1// SPDX-License-Identifier: GPL-2.0
2/*
3 * GPIO-controlled multiplexer driver
4 *
5 * Copyright (C) 2017 Axentia Technologies AB
6 *
7 * Author: Peter Rosin <peda@axentia.se>
8 */
9
10#include <linux/bitmap.h>
11#include <linux/err.h>
12#include <linux/gpio/consumer.h>
13#include <linux/mod_devicetable.h>
14#include <linux/module.h>
15#include <linux/mux/driver.h>
16#include <linux/platform_device.h>
17#include <linux/property.h>
18
19struct mux_gpio {
20	struct gpio_descs *gpios;
21};
22
23static int mux_gpio_set(struct mux_control *mux, int state)
24{
25	struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
26	DECLARE_BITMAP(values, BITS_PER_TYPE(state));
27	u32 value = state;
28
29	bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));
30
31	gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
32				       mux_gpio->gpios->desc,
33				       mux_gpio->gpios->info, values);
34
35	return 0;
36}
37
38static const struct mux_control_ops mux_gpio_ops = {
39	.set = mux_gpio_set,
40};
41
42static const struct of_device_id mux_gpio_dt_ids[] = {
43	{ .compatible = "gpio-mux", },
44	{ /* sentinel */ }
45};
46MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
47
48static int mux_gpio_probe(struct platform_device *pdev)
49{
50	struct device *dev = &pdev->dev;
51	struct mux_chip *mux_chip;
52	struct mux_gpio *mux_gpio;
53	int pins;
54	s32 idle_state;
55	int ret;
56
57	pins = gpiod_count(dev, "mux");
58	if (pins < 0)
59		return pins;
60
61	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
62	if (IS_ERR(mux_chip))
63		return PTR_ERR(mux_chip);
64
65	mux_gpio = mux_chip_priv(mux_chip);
66	mux_chip->ops = &mux_gpio_ops;
67
68	mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
69	if (IS_ERR(mux_gpio->gpios))
70		return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
71				     "failed to get gpios\n");
72	WARN_ON(pins != mux_gpio->gpios->ndescs);
73	mux_chip->mux->states = BIT(pins);
74
75	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
76	if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
77		if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
78			dev_err(dev, "invalid idle-state %u\n", idle_state);
79			return -EINVAL;
80		}
81
82		mux_chip->mux->idle_state = idle_state;
83	}
84
85	ret = devm_mux_chip_register(dev, mux_chip);
86	if (ret < 0)
87		return ret;
88
89	dev_info(dev, "%u-way mux-controller registered\n",
90		 mux_chip->mux->states);
91
92	return 0;
93}
94
95static struct platform_driver mux_gpio_driver = {
96	.driver = {
97		.name = "gpio-mux",
98		.of_match_table	= mux_gpio_dt_ids,
99	},
100	.probe = mux_gpio_probe,
101};
102module_platform_driver(mux_gpio_driver);
103
104MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
105MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
106MODULE_LICENSE("GPL v2");
107