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v6.8
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  GPIO interface for IT87xx Super I/O chips
  4 *
  5 *  Author: Diego Elio Pettenò <flameeyes@flameeyes.eu>
  6 *  Copyright (c) 2017 Google, Inc.
  7 *
  8 *  Based on it87_wdt.c     by Oliver Schuster
  9 *           gpio-it8761e.c by Denis Turischev
 10 *           gpio-stmpe.c   by Rabin Vincent
 
 
 
 
 
 
 
 
 
 
 
 
 
 11 */
 12
 13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 14
 15#include <linux/init.h>
 16#include <linux/kernel.h>
 17#include <linux/module.h>
 18#include <linux/io.h>
 19#include <linux/errno.h>
 20#include <linux/ioport.h>
 21#include <linux/slab.h>
 22#include <linux/gpio/driver.h>
 23
 24/* Chip Id numbers */
 25#define NO_DEV_ID	0xffff
 26#define IT8613_ID	0x8613
 27#define IT8620_ID	0x8620
 28#define IT8628_ID	0x8628
 29#define IT8718_ID       0x8718
 30#define IT8728_ID	0x8728
 31#define IT8732_ID	0x8732
 32#define IT8761_ID	0x8761
 33#define IT8772_ID	0x8772
 34#define IT8786_ID	0x8786
 35
 36/* IO Ports */
 37#define REG		0x2e
 38#define VAL		0x2f
 39
 40/* Logical device Numbers LDN */
 41#define GPIO		0x07
 42
 43/* Configuration Registers and Functions */
 44#define LDNREG		0x07
 45#define CHIPID		0x20
 46#define CHIPREV		0x22
 47
 48/**
 49 * struct it87_gpio - it87-specific GPIO chip
 50 * @chip: the underlying gpio_chip structure
 51 * @lock: a lock to avoid races between operations
 52 * @io_base: base address for gpio ports
 53 * @io_size: size of the port rage starting from io_base.
 54 * @output_base: Super I/O register address for Output Enable register
 55 * @simple_base: Super I/O 'Simple I/O' Enable register
 56 * @simple_size: Super IO 'Simple I/O' Enable register size; this is
 57 *	required because IT87xx chips might only provide Simple I/O
 58 *	switches on a subset of lines, whereas the others keep the
 59 *	same status all time.
 60 */
 61struct it87_gpio {
 62	struct gpio_chip chip;
 63	spinlock_t lock;
 64	u16 io_base;
 65	u16 io_size;
 66	u8 output_base;
 67	u8 simple_base;
 68	u8 simple_size;
 69};
 70
 71static struct it87_gpio it87_gpio_chip = {
 72	.lock = __SPIN_LOCK_UNLOCKED(it87_gpio_chip.lock),
 73};
 74
 75/* Superio chip access functions; copied from wdt_it87 */
 76
 77static inline int superio_enter(void)
 78{
 79	/*
 80	 * Try to reserve REG and REG + 1 for exclusive access.
 81	 */
 82	if (!request_muxed_region(REG, 2, KBUILD_MODNAME))
 83		return -EBUSY;
 84
 85	outb(0x87, REG);
 86	outb(0x01, REG);
 87	outb(0x55, REG);
 88	outb(0x55, REG);
 89	return 0;
 90}
 91
 92static inline void superio_exit(void)
 93{
 94	outb(0x02, REG);
 95	outb(0x02, VAL);
 96	release_region(REG, 2);
 97}
 98
 99static inline void superio_select(int ldn)
100{
101	outb(LDNREG, REG);
102	outb(ldn, VAL);
103}
104
105static inline int superio_inb(int reg)
106{
107	outb(reg, REG);
108	return inb(VAL);
109}
110
111static inline void superio_outb(int val, int reg)
112{
113	outb(reg, REG);
114	outb(val, VAL);
115}
116
117static inline int superio_inw(int reg)
118{
119	int val;
120
121	outb(reg++, REG);
122	val = inb(VAL) << 8;
123	outb(reg, REG);
124	val |= inb(VAL);
125	return val;
126}
127
 
 
 
 
 
 
 
