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 int *val; 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 int i; 27 28 for (i = 0; i < mux_gpio->gpios->ndescs; i++) 29 mux_gpio->val[i] = (state >> i) & 1; 30 31 gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs, 32 mux_gpio->gpios->desc, 33 mux_gpio->val); 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 pins * sizeof(*mux_gpio->val)); 63 if (IS_ERR(mux_chip)) 64 return PTR_ERR(mux_chip); 65 66 mux_gpio = mux_chip_priv(mux_chip); 67 mux_gpio->val = (int *)(mux_gpio + 1); 68 mux_chip->ops = &mux_gpio_ops; 69 70 mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); 71 if (IS_ERR(mux_gpio->gpios)) { 72 ret = PTR_ERR(mux_gpio->gpios); 73 if (ret != -EPROBE_DEFER) 74 dev_err(dev, "failed to get gpios\n"); 75 return ret; 76 } 77 WARN_ON(pins != mux_gpio->gpios->ndescs); 78 mux_chip->mux->states = 1 << pins; 79 80 ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); 81 if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { 82 if (idle_state < 0 || idle_state >= mux_chip->mux->states) { 83 dev_err(dev, "invalid idle-state %u\n", idle_state); 84 return -EINVAL; 85 } 86 87 mux_chip->mux->idle_state = idle_state; 88 } 89 90 ret = devm_mux_chip_register(dev, mux_chip); 91 if (ret < 0) 92 return ret; 93 94 dev_info(dev, "%u-way mux-controller registered\n", 95 mux_chip->mux->states); 96 97 return 0; 98 } 99 100 static struct platform_driver mux_gpio_driver = { 101 .driver = { 102 .name = "gpio-mux", 103 .of_match_table = of_match_ptr(mux_gpio_dt_ids), 104 }, 105 .probe = mux_gpio_probe, 106 }; 107 module_platform_driver(mux_gpio_driver); 108 109 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); 110 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); 111 MODULE_LICENSE("GPL v2"); 112