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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Bitbanging I2C bus driver using the GPIO API
4 *
5 * Copyright (C) 2007 Atmel Corporation
6 */
7#include <linux/completion.h>
8#include <linux/debugfs.h>
9#include <linux/delay.h>
10#include <linux/gpio/consumer.h>
11#include <linux/i2c-algo-bit.h>
12#include <linux/i2c.h>
13#include <linux/init.h>
14#include <linux/interrupt.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_data/i2c-gpio.h>
18#include <linux/platform_device.h>
19#include <linux/slab.h>
20
21struct i2c_gpio_private_data {
22 struct gpio_desc *sda;
23 struct gpio_desc *scl;
24 struct i2c_adapter adap;
25 struct i2c_algo_bit_data bit_data;
26 struct i2c_gpio_platform_data pdata;
27#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
28 struct dentry *debug_dir;
29 /* these must be protected by bus lock */
30 struct completion scl_irq_completion;
31 u64 scl_irq_data;
32#endif
33};
34
35/*
36 * Toggle SDA by changing the output value of the pin. This is only
37 * valid for pins configured as open drain (i.e. setting the value
38 * high effectively turns off the output driver.)
39 */
40static void i2c_gpio_setsda_val(void *data, int state)
41{
42 struct i2c_gpio_private_data *priv = data;
43
44 gpiod_set_value_cansleep(priv->sda, state);
45}
46
47/*
48 * Toggle SCL by changing the output value of the pin. This is used
49 * for pins that are configured as open drain and for output-only
50 * pins. The latter case will break the i2c protocol, but it will
51 * often work in practice.
52 */
53static void i2c_gpio_setscl_val(void *data, int state)
54{
55 struct i2c_gpio_private_data *priv = data;
56
57 gpiod_set_value_cansleep(priv->scl, state);
58}
59
60static int i2c_gpio_getsda(void *data)
61{
62 struct i2c_gpio_private_data *priv = data;
63
64 return gpiod_get_value_cansleep(priv->sda);
65}
66
67static int i2c_gpio_getscl(void *data)
68{
69 struct i2c_gpio_private_data *priv = data;
70
71 return gpiod_get_value_cansleep(priv->scl);
72}
73
74#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
75static struct dentry *i2c_gpio_debug_dir;
76
77#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
78#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
79#define getsda(bd) ((bd)->getsda((bd)->data))
80#define getscl(bd) ((bd)->getscl((bd)->data))
81
82#define WIRE_ATTRIBUTE(wire) \
83static int fops_##wire##_get(void *data, u64 *val) \
84{ \
85 struct i2c_gpio_private_data *priv = data; \
86 \
87 i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
88 *val = get##wire(&priv->bit_data); \
89 i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
90 return 0; \
91} \
92static int fops_##wire##_set(void *data, u64 val) \
93{ \
94 struct i2c_gpio_private_data *priv = data; \
95 \
96 i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
97 set##wire(&priv->bit_data, val); \
98 i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
99 return 0; \
100} \
101DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
102
103WIRE_ATTRIBUTE(scl);
104WIRE_ATTRIBUTE(sda);
105
106static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
107 u32 pattern, u8 pattern_size)
108{
109 struct i2c_algo_bit_data *bit_data = &priv->bit_data;
110 int i;
111
112 i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
113
114 /* START condition */
115 setsda(bit_data, 0);
116 udelay(bit_data->udelay);
117
118 /* Send pattern, request ACK, don't send STOP */
119 for (i = pattern_size - 1; i >= 0; i--) {
120 setscl(bit_data, 0);
121 udelay(bit_data->udelay / 2);
122 setsda(bit_data, (pattern >> i) & 1);
123 udelay((bit_data->udelay + 1) / 2);
124 setscl(bit_data, 1);
125 udelay(bit_data->udelay);
126 }
127
128 i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
129}
130
131static int fops_incomplete_addr_phase_set(void *data, u64 addr)
132{
133 struct i2c_gpio_private_data *priv = data;
134 u32 pattern;
135
136 if (addr > 0x7f)
137 return -EINVAL;
138
139 /* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
140 pattern = (addr << 2) | 3;
141
142 i2c_gpio_incomplete_transfer(priv, pattern, 9);
143
144 return 0;
145}
146DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");
147
148static int fops_incomplete_write_byte_set(void *data, u64 addr)
149{
150 struct i2c_gpio_private_data *priv = data;
151 u32 pattern;
152
153 if (addr > 0x7f)
154 return -EINVAL;
155
156 /* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
157 pattern = (addr << 2) | 1;