 
128static inline void superio_set_mask(int mask, int reg)
129{
130	u8 curr_val = superio_inb(reg);
131	u8 new_val = curr_val | mask;
132
133	if (curr_val != new_val)
134		superio_outb(new_val, reg);
135}
136
137static inline void superio_clear_mask(int mask, int reg)
138{
139	u8 curr_val = superio_inb(reg);
140	u8 new_val = curr_val & ~mask;
141
142	if (curr_val != new_val)
143		superio_outb(new_val, reg);
144}
145
146static int it87_gpio_request(struct gpio_chip *chip, unsigned gpio_num)
147{
148	u8 mask, group;
149	int rc = 0;
150	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
151
152	mask = 1 << (gpio_num % 8);
153	group = (gpio_num / 8);
154
155	spin_lock(&it87_gpio->lock);
156
157	rc = superio_enter();
158	if (rc)
159		goto exit;
160
161	/* not all the IT87xx chips support Simple I/O and not all of
162	 * them allow all the lines to be set/unset to Simple I/O.
163	 */
164	if (group < it87_gpio->simple_size)
165		superio_set_mask(mask, group + it87_gpio->simple_base);
166
167	/* clear output enable, setting the pin to input, as all the
168	 * newly-exported GPIO interfaces are set to input.
169	 */
170	superio_clear_mask(mask, group + it87_gpio->output_base);
171
172	superio_exit();
173
174exit:
175	spin_unlock(&it87_gpio->lock);
176	return rc;
177}
178
179static int it87_gpio_get(struct gpio_chip *chip, unsigned gpio_num)
180{
181	u16 reg;
182	u8 mask;
183	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
184
185	mask = 1 << (gpio_num % 8);
186	reg = (gpio_num / 8) + it87_gpio->io_base;
187
188	return !!(inb(reg) & mask);
189}
190
191static int it87_gpio_direction_in(struct gpio_chip *chip, unsigned gpio_num)
192{
193	u8 mask, group;
194	int rc = 0;
195	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
196
197	mask = 1 << (gpio_num % 8);
198	group = (gpio_num / 8);
199
200	spin_lock(&it87_gpio->lock);
201
202	rc = superio_enter();
203	if (rc)
204		goto exit;
205
206	/* clear the output enable bit */
207	superio_clear_mask(mask, group + it87_gpio->output_base);
208
209	superio_exit();
210
211exit:
212	spin_unlock(&it87_gpio->lock);
213	return rc;
214}
215
216static void it87_gpio_set(struct gpio_chip *chip,
217			  unsigned gpio_num, int val)
218{
219	u8 mask, curr_vals;
220	u16 reg;
221	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
222
223	mask = 1 << (gpio_num % 8);
224	reg = (gpio_num / 8) + it87_gpio->io_base;
225
226	curr_vals = inb(reg);
227	if (val)
228		outb(curr_vals | mask, reg);
229	else
230		outb(curr_vals & ~mask, reg);
231}
232
233static int it87_gpio_direction_out(struct gpio_chip *chip,
234				   unsigned gpio_num, int val)
235{
236	u8 mask, group;
237	int rc = 0;
238	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
239
240	mask = 1 << (gpio_num % 8);
241	group = (gpio_num / 8);
242
243	spin_lock(&it87_gpio->lock);
244
245	rc = superio_enter();
246	if (rc)
247		goto exit;
248
249	/* set the output enable bit */
250	superio_set_mask(mask, group + it87_gpio->output_base);
251
252	it87_gpio_set(chip, gpio_num, val);
253
254	superio_exit();
255
256exit:
257	spin_unlock(&it87_gpio->lock);
258	return rc;
259}
260
261static const struct gpio_chip it87_template_chip = {
262	.label			= KBUILD_MODNAME,
263	.owner			= THIS_MODULE,
264	.request		= it87_gpio_request,
265	.get			= it87_gpio_get,
266	.direction_input	= it87_gpio_direction_in,
267	.set			= it87_gpio_set,
268	.direction_output	= it87_gpio_direction_out,
269	.base			= -1
270};
271
272static int __init it87_gpio_init(void)
273{
274	int rc = 0, i;
275	u16 chip_type;
276	u8 chip_rev, gpio_ba_reg;
277	char *labels, **labels_table;
278
279	struct it87_gpio *it87_gpio = &it87_gpio_chip;
