1 /*
2 * mcp23s08.c - SPI gpio expander driver
3 */
4
5 #include <linux/kernel.h>
6 #include <linux/device.h>
7 #include <linux/workqueue.h>
8 #include <linux/mutex.h>
9
10 #include <linux/spi/spi.h>
11 #include <linux/spi/mcp23s08.h>
12
13 #include <asm/gpio.h>
14
15
16 /* Registers are all 8 bits wide.
17 *
18 * The mcp23s17 has twice as many bits, and can be configured to work
19 * with either 16 bit registers or with two adjacent 8 bit banks.
20 *
21 * Also, there are I2C versions of both chips.
22 */
23 #define MCP_IODIR 0x00 /* init/reset: all ones */
24 #define MCP_IPOL 0x01
25 #define MCP_GPINTEN 0x02
26 #define MCP_DEFVAL 0x03
27 #define MCP_INTCON 0x04
28 #define MCP_IOCON 0x05
29 # define IOCON_SEQOP (1 << 5)
30 # define IOCON_HAEN (1 << 3)
31 # define IOCON_ODR (1 << 2)
32 # define IOCON_INTPOL (1 << 1)
33 #define MCP_GPPU 0x06
34 #define MCP_INTF 0x07
35 #define MCP_INTCAP 0x08
36 #define MCP_GPIO 0x09
37 #define MCP_OLAT 0x0a
38
39 struct mcp23s08 {
40 struct spi_device *spi;
41 u8 addr;
42
43 u8 cache[11];
44 /* lock protects the cached values */
45 struct mutex lock;
46
47 struct gpio_chip chip;
48
49 struct work_struct work;
50 };
51
52 /* A given spi_device can represent up to four mcp23s08 chips
53 * sharing the same chipselect but using different addresses
54 * (e.g. chips #0 and #3 might be populated, but not #1 or $2).
55 * Driver data holds all the per-chip data.
56 */
57 struct mcp23s08_driver_data {
58 unsigned ngpio;
59 struct mcp23s08 *mcp[4];
60 struct mcp23s08 chip[];
61 };
62
mcp23s08_read(struct mcp23s08 * mcp,unsigned reg)63 static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
64 {
65 u8 tx[2], rx[1];
66 int status;
67
68 tx[0] = mcp->addr | 0x01;
69 tx[1] = reg;
70 status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
71 return (status < 0) ? status : rx[0];
72 }
73
mcp23s08_write(struct mcp23s08 * mcp,unsigned reg,u8 val)74 static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
75 {
76 u8 tx[3];
77
78 tx[0] = mcp->addr;
79 tx[1] = reg;
80 tx[2] = val;
81 return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
82 }
83
84 static int
mcp23s08_read_regs(struct mcp23s08 * mcp,unsigned reg,u8 * vals,unsigned n)85 mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
86 {
87 u8 tx[2];
88
89 if ((n + reg) > sizeof mcp->cache)
90 return -EINVAL;
91 tx[0] = mcp->addr | 0x01;
92 tx[1] = reg;
93 return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
94 }
95
96 /*----------------------------------------------------------------------*/
97
mcp23s08_direction_input(struct gpio_chip * chip,unsigned offset)98 static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
99 {
100 struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
101 int status;
102
103 mutex_lock(&mcp->lock);
104 mcp->cache[MCP_IODIR] |= (1 << offset);
105 status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
106 mutex_unlock(&mcp->lock);
107 return status;
108 }
109
mcp23s08_get(struct gpio_chip * chip,unsigned offset)110 static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
111 {
112 struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
113 int status;
114
115 mutex_lock(&mcp->lock);
116
117 /* REVISIT reading this clears any IRQ ... */
118 status = mcp23s08_read(mcp, MCP_GPIO);
119 if (status < 0)
120 status = 0;
121 else {
122 mcp->cache[MCP_GPIO] = status;
123 status = !!(status & (1 << offset));
124 }
125 mutex_unlock(&mcp->lock);
126 return status;
127 }
128
__mcp23s08_set(struct mcp23s08 * mcp,unsigned mask,int value)129 static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
130 {
131 u8 olat = mcp->cache[MCP_OLAT];
132
133 if (value)
134 olat |= mask;
135 else
136 olat &= ~mask;
137 mcp->cache[MCP_OLAT] = olat;
138 return mcp23s08_write(mcp, MCP_OLAT, olat);
139 }
140
mcp23s08_set(struct gpio_chip * chip,unsigned offset,int value)141 static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
142 {
143 struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
144 u8 mask = 1 << offset;
145
146 mutex_lock(&mcp->lock);
147 __mcp23s08_set(mcp, mask, value);
148 mutex_unlock(&mcp->lock);
149 }
150
151 static int
mcp23s08_direction_output(struct gpio_chip * chip,unsigned offset,int value)152 mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
153 {
154 struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
155 u8 mask = 1 << offset;
156 int status;
157
158 mutex_lock(&mcp->lock);
159 status = __mcp23s08_set(mcp, mask, value);
160 if (status == 0) {
161 mcp->cache[MCP_IODIR] &= ~mask;
162 status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
163 }
164 mutex_unlock(&mcp->lock);
165 return status;
166 }
167
168 /*----------------------------------------------------------------------*/
169
170 #ifdef CONFIG_DEBUG_FS
171
172 #include <linux/seq_file.h>
173
174 /*
175 * This shows more info than the generic gpio dump code:
176 * pullups, deglitching, open drain drive.
