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, 31 mux_gpio->gpios->info, values); 32 33 return 0; 34 } 35 36 static const struct mux_control_ops mux_gpio_ops = { 37 .set = mux_gpio_set, 38 }; 39 40 static const struct of_device_id mux_gpio_dt_ids[] = { 41 { .compatible = "gpio-mux", }, 42 { /* sentinel */ } 43 }; 44 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids); 45 46 static int mux_gpio_probe(struct platform_device *pdev) 47 { 48 struct device *dev = &pdev->dev; 49 struct mux_chip *mux_chip; 50 struct mux_gpio *mux_gpio; 51 int pins; 52 s32 idle_state; 53 int ret; 54 55 pins = gpiod_count(dev, "mux"); 56 if (pins < 0) 57 return pins; 58 59 mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio)); 60 if (IS_ERR(mux_chip)) 61 return PTR_ERR(mux_chip); 62 63 mux_gpio = mux_chip_priv(mux_chip); 64 mux_chip->ops = &mux_gpio_ops; 65 66 mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); 67 if (IS_ERR(mux_gpio->gpios)) { 68 ret = PTR_ERR(mux_gpio->gpios); 69 if (ret != -EPROBE_DEFER) 70 dev_err(dev, "failed to get gpios\n"); 71 return ret; 72 } 73 WARN_ON(pins != mux_gpio->gpios->ndescs); 74 mux_chip->mux->states = 1 << pins; 75 76 ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); 77 if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { 78 if (idle_state < 0 || idle_state >= mux_chip->mux->states) { 79 dev_err(dev, "invalid idle-state %u\n", idle_state); 80 return -EINVAL; 81 } 82 83 mux_chip->mux->idle_state = idle_state; 84 } 85 86 ret = devm_mux_chip_register(dev, mux_chip); 87 if (ret < 0) 88 return ret; 89 90 dev_info(dev, "%u-way mux-controller registered\n", 91 mux_chip->mux->states); 92 93 return 0; 94 } 95 96 static struct platform_driver mux_gpio_driver = { 97 .driver = { 98 .name = "gpio-mux", 99 .of_match_table = of_match_ptr(mux_gpio_dt_ids), 100 }, 101 .probe = mux_gpio_probe, 102 }; 103 module_platform_driver(mux_gpio_driver); 104 105 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); 106 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); 107 MODULE_LICENSE("GPL v2"); 108