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/err.h>
11#include <linux/gpio/consumer.h>
12#include <linux/module.h>
13#include <linux/mux/driver.h>
14#include <linux/of_platform.h>
15#include <linux/platform_device.h>
16#include <linux/property.h>
17
18struct mux_gpio {
19 struct gpio_descs *gpios;
20};
21
22static int mux_gpio_set(struct mux_control *mux, int state)
23{
24 struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
25 DECLARE_BITMAP(values, BITS_PER_TYPE(state));
26
27 values[0] = state;
28
29 gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
30 mux_gpio->gpios->desc,
31 mux_gpio->gpios->info, values);
32
33 return 0;
34}
35
36static const struct mux_control_ops mux_gpio_ops = {
37 .set = mux_gpio_set,
38};
39
40static const struct of_device_id mux_gpio_dt_ids[] = {
41 { .compatible = "gpio-mux", },
42 { /* sentinel */ }
43};
44MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
45
46static int mux_gpio_probe(struct platform_device *pdev)
47{
48 struct device *dev = &pdev->dev;
49 struct mux_chip *mux_chip;
50 struct mux_gpio *mux_gpio;
51 int pins;
52 s32 idle_state;
53 int ret;
54
55 pins = gpiod_count(dev, "mux");
56 if (pins < 0)
57 return pins;
58
59 mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
60 if (IS_ERR(mux_chip))
61 return PTR_ERR(mux_chip);
62
63 mux_gpio = mux_chip_priv(mux_chip);
64 mux_chip->ops = &mux_gpio_ops;
65
66 mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
67 if (IS_ERR(mux_gpio->gpios)) {
68 ret = PTR_ERR(mux_gpio->gpios);
69 if (ret != -EPROBE_DEFER)
70 dev_err(dev, "failed to get gpios\n");
71 return ret;
72 }
73 WARN_ON(pins != mux_gpio->gpios->ndescs);
74 mux_chip->mux->states = 1 << pins;
75
76 ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
77 if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
78 if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
79 dev_err(dev, "invalid idle-state %u\n", idle_state);
80 return -EINVAL;
81 }
82
83 mux_chip->mux->idle_state = idle_state;
84 }
85
86 ret = devm_mux_chip_register(dev, mux_chip);
87 if (ret < 0)
88 return ret;
89
90 dev_info(dev, "%u-way mux-controller registered\n",
91 mux_chip->mux->states);
92
93 return 0;
94}
95
96static struct platform_driver mux_gpio_driver = {
97 .driver = {
98 .name = "gpio-mux",
99 .of_match_table = of_match_ptr(mux_gpio_dt_ids),
100 },
101 .probe = mux_gpio_probe,
102};
103module_platform_driver(mux_gpio_driver);
104
105MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
106MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
107MODULE_LICENSE("GPL v2");
108