iio:pressure: initial zpa2326 barometer support

Introduce driver for Murata ZPA2326 pressure and temperature sensor:
http://www.murata.com/en-us/products/productdetail?partno=ZPA2326-0311A-RSigned-off-by: NGregor Boirie <gregor.boirie@parrot.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/pressure/zpa2326.txt

+Murata ZPA2326 pressure sensor
+
+Pressure sensor from Murata with SPI and I2C bus interfaces.
+
+Required properties:
+- compatible: "murata,zpa2326"
+- reg: the I2C address or SPI chip select the device will respond to
+
+Recommended properties for SPI bus usage:
+- spi-max-frequency: maximum SPI bus frequency as documented in
+  Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Optional properties:
+- vref-supply: an optional regulator that needs to be on to provide VREF
+  power to the sensor
+- vdd-supply: an optional regulator that needs to be on to provide VDD
+  power to the sensor
+- interrupt-parent: phandle to the parent interrupt controller as documented in
+  Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+- interrupts: interrupt mapping for IRQ as documented in
+  Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+
+Example:
+
+zpa2326@5c {
+	compatible = "murata,zpa2326";
+	reg = <0x5c>;
+	interrupt-parent = <&gpio>;
+	interrupts = <12>;
+	vdd-supply = <&ldo_1v8_gnss>;
+};

drivers/iio/pressure/Kconfig

@@ -187,4 +187,26 @@ config HP206C
 	  This driver can also be built as a module. If so, the module will
 	  be called hp206c.
 
+config ZPA2326
+	tristate "Murata ZPA2326 pressure sensor driver"
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP
+	select ZPA2326_I2C if I2C
+	select ZPA2326_SPI if SPI_MASTER
+	help
+	  Say Y here to build support for the Murata ZPA2326 pressure and
+	  temperature sensor.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called zpa2326.
+
+config ZPA2326_I2C
+	tristate
+	select REGMAP_I2C
+
+config ZPA2326_SPI
+	tristate
+	select REGMAP_SPI
+
 endmenu

drivers/iio/pressure/Makefile

@@ -22,6 +22,9 @@ st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o
 obj-$(CONFIG_T5403) += t5403.o
 obj-$(CONFIG_HP206C) += hp206c.o
+obj-$(CONFIG_ZPA2326) += zpa2326.o
+obj-$(CONFIG_ZPA2326_I2C) += zpa2326_i2c.o
+obj-$(CONFIG_ZPA2326_SPI) += zpa2326_spi.o
 
 obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
 obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o

