1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * FXL6408 GPIO driver
4 *
5 * Copyright 2023 Toradex
6 *
7 * Author: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
8 */
9
10 #include <linux/err.h>
11 #include <linux/gpio/regmap.h>
12 #include <linux/i2c.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/regmap.h>
16
17 #define FXL6408_REG_DEVICE_ID 0x01
18 #define FXL6408_MF_FAIRCHILD 0b101
19 #define FXL6408_MF_SHIFT 5
20
21 /* Bits set here indicate that the GPIO is an output. */
22 #define FXL6408_REG_IO_DIR 0x03
23
24 /*
25 * Bits set here, when the corresponding bit of IO_DIR is set, drive
26 * the output high instead of low.
27 */
28 #define FXL6408_REG_OUTPUT 0x05
29
30 /* Bits here make the output High-Z, instead of the OUTPUT value. */
31 #define FXL6408_REG_OUTPUT_HIGH_Z 0x07
32
33 /* Returns the current status (1 = HIGH) of the input pins. */
34 #define FXL6408_REG_INPUT_STATUS 0x0f
35
36 /*
37 * Return the current interrupt status
38 * This bit is HIGH if input GPIO != default state (register 09h).
39 * The flag is cleared after being read (bit returns to 0).
40 * The input must go back to default state and change again before this flag is raised again.
41 */
42 #define FXL6408_REG_INT_STS 0x13
43
44 #define FXL6408_NGPIO 8
45
46 static const struct regmap_range rd_range[] = {
47 { FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
48 { FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
49 { FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },
50 };
51
52 static const struct regmap_range wr_range[] = {
53 { FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
54 { FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
55 { FXL6408_REG_OUTPUT_HIGH_Z, FXL6408_REG_OUTPUT_HIGH_Z },
56 };
57
58 static const struct regmap_range volatile_range[] = {
59 { FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
60 { FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },
61 };
62
63 static const struct regmap_access_table rd_table = {
64 .yes_ranges = rd_range,
65 .n_yes_ranges = ARRAY_SIZE(rd_range),
66 };
67
68 static const struct regmap_access_table wr_table = {
69 .yes_ranges = wr_range,
70 .n_yes_ranges = ARRAY_SIZE(wr_range),
71 };
72
73 static const struct regmap_access_table volatile_table = {
74 .yes_ranges = volatile_range,
75 .n_yes_ranges = ARRAY_SIZE(volatile_range),
76 };
77
78 static const struct regmap_config regmap = {
79 .reg_bits = 8,
80 .val_bits = 8,
81
82 .max_register = FXL6408_REG_INT_STS,
83 .wr_table = &wr_table,
84 .rd_table = &rd_table,
85 .volatile_table = &volatile_table,
86
87 .cache_type = REGCACHE_RBTREE,
88 .num_reg_defaults_raw = FXL6408_REG_INT_STS + 1,
89 };
90
fxl6408_identify(struct device * dev,struct regmap * regmap)91 static int fxl6408_identify(struct device *dev, struct regmap *regmap)
92 {
93 int val, ret;
94
95 ret = regmap_read(regmap, FXL6408_REG_DEVICE_ID, &val);
96 if (ret)
97 return dev_err_probe(dev, ret, "error reading DEVICE_ID\n");
98 if (val >> FXL6408_MF_SHIFT != FXL6408_MF_FAIRCHILD)
99 return dev_err_probe(dev, -ENODEV, "invalid device id 0x%02x\n", val);
100
101 return 0;
102 }
103
fxl6408_probe(struct i2c_client * client)104 static int fxl6408_probe(struct i2c_client *client)
105 {
106 struct device *dev = &client->dev;
107 int ret;
108 struct gpio_regmap_config gpio_config = {
109 .parent = dev,
110 .ngpio = FXL6408_NGPIO,
111 .reg_dat_base = GPIO_REGMAP_ADDR(FXL6408_REG_INPUT_STATUS),
112 .reg_set_base = GPIO_REGMAP_ADDR(FXL6408_REG_OUTPUT),
113 .reg_dir_out_base = GPIO_REGMAP_ADDR(FXL6408_REG_IO_DIR),
114 .ngpio_per_reg = FXL6408_NGPIO,
115 };
116
117 gpio_config.regmap = devm_regmap_init_i2c(client, ®map);
118 if (IS_ERR(gpio_config.regmap))
119 return dev_err_probe(dev, PTR_ERR(gpio_config.regmap),
120 "failed to allocate register map\n");
121
122 ret = fxl6408_identify(dev, gpio_config.regmap);
123 if (ret)
124 return ret;
125
126 /* Disable High-Z of outputs, so that our OUTPUT updates actually take effect. */
127 ret = regmap_write(gpio_config.regmap, FXL6408_REG_OUTPUT_HIGH_Z, 0);
128 if (ret)
129 return dev_err_probe(dev, ret, "failed to write 'output high Z' register\n");
130
131 return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
132 }
133
134 static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {
135 { .compatible = "fcs,fxl6408" },
136 { }
137 };
138 MODULE_DEVICE_TABLE(of, fxl6408_dt_ids);
139
140 static const struct i2c_device_id fxl6408_id[] = {
141 { "fxl6408", 0 },
142 { }
143 };
144 MODULE_DEVICE_TABLE(i2c, fxl6408_id);
145
146 static struct i2c_driver fxl6408_driver = {
147 .driver = {
148 .name = "fxl6408",
149 .of_match_table = fxl6408_dt_ids,
150 },
151 .probe = fxl6408_probe,
152 .id_table = fxl6408_id,
153 };
154 module_i2c_driver(fxl6408_driver);
155
156 MODULE_AUTHOR("Emanuele Ghidoli <emanuele.ghidoli@toradex.com>");
157 MODULE_DESCRIPTION("FXL6408 GPIO driver");
158 MODULE_LICENSE("GPL");
159