iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs

This patch adds support for the AD5592R (spi) and AD5593R (i2c)
ADC/DAC/GPIO devices.

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/dac/ad5592r-base.h b/drivers/iio/dac/ad5592r-base.h
new file mode 100644
index 0000000..841457e
--- /dev/null
+++ b/drivers/iio/dac/ad5592r-base.h
@@ -0,0 +1,76 @@
+/*
+ * AD5592R / AD5593R Digital <-> Analog converters driver
+ *
+ * Copyright 2015-2016 Analog Devices Inc.
+ * Author: Paul Cercueil <paul.cercueil@analog.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef __DRIVERS_IIO_DAC_AD5592R_BASE_H__
+#define __DRIVERS_IIO_DAC_AD5592R_BASE_H__
+
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/mutex.h>
+#include <linux/gpio/driver.h>
+
+struct device;
+struct ad5592r_state;
+
+enum ad5592r_registers {
+	AD5592R_REG_NOOP		= 0x0,
+	AD5592R_REG_DAC_READBACK	= 0x1,
+	AD5592R_REG_ADC_SEQ		= 0x2,
+	AD5592R_REG_CTRL		= 0x3,
+	AD5592R_REG_ADC_EN		= 0x4,
+	AD5592R_REG_DAC_EN		= 0x5,
+	AD5592R_REG_PULLDOWN		= 0x6,
+	AD5592R_REG_LDAC		= 0x7,
+	AD5592R_REG_GPIO_OUT_EN		= 0x8,
+	AD5592R_REG_GPIO_SET		= 0x9,
+	AD5592R_REG_GPIO_IN_EN		= 0xA,
+	AD5592R_REG_PD			= 0xB,
+	AD5592R_REG_OPEN_DRAIN		= 0xC,
+	AD5592R_REG_TRISTATE		= 0xD,
+	AD5592R_REG_RESET		= 0xF,
+};
+
+#define AD5592R_REG_PD_EN_REF		BIT(9)
+#define AD5592R_REG_CTRL_ADC_RANGE	BIT(5)
+#define AD5592R_REG_CTRL_DAC_RANGE	BIT(4)
+
+struct ad5592r_rw_ops {
+	int (*write_dac)(struct ad5592r_state *st, unsigned chan, u16 value);
+	int (*read_adc)(struct ad5592r_state *st, unsigned chan, u16 *value);
+	int (*reg_write)(struct ad5592r_state *st, u8 reg, u16 value);
+	int (*reg_read)(struct ad5592r_state *st, u8 reg, u16 *value);
+	int (*gpio_read)(struct ad5592r_state *st, u8 *value);
+};
+
+struct ad5592r_state {
+	struct device *dev;
+	struct regulator *reg;
+	struct gpio_chip gpiochip;
+	struct mutex gpio_lock;	/* Protect cached gpio_out, gpio_val, etc. */
+	unsigned int num_channels;
+	const struct ad5592r_rw_ops *ops;
+	int scale_avail[2][2];
+	u16 cached_dac[8];
+	u16 cached_gp_ctrl;
+	u8 channel_modes[8];
+	u8 channel_offstate[8];
+	u8 gpio_map;
+	u8 gpio_out;
+	u8 gpio_in;
+	u8 gpio_val;
+
+	__be16 spi_msg ____cacheline_aligned;
+	__be16 spi_msg_nop;
+};
+
+int ad5592r_probe(struct device *dev, const char *name,
+		const struct ad5592r_rw_ops *ops);
+int ad5592r_remove(struct device *dev);
+
+#endif /* __DRIVERS_IIO_DAC_AD5592R_BASE_H__ */