158 /* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
159 pattern = (pattern << 9) | 1;
160
161 i2c_gpio_incomplete_transfer(priv, pattern, 18);
162
163 return 0;
164}
165DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
166
167static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
168 irqreturn_t handler(int, void*))
169{
170 int ret, irq = gpiod_to_irq(priv->scl);
171
172 if (irq < 0)
173 return irq;
174
175 i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
176
177 ret = gpiod_direction_input(priv->scl);
178 if (ret)
179 goto unlock;
180
181 reinit_completion(&priv->scl_irq_completion);
182
183 ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
184 "i2c_gpio_fault_injector_scl_irq", priv);
185 if (ret)
186 goto output;
187
188 wait_for_completion_interruptible(&priv->scl_irq_completion);
189
190 free_irq(irq, priv);
191 output:
192 ret = gpiod_direction_output(priv->scl, 1) ?: ret;
193 unlock:
194 i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
195
196 return ret;
197}
198
199static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
200{
201 struct i2c_gpio_private_data *priv = dev_id;
202
203 setsda(&priv->bit_data, 0);
204 udelay(priv->scl_irq_data);
205 setsda(&priv->bit_data, 1);
206
207 complete(&priv->scl_irq_completion);
208
209 return IRQ_HANDLED;
210}
211
212static int fops_lose_arbitration_set(void *data, u64 duration)
213{
214 struct i2c_gpio_private_data *priv = data;
215
216 if (duration > 100 * 1000)
217 return -EINVAL;
218
219 priv->scl_irq_data = duration;
220 /*
221 * Interrupt on falling SCL. This ensures that the master under test has
222 * really started the transfer. Interrupt on falling SDA did only
223 * exercise 'bus busy' detection on some HW but not 'arbitration lost'.
224 * Note that the interrupt latency may cause the first bits to be
225 * transmitted correctly.
226 */
227 return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
228}
229DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
230
231static irqreturn_t inject_panic_irq(int irq, void *dev_id)
232{
233 struct i2c_gpio_private_data *priv = dev_id;
234
235 udelay(priv->scl_irq_data);
236 panic("I2C fault injector induced panic");
237
238 return IRQ_HANDLED;
239}
240
241static int fops_inject_panic_set(void *data, u64 duration)
242{
243 struct i2c_gpio_private_data *priv = data;
244
245 if (duration > 100 * 1000)
246 return -EINVAL;
247
248 priv->scl_irq_data = duration;
249 /*
250 * Interrupt on falling SCL. This ensures that the master under test has
251 * really started the transfer.
252 */
253 return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
254}
255DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");
256
257static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
258{
259 struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
260
261 /*
262 * If there will be a debugfs-dir per i2c adapter somewhen, put the
263 * 'fault-injector' dir there. Until then, we have a global dir with
264 * all adapters as subdirs.
265 */
266 if (!i2c_gpio_debug_dir) {
267 i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
268 if (!i2c_gpio_debug_dir)
269 return;
270 }
271
272 priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
273 if (!priv->debug_dir)
274 return;
275
276 init_completion(&priv->scl_irq_completion);
277
278 debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
279 priv, &fops_incomplete_addr_phase);
280 debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
281 priv, &fops_incomplete_write_byte);
282 if (priv->bit_data.getscl) {
283 debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
284 priv, &fops_inject_panic);
285 debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
286 priv, &fops_lose_arbitration);
287 }
288 debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
289 debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
290}
291
292static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
293{
294 struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
295
296 debugfs_remove_recursive(priv->debug_dir);
297}
298#else
299static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
300static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
301#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
302
303static void of_i2c_gpio_get_props(struct device_node *np,
304 struct i2c_gpio_platform_data *pdata)
305{
306 u32 reg;
307
308 of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
309
