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Linux/drivers/gpio/gpio-pcf857x.c

  1 /*
  2  * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
  3  *
  4  * Copyright (C) 2007 David Brownell
  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 as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program; if not, write to the Free Software
 18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 19  */
 20 
 21 #include <linux/gpio.h>
 22 #include <linux/i2c.h>
 23 #include <linux/i2c/pcf857x.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/irq.h>
 26 #include <linux/irqdomain.h>
 27 #include <linux/kernel.h>
 28 #include <linux/module.h>
 29 #include <linux/of.h>
 30 #include <linux/of_device.h>
 31 #include <linux/slab.h>
 32 #include <linux/spinlock.h>
 33 
 34 
 35 static const struct i2c_device_id pcf857x_id[] = {
 36         { "pcf8574", 8 },
 37         { "pcf8574a", 8 },
 38         { "pca8574", 8 },
 39         { "pca9670", 8 },
 40         { "pca9672", 8 },
 41         { "pca9674", 8 },
 42         { "pcf8575", 16 },
 43         { "pca8575", 16 },
 44         { "pca9671", 16 },
 45         { "pca9673", 16 },
 46         { "pca9675", 16 },
 47         { "max7328", 8 },
 48         { "max7329", 8 },
 49         { "tca9554", 8 },
 50         { }
 51 };
 52 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
 53 
 54 #ifdef CONFIG_OF
 55 static const struct of_device_id pcf857x_of_table[] = {
 56         { .compatible = "nxp,pcf8574" },
 57         { .compatible = "nxp,pcf8574a" },
 58         { .compatible = "nxp,pca8574" },
 59         { .compatible = "nxp,pca9670" },
 60         { .compatible = "nxp,pca9672" },
 61         { .compatible = "nxp,pca9674" },
 62         { .compatible = "nxp,pcf8575" },
 63         { .compatible = "nxp,pca8575" },
 64         { .compatible = "nxp,pca9671" },
 65         { .compatible = "nxp,pca9673" },
 66         { .compatible = "nxp,pca9675" },
 67         { .compatible = "maxim,max7328" },
 68         { .compatible = "maxim,max7329" },
 69         { .compatible = "ti,tca9554" },
 70         { }
 71 };
 72 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
 73 #endif
 74 
 75 /*
 76  * The pcf857x, pca857x, and pca967x chips only expose one read and one
 77  * write register.  Writing a "one" bit (to match the reset state) lets
 78  * that pin be used as an input; it's not an open-drain model, but acts
 79  * a bit like one.  This is described as "quasi-bidirectional"; read the
 80  * chip documentation for details.
 81  *
 82  * Many other I2C GPIO expander chips (like the pca953x models) have
 83  * more complex register models and more conventional circuitry using
 84  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
 85  * pcf857x parts, making the "legacy" I2C driver model problematic.
 86  */
 87 struct pcf857x {
 88         struct gpio_chip        chip;
 89         struct i2c_client       *client;
 90         struct mutex            lock;           /* protect 'out' */
 91         unsigned                out;            /* software latch */
 92         unsigned                status;         /* current status */
 93         unsigned int            irq_parent;
 94         unsigned                irq_enabled;    /* enabled irqs */
 95 
 96         int (*write)(struct i2c_client *client, unsigned data);
 97         int (*read)(struct i2c_client *client);
 98 };
 99 
100 /*-------------------------------------------------------------------------*/
101 
102 /* Talk to 8-bit I/O expander */
103 
104 static int i2c_write_le8(struct i2c_client *client, unsigned data)
105 {
106         return i2c_smbus_write_byte(client, data);
107 }
108 
109 static int i2c_read_le8(struct i2c_client *client)
110 {
111         return (int)i2c_smbus_read_byte(client);
112 }
113 
114 /* Talk to 16-bit I/O expander */
115 
116 static int i2c_write_le16(struct i2c_client *client, unsigned word)
117 {
118         u8 buf[2] = { word & 0xff, word >> 8, };
119         int status;
120 
121         status = i2c_master_send(client, buf, 2);
122         return (status < 0) ? status : 0;
123 }
124 
125 static int i2c_read_le16(struct i2c_client *client)
126 {
127         u8 buf[2];
128         int status;
129 
130         status = i2c_master_recv(client, buf, 2);
131         if (status < 0)
132                 return status;
133         return (buf[1] << 8) | buf[0];
134 }
135 
136 /*-------------------------------------------------------------------------*/
137 
138 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
139 {
140         struct pcf857x  *gpio = gpiochip_get_data(chip);
141         int             status;
142 
143         mutex_lock(&gpio->lock);
144         gpio->out |= (1 << offset);
145         status = gpio->write(gpio->client, gpio->out);
146         mutex_unlock(&gpio->lock);
147 
148         return status;
149 }
150 
151 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
152 {
153         struct pcf857x  *gpio = gpiochip_get_data(chip);
154         int             value;
155 
156         value = gpio->read(gpio->client);
157         return (value < 0) ? value : !!(value & (1 << offset));
158 }
159 
160 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
161 {
162         struct pcf857x  *gpio = gpiochip_get_data(chip);
163         unsigned        bit = 1 << offset;
164         int             status;
165 
166         mutex_lock(&gpio->lock);
167         if (value)
168                 gpio->out |= bit;
169         else
170                 gpio->out &= ~bit;
171         status = gpio->write(gpio->client, gpio->out);
172         mutex_unlock(&gpio->lock);
173 
174         return status;
