mux: adg792a: add mux controller driver for ADG792A/G

Analog Devices ADG792A/G is a triple 4:1 mux.
Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mux/Kconfig

@@ -17,6 +17,18 @@ menuconfig MULTIPLEXER
 
 if MULTIPLEXER
 
+config MUX_ADG792A
+	tristate "Analog Devices ADG792A/ADG792G Multiplexers"
+	depends on I2C || COMPILE_TEST
+	help
+	  ADG792A and ADG792G Wide Bandwidth Triple 4:1 Multiplexers
+
+	  The driver supports both operating the three multiplexers in
+	  parallel and operating them independently.
+
+	  To compile the driver as a module, choose M here: the module will
+	  be called mux-adg792a.
+
 config MUX_GPIO
 	tristate "GPIO-controlled Multiplexer"
 	depends on GPIOLIB || COMPILE_TEST

drivers/mux/Makefile

@@ -3,4 +3,5 @@
 #
 
 obj-$(CONFIG_MULTIPLEXER)	+= mux-core.o
+obj-$(CONFIG_MUX_ADG792A)	+= mux-adg792a.o
 obj-$(CONFIG_MUX_GPIO)		+= mux-gpio.o

drivers/mux/mux-adg792a.c

+/*
+ * Multiplexer driver for Analog Devices ADG792A/G Triple 4:1 mux
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ *
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mux/driver.h>
+#include <linux/property.h>
+
+#define ADG792A_LDSW		BIT(0)
+#define ADG792A_RESETB		BIT(1)
+#define ADG792A_DISABLE(mux)	(0x50 | (mux))
+#define ADG792A_DISABLE_ALL	(0x5f)
+#define ADG792A_MUX(mux, state)	(0xc0 | (((mux) + 1) << 2) | (state))
+#define ADG792A_MUX_ALL(state)	(0xc0 | (state))
+
+static int adg792a_write_cmd(struct i2c_client *i2c, u8 cmd, int reset)
+{
+	u8 data = ADG792A_RESETB | ADG792A_LDSW;
+
+	/* ADG792A_RESETB is active low, the chip resets when it is zero. */
+	if (reset)
+		data &= ~ADG792A_RESETB;
+
+	return i2c_smbus_write_byte_data(i2c, cmd, data);
+}
+
+static int adg792a_set(struct mux_control *mux, int state)
+{
+	struct i2c_client *i2c = to_i2c_client(mux->chip->dev.parent);
+	u8 cmd;
+
+	if (mux->chip->controllers == 1) {
+		/* parallel mux controller operation */
+		if (state == MUX_IDLE_DISCONNECT)
+			cmd = ADG792A_DISABLE_ALL;
+		else
+			cmd = ADG792A_MUX_ALL(state);
+	} else {
+		unsigned int controller = mux_control_get_index(mux);
+
+		if (state == MUX_IDLE_DISCONNECT)
+			cmd = ADG792A_DISABLE(controller);
+		else
+			cmd = ADG792A_MUX(controller, state);
+	}
+
+	return adg792a_write_cmd(i2c, cmd, 0);
+}
+
+static const struct mux_control_ops adg792a_ops = {
+	.set = adg792a_set,
+};
+
+static int adg792a_probe(struct i2c_client *i2c,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &i2c->dev;
+	struct mux_chip *mux_chip;
+	s32 idle_state[3];
+	u32 cells;
+	int ret;
+	int i;
+
+	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	ret = device_property_read_u32(dev, "#mux-control-cells", &cells);
+	if (ret < 0)
+		return ret;
+	if (cells >= 2)
+		return -EINVAL;
+
+	mux_chip = devm_mux_chip_alloc(dev, cells ? 3 : 1, 0);
+	if (IS_ERR(mux_chip))
+		return PTR_ERR(mux_chip);
+
+	mux_chip->ops = &adg792a_ops;
+
+	ret = adg792a_write_cmd(i2c, ADG792A_DISABLE_ALL, 1);
+	if (ret < 0)
+		return ret;
+
+	ret = device_property_read_u32_array(dev, "idle-state",
+					     (u32 *)idle_state,
+					     mux_chip->controllers);
+	if (ret < 0) {
+		idle_state[0] = MUX_IDLE_AS_IS;
+		idle_state[1] = MUX_IDLE_AS_IS;
+		idle_state[2] = MUX_IDLE_AS_IS;
+	}
+
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		mux->states = 4;
+
+		switch (idle_state[i]) {
+		case MUX_IDLE_DISCONNECT:
+		case MUX_IDLE_AS_IS:
+		case 0 ... 4:
+			mux->idle_state = idle_state[i];
+			break;
+		default:
+			dev_err(dev, "invalid idle-state %d\n", idle_state[i]);
+			return -EINVAL;
+		}
+	}
+
+	ret = devm_mux_chip_register(dev, mux_chip);
+	if (ret < 0)
+		return ret;
+
+	if (cells)
+		dev_info(dev, "3x single pole quadruple throw muxes registered\n");
+	else
+		dev_info(dev, "triple pole quadruple throw mux registered\n");
+
+	return 0;
+}
+
+static const struct i2c_device_id adg792a_id[] = {
+	{ .name = "adg792a", },
+	{ .name = "adg792g", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, adg792a_id);
+
+static const struct of_device_id adg792a_of_match[] = {
+	{ .compatible = "adi,adg792a", },
+	{ .compatible = "adi,adg792g", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adg792a_of_match);
+
+static struct i2c_driver adg792a_driver = {
+	.driver		= {
+		.name		= "adg792a",
+		.of_match_table = of_match_ptr(adg792a_of_match),
+	},
+	.probe		= adg792a_probe,
+	.id_table	= adg792a_id,
+};
+module_i2c_driver(adg792a_driver);
+
+MODULE_DESCRIPTION("Analog Devices ADG792A/G Triple 4:1 mux driver");
+MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
+MODULE_LICENSE("GPL v2");