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/err.h> 11 #include <linux/gpio/consumer.h> 12 #include <linux/module.h> 13 #include <linux/mux/driver.h> 14 #include <linux/of_platform.h> 15 #include <linux/platform_device.h> 16 #include <linux/property.h> 17 18 struct mux_gpio { 19 struct gpio_descs *gpios; 20 }; 21 22 static int mux_gpio_set(struct mux_control *mux, int state) 23 { 24 struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip); 25 DECLARE_BITMAP(values, BITS_PER_TYPE(state)); 26 27 values[0] = state; 28 29 gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs, 30 mux_gpio->gpios->desc, values); 31 32 return 0; 33 } 34 35 static const struct mux_control_ops mux_gpio_ops = { 36 .set = mux_gpio_set, 37 }; 38 39 static const struct of_device_id mux_gpio_dt_ids[] = { 40 { .compatible = "gpio-mux", }, 41 { /* sentinel */ } 42 }; 43 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids); 44 45 static int mux_gpio_probe(struct platform_device *pdev) 46 { 47 struct device *dev = &pdev->dev; 48 struct mux_chip *mux_chip; 49 struct mux_gpio *mux_gpio; 50 int pins; 51 s32 idle_state; 52 int ret; 53 54 pins = gpiod_count(dev, "mux"); 55 if (pins < 0) 56 return pins; 57 58 mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio)); 59 if (IS_ERR(mux_chip)) 60 return PTR_ERR(mux_chip); 61 62 mux_gpio = mux_chip_priv(mux_chip); 63 mux_chip->ops = &mux_gpio_ops; 64 65 mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); 66 if (IS_ERR(mux_gpio->gpios)) { 67 ret = PTR_ERR(mux_gpio->gpios); 68 if (ret != -EPROBE_DEFER) 69 dev_err(dev, "failed to get gpios\n"); 70 return ret; 71 } 72 WARN_ON(pins != mux_gpio->gpios->ndescs); 73 mux_chip->mux->states = 1 << 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 = of_match_ptr(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