 master->num_chipselect = 2;
360
361 dev_set_drvdata(&pdev->dev, master);
362
363 rs = spi_controller_get_devdata(master);
364 rs->base = base;
365 rs->master = master;
366 rs->sys_freq = clk_get_rate(clk);
367 rs->pending_write = 0;
368 dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);
369
370 ret = device_reset(&pdev->dev);
371 if (ret) {
372 dev_err(&pdev->dev, "SPI reset failed!\n");
373 return ret;
374 }
375
376 return devm_spi_register_controller(&pdev->dev, master);
377 }
378
379 MODULE_ALIAS("platform:" DRIVER_NAME);
380
381 static struct platform_driver mt7621_spi_driver = {
382 .driver = {
383 .name = DRIVER_NAME,
384 .of_match_table = mt7621_spi_match,
385 },
386 .probe = mt7621_spi_probe,
387 };
388
389 module_platform_driver(mt7621_spi_driver);
390
391 MODULE_DESCRIPTION("MT7621 SPI driver");
392 MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
393 MODULE_LICENSE("GPL");
394
