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	if (reg & TS4900_GPIO_OE)
 48		return GPIO_LINE_DIRECTION_OUT;
 49
 50	return GPIO_LINE_DIRECTION_IN;
 51}
 52
 53static int ts4900_gpio_direction_input(struct gpio_chip *chip,
 54				       unsigned int offset)
 55{
 56	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 57
 58	/*
 59	 * This will clear the output enable bit, the other bits are
 60	 * dontcare when this is cleared
 61	 */
 62	return regmap_write(priv->regmap, offset, 0);
 63}
 64
 65static int ts4900_gpio_direction_output(struct gpio_chip *chip,
 66					unsigned int offset, int value)
 67{
 68	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 69	int ret;
 70
 71	if (value)
 72		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
 73							 TS4900_GPIO_OUT);
 74	else
 75		ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
 76
 77	return ret;
 78}
 79
 80static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
 81{
 82	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 83	unsigned int reg;
 84
 85	regmap_read(priv->regmap, offset, &reg);
 86
 87	return !!(reg & priv->input_bit);
 88}
 89
 90static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
 91			    int value)
 92{
 93	struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 94
 95	if (value)
 96		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
 97				   TS4900_GPIO_OUT);
 98	else
 99		regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
100}
101
102static const struct regmap_config ts4900_regmap_config = {
103	.reg_bits = 16,
104	.val_bits = 8,
105};
106
107static const struct gpio_chip template_chip = {
108	.label			= "ts4900-gpio",
109	.owner			= THIS_MODULE,
110	.get_direction		= ts4900_gpio_get_direction,
111	.direction_input	= ts4900_gpio_direction_input,
112	.direction_output	= ts4900_gpio_direction_output,
113	.get			= ts4900_gpio_get,
114	.set			= ts4900_gpio_set,
115	.base			= -1,
116	.can_sleep		= true,
117};
118
119static const struct of_device_id ts4900_gpio_of_match_table[] = {
120	{
121		.compatible = "technologic,ts4900-gpio",
122		.data = (void *)TS4900_GPIO_IN,
123	}, {
124		.compatible = "technologic,ts7970-gpio",
125		.data = (void *)TS7970_GPIO_IN,
126	},
127	{ /* sentinel */ },
128};
129MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
130
131static int ts4900_gpio_probe(struct i2c_client *client,
132			const struct i2c_device_id *id)
133{
134	struct ts4900_gpio_priv *priv;
135	u32 ngpio;
136	int ret;
137
138	if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
139		ngpio = DEFAULT_PIN_NUMBER;
140
141	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
142	if (!priv)
143		return -ENOMEM;
144
145	priv->gpio_chip = template_chip;
146	priv->gpio_chip.label = "ts4900-gpio";
147	priv->gpio_chip.ngpio = ngpio;
148	priv->gpio_chip.parent = &client->dev;
149	priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
150
151	priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
152	if (IS_ERR(priv->regmap)) {
153		ret = PTR_ERR(priv->regmap);
154		dev_err(&client->dev, "Failed to allocate register map: %d\n",
155			ret);
156		return ret;
157	}
158
159	ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
160	if (ret < 0) {
161		dev_err(&client->dev, "Unable to register gpiochip\n");
162		return ret;
163	}
164
165	i2c_set_clientdata(client, priv);
166
167	return 0;
168}
169
170static const struct i2c_device_id ts4900_gpio_id_table[] = {
171	{ "ts4900-gpio", },
172	{ /* sentinel */ }
173};
174MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
175
176static struct i2c_driver ts4900_gpio_driver = {
177	.driver = {
178		.name = "ts4900-gpio",
179		.of_match_table = ts4900_gpio_of_match_table,
180	},
181	.probe = ts4900_gpio_probe,
182	.id_table = ts4900_gpio_id_table,
183};
184module_i2c_driver(ts4900_gpio_driver);
185
186MODULE_AUTHOR("Technologic Systems");
187MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
188MODULE_LICENSE("GPL");