177 */
mcp23s08_dbg_show(struct seq_file * s,struct gpio_chip * chip)178 static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
179 {
180 struct mcp23s08 *mcp;
181 char bank;
182 int t;
183 unsigned mask;
184
185 mcp = container_of(chip, struct mcp23s08, chip);
186
187 /* NOTE: we only handle one bank for now ... */
188 bank = '0' + ((mcp->addr >> 1) & 0x3);
189
190 mutex_lock(&mcp->lock);
191 t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
192 if (t < 0) {
193 seq_printf(s, " I/O ERROR %d\n", t);
194 goto done;
195 }
196
197 for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
198 const char *label;
199
200 label = gpiochip_is_requested(chip, t);
201 if (!label)
202 continue;
203
204 seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
205 chip->base + t, bank, t, label,
206 (mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
207 (mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
208 (mcp->cache[MCP_GPPU] & mask) ? " " : "up");
209 /* NOTE: ignoring the irq-related registers */
210 seq_printf(s, "\n");
211 }
212 done:
213 mutex_unlock(&mcp->lock);
214 }
215
216 #else
217 #define mcp23s08_dbg_show NULL
218 #endif
219
220 /*----------------------------------------------------------------------*/
221
mcp23s08_probe_one(struct spi_device * spi,unsigned addr,unsigned base,unsigned pullups)222 static int mcp23s08_probe_one(struct spi_device *spi, unsigned addr,
223 unsigned base, unsigned pullups)
224 {
225 struct mcp23s08_driver_data *data = spi_get_drvdata(spi);
226 struct mcp23s08 *mcp = data->mcp[addr];
227 int status;
228 int do_update = 0;
229
230 mutex_init(&mcp->lock);
231
232 mcp->spi = spi;
233 mcp->addr = 0x40 | (addr << 1);
234
235 mcp->chip.label = "mcp23s08",
236
237 mcp->chip.direction_input = mcp23s08_direction_input;
238 mcp->chip.get = mcp23s08_get;
239 mcp->chip.direction_output = mcp23s08_direction_output;
240 mcp->chip.set = mcp23s08_set;
241 mcp->chip.dbg_show = mcp23s08_dbg_show;
242
243 mcp->chip.base = base;
244 mcp->chip.ngpio = 8;
245 mcp->chip.can_sleep = 1;
246 mcp->chip.dev = &spi->dev;
247 mcp->chip.owner = THIS_MODULE;
248
249 /* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
250 * and MCP_IOCON.HAEN = 1, so we work with all chips.