280
281	rc = superio_enter();
282	if (rc)
283		return rc;
284
285	chip_type = superio_inw(CHIPID);
286	chip_rev  = superio_inb(CHIPREV) & 0x0f;
287	superio_exit();
288
289	it87_gpio->chip = it87_template_chip;
290
291	switch (chip_type) {
292	case IT8613_ID:
293		gpio_ba_reg = 0x62;
294		it87_gpio->io_size = 8;  /* it8613 only needs 6, use 8 for alignment */
295		it87_gpio->output_base = 0xc8;
296		it87_gpio->simple_base = 0xc0;
297		it87_gpio->simple_size = 6;
298		it87_gpio->chip.ngpio = 64;  /* has 48, use 64 for convenient calc */
299		break;
300	case IT8620_ID:
301	case IT8628_ID:
302		gpio_ba_reg = 0x62;
303		it87_gpio->io_size = 11;
304		it87_gpio->output_base = 0xc8;
305		it87_gpio->simple_size = 0;
306		it87_gpio->chip.ngpio = 64;
307		break;
308	case IT8718_ID:
309	case IT8728_ID:
310	case IT8732_ID:
311	case IT8772_ID:
312	case IT8786_ID:
313		gpio_ba_reg = 0x62;
314		it87_gpio->io_size = 8;
315		it87_gpio->output_base = 0xc8;
316		it87_gpio->simple_base = 0xc0;
317		it87_gpio->simple_size = 5;
318		it87_gpio->chip.ngpio = 64;
319		break;
320	case IT8761_ID:
321		gpio_ba_reg = 0x60;
322		it87_gpio->io_size = 4;
323		it87_gpio->output_base = 0xf0;
324		it87_gpio->simple_size = 0;
325		it87_gpio->chip.ngpio = 16;
326		break;
327	case NO_DEV_ID:
328		pr_err("no device\n");
329		return -ENODEV;
330	default:
331		pr_err("Unknown Chip found, Chip %04x Revision %x\n",
332		       chip_type, chip_rev);
333		return -ENODEV;
334	}
335
336	rc = superio_enter();
337	if (rc)
338		return rc;
339
340	superio_select(GPIO);
341
342	/* fetch GPIO base address */
343	it87_gpio->io_base = superio_inw(gpio_ba_reg);
344
345	superio_exit();
346
347	pr_info("Found Chip IT%04x rev %x. %u GPIO lines starting at %04xh\n",
348		chip_type, chip_rev, it87_gpio->chip.ngpio,
349		it87_gpio->io_base);
350
351	if (!request_region(it87_gpio->io_base, it87_gpio->io_size,
352							KBUILD_MODNAME))
353		return -EBUSY;
354
355	/* Set up aliases for the GPIO connection.
356	 *
357	 * ITE documentation for recent chips such as the IT8728F
358	 * refers to the GPIO lines as GPxy, with a coordinates system
359	 * where x is the GPIO group (starting from 1) and y is the
360	 * bit within the group.
361	 *
362	 * By creating these aliases, we make it easier to understand
363	 * to which GPIO pin we're referring to.
364	 */
365	labels = kcalloc(it87_gpio->chip.ngpio, sizeof("it87_gpXY"),
366								GFP_KERNEL);
367	labels_table = kcalloc(it87_gpio->chip.ngpio, sizeof(const char *),
368								GFP_KERNEL);
369
370	if (!labels || !labels_table) {
371		rc = -ENOMEM;
372		goto labels_free;
373	}
374
375	for (i = 0; i < it87_gpio->chip.ngpio; i++) {
376		char *label = &labels[i * sizeof("it87_gpXY")];
377
378		sprintf(label, "it87_gp%u%u", 1+(i/8), i%8);
379		labels_table[i] = label;
380	}
381
382	it87_gpio->chip.names = (const char *const*)labels_table;
383
384	rc = gpiochip_add_data(&it87_gpio->chip, it87_gpio);
385	if (rc)
386		goto labels_free;
387
388	return 0;
389
390labels_free:
391	kfree(labels_table);
392	kfree(labels);
393	release_region(it87_gpio->io_base, it87_gpio->io_size);
394	return rc;
395}
396
397static void __exit it87_gpio_exit(void)
398{
399	struct it87_gpio *it87_gpio = &it87_gpio_chip;
400
401	gpiochip_remove(&it87_gpio->chip);
402	release_region(it87_gpio->io_base, it87_gpio->io_size);
403	kfree(it87_gpio->chip.names[0]);
404	kfree(it87_gpio->chip.names);
405}
406
407module_init(it87_gpio_init);
408module_exit(it87_gpio_exit);
409
410MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@flameeyes.eu>");
411MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
412MODULE_LICENSE("GPL");
v4.17
 