310 if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®))
311 pdata->timeout = msecs_to_jiffies(reg);
312
313 pdata->sda_is_open_drain =
314 of_property_read_bool(np, "i2c-gpio,sda-open-drain");
315 pdata->scl_is_open_drain =
316 of_property_read_bool(np, "i2c-gpio,scl-open-drain");
317 pdata->scl_is_output_only =
318 of_property_read_bool(np, "i2c-gpio,scl-output-only");
319}
320
321static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
322 const char *con_id,
323 unsigned int index,
324 enum gpiod_flags gflags)
325{
326 struct gpio_desc *retdesc;
327 int ret;
328
329 retdesc = devm_gpiod_get(dev, con_id, gflags);
330 if (!IS_ERR(retdesc)) {
331 dev_dbg(dev, "got GPIO from name %s\n", con_id);
332 return retdesc;
333 }
334
335 retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
336 if (!IS_ERR(retdesc)) {
337 dev_dbg(dev, "got GPIO from index %u\n", index);
338 return retdesc;
339 }
340
341 ret = PTR_ERR(retdesc);
342
343 /* FIXME: hack in the old code, is this really necessary? */
344 if (ret == -EINVAL)
345 retdesc = ERR_PTR(-EPROBE_DEFER);
346
347 /* This happens if the GPIO driver is not yet probed, let's defer */
348 if (ret == -ENOENT)
349 retdesc = ERR_PTR(-EPROBE_DEFER);
350
351 if (PTR_ERR(retdesc) != -EPROBE_DEFER)
352 dev_err(dev, "error trying to get descriptor: %d\n", ret);
353
354 return retdesc;
355}
356
357static int i2c_gpio_probe(struct platform_device *pdev)
358{
359 struct i2c_gpio_private_data *priv;
360 struct i2c_gpio_platform_data *pdata;
361 struct i2c_algo_bit_data *bit_data;
362 struct i2c_adapter *adap;
363 struct device *dev = &pdev->dev;
364 struct device_node *np = dev->of_node;
365 enum gpiod_flags gflags;
366 int ret;
367
368 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
369 if (!priv)
370 return -ENOMEM;
371
372 adap = &priv->adap;
373 bit_data = &priv->bit_data;
374 pdata = &priv->pdata;
375
376 if (np) {
377 of_i2c_gpio_get_props(np, pdata);
378 } else {
379 /*
380 * If all platform data settings are zero it is OK
381 * to not provide any platform data from the board.
382 */
383 if (dev_get_platdata(dev))
384 memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
385 }
386
387 /*
388 * First get the GPIO pins; if it fails, we'll defer the probe.
389 * If the SCL/SDA lines are marked "open drain" by platform data or
390 * device tree then this means that something outside of our control is
391 * marking these lines to be handled as open drain, and we should just
392 * handle them as we handle any other output. Else we enforce open
393 * drain as this is required for an I2C bus.
394 */
395 if (pdata->sda_is_open_drain)
396 gflags = GPIOD_OUT_HIGH;
397 else
398 gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
399 priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
400 if (IS_ERR(priv->sda))
401 return PTR_ERR(priv->sda);
402
403 if (pdata->scl_is_open_drain)
404 gflags = GPIOD_OUT_HIGH;
405 else
406 gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
407 priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
408 if (IS_ERR(priv->scl))
409 return PTR_ERR(priv->scl);
410
411 if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
412 dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
413 else
414 bit_data->can_do_atomic = true;
415
416 bit_data->setsda = i2c_gpio_setsda_val;
417 bit_data->setscl = i2c_gpio_setscl_val;
418
419 if (!pdata->scl_is_output_only)
420 bit_data->getscl = i2c_gpio_getscl;
421 bit_data->getsda = i2c_gpio_getsda;
422
423 if (pdata->udelay)
424 bit_data->udelay = pdata->udelay;
425 else if (pdata->scl_is_output_only)
426 bit_data->udelay = 50; /* 10 kHz */
427 else
428 bit_data->udelay = 5; /* 100 kHz */
429
430 if (pdata->timeout)
431 bit_data->timeout = pdata->timeout;
432 else
433 bit_data->timeout = HZ / 10; /* 100 ms */
434
435 bit_data->data = priv;
436
437 adap->owner = THIS_MODULE;
438 if (np)
439 strscpy(adap->name, dev_name(dev), sizeof(adap->name));
440 else
441 snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
442
443 adap->algo_data = bit_data;
444 adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
445 adap->dev.parent = dev;
446 adap->dev.of_node = np;
447
448 adap->nr = pdev->id;
449 ret = i2c_bit_add_numbered_bus(adap);
450 if (ret)
451 return ret;
452
453 platform_set_drvdata(pdev, priv);
454
455 /*
456 * FIXME: using global GPIO numbers is not helpful. If/when we
457 * get accessors to get the actual name of the GPIO line,
458 * from the descriptor, then provide that instead.
