iio: AK09911 : 3 axis compass support

Added IIO magnetometer driver for AK09911. In functionality is resembles
AK8975 or AK8963. But there are several differences, so instead of
modifying existing AK8975 driver and keep it clean, implemented as
a separate driver.
The key differences are:
- Register map is different and have different indexes
- AK09911 is a very compact interface with no DRDY pin. So no support
 of interrupt or GPIO poll
- Even for polled mode no mention on ST2 register, which is required in
ak8975 driver
- mode values are different for fuse access
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/magnetometer/Kconfig

@@ -17,6 +17,16 @@ config AK8975
 	  To compile this driver as a module, choose M here: the module
 	  will be called ak8975.
 
+config AK09911
+	tristate "Asahi Kasei AK09911 3-axis Compass"
+	depends on I2C
+	help
+	  Say yes here to build support for Asahi Kasei AK09911 3-Axis
+	  Magnetometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ak09911.
+
 config MAG3110
 	tristate "Freescale MAG3110 3-Axis Magnetometer"
 	depends on I2C

drivers/iio/magnetometer/Makefile

@@ -3,6 +3,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AK09911)	+= ak09911.o
 obj-$(CONFIG_AK8975)	+= ak8975.o
 obj-$(CONFIG_MAG3110)	+= mag3110.o
 obj-$(CONFIG_HID_SENSOR_MAGNETOMETER_3D) += hid-sensor-magn-3d.o

