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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
41struct tiny_spi {
42
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
61static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
62{
63 return spi_master_get_devdata(sdev->master);
64}
65
66static 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
73static 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
83static 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
98static 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
110static 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
117static 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
124static 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
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
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
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
215static 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
246static 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
280static int tiny_spi_of_probe(struct platform_device *pdev)
281{
282 return 0;
283}
284#endif
285
286static 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
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
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
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
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
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
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
365exit_gpio:
366 while (i-- > 0)
367 gpio_free(hw->gpio_cs[i]);
368exit_busy:
369 err = -EBUSY;
370exit:
371 platform_set_drvdata(pdev, NULL);
372 spi_master_put(master);
373 return err;
374}
375
376static 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
391static const struct of_device_id tiny_spi_match[] = {
392 { .compatible = "opencores,tiny-spi-rtlsvn2", },
393 {},
394};
395MODULE_DEVICE_TABLE(of, tiny_spi_match);
396#endif
397
398static struct platform_driver tiny_spi_driver = {
399 .probe = tiny_spi_probe,
400 .remove = tiny_spi_remove,
401 .driver = {
402 .name = DRV_NAME,
403 .owner = THIS_MODULE,
404 .pm = NULL,
405 .of_match_table = of_match_ptr(tiny_spi_match),
406 },
407};
408module_platform_driver(tiny_spi_driver);
409
410MODULE_DESCRIPTION("OpenCores tiny SPI driver");
411MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
412MODULE_LICENSE("GPL");
413MODULE_ALIAS("platform:" DRV_NAME);
414
