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 | |
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(gc: chip); |
35 | unsigned int reg; |
36 | |
37 | regmap_read(map: priv->regmap, reg: offset, val: ®); |
38 | |
39 | if (reg & TS4900_GPIO_OE) |
40 | return GPIO_LINE_DIRECTION_OUT; |
41 | |
42 | return GPIO_LINE_DIRECTION_IN; |
43 | } |
44 | |
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(gc: 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(map: priv->regmap, reg: offset, TS4900_GPIO_OE, val: 0); |
55 | } |
56 | |
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(gc: 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(map: priv->regmap, reg: offset, val: ®); |
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(map: priv->regmap, reg: offset, val: reg); |
77 | } |
78 | |
79 | if (value) |
80 | ret = regmap_write(map: priv->regmap, reg: offset, TS4900_GPIO_OE | |
81 | TS4900_GPIO_OUT); |
82 | else |
83 | ret = regmap_write(map: priv->regmap, reg: offset, TS4900_GPIO_OE); |
84 | |
85 | return ret; |
86 | } |
87 | |
88 | static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset) |
89 | { |
90 | struct ts4900_gpio_priv *priv = gpiochip_get_data(gc: chip); |
91 | unsigned int reg; |
92 | |
93 | regmap_read(map: priv->regmap, reg: offset, val: ®); |
94 | |
95 | return !!(reg & priv->input_bit); |
96 | } |
97 | |
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(gc: chip); |
102 | |
103 | if (value) |
104 | regmap_update_bits(map: priv->regmap, reg: offset, TS4900_GPIO_OUT, |
105 | TS4900_GPIO_OUT); |
106 | else |
107 | regmap_update_bits(map: priv->regmap, reg: offset, TS4900_GPIO_OUT, val: 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 | |
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(np: client->dev.of_node, propname: "ngpios" , out_value: &ngpio)) |
146 | ngpio = DEFAULT_PIN_NUMBER; |
147 | |
148 | priv = devm_kzalloc(dev: &client->dev, size: 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(dev: &client->dev); |
157 | |
158 | priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config); |
159 | if (IS_ERR(ptr: priv->regmap)) { |
160 | ret = PTR_ERR(ptr: 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, data: 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 | |