1/*
2 * TI/National Semiconductor LP3943 GPIO driver
3 *
4 * Copyright 2013 Texas Instruments
5 *
6 * Author: Milo Kim <milo.kim@ti.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; version 2.
11 */
12
13#include <linux/bitops.h>
14#include <linux/err.h>
15#include <linux/gpio/driver.h>
16#include <linux/i2c.h>
17#include <linux/mfd/lp3943.h>
18#include <linux/module.h>
19#include <linux/platform_device.h>
20#include <linux/slab.h>
21
22enum lp3943_gpios {
23 LP3943_GPIO1,
24 LP3943_GPIO2,
25 LP3943_GPIO3,
26 LP3943_GPIO4,
27 LP3943_GPIO5,
28 LP3943_GPIO6,
29 LP3943_GPIO7,
30 LP3943_GPIO8,
31 LP3943_GPIO9,
32 LP3943_GPIO10,
33 LP3943_GPIO11,
34 LP3943_GPIO12,
35 LP3943_GPIO13,
36 LP3943_GPIO14,
37 LP3943_GPIO15,
38 LP3943_GPIO16,
39 LP3943_MAX_GPIO,
40};
41
42struct lp3943_gpio {
43 struct gpio_chip chip;
44 struct lp3943 *lp3943;
45 u16 input_mask; /* 1 = GPIO is input direction, 0 = output */
46};
47
48static int lp3943_gpio_request(struct gpio_chip *chip, unsigned offset)
49{
50 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
51 struct lp3943 *lp3943 = lp3943_gpio->lp3943;
52
53 /* Return an error if the pin is already assigned */
54 if (test_and_set_bit(offset, &lp3943->pin_used))
55 return -EBUSY;
56
57 return 0;
58}
59
60static void lp3943_gpio_free(struct gpio_chip *chip, unsigned offset)
61{
62 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
63 struct lp3943 *lp3943 = lp3943_gpio->lp3943;
64
65 clear_bit(offset, &lp3943->pin_used);
66}
67
68static int lp3943_gpio_set_mode(struct lp3943_gpio *lp3943_gpio, u8 offset,
69 u8 val)
70{
71 struct lp3943 *lp3943 = lp3943_gpio->lp3943;
72 const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
73
74 return lp3943_update_bits(lp3943, mux[offset].reg, mux[offset].mask,
75 val << mux[offset].shift);
76}
77
78static int lp3943_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
79{
80 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
81
82 lp3943_gpio->input_mask |= BIT(offset);
83
84 return lp3943_gpio_set_mode(lp3943_gpio, offset, LP3943_GPIO_IN);
85}
86
87static int lp3943_get_gpio_in_status(struct lp3943_gpio *lp3943_gpio,
88 struct gpio_chip *chip, unsigned offset)
89{
90 u8 addr, read;
91 int err;
92
93 switch (offset) {
94 case LP3943_GPIO1 ... LP3943_GPIO8:
95 addr = LP3943_REG_GPIO_A;
96 break;
97 case LP3943_GPIO9 ... LP3943_GPIO16:
98 addr = LP3943_REG_GPIO_B;
99 offset = offset - 8;
100 break;
101 default:
102 return -EINVAL;
103 }
104
105 err = lp3943_read_byte(lp3943_gpio->lp3943, addr, &read);
106 if (err)
107 return err;
108
109 return !!(read & BIT(offset));
110}
111
112static int lp3943_get_gpio_out_status(struct lp3943_gpio *lp3943_gpio,
113 struct gpio_chip *chip, unsigned offset)
114{
115 struct lp3943 *lp3943 = lp3943_gpio->lp3943;
116 const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
117 u8 read;
118 int err;
119
120 err = lp3943_read_byte(lp3943, mux[offset].reg, &read);
121 if (err)
122 return err;
123
124 read = (read & mux[offset].mask) >> mux[offset].shift;
125
126 if (read == LP3943_GPIO_OUT_HIGH)
127 return 1;
128 else if (read == LP3943_GPIO_OUT_LOW)
129 return 0;
130 else
131 return -EINVAL;
132}
133
134static int lp3943_gpio_get(struct gpio_chip *chip, unsigned offset)
135{
136 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
137
138 /*
139 * Limitation:
140 * LP3943 doesn't have the GPIO direction register. It provides
141 * only input and output status registers.
142 * So, direction info is required to handle the 'get' operation.
143 * This variable is updated whenever the direction is changed and
144 * it is used here.
145 */
146
147 if (lp3943_gpio->input_mask & BIT(offset))
148 return lp3943_get_gpio_in_status(lp3943_gpio, chip, offset);
149 else
150 return lp3943_get_gpio_out_status(lp3943_gpio, chip, offset);
151}
152
153static void lp3943_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
154{
155 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
156 u8 data;
157
158 if (value)
159 data = LP3943_GPIO_OUT_HIGH;
160 else
161 data = LP3943_GPIO_OUT_LOW;
162
163 lp3943_gpio_set_mode(lp3943_gpio, offset, data);
164}
165
166static int lp3943_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
167 int value)
168{
169 struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
170
171 lp3943_gpio_set(chip, offset, value);
172 lp3943_gpio->input_mask &= ~BIT(offset);
173
174 return 0;
175}
176
177static const struct gpio_chip lp3943_gpio_chip = {
178 .label = "lp3943",
179 .owner = THIS_MODULE,
180 .request = lp3943_gpio_request,
181 .free = lp3943_gpio_free,
182 .direction_input = lp3943_gpio_direction_input,
183 .get = lp3943_gpio_get,
184 .direction_output = lp3943_gpio_direction_output,
185 .set = lp3943_gpio_set,
186 .base = -1,
187 .ngpio = LP3943_MAX_GPIO,
188 .can_sleep = 1,
189};
190
191static int lp3943_gpio_probe(struct platform_device *pdev)
192{
193 struct lp3943 *lp3943 = dev_get_drvdata(pdev->dev.parent);
194 struct lp3943_gpio *lp3943_gpio;
195
196 lp3943_gpio = devm_kzalloc(&pdev->dev, sizeof(*lp3943_gpio),
197 GFP_KERNEL);
198 if (!lp3943_gpio)
199 return -ENOMEM;
200
201 lp3943_gpio->lp3943 = lp3943;
202 lp3943_gpio->chip = lp3943_gpio_chip;
203 lp3943_gpio->chip.parent = &pdev->dev;
204
205 platform_set_drvdata(pdev, lp3943_gpio);
206
207 return devm_gpiochip_add_data(&pdev->dev, &lp3943_gpio->chip,
208 lp3943_gpio);
209}
210
211static const struct of_device_id lp3943_gpio_of_match[] = {
212 { .compatible = "ti,lp3943-gpio", },
213 { }
214};
215MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);
216
217static struct platform_driver lp3943_gpio_driver = {
218 .probe = lp3943_gpio_probe,
219 .driver = {
220 .name = "lp3943-gpio",
221 .of_match_table = lp3943_gpio_of_match,
222 },
223};
224module_platform_driver(lp3943_gpio_driver);
225
226MODULE_DESCRIPTION("LP3943 GPIO driver");
227MODULE_ALIAS("platform:lp3943-gpio");
228MODULE_AUTHOR("Milo Kim");
229MODULE_LICENSE("GPL");
230