  1/*
  2 *  GPIO interface for IT87xx Super I/O chips
  3 *
  4 *  Author: Diego Elio Pettenò <flameeyes@flameeyes.eu>
  5 *  Copyright (c) 2017 Google, Inc.
  6 *
  7 *  Based on it87_wdt.c     by Oliver Schuster
  8 *           gpio-it8761e.c by Denis Turischev
  9 *           gpio-stmpe.c   by Rabin Vincent
 10 *
 11 *  This program is free software; you can redistribute it and/or modify
 12 *  it under the terms of the GNU General Public License 2 as published
 13 *  by the Free Software Foundation.
 14 *
 15 *  This program is distributed in the hope that it will be useful,
 16 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 17 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 18 *  GNU General Public License for more details.
 19 *
 20 *  You should have received a copy of the GNU General Public License
 21 *  along with this program; see the file COPYING.  If not, write to
 22 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 23 */
 24
 25#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 26
 27#include <linux/init.h>
 28#include <linux/kernel.h>
 29#include <linux/module.h>
 30#include <linux/io.h>
 31#include <linux/errno.h>
 32#include <linux/ioport.h>
 33#include <linux/slab.h>
 34#include <linux/gpio/driver.h>
 35
 36/* Chip Id numbers */
 37#define NO_DEV_ID	0xffff
 
