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
33 struct ts4900_gpio_priv {
34 struct regmap *regmap;
35 struct gpio_chip gpio_chip;
36 unsigned int input_bit;
37 };
38
ts4900_gpio_get_direction(struct gpio_chip * chip,unsigned int offset)39 static 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, ®);
46
47 if (reg & TS4900_GPIO_OE)
48 return GPIO_LINE_DIRECTION_OUT;
49
50 return GPIO_LINE_DIRECTION_IN;
51 }
52
ts4900_gpio_direction_input(struct gpio_chip * chip,unsigned int offset)53 static 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
ts4900_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)65 static 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
ts4900_gpio_get(struct gpio_chip * chip,unsigned int offset)80 static 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, ®);
86
87 return !!(reg & priv->input_bit);
88 }
89
ts4900_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)90 static 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
102 static const struct regmap_config ts4900_regmap_config = {
103 .reg_bits = 16,
104 .val_bits = 8,
105 };
106
107 static 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
119 static 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 };
129 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
130
ts4900_gpio_probe(struct i2c_client * client,const struct i2c_device_id * id)131 static 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
170 static const struct i2c_device_id ts4900_gpio_id_table[] = {
171 { "ts4900-gpio", },
172 { /* sentinel */ }
173 };
174 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
175
176 static 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 };
184 module_i2c_driver(ts4900_gpio_driver);
185
186 MODULE_AUTHOR("Technologic Systems");
187 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
188 MODULE_LICENSE("GPL");
189