459 */
460 dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
461 desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
462 pdata->scl_is_output_only
463 ? ", no clock stretching" : "");
464
465 i2c_gpio_fault_injector_init(pdev);
466
467 return 0;
468}
469
470static int i2c_gpio_remove(struct platform_device *pdev)
471{
472 struct i2c_gpio_private_data *priv;
473 struct i2c_adapter *adap;
474
475 i2c_gpio_fault_injector_exit(pdev);
476
477 priv = platform_get_drvdata(pdev);
478 adap = &priv->adap;
479
480 i2c_del_adapter(adap);
481
482 return 0;
483}
484
485static const struct of_device_id i2c_gpio_dt_ids[] = {
486 { .compatible = "i2c-gpio", },
487 { /* sentinel */ }
488};
489
490MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
491
492static struct platform_driver i2c_gpio_driver = {
493 .driver = {
494 .name = "i2c-gpio",
495 .of_match_table = i2c_gpio_dt_ids,
496 },
497 .probe = i2c_gpio_probe,
498 .remove = i2c_gpio_remove,
499};
500
501static int __init i2c_gpio_init(void)
502{
503 int ret;
504
505 ret = platform_driver_register(&i2c_gpio_driver);
506 if (ret)
507 printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
508
509 return ret;
510}
511subsys_initcall(i2c_gpio_init);
512
513static void __exit i2c_gpio_exit(void)
514{
515 platform_driver_unregister(&i2c_gpio_driver);
516}
517module_exit(i2c_gpio_exit);
518
519MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
520MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
521MODULE_LICENSE("GPL v2");
522MODULE_ALIAS("platform:i2c-gpio");
1/*
2 * Bitbanging I2C bus driver using the GPIO API
3 *
4 * Copyright (C) 2007 Atmel Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#include <linux/debugfs.h>
11#include <linux/delay.h>
12#include <linux/i2c.h>
13#include <linux/i2c-algo-bit.h>
14#include <linux/i2c-gpio.h>
15#include <linux/init.h>
16#include <linux/module.h>
17#include <linux/slab.h>
18#include <linux/platform_device.h>
19#include <linux/gpio/consumer.h>
20#include <linux/of.h>
21
22struct i2c_gpio_private_data {
23 struct gpio_desc *sda;
24 struct gpio_desc *scl;
25 struct i2c_adapter adap;
26 struct i2c_algo_bit_data bit_data;
27 struct i2c_gpio_platform_data pdata;
28#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
29 struct dentry *debug_dir;
30#endif
31};
32
33/*
34 * Toggle SDA by changing the output value of the pin. This is only
35 * valid for pins configured as open drain (i.e. setting the value
36 * high effectively turns off the output driver.)
37 */
38static void i2c_gpio_setsda_val(void *data, int state)
39{
40 struct i2c_gpio_private_data *priv = data;
41
42 gpiod_set_value_cansleep(priv->sda, state);
43}
44
45/*
46 * Toggle SCL by changing the output value of the pin. This is used
47 * for pins that are configured as open drain and for output-only
48 * pins. The latter case will break the i2c protocol, but it will
49 * often work in practice.
50 */
51static void i2c_gpio_setscl_val(void *data, int state)
52{
53 struct i2c_gpio_private_data *priv = data;
54
55 gpiod_set_value_cansleep(priv->scl, state);
56}
57
58static int i2c_gpio_getsda(void *data)
59{
60 struct i2c_gpio_private_data *priv = data;
61
62 return gpiod_get_value_cansleep(priv->sda);
63}
64
65static int i2c_gpio_getscl(void *data)
66{
67 struct i2c_gpio_private_data *priv = data;
68
69 return gpiod_get_value_cansleep(priv->scl);
70}
71
72#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
73static struct dentry *i2c_gpio_debug_dir;
74
75#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
76#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
77#define getsda(bd) ((bd)->getsda((bd)->data))
78#define getscl(bd) ((bd)->getscl((bd)->data))
79
80#define WIRE_ATTRIBUTE(wire) \
81static int fops_##wire##_get(void *data, u64 *val) \
82{ \
83 struct i2c_gpio_private_data *priv = data; \
84 \
85 i2c_lock_adapter(&priv->adap); \
86 *val = get##wire(&priv->bit_data); \
87 i2c_unlock_adapter(&priv->adap); \
88 return 0; \
89} \
90static int fops_##wire##_set(void *data, u64 val) \
91{ \
92 struct i2c_gpio_private_data *priv = data; \
93 \
94 i2c_lock_adapter(&priv->adap); \
95 set##wire(&priv->bit_data, val); \
96 i2c_unlock_adapter(&priv->adap); \
97 return 0; \
98} \
99DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
100
101WIRE_ATTRIBUTE(scl);
102WIRE_ATTRIBUTE(sda);
103