175 }
176 
177 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
178 {
179         pcf857x_output(chip, offset, value);
180 }
181 
182 /*-------------------------------------------------------------------------*/
183 
184 static irqreturn_t pcf857x_irq(int irq, void *data)
185 {
186         struct pcf857x  *gpio = data;
187         unsigned long change, i, status;
188 
189         status = gpio->read(gpio->client);
190 
191         /*
192          * call the interrupt handler iff gpio is used as
193          * interrupt source, just to avoid bad irqs
194          */
195         mutex_lock(&gpio->lock);
196         change = (gpio->status ^ status) & gpio->irq_enabled;
197         gpio->status = status;
198         mutex_unlock(&gpio->lock);
199 
200         for_each_set_bit(i, &change, gpio->chip.ngpio)
201                 handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
202 
203         return IRQ_HANDLED;
204 }
205 
206 /*
207  * NOP functions
208  */
209 static void noop(struct irq_data *data) { }
210 
211 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
212 {
213         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
214 
215         int error = 0;
216 
217         if (gpio->irq_parent) {
218                 error = irq_set_irq_wake(gpio->irq_parent, on);
219                 if (error) {
220                         dev_dbg(&gpio->client->dev,
221                                 "irq %u doesn't support irq_set_wake\n",
222                                 gpio->irq_parent);
223                         gpio->irq_parent = 0;
224                 }
225         }
226         return error;
227 }
228 
229 static void pcf857x_irq_enable(struct irq_data *data)
230 {
231         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
232 
233         gpio->irq_enabled |= (1 << data->hwirq);
234 }
235 
236 static void pcf857x_irq_disable(struct irq_data *data)
237 {
238         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
239 
240         gpio->irq_enabled &= ~(1 << data->hwirq);
241 }
242 
243 static void pcf857x_irq_bus_lock(struct irq_data *data)
244 {
245         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
246 
247         mutex_lock(&gpio->lock);
248 }
249 
250 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
251 {
252         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
253 
254         mutex_unlock(&gpio->lock);
255 }
256 
257 static struct irq_chip pcf857x_irq_chip = {
258         .name           = "pcf857x",
259         .irq_enable     = pcf857x_irq_enable,
260         .irq_disable    = pcf857x_irq_disable,
261         .irq_ack        = noop,
262         .irq_mask       = noop,
263         .irq_unmask     = noop,
264         .irq_set_wake   = pcf857x_irq_set_wake,
265         .irq_bus_lock           = pcf857x_irq_bus_lock,
266         .irq_bus_sync_unlock    = pcf857x_irq_bus_sync_unlock,
267 };
268 
269 /*-------------------------------------------------------------------------*/
270 
271 static int pcf857x_probe(struct i2c_client *client,
272                          const struct i2c_device_id *id)
273 {
274         struct pcf857x_platform_data    *pdata = dev_get_platdata(&client->dev);
275         struct device_node              *np = client->dev.of_node;
276         struct pcf857x                  *gpio;
277         unsigned int                    n_latch = 0;
278         int                             status;
279 
280         if (IS_ENABLED(CONFIG_OF) && np)
281                 of_property_read_u32(np, "lines-initial-states", &n_latch);
282         else if (pdata)
283                 n_latch = pdata->n_latch;
284         else
285                 dev_dbg(&client->dev, "no platform data\n");
286 
287         /* Allocate, initialize, and register this gpio_chip. */
288         gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
289         if (!gpio)
290                 return -ENOMEM;
291 
292         mutex_init(&gpio->lock);
293 
294         gpio->chip.base                 = pdata ? pdata->gpio_base : -1;
295         gpio->chip.can_sleep            = true;
296         gpio->chip.parent               = &client->dev;
297         gpio->chip.owner                = THIS_MODULE;
298         gpio->chip.get                  = pcf857x_get;
299         gpio->chip.set                  = pcf857x_set;
300         gpio->chip.direction_input      = pcf857x_input;
301         gpio->chip.direction_output     = pcf857x_output;
302         gpio->chip.ngpio                = id->driver_data;
303 
304         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
305          * these parts, notably for output.  It has a low-resolution
306          * DAC instead of pin change IRQs; and its inputs can be the
307          * result of comparators.
308          */
309 
310         /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
311          * 9670, 9672, 9764, and 9764a use quite a variety.
312          *
313          * NOTE: we don't distinguish here between *4 and *4a parts.
314          */
315         if (gpio->chip.ngpio == 8) {
316                 gpio->write     = i2c_write_le8;
317                 gpio->read      = i2c_read_le8;
318 
319                 if (!i2c_check_functionality(client->adapter,
320                                 I2C_FUNC_SMBUS_BYTE))
321                         status = -EIO;
322 
323                 /* fail if there's no chip present */
324                 else
325                         status = i2c_smbus_read_byte(client);
326 
327         /* '75/'75c addresses are 0x20..0x27, just like the '74;
328          * the '75c doesn't have a current source pulling high.
