// SPDX-License-Identifier: GPL-2.0 /* * GPIO-controlled multiplexer driver * * Copyright (C) 2017 Axentia Technologies AB * * Author: Peter Rosin <peda@axentia.se> */ #include <linux/bitmap.h> #include <linux/err.h> #include <linux/gpio/consumer.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/mux/driver.h> #include <linux/platform_device.h> #include <linux/property.h> struct mux_gpio { struct gpio_descs *gpios; }; static int mux_gpio_set(struct mux_control *mux, int state) { struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip); DECLARE_BITMAP(values, BITS_PER_TYPE(state)); u32 value = state; bitmap_from_arr32(values, &value, BITS_PER_TYPE(value)); gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs, mux_gpio->gpios->desc, mux_gpio->gpios->info, values); return 0; } static const struct mux_control_ops mux_gpio_ops = { .set = mux_gpio_set, }; static const struct of_device_id mux_gpio_dt_ids[] = { { .compatible = "gpio-mux", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids); static int mux_gpio_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct mux_chip *mux_chip; struct mux_gpio *mux_gpio; int pins; s32 idle_state; int ret; pins = gpiod_count(dev, "mux"); if (pins < 0) return pins; mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio)); if (IS_ERR(mux_chip)) return PTR_ERR(mux_chip); mux_gpio = mux_chip_priv(mux_chip); mux_chip->ops = &mux_gpio_ops; mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); if (IS_ERR(mux_gpio->gpios)) return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios), "failed to get gpios\n"); WARN_ON(pins != mux_gpio->gpios->ndescs); mux_chip->mux->states = BIT(pins); ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { if (idle_state < 0 || idle_state >= mux_chip->mux->states) { dev_err(dev, "invalid idle-state %u\n", idle_state); return -EINVAL; } mux_chip->mux->idle_state = idle_state; } ret = devm_mux_chip_register(dev, mux_chip); if (ret < 0) return ret; dev_info(dev, "%u-way mux-controller registered\n", mux_chip->mux->states); return 0; } static struct platform_driver mux_gpio_driver = { .driver = { .name = "gpio-mux", .of_match_table = mux_gpio_dt_ids, }, .probe = mux_gpio_probe, }; module_platform_driver(mux_gpio_driver); MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); MODULE_LICENSE("GPL v2");