tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/interrupt.h>
19#include <linux/errno.h>
20#include <linux/module.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
40struct 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 int gpio_cs_count;
57 int *gpio_cs;
58};
59
60static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
61{
62 return spi_master_get_devdata(sdev->master);
63}
64
65static 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
72static 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 > 0) {
77 gpio_set_value(hw->gpio_cs[spi->chip_select],
78 (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
79 }
80}
81
82static 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
97static 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
109static 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
116static 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
123static 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 interrupt 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 {
156 /* we need to tighten the transfer loop */
157 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
158 for (i = 1; i < t->len; i++) {
159 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
160
161 if (rxp || (i != t->len - 1))
162 tiny_spi_wait_txr(hw);
163 if (rxp)
164 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
165 }
166 tiny_spi_wait_txe(hw);
167 if (rxp)
168 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
169 }
170
171 return t->len;
172}
173
174static irqreturn_t tiny_spi_irq(int irq, void *dev)
175{
176 struct tiny_spi *hw = dev;
177
178 writeb(0, hw->base + TINY_SPI_STATUS);
179 if (hw->rxc + 1 == hw->len) {
180 if (hw->rxp)
181 *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
182 hw->rxc++;
183 complete(&hw->done);
184 } else {
185 if (hw->rxp)
186 *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
187 hw->rxc++;
188 if (hw->txc < hw->len) {
189 writeb(hw->txp ? *hw->txp++ : 0,
190 hw->base + TINY_SPI_TXDATA);
191 hw->txc++;
192 writeb(TINY_SPI_STATUS_TXR,
193 hw->base + TINY_SPI_STATUS);
194 } else {
195 writeb(TINY_SPI_STATUS_TXE,
196 hw->base + TINY_SPI_STATUS);
197 }
198 }
199 return IRQ_HANDLED;
200}
201
202#ifdef CONFIG_OF
203#include <linux/of_gpio.h>
204
205static int tiny_spi_of_probe(struct platform_device *pdev)
206{
207 struct tiny_spi *hw = platform_get_drvdata(pdev);
208 struct device_node *np = pdev->dev.of_node;
209 unsigned int i;
210 u32 val;
211
212 if (!np)
213 return 0;
214 hw->gpio_cs_count = of_gpio_count(np);
215 if (hw->gpio_cs_count > 0) {
216 hw->gpio_cs = devm_kzalloc(&pdev->dev,
217 hw->gpio_cs_count * sizeof(unsigned int),
218 GFP_KERNEL);
219 if (!hw->gpio_cs)
220 return -ENOMEM;
221 }
222 for (i = 0; i < hw->gpio_cs_count; i++) {
223 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
224 if (hw->gpio_cs[i] < 0)
225 return -ENODEV;
226 }
227 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
228 if (!of_property_read_u32(np, "clock-frequency", &val))
229 hw->freq = val;
230 if (!of_property_read_u32(np, "baud-width", &val))
231 hw->baudwidth = val;
232 return 0;
233}
234#else /* !CONFIG_OF */
235static int tiny_spi_of_probe(struct platform_device *pdev)
236{
237 return 0;
238}
239#endif /* CONFIG_OF */
240
241static int tiny_spi_probe(struct platform_device *pdev)
242{
243 struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
244 struct tiny_spi *hw;
245 struct spi_master *master;
246 struct resource *res;
247 unsigned int i;
248 int err = -ENODEV;
249
250 master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
251 if (!master)
252 return err;
253
254 /* setup the master state. */
255 master->bus_num = pdev->id;
256 master->num_chipselect = 255;
257 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
258 master->setup = tiny_spi_setup;
259
260 hw = spi_master_get_devdata(master);
261 platform_set_drvdata(pdev, hw);
262
263 /* setup the state for the bitbang driver */
264 hw->bitbang.master = master;
265 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
266 hw->bitbang.chipselect = tiny_spi_chipselect;
267 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
268
269 /* find and map our resources */
270 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
271 hw->base = devm_ioremap_resource(&pdev->dev, res);
272 if (IS_ERR(hw->base)) {
273 err = PTR_ERR(hw->base);
274 goto exit;
275 }
276 /* irq is optional */
277 hw->irq = platform_get_irq(pdev, 0);
278 if (hw->irq >= 0) {
279 init_completion(&hw->done);
280 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
281 pdev->name, hw);
282 if (err)
283 goto exit;
284 }
285 /* find platform data */
286 if (platp) {
287 hw->gpio_cs_count = platp->gpio_cs_count;
288 hw->gpio_cs = platp->gpio_cs;
289 if (platp->gpio_cs_count && !platp->gpio_cs) {
290 err = -EBUSY;
291 goto exit;
292 }
293 hw->freq = platp->freq;
294 hw->baudwidth = platp->baudwidth;
295 } else {
296 err = tiny_spi_of_probe(pdev);
297 if (err)
298 goto exit;
299 }
300 for (i = 0; i < hw->gpio_cs_count; i++) {
301 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
302 if (err)
303 goto exit_gpio;
304 gpio_direction_output(hw->gpio_cs[i], 1);
305 }
306 hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);
307
308 /* register our spi controller */
309 err = spi_bitbang_start(&hw->bitbang);
310 if (err)
311 goto exit;
312 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
313
314 return 0;
315
316exit_gpio:
317 while (i-- > 0)
318 gpio_free(hw->gpio_cs[i]);
319exit:
320 spi_master_put(master);
321 return err;
322}
323
324static int tiny_spi_remove(struct platform_device *pdev)
325{
326 struct tiny_spi *hw = platform_get_drvdata(pdev);
327 struct spi_master *master = hw->bitbang.master;
328 unsigned int i;
329
330 spi_bitbang_stop(&hw->bitbang);
331 for (i = 0; i < hw->gpio_cs_count; i++)
332 gpio_free(hw->gpio_cs[i]);
333 spi_master_put(master);
334 return 0;
335}
336
337#ifdef CONFIG_OF
338static const struct of_device_id tiny_spi_match[] = {
339 { .compatible = "opencores,tiny-spi-rtlsvn2", },
340 {},
341};
342MODULE_DEVICE_TABLE(of, tiny_spi_match);
343#endif /* CONFIG_OF */
344
345static struct platform_driver tiny_spi_driver = {
346 .probe = tiny_spi_probe,
347 .remove = tiny_spi_remove,
348 .driver = {
349 .name = DRV_NAME,
350 .pm = NULL,
351 .of_match_table = of_match_ptr(tiny_spi_match),
352 },
353};
354module_platform_driver(tiny_spi_driver);
355
356MODULE_DESCRIPTION("OpenCores tiny SPI driver");
357MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
358MODULE_LICENSE("GPL");
359MODULE_ALIAS("platform:" DRV_NAME);