1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Digital I/O driver for Technologic Systems I2C FPGA Core
  4 *
  5 * Copyright (C) 2015, 2018 Technologic Systems
  6 * Copyright (C) 2016 Savoir-Faire Linux
  7 */
  8
  9#include <linux/gpio/driver.h>
 10#include <linux/i2c.h>
 11#include <linux/of.h>
 12#include <linux/module.h>
 13#include <linux/regmap.h>
 14
 15#define DEFAULT_PIN_NUMBER	32
 16/*
 17 * Register bits used by the GPIO device
 18 * Some boards, such as TS-7970 do not have a separate input bit
 19 */
 20#define TS4900_GPIO_OE		0x01
 21#define TS4900_GPIO_OUT		0x02
 22#define TS4900_GPIO_IN		0x04
 23#define TS7970_GPIO_IN		0x02
 24
 25struct ts4900_gpio_priv {
 26	struct regmap *regmap;
 27	struct gpio_chip gpio_chip;
 28	unsigned int input_bit;
 29};
 30
 31static int ts4900_gpio_get_direction(struct gpio_chip *chip,
 32				     unsigned int offset)
 33{
 34	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 35	unsigned int reg;
 36
 37	regmap_read(priv->regmap, offset, &reg);
 38
 39	if (reg & TS4900_GPIO_OE)
 40		return GPIO_LINE_DIRECTION_OUT;
 41
 42	return GPIO_LINE_DIRECTION_IN;
 43}
 44
 45static int ts4900_gpio_direction_input(struct gpio_chip *chip,
 46				       unsigned int offset)
 47{
 48	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 49
 50	/*
 51	 * Only clear the OE bit here, requires a RMW. Prevents a potential issue
 52	 * with OE and DAT getting to the physical pin at different times.
 53	 */
 54	return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0);
 55}
 56
 57static int ts4900_gpio_direction_output(struct gpio_chip *chip,
 58					unsigned int offset, int value)
 59{
 60	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 61	unsigned int reg;
 62	int ret;
 63
 64	/*
 65	 * If changing from an input to an output, we need to first set the
 66	 * GPIO's DAT bit to what is requested and then set the OE bit. This
 67	 * prevents a glitch that can occur on the IO line.
 68	 */
 69	regmap_read(priv->regmap, offset, &reg);
 70	if (!(reg & TS4900_GPIO_OE)) {
 71		if (value)
 72			reg = TS4900_GPIO_OUT;
 73		else
 74			reg &= ~TS4900_GPIO_OUT;
 75
 76		regmap_write(priv->regmap, offset, reg);
 77	}
 78
 79	if (value)
 80		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
 81							 TS4900_GPIO_OUT);
 82	else
 83		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
 84
 85	return ret;
 86}
 87
 88static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
 89{
 90	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 91	unsigned int reg;
 92
 93	regmap_read(priv->regmap, offset, &reg);
 94
 95	return !!(reg & priv->input_bit);
 96}
 97
 98static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
 99			    int value)
100{
101	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
102
103	if (value)
104		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
105				   TS4900_GPIO_OUT);
106	else
107		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
108}
109
110static const struct regmap_config ts4900_regmap_config = {
111	.reg_bits = 16,
112	.val_bits = 8,
113};
114
115static const struct gpio_chip template_chip = {
116	.label			= "ts4900-gpio",
117	.owner			= THIS_MODULE,
118	.get_direction		= ts4900_gpio_get_direction,
119	.direction_input	= ts4900_gpio_direction_input,
120	.direction_output	= ts4900_gpio_direction_output,
121	.get			= ts4900_gpio_get,
122	.set			= ts4900_gpio_set,
123	.base			= -1,
124	.can_sleep		= true,
125};
126
127static const struct of_device_id ts4900_gpio_of_match_table[] = {
128	{
129		.compatible = "technologic,ts4900-gpio",
130		.data = (void *)TS4900_GPIO_IN,
131	}, {
132		.compatible = "technologic,ts7970-gpio",
133		.data = (void *)TS7970_GPIO_IN,
134	},
135	{ /* sentinel */ },
136};
137MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
138
139static int ts4900_gpio_probe(struct i2c_client *client)
140{
141	struct ts4900_gpio_priv *priv;
142	u32 ngpio;
143	int ret;
144
145	if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
146		ngpio = DEFAULT_PIN_NUMBER;
147
148	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
149	if (!priv)
150		return -ENOMEM;
151
152	priv->gpio_chip = template_chip;
153	priv->gpio_chip.label = "ts4900-gpio";
154	priv->gpio_chip.ngpio = ngpio;
155	priv->gpio_chip.parent = &client->dev;
156	priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
157
158	priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
159	if (IS_ERR(priv->regmap)) {
160		ret = PTR_ERR(priv->regmap);
161		dev_err(&client->dev, "Failed to allocate register map: %d\n",
162			ret);
163		return ret;
164	}
165
166	ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
167	if (ret < 0) {
168		dev_err(&client->dev, "Unable to register gpiochip\n");
169		return ret;
170	}
171
172	i2c_set_clientdata(client, priv);
173
174	return 0;
175}
176
177static const struct i2c_device_id ts4900_gpio_id_table[] = {
178	{ "ts4900-gpio", },
179	{ /* sentinel */ }
180};
181MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
182
183static struct i2c_driver ts4900_gpio_driver = {
184	.driver = {
185		.name = "ts4900-gpio",
186		.of_match_table = ts4900_gpio_of_match_table,
187	},
188	.probe = ts4900_gpio_probe,
189	.id_table = ts4900_gpio_id_table,
190};
191module_i2c_driver(ts4900_gpio_driver);
192
193MODULE_AUTHOR("Technologic Systems");
194MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
195MODULE_LICENSE("GPL");