104static int fops_incomplete_transfer_set(void *data, u64 addr)
105{
106 struct i2c_gpio_private_data *priv = data;
107 struct i2c_algo_bit_data *bit_data = &priv->bit_data;
108 int i, pattern;
109
110 if (addr > 0x7f)
111 return -EINVAL;
112
113 /* ADDR (7 bit) + RD (1 bit) + SDA hi (1 bit) */
114 pattern = (addr << 2) | 3;
115
116 i2c_lock_adapter(&priv->adap);
117
118 /* START condition */
119 setsda(bit_data, 0);
120 udelay(bit_data->udelay);
121
122 /* Send ADDR+RD, request ACK, don't send STOP */
123 for (i = 8; i >= 0; i--) {
124 setscl(bit_data, 0);
125 udelay(bit_data->udelay / 2);
126 setsda(bit_data, (pattern >> i) & 1);
127 udelay((bit_data->udelay + 1) / 2);
128 setscl(bit_data, 1);
129 udelay(bit_data->udelay);
130 }
131
132 i2c_unlock_adapter(&priv->adap);
133
134 return 0;
135}
136DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_transfer, NULL, fops_incomplete_transfer_set, "%llu\n");
137
138static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
139{
140 struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
141
142 /*
143 * If there will be a debugfs-dir per i2c adapter somewhen, put the
144 * 'fault-injector' dir there. Until then, we have a global dir with
145 * all adapters as subdirs.
146 */
147 if (!i2c_gpio_debug_dir) {
148 i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
149 if (!i2c_gpio_debug_dir)
150 return;
151 }
152
153 priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
154 if (!priv->debug_dir)
155 return;
156
157 debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
158 debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
159 debugfs_create_file_unsafe("incomplete_transfer", 0200, priv->debug_dir,
160 priv, &fops_incomplete_transfer);
161}
162
163static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
164{
165 struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
166
167 debugfs_remove_recursive(priv->debug_dir);
168}
169#else
170static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
171static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
172#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
173
174static void of_i2c_gpio_get_props(struct device_node *np,
175 struct i2c_gpio_platform_data *pdata)
176{
177 u32 reg;
178
179 of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
180
181 if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®))
182 pdata->timeout = msecs_to_jiffies(reg);
183
184 pdata->sda_is_open_drain =
185 of_property_read_bool(np, "i2c-gpio,sda-open-drain");
186 pdata->scl_is_open_drain =
187 of_property_read_bool(np, "i2c-gpio,scl-open-drain");
188 pdata->scl_is_output_only =
189 of_property_read_bool(np, "i2c-gpio,scl-output-only");
190}
191
192static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
193 const char *con_id,
194 unsigned int index,
195 enum gpiod_flags gflags)
196{
197 struct gpio_desc *retdesc;
198 int ret;
199
200 retdesc = devm_gpiod_get(dev, con_id, gflags);
201 if (!IS_ERR(retdesc)) {
202 dev_dbg(dev, "got GPIO from name %s\n", con_id);
203 return retdesc;
204 }
205
206 retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
207 if (!IS_ERR(retdesc)) {
208 dev_dbg(dev, "got GPIO from index %u\n", index);
209 return retdesc;
210 }
211
212 ret = PTR_ERR(retdesc);
213
214 /* FIXME: hack in the old code, is this really necessary? */
215 if (ret == -EINVAL)
216 retdesc = ERR_PTR(-EPROBE_DEFER);
217
218 /* This happens if the GPIO driver is not yet probed, let's defer */
219 if (ret == -ENOENT)
220 retdesc = ERR_PTR(-EPROBE_DEFER);
221
222 if (ret != -EPROBE_DEFER)
223 dev_err(dev, "error trying to get descriptor: %d\n", ret);
224
225 return retdesc;
226}
227
228static int i2c_gpio_probe(struct platform_device *pdev)
229{
230 struct i2c_gpio_private_data *priv;
231 struct i2c_gpio_platform_data *pdata;
232 struct i2c_algo_bit_data *bit_data;
233 struct i2c_adapter *adap;
234 struct device *dev = &pdev->dev;
235 struct device_node *np = dev->of_node;
236 enum gpiod_flags gflags;
237 int ret;
238
239 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
240 if (!priv)
241 return -ENOMEM;
242
243 adap = &priv->adap;
244 bit_data = &priv->bit_data;
245 pdata = &priv->pdata;
246
247 if (np) {
248 of_i2c_gpio_get_props(np, pdata);
249 } else {
250 /*
251 * If all platform data settings are zero it is OK
252 * to not provide any platform data from the board.