 38#define IT8620_ID	0x8620
 39#define IT8628_ID	0x8628
 
 40#define IT8728_ID	0x8728
 41#define IT8732_ID	0x8732
 42#define IT8761_ID	0x8761
 43#define IT8772_ID	0x8772
 
 44
 45/* IO Ports */
 46#define REG		0x2e
 47#define VAL		0x2f
 48
 49/* Logical device Numbers LDN */
 50#define GPIO		0x07
 51
 52/* Configuration Registers and Functions */
 53#define LDNREG		0x07
 54#define CHIPID		0x20
 55#define CHIPREV		0x22
 56
 57/**
 58 * struct it87_gpio - it87-specific GPIO chip
 59 * @chip the underlying gpio_chip structure
 60 * @lock a lock to avoid races between operations
 61 * @io_base base address for gpio ports
 62 * @io_size size of the port rage starting from io_base.
 63 * @output_base Super I/O register address for Output Enable register
 64 * @simple_base Super I/O 'Simple I/O' Enable register
 65 * @simple_size Super IO 'Simple I/O' Enable register size; this is
 66 *	required because IT87xx chips might only provide Simple I/O
 67 *	switches on a subset of lines, whereas the others keep the
 68 *	same status all time.
 69 */
 70struct it87_gpio {
 71	struct gpio_chip chip;
 72	spinlock_t lock;
 73	u16 io_base;
 74	u16 io_size;
 75	u8 output_base;
 76	u8 simple_base;
 77	u8 simple_size;
 78};
 79
 80static struct it87_gpio it87_gpio_chip = {
 81	.lock = __SPIN_LOCK_UNLOCKED(it87_gpio_chip.lock),
 82};
 83
 84/* Superio chip access functions; copied from wdt_it87 */
 85
 86static inline int superio_enter(void)
 87{
 88	/*
 89	 * Try to reserve REG and REG + 1 for exclusive access.
 90	 */
 91	if (!request_muxed_region(REG, 2, KBUILD_MODNAME))
 92		return -EBUSY;
 93
 94	outb(0x87, REG);
 95	outb(0x01, REG);
 96	outb(0x55, REG);
 97	outb(0x55, REG);
 98	return 0;
 99}
100
101static inline void superio_exit(void)
102{
103	outb(0x02, REG);
104	outb(0x02, VAL);
105	release_region(REG, 2);
106}
107
108static inline void superio_select(int ldn)
109{
110	outb(LDNREG, REG);
111	outb(ldn, VAL);
112}
113
114static inline int superio_inb(int reg)
115{
116	outb(reg, REG);
117	return inb(VAL);
118}
119
120static inline void superio_outb(int val, int reg)
121{
122	outb(reg, REG);
123	outb(val, VAL);
124}
125
126static inline int superio_inw(int reg)
127{
128	int val;
129
130	outb(reg++, REG);
131	val = inb(VAL) << 8;
132	outb(reg, REG);
133	val |= inb(VAL);
134	return val;
135}
136
137static inline void superio_outw(int val, int reg)
138{
139	outb(reg++, REG);
140	outb(val >> 8, VAL);
141	outb(reg, REG);
142	outb(val, VAL);
143}
144
145static inline void superio_set_mask(int mask, int reg)
146{
147	u8 curr_val = superio_inb(reg);
148	u8 new_val = curr_val | mask;
149
150	if (curr_val != new_val)
151		superio_outb(new_val, reg);
152}
153
154static inline void superio_clear_mask(int mask, int reg)
155{
156	u8 curr_val = superio_inb(reg);
157	u8 new_val = curr_val & ~mask;
158
159	if (curr_val != new_val)
160		superio_outb(new_val, reg);
161}
162
163static int it87_gpio_request(struct gpio_chip *chip, unsigned gpio_num)
164{
165	u8 mask, group;
166	int rc = 0;
167	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
168
169	mask = 1 << (gpio_num % 8);
170	group = (gpio_num / 8);
171
172	spin_lock(&it87_gpio->lock);
173
174	rc = superio_enter();
175	if (rc)
176		goto exit;
177
178	/* not all the IT87xx chips support Simple I/O and not all of
179	 * them allow all the lines to be set/unset to Simple I/O.
180	 */
181	if (group < it87_gpio->simple_size)
182		superio_set_mask(mask, group + it87_gpio->simple_base);
183
184	/* clear output enable, setting the pin to input, as all the
185	 * newly-exported GPIO interfaces are set to input.
186	 */
187	superio_clear_mask(mask, group + it87_gpio->output_base);
188
189	superio_exit();
190
191exit:
192	spin_unlock(&it87_gpio->lock);
193	return rc;
194}
195
196static int it87_gpio_get(struct gpio_chip *chip, unsigned gpio_num)
197{
198	u16 reg;
199	u8 mask;
200	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
201
202	mask = 1 << (gpio_num % 8);
203	reg = (gpio_num / 8) + it87_gpio->io_base;
204
205	return !!(inb(reg) & mask);
206}
207
208static int it87_gpio_direction_in(struct gpio_chip *chip, unsigned gpio_num)
209{
210	u8 mask, group;
211	int rc = 0;
212	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
213
214	mask = 1 << (gpio_num % 8);
215	group = (gpio_num / 8);
216
217	spin_lock(&it87_gpio->lock);
218
219	rc = superio_enter();
220	if (rc)
221		goto exit;
222
223	/* clear the output enable bit */
224	superio_clear_mask(mask, group + it87_gpio->output_base);
225
226	superio_exit();
227
228exit:
229	spin_unlock(&it87_gpio->lock);
230	return rc;
231}
232
233static void it87_gpio_set(struct gpio_chip *chip,
234			  unsigned gpio_num, int val)
235{
236	u8 mask, curr_vals;
237	u16 reg;
238	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
239
240	mask = 1 << (gpio_num % 8);
241	reg = (gpio_num / 8) + it87_gpio->io_base;
242
243	curr_vals = inb(reg);
244	if (val)
245		outb(curr_vals | mask, reg);
246	else
247		outb(curr_vals & ~mask, reg);
248}
249
250static int it87_gpio_direction_out(struct gpio_chip *chip,
251				   unsigned gpio_num, int val)
252{
253	u8 mask, group;
254	int rc = 0;
255	struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
256
257	mask = 1 << (gpio_num % 8);
258	group = (gpio_num / 8);
259
260	spin_lock(&it87_gpio->lock);
261
262	rc = superio_enter();
263	if (rc)
264		goto exit;
265
266	/* set the output enable bit */
267	superio_set_mask(mask, group + it87_gpio->output_base);
268
269	it87_gpio_set(chip, gpio_num, val);
270
271	superio_exit();
272
273exit:
274	spin_unlock(&it87_gpio->lock);
275	return rc;
276}
277
278static const struct gpio_chip it87_template_chip = {
279	.label			= KBUILD_MODNAME,
280	.owner			= THIS_MODULE,
281	.request		= it87_gpio_request,
282	.get			= it87_gpio_get,
283	.direction_input	= it87_gpio_direction_in,
284	.set			= it87_gpio_set,
285	.direction_output	= it87_gpio_direction_out,
286	.base			= -1
287};
288
289static int __init it87_gpio_init(void)
290{
291	int rc = 0, i;
292	u16 chip_type;
293	u8 chip_rev, gpio_ba_reg;
294	char *labels, **labels_table;
295
296	struct it87_gpio *it87_gpio = &it87_gpio_chip;
297
298	rc = superio_enter();
299	if (rc)
300		return rc;
301
302	chip_type = superio_inw(CHIPID);
303	chip_rev  = superio_inb(CHIPREV) & 0x0f;
304	superio_exit();
305
306	it87_gpio->chip = it87_template_chip;
307
308	switch (chip_type) {
 