drivers/iio/pressure/zpa2326.h

+/*
+ * Murata ZPA2326 pressure and temperature sensor IIO driver
+ *
+ * Copyright (c) 2016 Parrot S.A.
+ *
+ * Author: Gregor Boirie <gregor.boirie@parrot.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef _ZPA2326_H
+#define _ZPA2326_H
+
+/* Register map. */
+#define ZPA2326_REF_P_XL_REG              (0x8)
+#define ZPA2326_REF_P_L_REG               (0x9)
+#define ZPA2326_REF_P_H_REG               (0xa)
+#define ZPA2326_DEVICE_ID_REG             (0xf)
+#define ZPA2326_DEVICE_ID                 (0xb9)
+#define ZPA2326_RES_CONF_REG              (0x10)
+#define ZPA2326_CTRL_REG0_REG             (0x20)
+#define ZPA2326_CTRL_REG0_ONE_SHOT        BIT(0)
+#define ZPA2326_CTRL_REG0_ENABLE          BIT(1)
+#define ZPA2326_CTRL_REG1_REG             (0x21)
+#define ZPA2326_CTRL_REG1_MASK_DATA_READY BIT(2)
+#define ZPA2326_CTRL_REG2_REG             (0x22)
+#define ZPA2326_CTRL_REG2_SWRESET         BIT(2)
+#define ZPA2326_CTRL_REG3_REG             (0x23)
+#define ZPA2326_CTRL_REG3_ODR_SHIFT       (4)
+#define ZPA2326_CTRL_REG3_ENABLE_MEAS     BIT(7)
+#define ZPA2326_INT_SOURCE_REG            (0x24)
+#define ZPA2326_INT_SOURCE_DATA_READY     BIT(2)
+#define ZPA2326_THS_P_LOW_REG             (0x25)
+#define ZPA2326_THS_P_HIGH_REG            (0x26)
+#define ZPA2326_STATUS_REG                (0x27)
+#define ZPA2326_STATUS_P_DA               BIT(1)
+#define ZPA2326_STATUS_FIFO_E             BIT(2)
+#define ZPA2326_STATUS_P_OR               BIT(5)
+#define ZPA2326_PRESS_OUT_XL_REG          (0x28)
+#define ZPA2326_PRESS_OUT_L_REG           (0x29)
+#define ZPA2326_PRESS_OUT_H_REG           (0x2a)
+#define ZPA2326_TEMP_OUT_L_REG            (0x2b)
+#define ZPA2326_TEMP_OUT_H_REG            (0x2c)
+
+struct device;
+struct regmap;
+
+bool zpa2326_isreg_writeable(struct device *dev, unsigned int reg);
+bool zpa2326_isreg_readable(struct device *dev, unsigned int reg);
+bool zpa2326_isreg_precious(struct device *dev, unsigned int reg);
+
+/**
+ * zpa2326_probe() - Instantiate and register core ZPA2326 IIO device
+ * @parent: Hardware sampling device the created IIO device will be a child of.
+ * @name:   Arbitrary name to identify the device.
+ * @irq:    Interrupt line, negative if none.
+ * @hwid:   Expected device hardware id.
+ * @regmap: Registers map used to abstract underlying bus accesses.
+ *
+ * Return: Zero when successful, a negative error code otherwise.
+ */
+int zpa2326_probe(struct device        *parent,
+		  const char           *name,
+		  int                   irq,
+		  unsigned int          hwid,
+		  struct regmap        *regmap);
+
+/**
+ * zpa2326_remove() - Unregister and destroy core ZPA2326 IIO device.
+ * @parent: Hardware sampling device the IIO device to remove is a child of.
+ */
+void zpa2326_remove(const struct device *parent);
+
+#ifdef CONFIG_PM
+#include <linux/pm.h>
+extern const struct dev_pm_ops zpa2326_pm_ops;
+#define ZPA2326_PM_OPS (&zpa2326_pm_ops)
+#else
+#define ZPA2326_PM_OPS (NULL)
+#endif
+
+#endif

drivers/iio/pressure/zpa2326_i2c.c

+/*
+ * Murata ZPA2326 I2C pressure and temperature sensor driver
+ *
+ * Copyright (c) 2016 Parrot S.A.
+ *
+ * Author: Gregor Boirie <gregor.boirie@parrot.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/i2c.h>
+#include <linux/of_device.h>
+#include "zpa2326.h"
+
+/*
+ * read_flag_mask:
+ *   - address bit 7 must be set to request a register read operation
+ */
+static const struct regmap_config zpa2326_regmap_i2c_config = {
+	.reg_bits       = 8,
+	.val_bits       = 8,
+	.writeable_reg  = zpa2326_isreg_writeable,
+	.readable_reg   = zpa2326_isreg_readable,
+	.precious_reg   = zpa2326_isreg_precious,
+	.max_register   = ZPA2326_TEMP_OUT_H_REG,
+	.read_flag_mask = BIT(7),
+	.cache_type     = REGCACHE_NONE,
+};
+
+static unsigned int zpa2326_i2c_hwid(const struct i2c_client *client)
+{
+#define ZPA2326_SA0(_addr)          (_addr & BIT(0))
+#define ZPA2326_DEVICE_ID_SA0_SHIFT (1)
+
+	/* Identification register bit 1 mirrors device address bit 0. */
+	return (ZPA2326_DEVICE_ID |
+		(ZPA2326_SA0(client->addr) << ZPA2326_DEVICE_ID_SA0_SHIFT));
+}
+
+static int zpa2326_probe_i2c(struct i2c_client          *client,
+			     const struct i2c_device_id *i2c_id)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_i2c(client, &zpa2326_regmap_i2c_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "failed to init registers map");
+		return PTR_ERR(regmap);
+	}
+
+	return zpa2326_probe(&client->dev, i2c_id->name, client->irq,
+			     zpa2326_i2c_hwid(client), regmap);
+}
+
+static int zpa2326_remove_i2c(struct i2c_client *client)
+{
+	zpa2326_remove(&client->dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id zpa2326_i2c_ids[] = {
+	{ "zpa2326", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, zpa2326_i2c_ids);
+
+#if defined(CONFIG_OF)
+static const struct of_device_id zpa2326_i2c_matches[] = {
+	{ .compatible = "murata,zpa2326" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, zpa2326_i2c_matches);
+#endif
+
+static struct i2c_driver zpa2326_i2c_driver = {
+	.driver = {
+		.name           = "zpa2326-i2c",
+		.of_match_table = of_match_ptr(zpa2326_i2c_matches),
+		.pm             = ZPA2326_PM_OPS,
+	},
+	.probe    = zpa2326_probe_i2c,
+	.remove   = zpa2326_remove_i2c,
+	.id_table = zpa2326_i2c_ids,
+};
+module_i2c_driver(zpa2326_i2c_driver);
+
+MODULE_AUTHOR("Gregor Boirie <gregor.boirie@parrot.com>");
+MODULE_DESCRIPTION("I2C driver for Murata ZPA2326 pressure sensor");
+MODULE_LICENSE("GPL v2");

