1/*
  2 * Digital I/O driver for Technologic Systems I2C FPGA Core
  3 *
  4 * Copyright (C) 2015 Technologic Systems
  5 * Copyright (C) 2016 Savoir-Faire Linux
  6 *
  7 * This program is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 12 * kind, whether expressed or implied; without even the implied warranty
 13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License version 2 for more details.
 15 */
 16
 17#include <linux/gpio/driver.h>
 18#include <linux/i2c.h>
 19#include <linux/of_device.h>
 20#include <linux/module.h>
 21#include <linux/regmap.h>
 22
 23#define DEFAULT_PIN_NUMBER	32
 24/*
 25 * Register bits used by the GPIO device
 26 * Some boards, such as TS-7970 do not have a separate input bit
 27 */
 28#define TS4900_GPIO_OE		0x01
 29#define TS4900_GPIO_OUT		0x02
 30#define TS4900_GPIO_IN		0x04
 31#define TS7970_GPIO_IN		0x02
 32
 33struct ts4900_gpio_priv {
 34	struct regmap *regmap;
 35	struct gpio_chip gpio_chip;
 36	unsigned int input_bit;
 37};
 38
 39static int ts4900_gpio_get_direction(struct gpio_chip *chip,
 40				     unsigned int offset)
 41{
 42	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 43	unsigned int reg;
 44
 45	regmap_read(priv->regmap, offset, &reg);
 46
 47	return !(reg & TS4900_GPIO_OE);
 48}
 49
 50static int ts4900_gpio_direction_input(struct gpio_chip *chip,
 51				       unsigned int offset)
 52{
 53	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 54
 55	/*
 56	 * This will clear the output enable bit, the other bits are
 57	 * dontcare when this is cleared
 58	 */
 59	return regmap_write(priv->regmap, offset, 0);
 60}
 61
 62static int ts4900_gpio_direction_output(struct gpio_chip *chip,
 63					unsigned int offset, int value)
 64{
 65	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 66	int ret;
 67
 68	if (value)
 69		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
 70							 TS4900_GPIO_OUT);
 71	else
 72		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
 73
 74	return ret;
 75}
 76
 77static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
 78{
 79	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 80	unsigned int reg;
 81
 82	regmap_read(priv->regmap, offset, &reg);
 83
 84	return !!(reg & priv->input_bit);
 85}
 86
 87static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
 88			    int value)
 89{
 90	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 91
 92	if (value)
 93		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
 94				   TS4900_GPIO_OUT);
 95	else
 96		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
 97}
 98
 99static const struct regmap_config ts4900_regmap_config = {
100	.reg_bits = 16,
101	.val_bits = 8,
102};
103
104static const struct gpio_chip template_chip = {
105	.label			= "ts4900-gpio",
106	.owner			= THIS_MODULE,
107	.get_direction		= ts4900_gpio_get_direction,
108	.direction_input	= ts4900_gpio_direction_input,
109	.direction_output	= ts4900_gpio_direction_output,
110	.get			= ts4900_gpio_get,
111	.set			= ts4900_gpio_set,
112	.base			= -1,
113	.can_sleep		= true,
114};
115
116static const struct of_device_id ts4900_gpio_of_match_table[] = {
117	{
118		.compatible = "technologic,ts4900-gpio",
119		.data = (void *)TS4900_GPIO_IN,
120	}, {
121		.compatible = "technologic,ts7970-gpio",
122		.data = (void *)TS7970_GPIO_IN,
123	},
124	{ /* sentinel */ },
125};
126MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
127
128static int ts4900_gpio_probe(struct i2c_client *client,
129			const struct i2c_device_id *id)
130{
131	struct ts4900_gpio_priv *priv;
132	u32 ngpio;
133	int ret;
134
135	if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
136		ngpio = DEFAULT_PIN_NUMBER;
137
138	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
139	if (!priv)
140		return -ENOMEM;
141
142	priv->gpio_chip = template_chip;
143	priv->gpio_chip.label = "ts4900-gpio";
144	priv->gpio_chip.ngpio = ngpio;
145	priv->gpio_chip.parent = &client->dev;
146	priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
147
148	priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
149	if (IS_ERR(priv->regmap)) {
150		ret = PTR_ERR(priv->regmap);
151		dev_err(&client->dev, "Failed to allocate register map: %d\n",
152			ret);
153		return ret;
154	}
155
156	ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
157	if (ret < 0) {
158		dev_err(&client->dev, "Unable to register gpiochip\n");
159		return ret;
160	}
161
162	i2c_set_clientdata(client, priv);
163
164	return 0;
165}
166
167static const struct i2c_device_id ts4900_gpio_id_table[] = {
168	{ "ts4900-gpio", },
169	{ /* sentinel */ }
170};
171MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
172
173static struct i2c_driver ts4900_gpio_driver = {
174	.driver = {
175		.name = "ts4900-gpio",
176		.of_match_table = ts4900_gpio_of_match_table,
177	},
178	.probe = ts4900_gpio_probe,
179	.id_table = ts4900_gpio_id_table,
180};
181module_i2c_driver(ts4900_gpio_driver);
182
183MODULE_AUTHOR("Technologic Systems");
184MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
185MODULE_LICENSE("GPL");