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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
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
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
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
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 const __be32 *val;
211 int len;
212
213 if (!np)
214 return 0;
215 hw->gpio_cs_count = of_gpio_count(np);
216 if (hw->gpio_cs_count > 0) {
217 hw->gpio_cs = devm_kzalloc(&pdev->dev,
218 hw->gpio_cs_count * sizeof(unsigned int),
219 GFP_KERNEL);
220 if (!hw->gpio_cs)
221 return -ENOMEM;
222 }
223 for (i = 0; i < hw->gpio_cs_count; i++) {
224 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
225 if (hw->gpio_cs[i] < 0)
226 return -ENODEV;
227 }
228 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
229 val = of_get_property(pdev->dev.of_node,
230 "clock-frequency", &len);
231 if (val && len >= sizeof(__be32))
232 hw->freq = be32_to_cpup(val);
233 val = of_get_property(pdev->dev.of_node, "baud-width", &len);
234 if (val && len >= sizeof(__be32))
235 hw->baudwidth = be32_to_cpup(val);
236 return 0;
237}
238#else
239static int tiny_spi_of_probe(struct platform_device *pdev)
240{
241 return 0;
242}
243#endif
244
245static int tiny_spi_probe(struct platform_device *pdev)
246{
247 struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
248 struct tiny_spi *hw;
249 struct spi_master *master;
250 struct resource *res;
251 unsigned int i;
252 int err = -ENODEV;
253
254 master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
255 if (!master)
256 return err;
257
258
259 master->bus_num = pdev->id;
260 master->num_chipselect = 255;
261 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
262 master->setup = tiny_spi_setup;
263
264 hw = spi_master_get_devdata(master);
265 platform_set_drvdata(pdev, hw);
266
267
268 hw->bitbang.master = master;
269 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
270 hw->bitbang.chipselect = tiny_spi_chipselect;
271 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
272
273
274 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
275 hw->base = devm_ioremap_resource(&pdev->dev, res);
276 if (IS_ERR(hw->base)) {
277 err = PTR_ERR(hw->base);
278 goto exit;
279 }
280
281 hw->irq = platform_get_irq(pdev, 0);
282 if (hw->irq >= 0) {
283 init_completion(&hw->done);
284 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
285 pdev->name, hw);
286 if (err)
287 goto exit;
288 }
289
290 if (platp) {
291 hw->gpio_cs_count = platp->gpio_cs_count;
292 hw->gpio_cs = platp->gpio_cs;
293 if (platp->gpio_cs_count && !platp->gpio_cs) {
294 err = -EBUSY;
295 goto exit;
296 }
297 hw->freq = platp->freq;
298 hw->baudwidth = platp->baudwidth;
299 } else {
300 err = tiny_spi_of_probe(pdev);
301 if (err)
302 goto exit;
303 }
304 for (i = 0; i < hw->gpio_cs_count; i++) {
305 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
306 if (err)
307 goto exit_gpio;
308 gpio_direction_output(hw->gpio_cs[i], 1);
309 }
310 hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);
311
312
313 err = spi_bitbang_start(&hw->bitbang);
314 if (err)
315 goto exit;
316 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
317
318 return 0;
319
320exit_gpio:
321 while (i-- > 0)
322 gpio_free(hw->gpio_cs[i]);
323exit:
324 spi_master_put(master);
325 return err;
326}
327
328static int tiny_spi_remove(struct platform_device *pdev)
329{
330 struct tiny_spi *hw = platform_get_drvdata(pdev);
331 struct spi_master *master = hw->bitbang.master;
332 unsigned int i;
333
334 spi_bitbang_stop(&hw->bitbang);
335 for (i = 0; i < hw->gpio_cs_count; i++)
336 gpio_free(hw->gpio_cs[i]);
337 spi_master_put(master);
338 return 0;
339}
340
341#ifdef CONFIG_OF
342static const struct of_device_id tiny_spi_match[] = {
343 { .compatible = "opencores,tiny-spi-rtlsvn2", },
344 {},
345};
346MODULE_DEVICE_TABLE(of, tiny_spi_match);
347#endif
348
349static struct platform_driver tiny_spi_driver = {
350 .probe = tiny_spi_probe,
351 .remove = tiny_spi_remove,
352 .driver = {
353 .name = DRV_NAME,
354 .pm = NULL,
355 .of_match_table = of_match_ptr(tiny_spi_match),
356 },
357};
358module_platform_driver(tiny_spi_driver);
359
360MODULE_DESCRIPTION("OpenCores tiny SPI driver");
361MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
362MODULE_LICENSE("GPL");
363MODULE_ALIAS("platform:" DRV_NAME);
364