329          * 9671, 9673, and 9765 use quite a variety of addresses.
330          *
331          * NOTE: we don't distinguish here between '75 and '75c parts.
332          */
333         } else if (gpio->chip.ngpio == 16) {
334                 gpio->write     = i2c_write_le16;
335                 gpio->read      = i2c_read_le16;
336 
337                 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
338                         status = -EIO;
339 
340                 /* fail if there's no chip present */
341                 else
342                         status = i2c_read_le16(client);
343 
344         } else {
345                 dev_dbg(&client->dev, "unsupported number of gpios\n");
346                 status = -EINVAL;
347         }
348 
349         if (status < 0)
350                 goto fail;
351 
352         gpio->chip.label = client->name;
353 
354         gpio->client = client;
355         i2c_set_clientdata(client, gpio);
356 
357         /* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
358          * We can't actually know whether a pin is configured (a) as output
359          * and driving the signal low, or (b) as input and reporting a low
360          * value ... without knowing the last value written since the chip
361          * came out of reset (if any).  We can't read the latched output.
362          *
363          * In short, the only reliable solution for setting up pin direction
364          * is to do it explicitly.  The setup() method can do that, but it
365          * may cause transient glitching since it can't know the last value
366          * written (some pins may need to be driven low).
367          *
368          * Using n_latch avoids that trouble.  When left initialized to zero,
369          * our software copy of the "latch" then matches the chip's all-ones
370          * reset state.  Otherwise it flags pins to be driven low.
371          */
372         gpio->out = ~n_latch;
373         gpio->status = gpio->out;
374 
375         status = gpiochip_add_data(&gpio->chip, gpio);
376         if (status < 0)
377                 goto fail;
378 
379         /* Enable irqchip if we have an interrupt */
380         if (client->irq) {
381                 status = gpiochip_irqchip_add(&gpio->chip, &pcf857x_irq_chip,
382                                               0, handle_level_irq,
383                                               IRQ_TYPE_NONE);
384                 if (status) {
385                         dev_err(&client->dev, "cannot add irqchip\n");
386                         goto fail_irq;
387                 }
388 
389                 status = devm_request_threaded_irq(&client->dev, client->irq,
390                                         NULL, pcf857x_irq, IRQF_ONESHOT |
391                                         IRQF_TRIGGER_FALLING | IRQF_SHARED,
392                                         dev_name(&client->dev), gpio);
393                 if (status)
394                         goto fail_irq;
395 
396                 gpiochip_set_chained_irqchip(&gpio->chip, &pcf857x_irq_chip,
397                                              client->irq, NULL);
398                 gpio->irq_parent = client->irq;
399         }
400 
401         /* Let platform code set up the GPIOs and their users.
402          * Now is the first time anyone could use them.
403          */
404         if (pdata && pdata->setup) {
405                 status = pdata->setup(client,
406                                 gpio->chip.base, gpio->chip.ngpio,
407                                 pdata->context);
408                 if (status < 0)
409                         dev_warn(&client->dev, "setup --> %d\n", status);
410         }
411 
412         dev_info(&client->dev, "probed\n");
413 
414         return 0;
415 
416 fail_irq:
417         gpiochip_remove(&gpio->chip);
418 
419 fail:
420         dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
421                 client->name);
422 
423         return status;
424 }
425 
426 static int pcf857x_remove(struct i2c_client *client)
427 {
428         struct pcf857x_platform_data    *pdata = dev_get_platdata(&client->dev);
429         struct pcf857x                  *gpio = i2c_get_clientdata(client);
430         int                             status = 0;
431 
432         if (pdata && pdata->teardown) {
433                 status = pdata->teardown(client,
434                                 gpio->chip.base, gpio->chip.ngpio,
435                                 pdata->context);
436                 if (status < 0) {
437                         dev_err(&client->dev, "%s --> %d\n",
438                                         "teardown", status);
439                         return status;
440                 }
441         }
442 
443         gpiochip_remove(&gpio->chip);
444         return status;
445 }
446 
447 static struct i2c_driver pcf857x_driver = {
448         .driver = {
449                 .name   = "pcf857x",
450                 .of_match_table = of_match_ptr(pcf857x_of_table),
451         },
452         .probe  = pcf857x_probe,
453         .remove = pcf857x_remove,
454         .id_table = pcf857x_id,
455 };
456 
457 static int __init pcf857x_init(void)
458 {
459         return i2c_add_driver(&pcf857x_driver);
460 }
461 /* register after i2c postcore initcall and before
462  * subsys initcalls that may rely on these GPIOs
463  */
464 subsys_initcall(pcf857x_init);
465 
466 static void __exit pcf857x_exit(void)
467 {
468         i2c_del_driver(&pcf857x_driver);
469 }
470 module_exit(pcf857x_exit);
471 
472 MODULE_LICENSE("GPL");
473 MODULE_AUTHOR("David Brownell");
474 

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