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");
196