drivers/iio/pressure/zpa2326_spi.c

+/*
+ * Murata ZPA2326 SPI pressure and temperature sensor driver
+ *
+ * Copyright (c) 2016 Parrot S.A.
+ *
+ * Author: Gregor Boirie <gregor.boirie@parrot.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/of_device.h>
+#include "zpa2326.h"
+
+/*
+ * read_flag_mask:
+ *   - address bit 7 must be set to request a register read operation
+ *   - address bit 6 must be set to request register address auto increment
+ */
+static const struct regmap_config zpa2326_regmap_spi_config = {
+	.reg_bits       = 8,
+	.val_bits       = 8,
+	.writeable_reg  = zpa2326_isreg_writeable,
+	.readable_reg   = zpa2326_isreg_readable,
+	.precious_reg   = zpa2326_isreg_precious,
+	.max_register   = ZPA2326_TEMP_OUT_H_REG,
+	.read_flag_mask = BIT(7) | BIT(6),
+	.cache_type     = REGCACHE_NONE,
+};
+
+static int zpa2326_probe_spi(struct spi_device *spi)
+{
+	struct regmap *regmap;
+	int            err;
+
+	regmap = devm_regmap_init_spi(spi, &zpa2326_regmap_spi_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&spi->dev, "failed to init registers map");
+		return PTR_ERR(regmap);
+	}
+
+	/*
+	 * Enforce SPI slave settings to prevent from DT misconfiguration.
+	 *
+	 * Clock is idle high. Sampling happens on trailing edge, i.e., rising
+	 * edge. Maximum bus frequency is 1 MHz. Registers are 8 bits wide.
+	 */
+	spi->mode = SPI_MODE_3;
+	spi->max_speed_hz = min(spi->max_speed_hz, 1000000U);
+	spi->bits_per_word = 8;
+	err = spi_setup(spi);
+	if (err < 0)
+		return err;
+
+	return zpa2326_probe(&spi->dev, spi_get_device_id(spi)->name,
+			     spi->irq, ZPA2326_DEVICE_ID, regmap);
+}
+
+static int zpa2326_remove_spi(struct spi_device *spi)
+{
+	zpa2326_remove(&spi->dev);
+
+	return 0;
+}
+
+static const struct spi_device_id zpa2326_spi_ids[] = {
+	{ "zpa2326", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, zpa2326_spi_ids);
+
+#if defined(CONFIG_OF)
+static const struct of_device_id zpa2326_spi_matches[] = {
+	{ .compatible = "murata,zpa2326" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, zpa2326_spi_matches);
+#endif
+
+static struct spi_driver zpa2326_spi_driver = {
+	.driver = {
+		.name           = "zpa2326-spi",
+		.of_match_table = of_match_ptr(zpa2326_spi_matches),
+		.pm             = ZPA2326_PM_OPS,
+	},
+	.probe    = zpa2326_probe_spi,
+	.remove   = zpa2326_remove_spi,
+	.id_table = zpa2326_spi_ids,
+};
+module_spi_driver(zpa2326_spi_driver);
+
+MODULE_AUTHOR("Gregor Boirie <gregor.boirie@parrot.com>");
+MODULE_DESCRIPTION("SPI driver for Murata ZPA2326 pressure sensor");
+MODULE_LICENSE("GPL v2");