xref: /openbmc/linux/drivers/gpio/gpio-fxl6408.c (revision b41cabb7)
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, &regmap);
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