drivers/mux/gpio.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * GPIO-controlled multiplexer driver
0004  *
0005  * Copyright (C) 2017 Axentia Technologies AB
0006  *
0007  * Author: Peter Rosin <peda@axentia.se>
0008  */
0009
0010 #include <linux/bitmap.h>
0011 #include <linux/err.h>
0012 #include <linux/gpio/consumer.h>
0013 #include <linux/mod_devicetable.h>
0014 #include <linux/module.h>
0015 #include <linux/mux/driver.h>
0016 #include <linux/platform_device.h>
0017 #include <linux/property.h>
0018
0019 struct mux_gpio {
0020     struct gpio_descs *gpios;
0021 };
0022
0023 static int mux_gpio_set(struct mux_control *mux, int state)
0024 {
0025     struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
0026     DECLARE_BITMAP(values, BITS_PER_TYPE(state));
0027     u32 value = state;
0028
0029     bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));
0030
0031     gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
0032                        mux_gpio->gpios->desc,
0033                        mux_gpio->gpios->info, values);
0034
0035     return 0;
0036 }
0037
0038 static const struct mux_control_ops mux_gpio_ops = {
0039     .set = mux_gpio_set,
0040 };
0041
0042 static const struct of_device_id mux_gpio_dt_ids[] = {
0043     { .compatible = "gpio-mux", },
0044     { /* sentinel */ }
0045 };
0046 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
0047
0048 static int mux_gpio_probe(struct platform_device *pdev)
0049 {
0050     struct device *dev = &pdev->dev;
0051     struct mux_chip *mux_chip;
0052     struct mux_gpio *mux_gpio;
0053     int pins;
0054     s32 idle_state;
0055     int ret;
0056
0057     pins = gpiod_count(dev, "mux");
0058     if (pins < 0)
0059         return pins;
0060
0061     mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
0062     if (IS_ERR(mux_chip))
0063         return PTR_ERR(mux_chip);
0064
0065     mux_gpio = mux_chip_priv(mux_chip);
0066     mux_chip->ops = &mux_gpio_ops;
0067
0068     mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
0069     if (IS_ERR(mux_gpio->gpios))
0070         return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
0071                      "failed to get gpios\n");
0072     WARN_ON(pins != mux_gpio->gpios->ndescs);
0073     mux_chip->mux->states = BIT(pins);
0074
0075     ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
0076     if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
0077         if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
0078             dev_err(dev, "invalid idle-state %u\n", idle_state);
0079             return -EINVAL;
0080         }
0081
0082         mux_chip->mux->idle_state = idle_state;
0083     }
0084
0085     ret = devm_mux_chip_register(dev, mux_chip);
0086     if (ret < 0)
0087         return ret;
0088
0089     dev_info(dev, "%u-way mux-controller registered\n",
0090          mux_chip->mux->states);
0091
0092     return 0;
0093 }
0094
0095 static struct platform_driver mux_gpio_driver = {
0096     .driver = {
0097         .name = "gpio-mux",
0098         .of_match_table = mux_gpio_dt_ids,
0099     },
0100     .probe = mux_gpio_probe,
0101 };
0102 module_platform_driver(mux_gpio_driver);
0103
0104 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
0105 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
0106 MODULE_LICENSE("GPL v2");