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Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/upstream-linus
[linux-btrfs-devel.git] / drivers / spi / spi-oc-tiny.c
blobf1bde66cea1940efefd812df590c415a46dd1c40
1 /*
2 * OpenCores tiny SPI master driver
3 *
4 * http://opencores.org/project,tiny_spi
5 *
6 * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
7 *
8 * Based on spi_s3c24xx.c, which is:
9 * Copyright (c) 2006 Ben Dooks
10 * Copyright (c) 2006 Simtec Electronics
11 * Ben Dooks <ben@simtec.co.uk>
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2 as
15 * published by the Free Software Foundation.
16 */
17
18 #include <linux/init.h>
19 #include <linux/interrupt.h>
20 #include <linux/errno.h>
21 #include <linux/platform_device.h>
22 #include <linux/spi/spi.h>
23 #include <linux/spi/spi_bitbang.h>
24 #include <linux/spi/spi_oc_tiny.h>
25 #include <linux/io.h>
26 #include <linux/gpio.h>
27 #include <linux/of.h>
28
29 #define DRV_NAME "spi_oc_tiny"
30
31 #define TINY_SPI_RXDATA 0
32 #define TINY_SPI_TXDATA 4
33 #define TINY_SPI_STATUS 8
34 #define TINY_SPI_CONTROL 12
35 #define TINY_SPI_BAUD 16
36
37 #define TINY_SPI_STATUS_TXE 0x1
38 #define TINY_SPI_STATUS_TXR 0x2
39
40 struct tiny_spi {
41 /* bitbang has to be first */
42 struct spi_bitbang bitbang;
43 struct completion done;
44
45 void __iomem *base;
46 int irq;
47 unsigned int freq;
48 unsigned int baudwidth;
49 unsigned int baud;
50 unsigned int speed_hz;
51 unsigned int mode;
52 unsigned int len;
53 unsigned int txc, rxc;
54 const u8 *txp;
55 u8 *rxp;
56 unsigned int gpio_cs_count;
57 int *gpio_cs;
58 };
59
60 static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
61 {
62 return spi_master_get_devdata(sdev->master);
63 }
64
65 static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
66 {
67 struct tiny_spi *hw = tiny_spi_to_hw(spi);
68
69 return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
70 }
71
72 static void tiny_spi_chipselect(struct spi_device *spi, int is_active)
73 {
74 struct tiny_spi *hw = tiny_spi_to_hw(spi);
75
76 if (hw->gpio_cs_count) {
77 gpio_set_value(hw->gpio_cs[spi->chip_select],
78 (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
79 }
80 }
81
82 static int tiny_spi_setup_transfer(struct spi_device *spi,
83 struct spi_transfer *t)
84 {
85 struct tiny_spi *hw = tiny_spi_to_hw(spi);
86 unsigned int baud = hw->baud;
87
88 if (t) {
89 if (t->speed_hz && t->speed_hz != hw->speed_hz)
90 baud = tiny_spi_baud(spi, t->speed_hz);
91 }
92 writel(baud, hw->base + TINY_SPI_BAUD);
93 writel(hw->mode, hw->base + TINY_SPI_CONTROL);
94 return 0;
95 }
96
97 static int tiny_spi_setup(struct spi_device *spi)
98 {
99 struct tiny_spi *hw = tiny_spi_to_hw(spi);
100
101 if (spi->max_speed_hz != hw->speed_hz) {
102 hw->speed_hz = spi->max_speed_hz;
103 hw->baud = tiny_spi_baud(spi, hw->speed_hz);
104 }
105 hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA);
106 return 0;
107 }
108
109 static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
110 {
111 while (!(readb(hw->base + TINY_SPI_STATUS) &
112 TINY_SPI_STATUS_TXR))
113 cpu_relax();
114 }
115
116 static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
117 {
118 while (!(readb(hw->base + TINY_SPI_STATUS) &
119 TINY_SPI_STATUS_TXE))
120 cpu_relax();
121 }
122
123 static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
124 {
125 struct tiny_spi *hw = tiny_spi_to_hw(spi);
126 const u8 *txp = t->tx_buf;
127 u8 *rxp = t->rx_buf;
128 unsigned int i;
129
130 if (hw->irq >= 0) {
131 /* use intrrupt driven data transfer */
132 hw->len = t->len;
133 hw->txp = t->tx_buf;
134 hw->rxp = t->rx_buf;
135 hw->txc = 0;
136 hw->rxc = 0;
137
138 /* send the first byte */
139 if (t->len > 1) {
140 writeb(hw->txp ? *hw->txp++ : 0,
141 hw->base + TINY_SPI_TXDATA);
142 hw->txc++;
143 writeb(hw->txp ? *hw->txp++ : 0,
144 hw->base + TINY_SPI_TXDATA);
145 hw->txc++;
146 writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
