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_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
38 static const struct mux_control_ops mux_gpio_ops = {
39 .set = mux_gpio_set,
40 };
41
42 static const struct of_device_id mux_gpio_dt_ids[] = {
43 { .compatible = "gpio-mux", },
44 { /* sentinel */ }
45 };
46 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
47
mux_gpio_probe(struct platform_device * pdev)48 static 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
95 static 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 };
102 module_platform_driver(mux_gpio_driver);
103
104 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
105 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
106 MODULE_LICENSE("GPL v2");
107