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 return !(reg & TS4900_GPIO_OE);
48 }
49
ts4900_gpio_direction_input(struct gpio_chip * chip,unsigned int offset)50 static 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
ts4900_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)62 static 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
ts4900_gpio_get(struct gpio_chip * chip,unsigned int offset)77 static 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, ®);
83
84 return !!(reg & priv->input_bit);
85 }
86
ts4900_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)87 static 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
99 static const struct regmap_config ts4900_regmap_config = {
100 .reg_bits = 16,
101 .val_bits = 8,
102 };
103
104 static 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
116 static 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 };
126 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
127
ts4900_gpio_probe(struct i2c_client * client,const struct i2c_device_id * id)128 static 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
167 static const struct i2c_device_id ts4900_gpio_id_table[] = {
168 { "ts4900-gpio", },
169 { /* sentinel */ }
170 };
171 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
172
173 static 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 };
181 module_i2c_driver(ts4900_gpio_driver);
182
183 MODULE_AUTHOR("Technologic Systems");
184 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
185 MODULE_LICENSE("GPL");
186