147 } else {
148 writeb(hw->txp ? *hw->txp++ : 0,
149 hw->base + TINY_SPI_TXDATA);
150 hw->txc++;
151 writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
152 }
153
154 wait_for_completion(&hw->done);
155 } else if (txp && rxp) {
156 /* we need to tighten the transfer loop */
157 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
158 if (t->len > 1) {
159 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
160 for (i = 2; i < t->len; i++) {
161 u8 rx, tx = *txp++;
162 tiny_spi_wait_txr(hw);
163 rx = readb(hw->base + TINY_SPI_TXDATA);
164 writeb(tx, hw->base + TINY_SPI_TXDATA);
165 *rxp++ = rx;
166 }
167 tiny_spi_wait_txr(hw);
168 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
169 }
170 tiny_spi_wait_txe(hw);
171 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
172 } else if (rxp) {
173 writeb(0, hw->base + TINY_SPI_TXDATA);
174 if (t->len > 1) {
175 writeb(0,
176 hw->base + TINY_SPI_TXDATA);
177 for (i = 2; i < t->len; i++) {
178 u8 rx;
179 tiny_spi_wait_txr(hw);
180 rx = readb(hw->base + TINY_SPI_TXDATA);
181 writeb(0, hw->base + TINY_SPI_TXDATA);
182 *rxp++ = rx;
183 }
184 tiny_spi_wait_txr(hw);
185 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
186 }
187 tiny_spi_wait_txe(hw);
188 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
189 } else if (txp) {
190 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
191 if (t->len > 1) {
192 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
193 for (i = 2; i < t->len; i++) {
194 u8 tx = *txp++;
195 tiny_spi_wait_txr(hw);
196 writeb(tx, hw->base + TINY_SPI_TXDATA);
197 }
198 }
199 tiny_spi_wait_txe(hw);
200 } else {
201 writeb(0, hw->base + TINY_SPI_TXDATA);
202 if (t->len > 1) {
203 writeb(0, hw->base + TINY_SPI_TXDATA);
204 for (i = 2; i < t->len; i++) {
205 tiny_spi_wait_txr(hw);
206 writeb(0, hw->base + TINY_SPI_TXDATA);
207 }
208 }
209 tiny_spi_wait_txe(hw);
210 }
211 return t->len;
212 }
213
214 static irqreturn_t tiny_spi_irq(int irq, void *dev)
215 {
216 struct tiny_spi *hw = dev;
217
218 writeb(0, hw->base + TINY_SPI_STATUS);
219 if (hw->rxc + 1 == hw->len) {
220 if (hw->rxp)
221 *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
222 hw->rxc++;
223 complete(&hw->done);
224 } else {
225 if (hw->rxp)
226 *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
227 hw->rxc++;
228 if (hw->txc < hw->len) {
229 writeb(hw->txp ? *hw->txp++ : 0,
230 hw->base + TINY_SPI_TXDATA);
231 hw->txc++;
232 writeb(TINY_SPI_STATUS_TXR,
233 hw->base + TINY_SPI_STATUS);
234 } else {
235 writeb(TINY_SPI_STATUS_TXE,
236 hw->base + TINY_SPI_STATUS);
237 }
238 }
239 return IRQ_HANDLED;
240 }
241
242 #ifdef CONFIG_OF
243 #include <linux/of_gpio.h>
244
245 static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
246 {
247 struct tiny_spi *hw = platform_get_drvdata(pdev);
248 struct device_node *np = pdev->dev.of_node;
249 unsigned int i;
250 const __be32 *val;
251 int len;
252
253 if (!np)
254 return 0;
255 hw->gpio_cs_count = of_gpio_count(np);
256 if (hw->gpio_cs_count) {
257 hw->gpio_cs = devm_kzalloc(&pdev->dev,
258 hw->gpio_cs_count * sizeof(unsigned int),
259 GFP_KERNEL);
260 if (!hw->gpio_cs)
261 return -ENOMEM;
262 }
263 for (i = 0; i < hw->gpio_cs_count; i++) {
264 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
265 if (hw->gpio_cs[i] < 0)
266 return -ENODEV;
267 }
268 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
269 val = of_get_property(pdev->dev.of_node,
270 "clock-frequency", &len);
271 if (val && len >= sizeof(__be32))
272 hw->freq = be32_to_cpup(val);
273 val = of_get_property(pdev->dev.of_node, "baud-width", &len);
274 if (val && len >= sizeof(__be32))
275 hw->baudwidth = be32_to_cpup(val);
276 return 0;
277 }
278 #else /* !CONFIG_OF */
279 static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
280 {
281 return 0;
282 }
283 #endif /* CONFIG_OF */
284
285 static int __devinit tiny_spi_probe(struct platform_device *pdev)
286 {
