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/*
* A sensor driver for the magnetometer AK8975.
*
* Magnetic compass sensor driver for monitoring magnetic flux information.
*
* Copyright (c) 2010, NVIDIA Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/*
* Register definitions, as well as various shifts and masks to get at the
* individual fields of the registers.
*/
#define AK8975_REG_WIA 0x00
#define AK8975_DEVICE_ID 0x48
#define AK8975_REG_INFO 0x01
#define AK8975_REG_ST1 0x02
#define AK8975_REG_ST1_DRDY_SHIFT 0
#define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT)
#define AK8975_REG_HXL 0x03
#define AK8975_REG_HXH 0x04
#define AK8975_REG_HYL 0x05
#define AK8975_REG_HYH 0x06
#define AK8975_REG_HZL 0x07
#define AK8975_REG_HZH 0x08
#define AK8975_REG_ST2 0x09
#define AK8975_REG_ST2_DERR_SHIFT 2
#define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT)
#define AK8975_REG_ST2_HOFL_SHIFT 3
#define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
#define AK8975_REG_CNTL 0x0A
#define AK8975_REG_CNTL_MODE_SHIFT 0
#define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT)
#define AK8975_REG_CNTL_MODE_POWER_DOWN 0
#define AK8975_REG_CNTL_MODE_ONCE 1
#define AK8975_REG_CNTL_MODE_SELF_TEST 8
#define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF
#define AK8975_REG_RSVC 0x0B
#define AK8975_REG_ASTC 0x0C
#define AK8975_REG_TS1 0x0D
#define AK8975_REG_TS2 0x0E
#define AK8975_REG_I2CDIS 0x0F
#define AK8975_REG_ASAX 0x10
#define AK8975_REG_ASAY 0x11
#define AK8975_REG_ASAZ 0x12
#define AK8975_MAX_REGS AK8975_REG_ASAZ
/*
* Miscellaneous values.
*/
#define AK8975_MAX_CONVERSION_TIMEOUT 500
#define AK8975_CONVERSION_DONE_POLL_TIME 10
#define AK8975_DATA_READY_TIMEOUT ((100*HZ)/1000)
/*
* Per-instance context data for the device.
*/
struct ak8975_data {
struct i2c_client *client;
struct attribute_group attrs;
struct mutex lock;
u8 asa[3];
long raw_to_gauss[3];
u8 reg_cache[AK8975_MAX_REGS];
int eoc_gpio;
int eoc_irq;
wait_queue_head_t data_ready_queue;
unsigned long flags;
};
static const int ak8975_index_to_reg[] = {
AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
};
/*
* Helper function to write to the I2C device's registers.
*/
static int ak8975_write_data(struct i2c_client *client,
u8 reg, u8 val, u8 mask, u8 shift)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
struct ak8975_data *data = iio_priv(indio_dev);
u8 regval;
int ret;
regval = (data->reg_cache[reg] & ~mask) | (val << shift);
ret = i2c_smbus_write_byte_data(client, reg, regval);
if (ret < 0) {
dev_err(&client->dev, "Write to device fails status %x\n", ret);
return ret;
}
data->reg_cache[reg] = regval;
return 0;
}
/*
* Handle data ready irq
*/
static irqreturn_t ak8975_irq_handler(int irq, void *data)
{
struct ak8975_data *ak8975 = data;
set_bit(0, &ak8975->flags);
wake_up(&ak8975->data_ready_queue);
return IRQ_HANDLED;
}
/*
* Install data ready interrupt handler
*/
static int ak8975_setup_irq(struct ak8975_data *data)
{
struct i2c_client *client = data->client;
int rc;
int irq;
if (client->irq)
irq = client->irq;
else
irq = gpio_to_irq(data->eoc_gpio);
rc = request_irq(irq, ak8975_irq_handler,
IRQF_TRIGGER_RISING | IRQF_ONESHOT,
dev_name(&client->dev), data);
if (rc < 0) {
dev_err(&client->dev,
"irq %d request failed, (gpio %d): %d\n",
irq, data->eoc_gpio, rc);
return rc;
}
init_waitqueue_head(&data->data_ready_queue);
clear_bit(0, &data->flags);
data->eoc_irq = irq;
return rc;
}
/*
* Perform some start-of-day setup, including reading the asa calibration
* values and caching them.
*/
static int ak8975_setup(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
struct ak8975_data *data = iio_priv(indio_dev);
u8 device_id;
int ret;
/* Confirm that the device we're talking to is really an AK8975. */
ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
if (ret < 0) {
dev_err(&client->dev, "Error reading WIA\n");
return ret;
}
device_id = ret;
if (device_id != AK8975_DEVICE_ID) {
dev_err(&client->dev, "Device ak8975 not found\n");
return -ENODEV;
}
/* Write the fused rom access mode. */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_FUSE_ROM,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting fuse access mode\n");
return ret;
}
/* Get asa data and store in the device data. */
ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX,
3, data->asa);
if (ret < 0) {
dev_err(&client->dev, "Not able to read asa data\n");
return ret;
}
/* After reading fuse ROM data set power-down mode */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_POWER_DOWN,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (data->eoc_gpio > 0 || client->irq) {
ret = ak8975_setup_irq(data);
if (ret < 0) {
dev_err(&client->dev,
"Error setting data ready interrupt\n");
return ret;
}
}
if (ret < 0) {
dev_err(&client->dev, "Error in setting power-down mode\n");
return ret;
}
/*
* Precalculate scale factor (in Gauss units) for each axis and
* store in the device data.
*
* This scale factor is axis-dependent, and is derived from 3 calibration
* factors ASA(x), ASA(y), and ASA(z).
*
* These ASA values are read from the sensor device at start of day, and
* cached in the device context struct.
*
* Adjusting the flux value with the sensitivity adjustment value should be
* done via the following formula:
*
* Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
*
* where H is the raw value, ASA is the sensitivity adjustment, and Hadj
* is the resultant adjusted value.
*
* We reduce the formula to:
*
* Hadj = H * (ASA + 128) / 256
*
* H is in the range of -4096 to 4095. The magnetometer has a range of
* +-1229uT. To go from the raw value to uT is:
*
* HuT = H * 1229/4096, or roughly, 3/10.
*
* Since 1uT = 0.01 gauss, our final scale factor becomes:
*
* Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
* Hadj = H * ((ASA + 128) * 30 / 256
*
* Since ASA doesn't change, we cache the resultant scale factor into the
* device context in ak8975_setup().
*/
data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
return 0;
}
static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
struct i2c_client *client = data->client;
u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
int ret;
/* Wait for the conversion to complete. */
while (timeout_ms) {
msleep(AK8975_CONVERSION_DONE_POLL_TIME);
if (gpio_get_value(data->eoc_gpio))
break;
timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
}
if (!timeout_ms) {
dev_err(&client->dev, "Conversion timeout happened\n");
return -EINVAL;
}
ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
if (ret <
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