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 */
61 struct 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
71 static 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
superio_enter(void)77 static 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
superio_exit(void)92 static inline void superio_exit(void)
93 {
94 outb(0x02, REG);
95 outb(0x02, VAL);
96 release_region(REG, 2);
97 }
98
superio_select(int ldn)99 static inline void superio_select(int ldn)
100 {
101 outb(LDNREG, REG);
102 outb(ldn, VAL);
103 }
104
superio_inb(int reg)105 static inline int superio_inb(int reg)
106 {
107 outb(reg, REG);
108 return inb(VAL);
109 }
110
superio_outb(int val,int reg)111 static inline void superio_outb(int val, int reg)
112 {
113 outb(reg, REG);
114 outb(val, VAL);
115 }
116
superio_inw(int reg)117 static 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
superio_set_mask(int mask,int reg)128 static 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
superio_clear_mask(int mask,int reg)137 static 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
it87_gpio_request(struct gpio_chip * chip,unsigned gpio_num)146 static 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
174 exit:
175 spin_unlock(&it87_gpio->lock);
176 return rc;
177 }
178
it87_gpio_get(struct gpio_chip * chip,unsigned gpio_num)179 static 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
it87_gpio_direction_in(struct gpio_chip * chip,unsigned gpio_num)191 static 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
211 exit:
212 spin_unlock(&it87_gpio->lock);
213 return rc;
214 }
215
it87_gpio_set(struct gpio_chip * chip,unsigned gpio_num,int val)216 static 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
it87_gpio_direction_out(struct gpio_chip * chip,unsigned gpio_num,int val)233 static 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
256 exit:
257 spin_unlock(&it87_gpio->lock);
258 return rc;
259 }
260
261 static 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
it87_gpio_init(void)272 static 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
390 labels_free:
391 kfree(labels_table);
392 kfree(labels);
393 release_region(it87_gpio->io_base, it87_gpio->io_size);
394 return rc;
395 }
396
it87_gpio_exit(void)397 static 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
407 module_init(it87_gpio_init);
408 module_exit(it87_gpio_exit);
409
410 MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@flameeyes.eu>");
411 MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
412 MODULE_LICENSE("GPL");
413