287 struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
288 struct tiny_spi *hw;
289 struct spi_master *master;
290 struct resource *res;
291 unsigned int i;
292 int err = -ENODEV;
293
294 master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
295 if (!master)
296 return err;
297
298 /* setup the master state. */
299 master->bus_num = pdev->id;
300 master->num_chipselect = 255;
301 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
302 master->setup = tiny_spi_setup;
303
304 hw = spi_master_get_devdata(master);
305 platform_set_drvdata(pdev, hw);
306
307 /* setup the state for the bitbang driver */
308 hw->bitbang.master = spi_master_get(master);
309 if (!hw->bitbang.master)
310 return err;
311 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
312 hw->bitbang.chipselect = tiny_spi_chipselect;
313 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
314
315 /* find and map our resources */
316 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
317 if (!res)
318 goto exit_busy;
319 if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
320 pdev->name))
321 goto exit_busy;
322 hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
323 resource_size(res));
324 if (!hw->base)
325 goto exit_busy;
326 /* irq is optional */
327 hw->irq = platform_get_irq(pdev, 0);
328 if (hw->irq >= 0) {
329 init_completion(&hw->done);
330 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
331 pdev->name, hw);
332 if (err)
333 goto exit;
334 }
335 /* find platform data */
336 if (platp) {
337 hw->gpio_cs_count = platp->gpio_cs_count;
338 hw->gpio_cs = platp->gpio_cs;
339 if (platp->gpio_cs_count && !platp->gpio_cs)
340 goto exit_busy;
341 hw->freq = platp->freq;
342 hw->baudwidth = platp->baudwidth;
343 } else {
344 err = tiny_spi_of_probe(pdev);
345 if (err)
346 goto exit;
347 }
348 for (i = 0; i < hw->gpio_cs_count; i++) {
349 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
350 if (err)
351 goto exit_gpio;
352 gpio_direction_output(hw->gpio_cs[i], 1);
353 }
354 hw->bitbang.master->num_chipselect = max(1U, hw->gpio_cs_count);
355
356 /* register our spi controller */
357 err = spi_bitbang_start(&hw->bitbang);
358 if (err)
359 goto exit;
360 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
361
362 return 0;
363
364 exit_gpio:
365 while (i-- > 0)
366 gpio_free(hw->gpio_cs[i]);
367 exit_busy:
368 err = -EBUSY;
369 exit:
370 platform_set_drvdata(pdev, NULL);
371 spi_master_put(master);
372 return err;
373 }
374
375 static int __devexit tiny_spi_remove(struct platform_device *pdev)
376 {
377 struct tiny_spi *hw = platform_get_drvdata(pdev);
378 struct spi_master *master = hw->bitbang.master;
379 unsigned int i;
380
381 spi_bitbang_stop(&hw->bitbang);
382 for (i = 0; i < hw->gpio_cs_count; i++)
383 gpio_free(hw->gpio_cs[i]);
384 platform_set_drvdata(pdev, NULL);
385 spi_master_put(master);
386 return 0;
387 }
388
389 #ifdef CONFIG_OF
390 static const struct of_device_id tiny_spi_match[] = {
391 { .compatible = "opencores,tiny-spi-rtlsvn2", },
392 {},
393 };
394 MODULE_DEVICE_TABLE(of, tiny_spi_match);
395 #else /* CONFIG_OF */
396 #define tiny_spi_match NULL
397 #endif /* CONFIG_OF */
398
399 static struct platform_driver tiny_spi_driver = {
400 .probe = tiny_spi_probe,
401 .remove = __devexit_p(tiny_spi_remove),
402 .driver = {
403 .name = DRV_NAME,
404 .owner = THIS_MODULE,
405 .pm = NULL,
406 .of_match_table = tiny_spi_match,
407 },
408 };
409
410 static int __init tiny_spi_init(void)
411 {
412 return platform_driver_register(&tiny_spi_driver);
413 }
414 module_init(tiny_spi_init);
415
416 static void __exit tiny_spi_exit(void)
417 {
418 platform_driver_unregister(&tiny_spi_driver);
419 }
420 module_exit(tiny_spi_exit);
421
422 MODULE_DESCRIPTION("OpenCores tiny SPI driver");
423 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
424 MODULE_LICENSE("GPL");
425 MODULE_ALIAS("platform:" DRV_NAME);
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