1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Congatec Board Controller GPIO driver
  4 *
  5 * Copyright (C) 2024 Bootlin
  6 * Author: Thomas Richard <thomas.richard@bootlin.com>
  7 */
  8
  9#include <linux/gpio/driver.h>
 10#include <linux/mfd/cgbc.h>
 11#include <linux/module.h>
 12#include <linux/mutex.h>
 13#include <linux/platform_device.h>
 14
 15#define CGBC_GPIO_NGPIO	14
 16
 17#define CGBC_GPIO_CMD_GET	0x64
 18#define CGBC_GPIO_CMD_SET	0x65
 19#define CGBC_GPIO_CMD_DIR_GET	0x66
 20#define CGBC_GPIO_CMD_DIR_SET	0x67
 21
 22struct cgbc_gpio_data {
 23	struct gpio_chip	chip;
 24	struct cgbc_device_data	*cgbc;
 25	struct mutex lock;
 26};
 27
 28static int cgbc_gpio_cmd(struct cgbc_device_data *cgbc,
 29			 u8 cmd0, u8 cmd1, u8 cmd2, u8 *value)
 30{
 31	u8 cmd[3] = {cmd0, cmd1, cmd2};
 32
 33	return cgbc_command(cgbc, cmd, sizeof(cmd), value, 1, NULL);
 34}
 35
 36static int cgbc_gpio_get(struct gpio_chip *chip, unsigned int offset)
 37{
 38	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
 39	struct cgbc_device_data *cgbc = gpio->cgbc;
 40	int ret;
 41	u8 val;
 42
 43	scoped_guard(mutex, &gpio->lock)
 44		ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);
 45
 46	offset %= 8;
 47
 48	if (ret)
 49		return ret;
 50	else
 51		return (int)(val & (u8)BIT(offset));
 52}
 53
 54static void __cgbc_gpio_set(struct gpio_chip *chip,
 55			    unsigned int offset, int value)
 56{
 57	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
 58	struct cgbc_device_data *cgbc = gpio->cgbc;
 59	u8 val;
 60	int ret;
 61
 62	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);
 63	if (ret)
 64		return;
 65
 66	if (value)
 67		val |= BIT(offset % 8);
 68	else
 69		val &= ~(BIT(offset % 8));
 70
 71	cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_SET, (offset > 7) ? 1 : 0, val, &val);
 72}
 73
 74static void cgbc_gpio_set(struct gpio_chip *chip,
 75			  unsigned int offset, int value)
 76{
 77	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
 78
 79	scoped_guard(mutex, &gpio->lock)
 80		__cgbc_gpio_set(chip, offset, value);
 81}
 82
 83static int cgbc_gpio_direction_set(struct gpio_chip *chip,
 84				   unsigned int offset, int direction)
 85{
 86	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
 87	struct cgbc_device_data *cgbc = gpio->cgbc;
 88	int ret;
 89	u8 val;
 90
 91	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
 92	if (ret)
 93		goto end;
 94
 95	if (direction == GPIO_LINE_DIRECTION_IN)
 96		val &= ~(BIT(offset % 8));
 97	else
 98		val |= BIT(offset % 8);
 99
100	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_SET, (offset > 7) ? 1 : 0, val, &val);
101
102end:
103	return ret;
104}
105
106static int cgbc_gpio_direction_input(struct gpio_chip *chip,
107				     unsigned int offset)
108{
109	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
110
111	guard(mutex)(&gpio->lock);
112	return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_IN);
113}
114
115static int cgbc_gpio_direction_output(struct gpio_chip *chip,
116				      unsigned int offset, int value)
117{
118	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
119
120	guard(mutex)(&gpio->lock);
121
122	__cgbc_gpio_set(chip, offset, value);
123	return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_OUT);
124}
125
126static int cgbc_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
127{
128	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
129	struct cgbc_device_data *cgbc = gpio->cgbc;
130	int ret;
131	u8 val;
132
133	scoped_guard(mutex, &gpio->lock)
134		ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
135
136	if (ret)
137		return ret;
138
139	if (val & BIT(offset % 8))
140		return GPIO_LINE_DIRECTION_OUT;
141	else
142		return GPIO_LINE_DIRECTION_IN;
143}
144
145static int cgbc_gpio_probe(struct platform_device *pdev)
146{
147	struct device *dev = &pdev->dev;
148	struct cgbc_device_data *cgbc = dev_get_drvdata(dev->parent);
149	struct cgbc_gpio_data *gpio;
150	struct gpio_chip *chip;
151	int ret;
152
153	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
154	if (!gpio)
155		return -ENOMEM;
156
157	gpio->cgbc = cgbc;
158
159	platform_set_drvdata(pdev, gpio);
160
161	chip = &gpio->chip;
162	chip->label = dev_name(&pdev->dev);
163	chip->owner = THIS_MODULE;
164	chip->parent = dev;
165	chip->base = -1;
166	chip->direction_input = cgbc_gpio_direction_input;
167	chip->direction_output = cgbc_gpio_direction_output;
168	chip->get_direction = cgbc_gpio_get_direction;
169	chip->get = cgbc_gpio_get;
170	chip->set = cgbc_gpio_set;
171	chip->ngpio = CGBC_GPIO_NGPIO;
172
173	ret = devm_mutex_init(dev, &gpio->lock);
174	if (ret)
175		return ret;
176
177	ret = devm_gpiochip_add_data(dev, chip, gpio);
178	if (ret)
179		return dev_err_probe(dev, ret, "Could not register GPIO chip\n");
180
181	return 0;
182}
183
184static struct platform_driver cgbc_gpio_driver = {
185	.driver = {
186		.name = "cgbc-gpio",
187	},
188	.probe	= cgbc_gpio_probe,
189};
190
191module_platform_driver(cgbc_gpio_driver);
192
193MODULE_DESCRIPTION("Congatec Board Controller GPIO Driver");
194MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
195MODULE_LICENSE("GPL");
196MODULE_ALIAS("platform:cgbc-gpio");