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
25 struct ts4900_gpio_priv {
26 struct regmap *regmap;
27 struct gpio_chip gpio_chip;
28 unsigned int input_bit;
29 };
30
ts4900_gpio_get_direction(struct gpio_chip * chip,unsigned int offset)31 static 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, ®);
38
39 if (reg & TS4900_GPIO_OE)
40 return GPIO_LINE_DIRECTION_OUT;
41
42 return GPIO_LINE_DIRECTION_IN;
43 }
44
ts4900_gpio_direction_input(struct gpio_chip * chip,unsigned int offset)45 static 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
ts4900_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)57 static 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, ®);
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
ts4900_gpio_get(struct gpio_chip * chip,unsigned int offset)88 static 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, ®);
94
95 return !!(reg & priv->input_bit);
96 }
97
ts4900_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)98 static 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
110 static const struct regmap_config ts4900_regmap_config = {
111 .reg_bits = 16,
112 .val_bits = 8,
113 };
114
115 static 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
127 static 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 };
137 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
138
ts4900_gpio_probe(struct i2c_client * client)139 static 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
177 static const struct i2c_device_id ts4900_gpio_id_table[] = {
178 { "ts4900-gpio", },
179 { /* sentinel */ }
180 };
181 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
182
183 static 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 };
191 module_i2c_driver(ts4900_gpio_driver);
192
193 MODULE_AUTHOR("Technologic Systems");
194 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
195 MODULE_LICENSE("GPL");
196