gpio-cgbc.c

  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 int __cgbc_gpio_set(struct gpio_chip *chip, unsigned int offset,
 55			   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 ret;
 65
 66	if (value)
 67		val |= BIT(offset % 8);
 68	else
 69		val &= ~(BIT(offset % 8));
 70
 71	return cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_SET, (offset > 7) ? 1 : 0, val, &val);
 72}
 73
 74static int cgbc_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
 75{
 76	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
 77
 78	guard(mutex)(&gpio->lock);
 79
 80	return __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	int ret;
120
121	guard(mutex)(&gpio->lock);
122
123	ret = __cgbc_gpio_set(chip, offset, value);
124	if (ret)
125		return ret;
126
127	return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_OUT);
128}
129
130static int cgbc_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
131{
132	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
133	struct cgbc_device_data *cgbc = gpio->cgbc;
134	int ret;
135	u8 val;
136
137	scoped_guard(mutex, &gpio->lock)
138		ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
139
140	if (ret)
141		return ret;
142
143	if (val & BIT(offset % 8))
144		return GPIO_LINE_DIRECTION_OUT;
145	else
146		return GPIO_LINE_DIRECTION_IN;
147}
148
149static int cgbc_gpio_probe(struct platform_device *pdev)
150{
151	struct device *dev = &pdev->dev;
152	struct cgbc_device_data *cgbc = dev_get_drvdata(dev->parent);
153	struct cgbc_gpio_data *gpio;
154	struct gpio_chip *chip;
155	int ret;
156
157	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
158	if (!gpio)
159		return -ENOMEM;
160
161	gpio->cgbc = cgbc;
162
163	platform_set_drvdata(pdev, gpio);
164
165	chip = &gpio->chip;
166	chip->label = dev_name(&pdev->dev);
167	chip->owner = THIS_MODULE;
168	chip->parent = dev;
169	chip->base = -1;
170	chip->direction_input = cgbc_gpio_direction_input;
171	chip->direction_output = cgbc_gpio_direction_output;
172	chip->get_direction = cgbc_gpio_get_direction;
173	chip->get = cgbc_gpio_get;
174	chip->set = cgbc_gpio_set;
175	chip->ngpio = CGBC_GPIO_NGPIO;
176
177	ret = devm_mutex_init(dev, &gpio->lock);
178	if (ret)
179		return ret;
180
181	ret = devm_gpiochip_add_data(dev, chip, gpio);
182	if (ret)
183		return dev_err_probe(dev, ret, "Could not register GPIO chip\n");
184
185	return 0;
186}
187
188static struct platform_driver cgbc_gpio_driver = {
189	.driver = {
190		.name = "cgbc-gpio",
191	},
192	.probe	= cgbc_gpio_probe,
193};
194
195module_platform_driver(cgbc_gpio_driver);
196
197MODULE_DESCRIPTION("Congatec Board Controller GPIO Driver");
198MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
199MODULE_LICENSE("GPL");
200MODULE_ALIAS("platform:cgbc-gpio");