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 
19 enum 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 
39 struct lp3943_gpio {
40 	struct gpio_chip chip;
41 	struct lp3943 *lp3943;
42 	u16 input_mask;		/* 1 = GPIO is input direction, 0 = output */
43 };
44 
lp3943_gpio_request(struct gpio_chip * chip,unsigned int offset)45 static 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 
lp3943_gpio_free(struct gpio_chip * chip,unsigned int offset)57 static 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 
lp3943_gpio_set_mode(struct lp3943_gpio * lp3943_gpio,u8 offset,u8 val)65 static 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 
lp3943_gpio_direction_input(struct gpio_chip * chip,unsigned int offset)75 static 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 
lp3943_get_gpio_in_status(struct lp3943_gpio * lp3943_gpio,struct gpio_chip * chip,unsigned int offset)84 static 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 
lp3943_get_gpio_out_status(struct lp3943_gpio * lp3943_gpio,struct gpio_chip * chip,unsigned int offset)109 static 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 
lp3943_gpio_get(struct gpio_chip * chip,unsigned int offset)131 static 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 
lp3943_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)150 static 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 
lp3943_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)163 static 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 
174 static 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 
lp3943_gpio_probe(struct platform_device * pdev)188 static 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 
206 static const struct of_device_id lp3943_gpio_of_match[] = {
207 	{ .compatible = "ti,lp3943-gpio", },
208 	{ }
209 };
210 MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);
211 
212 static 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 };
219 module_platform_driver(lp3943_gpio_driver);
220 
221 MODULE_DESCRIPTION("LP3943 GPIO driver");
222 MODULE_ALIAS("platform:lp3943-gpio");
223 MODULE_AUTHOR("Milo Kim");
224 MODULE_LICENSE("GPL");
225