drivers/iio/magnetometer/ak09911.c

+/*
+ * AK09911 3-axis compass driver
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/acpi.h>
+#include <linux/iio/iio.h>
+
+#define AK09911_REG_WIA1		0x00
+#define AK09911_REG_WIA2		0x01
+#define AK09911_WIA1_VALUE		0x48
+#define AK09911_WIA2_VALUE		0x05
+
+#define AK09911_REG_ST1			0x10
+#define AK09911_REG_HXL			0x11
+#define AK09911_REG_HXH			0x12
+#define AK09911_REG_HYL			0x13
+#define AK09911_REG_HYH			0x14
+#define AK09911_REG_HZL			0x15
+#define AK09911_REG_HZH			0x16
+
+#define AK09911_REG_ASAX		0x60
+#define AK09911_REG_ASAY		0x61
+#define AK09911_REG_ASAZ		0x62
+
+#define AK09911_REG_CNTL1		0x30
+#define AK09911_REG_CNTL2		0x31
+#define AK09911_REG_CNTL3		0x32
+
+#define AK09911_MODE_SNG_MEASURE	0x01
+#define AK09911_MODE_SELF_TEST		0x10
+#define AK09911_MODE_FUSE_ACCESS	0x1F
+#define AK09911_MODE_POWERDOWN		0x00
+#define AK09911_RESET_DATA		0x01
+
+#define AK09911_REG_CNTL1		0x30
+#define AK09911_REG_CNTL2		0x31
+#define AK09911_REG_CNTL3		0x32
+
+#define AK09911_RAW_TO_GAUSS(asa)	((((asa) + 128) * 6000) / 256)
+
+#define AK09911_MAX_CONVERSION_TIMEOUT_MS	500
+#define AK09911_CONVERSION_DONE_POLL_TIME_MS	10
+
+struct ak09911_data {
+	struct i2c_client	*client;
+	struct mutex		lock;
+	u8			asa[3];
+	long			raw_to_gauss[3];
+};
+
+static const int ak09911_index_to_reg[] = {
+	AK09911_REG_HXL, AK09911_REG_HYL, AK09911_REG_HZL,
+};
+
+static int ak09911_set_mode(struct i2c_client *client, u8 mode)
+{
+	int ret;
+
+	switch (mode) {
+	case AK09911_MODE_SNG_MEASURE:
+	case AK09911_MODE_SELF_TEST:
+	case AK09911_MODE_FUSE_ACCESS:
+	case AK09911_MODE_POWERDOWN:
+		ret = i2c_smbus_write_byte_data(client,
+						AK09911_REG_CNTL2, mode);
+		if (ret < 0) {
+			dev_err(&client->dev, "set_mode error\n");
+			return ret;
+		}
+		/* After mode change wait atleast 100us */
+		usleep_range(100, 500);
+		break;
+	default:
+		dev_err(&client->dev,
+			"%s: Unknown mode(%d).", __func__, mode);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+/* Get Sensitivity Adjustment value */
+static int ak09911_get_asa(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ak09911_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = ak09911_set_mode(client, AK09911_MODE_FUSE_ACCESS);
+	if (ret < 0)
+		return ret;
+
+	/* Get asa data and store in the device data. */
+	ret = i2c_smbus_read_i2c_block_data(client, AK09911_REG_ASAX,
+					    3, data->asa);
+	if (ret < 0) {
+		dev_err(&client->dev, "Not able to read asa data\n");
+		return ret;
+	}
+
+	ret = ak09911_set_mode(client,  AK09911_MODE_POWERDOWN);
+	if (ret < 0)
+		return ret;
+
+	data->raw_to_gauss[0] = AK09911_RAW_TO_GAUSS(data->asa[0]);
+	data->raw_to_gauss[1] = AK09911_RAW_TO_GAUSS(data->asa[1]);
+	data->raw_to_gauss[2] = AK09911_RAW_TO_GAUSS(data->asa[2]);
+
+	return 0;
+}
+
+static int ak09911_verify_chip_id(struct i2c_client *client)
+{
+	u8 wia_val[2];
+	int ret;
+
+	ret = i2c_smbus_read_i2c_block_data(client, AK09911_REG_WIA1,
+					    2, wia_val);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading WIA\n");
+		return ret;
+	}
+
+	dev_dbg(&client->dev, "WIA %02x %02x\n", wia_val[0], wia_val[1]);
+
+	if (wia_val[0] != AK09911_WIA1_VALUE ||
+		wia_val[1] != AK09911_WIA2_VALUE) {
+		dev_err(&client->dev, "Device ak09911 not found\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int wait_conversion_complete_polled(struct ak09911_data *data)
+{
+	struct i2c_client *client = data->client;
+	u8 read_status;
+	u32 timeout_ms = AK09911_MAX_CONVERSION_TIMEOUT_MS;
+	int ret;
+
+	/* Wait for the conversion to complete. */
+	while (timeout_ms) {
+		msleep_interruptible(AK09911_CONVERSION_DONE_POLL_TIME_MS);
+		ret = i2c_smbus_read_byte_data(client, AK09911_REG_ST1);
+		if (ret < 0) {
+			dev_err(&client->dev, "Error in reading ST1\n");
+			return ret;
+		}
+		read_status = ret & 0x01;
+		if (read_status)
+			break;
+		timeout_ms -= AK09911_CONVERSION_DONE_POLL_TIME_MS;
+	}
+	if (!timeout_ms) {
+		dev_err(&client->dev, "Conversion timeout happened\n");
+		return -EIO;
+	}
+
+	return read_status;
+}
+
+static int ak09911_read_axis(struct iio_dev *indio_dev, int index, int *val)
+{
+	struct ak09911_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	ret = ak09911_set_mode(client, AK09911_MODE_SNG_MEASURE);
+	if (ret < 0)
+		goto fn_exit;
+
+	ret = wait_conversion_complete_polled(data);
+	if (ret < 0)
+		goto fn_exit;
+
+	/* Read data */
+	ret = i2c_smbus_read_word_data(client, ak09911_index_to_reg[index]);
+	if (ret < 0) {
+		dev_err(&client->dev, "Read axis data fails\n");
+		goto fn_exit;
+	}
+
+	mutex_unlock(&data->lock);
+
+	/* Clamp to valid range. */
+	*val = sign_extend32(clamp_t(s16, ret, -8192, 8191), 13);
+
+	return IIO_VAL_INT;
+
+fn_exit:
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int ak09911_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2,
+			    long mask)
+{
+	struct ak09911_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return ak09911_read_axis(indio_dev, chan->address, val);
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = data->raw_to_gauss[chan->address];
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return -EINVAL;
+}
+
+#define AK09911_CHANNEL(axis, index)					\
+	{								\
+		.type = IIO_MAGN,					\
+		.modified = 1,						\
+		.channel2 = IIO_MOD_##axis,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			     BIT(IIO_CHAN_INFO_SCALE),			\
+		.address = index,					\
+	}
+
+static const struct iio_chan_spec ak09911_channels[] = {
+	AK09911_CHANNEL(X, 0), AK09911_CHANNEL(Y, 1), AK09911_CHANNEL(Z, 2),
+};
+
+static const struct iio_info ak09911_info = {
+	.read_raw = &ak09911_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static const struct acpi_device_id ak_acpi_match[] = {
+	{"AK009911", 0},
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, ak_acpi_match);
+
+static int ak09911_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct ak09911_data *data;
+	const char *name;
+	int ret;
+
+	ret = ak09911_verify_chip_id(client);
+	if (ret) {
+		dev_err(&client->dev, "AK00911 not detected\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+
+	data->client = client;
+	mutex_init(&data->lock);
+
+	ret = ak09911_get_asa(client);
+	if (ret)
+		return ret;
+
+	if (id)
+		name = id->name;
+	else if (ACPI_HANDLE(&client->dev))
+		name = dev_name(&client->dev);
+	else
+		return -ENODEV;
+
+	dev_dbg(&client->dev, "Asahi compass chip %s\n", name);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = ak09911_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ak09911_channels);
+	indio_dev->info = &ak09911_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = name;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id ak09911_id[] = {
+	{"ak09911", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ak09911_id);
+
+static struct i2c_driver ak09911_driver = {
+	.driver = {
+		.name	= "ak09911",
+		.acpi_match_table = ACPI_PTR(ak_acpi_match),
+	},
+	.probe		= ak09911_probe,
+	.id_table	= ak09911_id,
+};
+module_i2c_driver(ak09911_driver);
+
+MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("AK09911 Compass driver");