forked from luck/tmp_suning_uos_patched
2c089f08e0
The driver builds a single multiplexer controller using a number of gpio pins. For N pins, there will be 2^N possible multiplexer states. The GPIO pins can be connected (by the hardware) to several multiplexers, which in that case will be operated in parallel. Reviewed-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Peter Rosin <peda@axentia.se> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
115 lines
2.7 KiB
C
115 lines
2.7 KiB
C
/*
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* GPIO-controlled multiplexer driver
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*
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* Copyright (C) 2017 Axentia Technologies AB
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*
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* Author: Peter Rosin <peda@axentia.se>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/module.h>
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#include <linux/mux/driver.h>
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#include <linux/of_platform.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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struct mux_gpio {
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struct gpio_descs *gpios;
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int *val;
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};
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static int mux_gpio_set(struct mux_control *mux, int state)
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{
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struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
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int i;
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for (i = 0; i < mux_gpio->gpios->ndescs; i++)
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mux_gpio->val[i] = (state >> i) & 1;
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gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
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mux_gpio->gpios->desc,
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mux_gpio->val);
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return 0;
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}
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static const struct mux_control_ops mux_gpio_ops = {
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.set = mux_gpio_set,
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};
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static const struct of_device_id mux_gpio_dt_ids[] = {
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{ .compatible = "gpio-mux", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
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static int mux_gpio_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct mux_chip *mux_chip;
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struct mux_gpio *mux_gpio;
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int pins;
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s32 idle_state;
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int ret;
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pins = gpiod_count(dev, "mux");
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if (pins < 0)
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return pins;
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mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) +
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pins * sizeof(*mux_gpio->val));
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if (IS_ERR(mux_chip))
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return PTR_ERR(mux_chip);
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mux_gpio = mux_chip_priv(mux_chip);
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mux_gpio->val = (int *)(mux_gpio + 1);
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mux_chip->ops = &mux_gpio_ops;
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mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
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if (IS_ERR(mux_gpio->gpios)) {
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ret = PTR_ERR(mux_gpio->gpios);
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if (ret != -EPROBE_DEFER)
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dev_err(dev, "failed to get gpios\n");
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return ret;
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}
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WARN_ON(pins != mux_gpio->gpios->ndescs);
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mux_chip->mux->states = 1 << pins;
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ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
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if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
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if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
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dev_err(dev, "invalid idle-state %u\n", idle_state);
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return -EINVAL;
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}
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mux_chip->mux->idle_state = idle_state;
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}
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ret = devm_mux_chip_register(dev, mux_chip);
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if (ret < 0)
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return ret;
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dev_info(dev, "%u-way mux-controller registered\n",
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mux_chip->mux->states);
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return 0;
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}
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static struct platform_driver mux_gpio_driver = {
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.driver = {
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.name = "gpio-mux",
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.of_match_table = of_match_ptr(mux_gpio_dt_ids),
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},
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.probe = mux_gpio_probe,
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};
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module_platform_driver(mux_gpio_driver);
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MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
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MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
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MODULE_LICENSE("GPL v2");
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