1 /*
2 * Digital I/O driver for Technologic Systems I2C FPGA Core
3 *
4 * Copyright (C) 2015, 2018 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 /* Only clear the OE bit here, requires a RMW. Prevents potential issue
56 * with OE and data getting to the physical pin at different times.
57 */
58 return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0);
59 }
60
ts4900_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)61 static int ts4900_gpio_direction_output(struct gpio_chip *chip,
62 unsigned int offset, int value)
63 {
64 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
65 unsigned int reg;
66 int ret;
67
68 /* If changing from an input to an output, we need to first set the
69 * proper data bit to what is requested and then set OE bit. This
70 * prevents a glitch that can occur on the IO line
71 */
72 regmap_read(priv->regmap, offset, ®);
73 if (!(reg & TS4900_GPIO_OE)) {
74 if (value)
75 reg = TS4900_GPIO_OUT;
76 else
77 reg &= ~TS4900_GPIO_OUT;
78
79 regmap_write(priv->regmap, offset, reg);
80 }
81
82 if (value)
83 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
84 TS4900_GPIO_OUT);
85 else
86 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
87
88 return ret;
89 }
90
ts4900_gpio_get(struct gpio_chip * chip,unsigned int offset)91 static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
92 {
93 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
94 unsigned int reg;
95
96 regmap_read(priv->regmap, offset, ®);
97
98 return !!(reg & priv->input_bit);
99 }
100
ts4900_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)101 static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
102 int value)
103 {
104 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
105
106 if (value)
107 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
108 TS4900_GPIO_OUT);
109 else
110 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
111 }
112
113 static const struct regmap_config ts4900_regmap_config = {
114 .reg_bits = 16,
115 .val_bits = 8,
116 };
117
118 static const struct gpio_chip template_chip = {
119 .label = "ts4900-gpio",
120 .owner = THIS_MODULE,
121 .get_direction = ts4900_gpio_get_direction,
122 .direction_input = ts4900_gpio_direction_input,
123 .direction_output = ts4900_gpio_direction_output,
124 .get = ts4900_gpio_get,
125 .set = ts4900_gpio_set,
126 .base = -1,
127 .can_sleep = true,
128 };
129
130 static const struct of_device_id ts4900_gpio_of_match_table[] = {
131 {
132 .compatible = "technologic,ts4900-gpio",
133 .data = (void *)TS4900_GPIO_IN,
134 }, {
135 .compatible = "technologic,ts7970-gpio",
136 .data = (void *)TS7970_GPIO_IN,
137 },
138 { /* sentinel */ },
139 };
140 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
141
ts4900_gpio_probe(struct i2c_client * client,const struct i2c_device_id * id)142 static int ts4900_gpio_probe(struct i2c_client *client,
143 const struct i2c_device_id *id)
144 {
145 struct ts4900_gpio_priv *priv;
146 u32 ngpio;
147 int ret;
148
149 if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
150 ngpio = DEFAULT_PIN_NUMBER;
151
152 priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
153 if (!priv)
154 return -ENOMEM;
155
156 priv->gpio_chip = template_chip;
157 priv->gpio_chip.label = "ts4900-gpio";
158 priv->gpio_chip.ngpio = ngpio;
159 priv->gpio_chip.parent = &client->dev;
160 priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
161
162 priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
163 if (IS_ERR(priv->regmap)) {
164 ret = PTR_ERR(priv->regmap);
165 dev_err(&client->dev, "Failed to allocate register map: %d\n",
166 ret);
167 return ret;
168 }
169
170 ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
171 if (ret < 0) {
172 dev_err(&client->dev, "Unable to register gpiochip\n");
173 return ret;
174 }
175
176 i2c_set_clientdata(client, priv);
177
178 return 0;
179 }
180
181 static const struct i2c_device_id ts4900_gpio_id_table[] = {
182 { "ts4900-gpio", },
183 { /* sentinel */ }
184 };
185 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
186
187 static struct i2c_driver ts4900_gpio_driver = {
188 .driver = {
189 .name = "ts4900-gpio",
190 .of_match_table = ts4900_gpio_of_match_table,
191 },
192 .probe = ts4900_gpio_probe,
193 .id_table = ts4900_gpio_id_table,
194 };
195 module_i2c_driver(ts4900_gpio_driver);
196
197 MODULE_AUTHOR("Technologic Systems");
198 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
199 MODULE_LICENSE("GPL");
200