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
46static 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
52static 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
58static 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
63static const struct regmap_access_table rd_table = {
64	.yes_ranges = rd_range,
65	.n_yes_ranges = ARRAY_SIZE(rd_range),
66};
67
68static const struct regmap_access_table wr_table = {
69	.yes_ranges = wr_range,
70	.n_yes_ranges = ARRAY_SIZE(wr_range),
71};
72
73static const struct regmap_access_table volatile_table = {
74	.yes_ranges = volatile_range,
75	.n_yes_ranges = ARRAY_SIZE(volatile_range),
76};
77
78static 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_MAPLE,
88	.num_reg_defaults_raw = FXL6408_REG_INT_STS + 1,
89};
90
91static 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
104static 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
134static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {
135	{ .compatible = "fcs,fxl6408" },
136	{ }
137};
138MODULE_DEVICE_TABLE(of, fxl6408_dt_ids);
139
140static const struct i2c_device_id fxl6408_id[] = {
141	{ "fxl6408", 0 },
142	{ }
143};
144MODULE_DEVICE_TABLE(i2c, fxl6408_id);
145
146static 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};
154module_i2c_driver(fxl6408_driver);
155
156MODULE_AUTHOR("Emanuele Ghidoli <emanuele.ghidoli@toradex.com>");
157MODULE_DESCRIPTION("FXL6408 GPIO driver");
158MODULE_LICENSE("GPL");
159