1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * TI/National Semiconductor LP3943 GPIO driver
4 *
5 * Copyright 2013 Texas Instruments
6 *
7 * Author: Milo Kim <milo.kim@ti.com>
8 */
9
10#include <linux/bitops.h>
11#include <linux/err.h>
12#include <linux/gpio/driver.h>
13#include <linux/i2c.h>
14#include <linux/mfd/lp3943.h>
15#include <linux/module.h>
16#include <linux/platform_device.h>
17#include <linux/slab.h>
18
19enum lp3943_gpios {
20	LP3943_GPIO1,
21	LP3943_GPIO2,
22	LP3943_GPIO3,
23	LP3943_GPIO4,
24	LP3943_GPIO5,
25	LP3943_GPIO6,
26	LP3943_GPIO7,
27	LP3943_GPIO8,
28	LP3943_GPIO9,
29	LP3943_GPIO10,
30	LP3943_GPIO11,
31	LP3943_GPIO12,
32	LP3943_GPIO13,
33	LP3943_GPIO14,
34	LP3943_GPIO15,
35	LP3943_GPIO16,
36	LP3943_MAX_GPIO,
37};
38
39struct lp3943_gpio {
40	struct gpio_chip chip;
41	struct lp3943 *lp3943;
42	u16 input_mask;		/* 1 = GPIO is input direction, 0 = output */
43};
44
45static int lp3943_gpio_request(struct gpio_chip *chip, unsigned int offset)
46{
47	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
48	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
49
50	/* Return an error if the pin is already assigned */
51	if (test_and_set_bit(offset, &lp3943->pin_used))
52		return -EBUSY;
53
54	return 0;
55}
56
57static void lp3943_gpio_free(struct gpio_chip *chip, unsigned int offset)
58{
59	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
60	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
61
62	clear_bit(offset, &lp3943->pin_used);
63}
64
65static int lp3943_gpio_set_mode(struct lp3943_gpio *lp3943_gpio, u8 offset,
66				u8 val)
67{
68	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
69	const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
70
71	return lp3943_update_bits(lp3943, mux[offset].reg, mux[offset].mask,
72				  val << mux[offset].shift);
73}
74
75static int lp3943_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
76{
77	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
78
79	lp3943_gpio->input_mask |= BIT(offset);
80
81	return lp3943_gpio_set_mode(lp3943_gpio, offset, LP3943_GPIO_IN);
82}
83
84static int lp3943_get_gpio_in_status(struct lp3943_gpio *lp3943_gpio,
85				     struct gpio_chip *chip, unsigned int offset)
86{
87	u8 addr, read;
88	int err;
89
90	switch (offset) {
91	case LP3943_GPIO1 ... LP3943_GPIO8:
92		addr = LP3943_REG_GPIO_A;
93		break;
94	case LP3943_GPIO9 ... LP3943_GPIO16:
95		addr = LP3943_REG_GPIO_B;
96		offset = offset - 8;
97		break;
98	default:
99		return -EINVAL;
100	}
101
102	err = lp3943_read_byte(lp3943_gpio->lp3943, addr, &read);
103	if (err)
104		return err;
105
106	return !!(read & BIT(offset));
107}
108
109static int lp3943_get_gpio_out_status(struct lp3943_gpio *lp3943_gpio,
110				      struct gpio_chip *chip, unsigned int offset)
111{
112	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
113	const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
114	u8 read;
115	int err;
116
117	err = lp3943_read_byte(lp3943, mux[offset].reg, &read);
118	if (err)
119		return err;
120
121	read = (read & mux[offset].mask) >> mux[offset].shift;
122
123	if (read == LP3943_GPIO_OUT_HIGH)
124		return 1;
125	else if (read == LP3943_GPIO_OUT_LOW)
126		return 0;
127	else
128		return -EINVAL;
129}
130
131static int lp3943_gpio_get(struct gpio_chip *chip, unsigned int offset)
132{
133	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
134
135	/*
136	 * Limitation:
137	 *   LP3943 doesn't have the GPIO direction register. It provides
138	 *   only input and output status registers.
139	 *   So, direction info is required to handle the 'get' operation.
140	 *   This variable is updated whenever the direction is changed and
141	 *   it is used here.
142	 */
143
144	if (lp3943_gpio->input_mask & BIT(offset))
145		return lp3943_get_gpio_in_status(lp3943_gpio, chip, offset);
146	else
147		return lp3943_get_gpio_out_status(lp3943_gpio, chip, offset);
148}
149
150static void lp3943_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
151{
152	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
153	u8 data;
154
155	if (value)
156		data = LP3943_GPIO_OUT_HIGH;
157	else
158		data = LP3943_GPIO_OUT_LOW;
159
160	lp3943_gpio_set_mode(lp3943_gpio, offset, data);
161}
162
163static int lp3943_gpio_direction_output(struct gpio_chip *chip, unsigned int offset,
164					int value)
165{
166	struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
167
168	lp3943_gpio_set(chip, offset, value);
169	lp3943_gpio->input_mask &= ~BIT(offset);
170
171	return 0;
172}
173
174static const struct gpio_chip lp3943_gpio_chip = {
175	.label			= "lp3943",
176	.owner			= THIS_MODULE,
177	.request		= lp3943_gpio_request,
178	.free			= lp3943_gpio_free,
179	.direction_input	= lp3943_gpio_direction_input,
180	.get			= lp3943_gpio_get,
181	.direction_output	= lp3943_gpio_direction_output,
182	.set			= lp3943_gpio_set,
183	.base			= -1,
184	.ngpio			= LP3943_MAX_GPIO,
185	.can_sleep		= 1,
186};
187
188static int lp3943_gpio_probe(struct platform_device *pdev)
189{
190	struct lp3943 *lp3943 = dev_get_drvdata(pdev->dev.parent);
191	struct lp3943_gpio *lp3943_gpio;
192
193	lp3943_gpio = devm_kzalloc(&pdev->dev, sizeof(*lp3943_gpio),
194				GFP_KERNEL);
195	if (!lp3943_gpio)
196		return -ENOMEM;
197
198	lp3943_gpio->lp3943 = lp3943;
199	lp3943_gpio->chip = lp3943_gpio_chip;
200	lp3943_gpio->chip.parent = &pdev->dev;
201
202	return devm_gpiochip_add_data(&pdev->dev, &lp3943_gpio->chip,
203				      lp3943_gpio);
204}
205
206static const struct of_device_id lp3943_gpio_of_match[] = {
207	{ .compatible = "ti,lp3943-gpio", },
208	{ }
209};
210MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);
211
212static struct platform_driver lp3943_gpio_driver = {
213	.probe = lp3943_gpio_probe,
214	.driver = {
215		.name = "lp3943-gpio",
216		.of_match_table = lp3943_gpio_of_match,
217	},
218};
219module_platform_driver(lp3943_gpio_driver);
220
221MODULE_DESCRIPTION("LP3943 GPIO driver");
222MODULE_ALIAS("platform:lp3943-gpio");
223MODULE_AUTHOR("Milo Kim");
224MODULE_LICENSE("GPL");
225