| Peter Rosin | 2c089f0 | 2017-05-14 21:51:07 +0200 | [diff] [blame] | 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"); |