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 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 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 ret = PTR_ERR(mux_gpio->gpios); 71 if (ret != -EPROBE_DEFER) 72 dev_err(dev, "failed to get gpios\n"); 73 return ret; 74 } 75 WARN_ON(pins != mux_gpio->gpios->ndescs); 76 mux_chip->mux->states = BIT(pins); 77 78 ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); 79 if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { 80 if (idle_state < 0 || idle_state >= mux_chip->mux->states) { 81 dev_err(dev, "invalid idle-state %u\n", idle_state); 82 return -EINVAL; 83 } 84 85 mux_chip->mux->idle_state = idle_state; 86 } 87 88 ret = devm_mux_chip_register(dev, mux_chip); 89 if (ret < 0) 90 return ret; 91 92 dev_info(dev, "%u-way mux-controller registered\n", 93 mux_chip->mux->states); 94 95 return 0; 96 } 97 98 static struct platform_driver mux_gpio_driver = { 99 .driver = { 100 .name = "gpio-mux", 101 .of_match_table = mux_gpio_dt_ids, 102 }, 103 .probe = mux_gpio_probe, 104 }; 105 module_platform_driver(mux_gpio_driver); 106 107 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); 108 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); 109 MODULE_LICENSE("GPL v2"); 110