251 */
252 status = mcp23s08_read(mcp, MCP_IOCON);
253 if (status < 0)
254 goto fail;
255 if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN)) {
256 status &= ~IOCON_SEQOP;
257 status |= IOCON_HAEN;
258 status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
259 if (status < 0)
260 goto fail;
261 }
262
263 /* configure ~100K pullups */
264 status = mcp23s08_write(mcp, MCP_GPPU, pullups);
265 if (status < 0)
266 goto fail;
267
268 status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
269 if (status < 0)
270 goto fail;
271
272 /* disable inverter on input */
273 if (mcp->cache[MCP_IPOL] != 0) {
274 mcp->cache[MCP_IPOL] = 0;
275 do_update = 1;
276 }
277
278 /* disable irqs */
279 if (mcp->cache[MCP_GPINTEN] != 0) {
280 mcp->cache[MCP_GPINTEN] = 0;
281 do_update = 1;
282 }
283
284 if (do_update) {
285 u8 tx[4];
286
287 tx[0] = mcp->addr;
288 tx[1] = MCP_IPOL;
289 memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
290 status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
291 if (status < 0)
292 goto fail;
293 }
294
295 status = gpiochip_add(&mcp->chip);
296 fail:
297 if (status < 0)
298 dev_dbg(&spi->dev, "can't setup chip %d, --> %d\n",
299 addr, status);
300 return status;
301 }
302
mcp23s08_probe(struct spi_device * spi)303 static int mcp23s08_probe(struct spi_device *spi)
304 {
305 struct mcp23s08_platform_data *pdata;
306 unsigned addr;
307 unsigned chips = 0;
308 struct mcp23s08_driver_data *data;
309 int status;
310 unsigned base;
311
312 pdata = spi->dev.platform_data;
313 if (!pdata || !gpio_is_valid(pdata->base)) {
314 dev_dbg(&spi->dev, "invalid or missing platform data\n");
315 return -EINVAL;
316 }
317
318 for (addr = 0; addr < 4; addr++) {
319 if (!pdata->chip[addr].is_present)
320 continue;
321 chips++;
322 }
323 if (!chips)
324 return -ENODEV;
325
326 data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
327 GFP_KERNEL);
328 if (!data)
329 return -ENOMEM;
330 spi_set_drvdata(spi, data);
331
332 base = pdata->base;
333 for (addr = 0; addr < 4; addr++) {
334 if (!pdata->chip[addr].is_present)
335 continue;
336 chips--;
337 data->mcp[addr] = &data->chip[chips];
338 status = mcp23s08_probe_one(spi, addr, base,
339 pdata->chip[addr].pullups);
340 if (status < 0)
341 goto fail;
342 base += 8;
343 }
344 data->ngpio = base - pdata->base;
345
346 /* NOTE: these chips have a relatively sane IRQ framework, with
347 * per-signal masking and level/edge triggering. It's not yet
348 * handled here...
349 */
350
351 if (pdata->setup) {
352 status = pdata->setup(spi,
353 pdata->base, data->ngpio,
354 pdata->context);
355 if (status < 0)
356 dev_dbg(&spi->dev, "setup --> %d\n", status);
357 }
358
359 return 0;
360
361 fail:
362 for (addr = 0; addr < 4; addr++) {
363 int tmp;
364
365 if (!data->mcp[addr])
366 continue;
367 tmp = gpiochip_remove(&data->mcp[addr]->chip);
368 if (tmp < 0)
369 dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
370 }
371 kfree(data);
372 return status;
373 }
374
mcp23s08_remove(struct spi_device * spi)375 static int mcp23s08_remove(struct spi_device *spi)
376 {
377 struct mcp23s08_driver_data *data = spi_get_drvdata(spi);
378 struct mcp23s08_platform_data *pdata = spi->dev.platform_data;
379 unsigned addr;
380 int status = 0;
381
382 if (pdata->teardown) {
383 status = pdata->teardown(spi,
384 pdata->base, data->ngpio,
385 pdata->context);
386 if (status < 0) {
387 dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
388 return status;
389 }
390 }
391
392 for (addr = 0; addr < 4; addr++) {
393 int tmp;
394
395 if (!data->mcp[addr])
396 continue;
397
398 tmp = gpiochip_remove(&data->mcp[addr]->chip);
399 if (tmp < 0) {
400 dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
401 status = tmp;
402 }
403 }
404 if (status == 0)
405 kfree(data);
406 return status;
407 }
408
409 static struct spi_driver mcp23s08_driver = {
410 .probe = mcp23s08_probe,
411 .remove = mcp23s08_remove,
412 .driver = {
413 .name = "mcp23s08",
414 .owner = THIS_MODULE,
415 },
416 };
417
418 /*----------------------------------------------------------------------*/
419
mcp23s08_init(void)420 static int __init mcp23s08_init(void)
421 {
422 return spi_register_driver(&mcp23s08_driver);
423 }
424 /* register after spi postcore initcall and before
425 * subsys initcalls that may rely on these GPIOs
426 */
427 subsys_initcall(mcp23s08_init);
428
mcp23s08_exit(void)429 static void __exit mcp23s08_exit(void)
430 {
431 spi_unregister_driver(&mcp23s08_driver);
432 }
433 module_exit(mcp23s08_exit);
434
435 MODULE_LICENSE("GPL");
436