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