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