 
 
 
 
 
 
 
309	case IT8620_ID:
310	case IT8628_ID:
311		gpio_ba_reg = 0x62;
312		it87_gpio->io_size = 11;
313		it87_gpio->output_base = 0xc8;
314		it87_gpio->simple_size = 0;
315		it87_gpio->chip.ngpio = 64;
316		break;
 
317	case IT8728_ID:
318	case IT8732_ID:
319	case IT8772_ID:
 
320		gpio_ba_reg = 0x62;
321		it87_gpio->io_size = 8;
322		it87_gpio->output_base = 0xc8;
323		it87_gpio->simple_base = 0xc0;
324		it87_gpio->simple_size = 5;
325		it87_gpio->chip.ngpio = 64;
326		break;
327	case IT8761_ID:
328		gpio_ba_reg = 0x60;
329		it87_gpio->io_size = 4;
330		it87_gpio->output_base = 0xf0;
331		it87_gpio->simple_size = 0;
332		it87_gpio->chip.ngpio = 16;
333		break;
334	case NO_DEV_ID:
335		pr_err("no device\n");
336		return -ENODEV;
337	default:
338		pr_err("Unknown Chip found, Chip %04x Revision %x\n",
339		       chip_type, chip_rev);
340		return -ENODEV;
341	}
342
343	rc = superio_enter();
344	if (rc)
345		return rc;
346
347	superio_select(GPIO);
348
349	/* fetch GPIO base address */
350	it87_gpio->io_base = superio_inw(gpio_ba_reg);
351
352	superio_exit();
353
354	pr_info("Found Chip IT%04x rev %x. %u GPIO lines starting at %04xh\n",
355		chip_type, chip_rev, it87_gpio->chip.ngpio,
356		it87_gpio->io_base);
357
358	if (!request_region(it87_gpio->io_base, it87_gpio->io_size,
359							KBUILD_MODNAME))
360		return -EBUSY;
361
362	/* Set up aliases for the GPIO connection.
363	 *
364	 * ITE documentation for recent chips such as the IT8728F
365	 * refers to the GPIO lines as GPxy, with a coordinates system
366	 * where x is the GPIO group (starting from 1) and y is the
367	 * bit within the group.
368	 *
369	 * By creating these aliases, we make it easier to understand
370	 * to which GPIO pin we're referring to.
371	 */
372	labels = kcalloc(it87_gpio->chip.ngpio, sizeof("it87_gpXY"),
373								GFP_KERNEL);
374	labels_table = kcalloc(it87_gpio->chip.ngpio, sizeof(const char *),
375								GFP_KERNEL);
376
377	if (!labels || !labels_table) {
378		rc = -ENOMEM;
379		goto labels_free;
380	}
381
382	for (i = 0; i < it87_gpio->chip.ngpio; i++) {
383		char *label = &labels[i * sizeof("it87_gpXY")];
384
385		sprintf(label, "it87_gp%u%u", 1+(i/8), i%8);
386		labels_table[i] = label;
387	}
388
389	it87_gpio->chip.names = (const char *const*)labels_table;
390
391	rc = gpiochip_add_data(&it87_gpio->chip, it87_gpio);
392	if (rc)
393		goto labels_free;
394
395	return 0;
396
397labels_free:
398	kfree(labels_table);
399	kfree(labels);
400	release_region(it87_gpio->io_base, it87_gpio->io_size);
401	return rc;
402}
403
404static void __exit it87_gpio_exit(void)
405{
406	struct it87_gpio *it87_gpio = &it87_gpio_chip;
407
408	gpiochip_remove(&it87_gpio->chip);
409	release_region(it87_gpio->io_base, it87_gpio->io_size);
410	kfree(it87_gpio->chip.names[0]);
411	kfree(it87_gpio->chip.names);
412}
413
414module_init(it87_gpio_init);
415module_exit(it87_gpio_exit);
416
417MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@flameeyes.eu>");
418MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
419MODULE_LICENSE("GPL");