drivers/mux/adgs1408.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ADGS1408/ADGS1409 SPI MUX driver
 *
 * Copyright 2018 Analog Devices Inc.
 */

#include <linux/err.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mux/driver.h>
#include <linux/property.h>
#include <linux/spi/spi.h>

#define ADGS1408_SW_DATA       (0x01)
#define ADGS1408_REG_READ(reg) ((reg) | 0x80)
#define ADGS1408_DISABLE       (0x00)
#define ADGS1408_MUX(state)    (((state) << 1) | 1)

enum adgs1408_chip_id {
	ADGS1408 = 1,
	ADGS1409,
};

static int adgs1408_spi_reg_write(struct spi_device *spi,
				  u8 reg_addr, u8 reg_data)
{
	u8 tx_buf[2];

	tx_buf[0] = reg_addr;
	tx_buf[1] = reg_data;

	return spi_write_then_read(spi, tx_buf, sizeof(tx_buf), NULL, 0);
}

static int adgs1408_set(struct mux_control *mux, int state)
{
	struct spi_device *spi = to_spi_device(mux->chip->dev.parent);
	u8 reg;

	if (state == MUX_IDLE_DISCONNECT)
		reg = ADGS1408_DISABLE;
	else
		reg = ADGS1408_MUX(state);

	return adgs1408_spi_reg_write(spi, ADGS1408_SW_DATA, reg);
}

static const struct mux_control_ops adgs1408_ops = {
	.set = adgs1408_set,
};

static int adgs1408_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	enum adgs1408_chip_id chip_id;
	struct mux_chip *mux_chip;
	struct mux_control *mux;
	s32 idle_state;
	int ret;

	chip_id = (kernel_ulong_t)spi_get_device_match_data(spi);

	mux_chip = devm_mux_chip_alloc(dev, 1, 0);
	if (IS_ERR(mux_chip))
		return PTR_ERR(mux_chip);

	mux_chip->ops = &adgs1408_ops;

	ret = adgs1408_spi_reg_write(spi, ADGS1408_SW_DATA, ADGS1408_DISABLE);
	if (ret < 0)
		return ret;

	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
	if (ret < 0)
		idle_state = MUX_IDLE_AS_IS;

	mux = mux_chip->mux;

	if (chip_id == ADGS1408)
		mux->states = 8;
	else
		mux->states = 4;

	switch (idle_state) {
	case MUX_IDLE_DISCONNECT:
	case MUX_IDLE_AS_IS:
	case 0 ... 7:
		/* adgs1409 supports only 4 states */
		if (idle_state < mux->states) {
			mux->idle_state = idle_state;
			break;
		}
		fallthrough;
	default:
		dev_err(dev, "invalid idle-state %d\n", idle_state);
		return -EINVAL;
	}

	return devm_mux_chip_register(dev, mux_chip);
}

static const struct spi_device_id adgs1408_spi_id[] = {
	{ "adgs1408", ADGS1408 },
	{ "adgs1409", ADGS1409 },
	{ }
};
MODULE_DEVICE_TABLE(spi, adgs1408_spi_id);

static const struct of_device_id adgs1408_of_match[] = {
	{ .compatible = "adi,adgs1408", .data = (void *)ADGS1408, },
	{ .compatible = "adi,adgs1409", .data = (void *)ADGS1409, },
	{ }
};
MODULE_DEVICE_TABLE(of, adgs1408_of_match);

static struct spi_driver adgs1408_driver = {
	.driver = {
		.name = "adgs1408",
		.of_match_table = adgs1408_of_match,
	},
	.probe = adgs1408_probe,
	.id_table = adgs1408_spi_id,
};
module_spi_driver(adgs1408_driver);

MODULE_AUTHOR("Mircea Caprioru <mircea.caprioru@analog.com>");
MODULE_DESCRIPTION("Analog Devices ADGS1408 MUX driver");
MODULE_LICENSE("GPL");