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
19 struct mux_gpio {
20 struct gpio_descs *gpios;
21 };
22
mux_gpio_set(struct mux_control * mux,int state)23 static 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_multi_set_value_cansleep(mux_gpio->gpios, values);
32
33 return 0;
34 }
35
36 static const struct mux_control_ops mux_gpio_ops = {
37 .set = mux_gpio_set,
38 };
39
40 static const struct of_device_id mux_gpio_dt_ids[] = {
41 { .compatible = "gpio-mux", },
42 { /* sentinel */ }
43 };
44 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
45
mux_gpio_probe(struct platform_device * pdev)46 static 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 return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
69 "failed to get gpios\n");
70 WARN_ON(pins != mux_gpio->gpios->ndescs);
71 mux_chip->mux->states = BIT(pins);
72
73 ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
74 if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
75 if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
76 dev_err(dev, "invalid idle-state %u\n", idle_state);
77 return -EINVAL;
78 }
79
80 mux_chip->mux->idle_state = idle_state;
81 }
82
83 ret = devm_mux_chip_register(dev, mux_chip);
84 if (ret < 0)
85 return ret;
86
87 dev_info(dev, "%u-way mux-controller registered\n",
88 mux_chip->mux->states);
89
90 return 0;
91 }
92
93 static struct platform_driver mux_gpio_driver = {
94 .driver = {
95 .name = "gpio-mux",
96 .of_match_table = mux_gpio_dt_ids,
97 },
98 .probe = mux_gpio_probe,
99 };
100 module_platform_driver(mux_gpio_driver);
101
102 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
103 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
104 MODULE_LICENSE("GPL v2");
105