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1 | /* | |
2 | * GPIO-controlled multiplexer driver | |
3 | * | |
4 | * Copyright (C) 2017 Axentia Technologies AB | |
5 | * | |
6 | * Author: Peter Rosin <peda@axentia.se> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | */ | |
12 | ||
13 | #include <linux/err.h> | |
14 | #include <linux/gpio/consumer.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/mux/driver.h> | |
17 | #include <linux/of_platform.h> | |
18 | #include <linux/platform_device.h> | |
19 | #include <linux/property.h> | |
20 | ||
21 | struct mux_gpio { | |
22 | struct gpio_descs *gpios; | |
23 | int *val; | |
24 | }; | |
25 | ||
26 | static int mux_gpio_set(struct mux_control *mux, int state) | |
27 | { | |
28 | struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip); | |
29 | int i; | |
30 | ||
31 | for (i = 0; i < mux_gpio->gpios->ndescs; i++) | |
32 | mux_gpio->val[i] = (state >> i) & 1; | |
33 | ||
34 | gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs, | |
35 | mux_gpio->gpios->desc, | |
36 | mux_gpio->val); | |
37 | ||
38 | return 0; | |
39 | } | |
40 | ||
41 | static const struct mux_control_ops mux_gpio_ops = { | |
42 | .set = mux_gpio_set, | |
43 | }; | |
44 | ||
45 | static const struct of_device_id mux_gpio_dt_ids[] = { | |
46 | { .compatible = "gpio-mux", }, | |
47 | { /* sentinel */ } | |
48 | }; | |
49 | MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids); | |
50 | ||
51 | static int mux_gpio_probe(struct platform_device *pdev) | |
52 | { | |
53 | struct device *dev = &pdev->dev; | |
54 | struct mux_chip *mux_chip; | |
55 | struct mux_gpio *mux_gpio; | |
56 | int pins; | |
57 | s32 idle_state; | |
58 | int ret; | |
59 | ||
60 | pins = gpiod_count(dev, "mux"); | |
61 | if (pins < 0) | |
62 | return pins; | |
63 | ||
64 | mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) + | |
65 | pins * sizeof(*mux_gpio->val)); | |
66 | if (IS_ERR(mux_chip)) | |
67 | return PTR_ERR(mux_chip); | |
68 | ||
69 | mux_gpio = mux_chip_priv(mux_chip); | |
70 | mux_gpio->val = (int *)(mux_gpio + 1); | |
71 | mux_chip->ops = &mux_gpio_ops; | |
72 | ||
73 | mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); | |
74 | if (IS_ERR(mux_gpio->gpios)) { | |
75 | ret = PTR_ERR(mux_gpio->gpios); | |
76 | if (ret != -EPROBE_DEFER) | |
77 | dev_err(dev, "failed to get gpios\n"); | |
78 | return ret; | |
79 | } | |
80 | WARN_ON(pins != mux_gpio->gpios->ndescs); | |
81 | mux_chip->mux->states = 1 << pins; | |
82 | ||
83 | ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); | |
84 | if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { | |
85 | if (idle_state < 0 || idle_state >= mux_chip->mux->states) { | |
86 | dev_err(dev, "invalid idle-state %u\n", idle_state); | |
87 | return -EINVAL; | |
88 | } | |
89 | ||
90 | mux_chip->mux->idle_state = idle_state; | |
91 | } | |
92 | ||
93 | ret = devm_mux_chip_register(dev, mux_chip); | |
94 | if (ret < 0) | |
95 | return ret; | |
96 | ||
97 | dev_info(dev, "%u-way mux-controller registered\n", | |
98 | mux_chip->mux->states); | |
99 | ||
100 | return 0; | |
101 | } | |
102 | ||
103 | static struct platform_driver mux_gpio_driver = { | |
104 | .driver = { | |
105 | .name = "gpio-mux", | |
106 | .of_match_table = of_match_ptr(mux_gpio_dt_ids), | |
107 | }, | |
108 | .probe = mux_gpio_probe, | |
109 | }; | |
110 | module_platform_driver(mux_gpio_driver); | |
111 | ||
112 | MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); | |
113 | MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); | |
114 | MODULE_LICENSE("GPL v2"); |