253 */
254 if (dev_get_platdata(dev))
255 memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
256 }
257
258 /*
259 * First get the GPIO pins; if it fails, we'll defer the probe.
260 * If the SDA line is marked from platform data or device tree as
261 * "open drain" it means something outside of our control is making
262 * this line being handled as open drain, and we should just handle
263 * it as any other output. Else we enforce open drain as this is
264 * required for an I2C bus.
265 */
266 if (pdata->sda_is_open_drain)
267 gflags = GPIOD_OUT_HIGH;
268 else
269 gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
270 priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
271 if (IS_ERR(priv->sda))
272 return PTR_ERR(priv->sda);
273
274 /*
275 * If the SCL line is marked from platform data or device tree as
276 * "open drain" it means something outside of our control is making
277 * this line being handled as open drain, and we should just handle
278 * it as any other output. Else we enforce open drain as this is
279 * required for an I2C bus.
280 */
281 if (pdata->scl_is_open_drain)
282 gflags = GPIOD_OUT_LOW;
283 else
284 gflags = GPIOD_OUT_LOW_OPEN_DRAIN;
285 priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
286 if (IS_ERR(priv->scl))
287 return PTR_ERR(priv->scl);
288
289 if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
290 dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
291
292 bit_data->setsda = i2c_gpio_setsda_val;
293 bit_data->setscl = i2c_gpio_setscl_val;
294
295 if (!pdata->scl_is_output_only)
296 bit_data->getscl = i2c_gpio_getscl;
297 bit_data->getsda = i2c_gpio_getsda;
298
299 if (pdata->udelay)
300 bit_data->udelay = pdata->udelay;
301 else if (pdata->scl_is_output_only)
302 bit_data->udelay = 50; /* 10 kHz */
303 else
304 bit_data->udelay = 5; /* 100 kHz */
305
306 if (pdata->timeout)
307 bit_data->timeout = pdata->timeout;
308 else
309 bit_data->timeout = HZ / 10; /* 100 ms */
310
311 bit_data->data = priv;
312
313 adap->owner = THIS_MODULE;
314 if (np)
315 strlcpy(adap->name, dev_name(dev), sizeof(adap->name));
316 else
317 snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
318
319 adap->algo_data = bit_data;
320 adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
321 adap->dev.parent = dev;
322 adap->dev.of_node = np;
323
324 adap->nr = pdev->id;
325 ret = i2c_bit_add_numbered_bus(adap);
326 if (ret)
327 return ret;
328
329 platform_set_drvdata(pdev, priv);
330
331 /*
332 * FIXME: using global GPIO numbers is not helpful. If/when we
333 * get accessors to get the actual name of the GPIO line,
334 * from the descriptor, then provide that instead.
335 */
336 dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
337 desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
338 pdata->scl_is_output_only
339 ? ", no clock stretching" : "");
340
341 i2c_gpio_fault_injector_init(pdev);
342
343 return 0;
344}
345
346static int i2c_gpio_remove(struct platform_device *pdev)
347{
348 struct i2c_gpio_private_data *priv;
349 struct i2c_adapter *adap;
350
351 i2c_gpio_fault_injector_exit(pdev);
352
353 priv = platform_get_drvdata(pdev);
354 adap = &priv->adap;
355
356 i2c_del_adapter(adap);
357
358 return 0;
359}
360
361#if defined(CONFIG_OF)
362static const struct of_device_id i2c_gpio_dt_ids[] = {
363 { .compatible = "i2c-gpio", },
364 { /* sentinel */ }
365};
366
367MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
368#endif
369
370static struct platform_driver i2c_gpio_driver = {
371 .driver = {
372 .name = "i2c-gpio",
373 .of_match_table = of_match_ptr(i2c_gpio_dt_ids),
374 },
375 .probe = i2c_gpio_probe,
376 .remove = i2c_gpio_remove,
377};
378
379static int __init i2c_gpio_init(void)
380{
381 int ret;
382
383 ret = platform_driver_register(&i2c_gpio_driver);
384 if (ret)
385 printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
386
387 return ret;
388}
389subsys_initcall(i2c_gpio_init);
390
391static void __exit i2c_gpio_exit(void)
392{
393 platform_driver_unregister(&i2c_gpio_driver);
394}
395module_exit(i2c_gpio_exit);
396
397MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
398MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
399MODULE_LICENSE("GPL");
400MODULE_ALIAS("platform:i2c-gpio");