X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=drivers%2Fstaging%2Fiio%2Fmagnetometer%2Fak8975.c;fp=drivers%2Fstaging%2Fiio%2Fmagnetometer%2Fak8975.c;h=420f206cf517618495f0c0885f4634bd0aa77203;hb=59f40aff7930052a74ddf5c297aa1974b0838529;hp=0000000000000000000000000000000000000000;hpb=291b7c3a02a7eafbb8ea89a2c0e93676d6972926;p=mv-sheeva.git diff --git a/drivers/staging/iio/magnetometer/ak8975.c b/drivers/staging/iio/magnetometer/ak8975.c new file mode 100644 index 00000000000..420f206cf51 --- /dev/null +++ b/drivers/staging/iio/magnetometer/ak8975.c @@ -0,0 +1,558 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include + +#include + +#include "../iio.h" +#include "magnet.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 + +/* + * Per-instance context data for the device. + */ +struct ak8975_data { + struct i2c_client *client; + struct iio_dev *indio_dev; + struct attribute_group attrs; + struct mutex lock; + u8 asa[3]; + long raw_to_gauss[3]; + unsigned long mode; + u8 reg_cache[AK8975_MAX_REGS]; + int eoc_gpio; + int eoc_irq; +}; + +/* + * 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) +{ + u8 regval; + struct i2c_msg msg; + u8 w_data[2]; + int ret = 0; + + struct ak8975_data *data = i2c_get_clientdata(client); + + regval = data->reg_cache[reg]; + regval &= ~mask; + regval |= val << shift; + + w_data[0] = reg; + w_data[1] = regval; + + msg.addr = client->addr; + msg.flags = 0; + msg.len = 2; + msg.buf = w_data; + + ret = i2c_transfer(client->adapter, &msg, 1); + if (ret < 0) { + dev_err(&client->dev, "Write to device fails status %x\n", ret); + return ret; + } + data->reg_cache[reg] = regval; + + return 0; +} + +/* + * Helper function to read a contiguous set of the I2C device's registers. + */ +static int ak8975_read_data(struct i2c_client *client, + u8 reg, u8 length, u8 *buffer) +{ + struct i2c_msg msg[2]; + u8 w_data[2]; + int ret; + + w_data[0] = reg; + + msg[0].addr = client->addr; + msg[0].flags = I2C_M_NOSTART; /* set repeated start and write */ + msg[0].len = 1; + msg[0].buf = w_data; + + msg[1].addr = client->addr; + msg[1].flags = I2C_M_RD; + msg[1].len = length; + msg[1].buf = buffer; + + ret = i2c_transfer(client->adapter, msg, 2); + if (ret < 0) { + dev_err(&client->dev, "Read from device fails\n"); + return ret; + } + + return 0; +} + +/* + * Perform some start-of-day setup, including reading the asa calibration + * values and caching them. + */ +static int ak8975_setup(struct i2c_client *client) +{ + struct ak8975_data *data = i2c_get_clientdata(client); + u8 device_id; + int ret; + + /* Confirm that the device we're talking to is really an AK8975. */ + ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id); + if (ret < 0) { + dev_err(&client->dev, "Error reading WIA\n"); + return 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 = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa); + if (ret < 0) { + dev_err(&client->dev, "Not able to read asa data\n"); + return ret; + } + + /* Precalculate scale factor for each axis and + store in the device data. */ + 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; +} + +/* + * Shows the device's mode. 0 = off, 1 = on. + */ +static ssize_t show_mode(struct device *dev, struct device_attribute *devattr, + char *buf) +{ + struct iio_dev *indio_dev = dev_get_drvdata(dev); + struct ak8975_data *data = indio_dev->dev_data; + + return sprintf(buf, "%lu\n", data->mode); +} + +/* + * Sets the device's mode. 0 = off, 1 = on. The device's mode must be on + * for the magn raw attributes to be available. + */ +static ssize_t store_mode(struct device *dev, struct device_attribute *devattr, + const char *buf, size_t count) +{ + struct iio_dev *indio_dev = dev_get_drvdata(dev); + struct ak8975_data *data = indio_dev->dev_data; + struct i2c_client *client = data->client; + unsigned long oval; + int ret; + + /* Convert mode string and do some basic sanity checking on it. + only 0 or 1 are valid. */ + if (strict_strtoul(buf, 10, &oval)) + return -EINVAL; + + if (oval > 1) { + dev_err(dev, "mode value is not supported\n"); + return -EINVAL; + } + + mutex_lock(&data->lock); + + /* Write the mode to the device. */ + if (data->mode != oval) { + ret = ak8975_write_data(client, + AK8975_REG_CNTL, + (u8)oval, + AK8975_REG_CNTL_MODE_MASK, + AK8975_REG_CNTL_MODE_SHIFT); + + if (ret < 0) { + dev_err(&client->dev, "Error in setting mode\n"); + mutex_unlock(&data->lock); + return ret; + } + data->mode = oval; + } + + mutex_unlock(&data->lock); + + return count; +} + +/* + * Emits the scale factor to bring the raw value into Gauss units. + * + * 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 = 100 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(). + */ +static ssize_t show_scale(struct device *dev, struct device_attribute *devattr, + char *buf) +{ + struct iio_dev *indio_dev = dev_get_drvdata(dev); + struct ak8975_data *data = indio_dev->dev_data; + struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr); + + return sprintf(buf, "%ld\n", data->raw_to_gauss[this_attr->address]); +} + +/* + * Emits the raw flux value for the x, y, or z axis. + */ +static ssize_t show_raw(struct device *dev, struct device_attribute *devattr, + char *buf) +{ + struct iio_dev *indio_dev = dev_get_drvdata(dev); + struct ak8975_data *data = indio_dev->dev_data; + struct i2c_client *client = data->client; + struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr); + u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT; + u16 meas_reg; + s16 raw; + u8 read_status; + int ret; + + mutex_lock(&data->lock); + + if (data->mode == 0) { + dev_err(&client->dev, "Operating mode is in power down mode\n"); + ret = -EBUSY; + goto exit; + } + + /* Set up the device for taking a sample. */ + ret = ak8975_write_data(client, + AK8975_REG_CNTL, + AK8975_REG_CNTL_MODE_ONCE, + AK8975_REG_CNTL_MODE_MASK, + AK8975_REG_CNTL_MODE_SHIFT); + if (ret < 0) { + dev_err(&client->dev, "Error in setting operating mode\n"); + goto exit; + } + + /* 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"); + ret = -EINVAL; + goto exit; + } + + ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status); + if (ret < 0) { + dev_err(&client->dev, "Error in reading ST1\n"); + goto exit; + } + + if (read_status & AK8975_REG_ST1_DRDY_MASK) { + ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status); + if (ret < 0) { + dev_err(&client->dev, "Error in reading ST2\n"); + goto exit; + } + if (read_status & (AK8975_REG_ST2_DERR_MASK | + AK8975_REG_ST2_HOFL_MASK)) { + dev_err(&client->dev, "ST2 status error 0x%x\n", + read_status); + ret = -EINVAL; + goto exit; + } + } + + /* Read the flux value from the appropriate register + (the register is specified in the iio device attributes). */ + ret = ak8975_read_data(client, this_attr->address, 2, (u8 *)&meas_reg); + if (ret < 0) { + dev_err(&client->dev, "Read axis data fails\n"); + goto exit; + } + + mutex_unlock(&data->lock); + + /* Endian conversion of the measured values. */ + raw = (s16) (le16_to_cpu(meas_reg)); + + /* Clamp to valid range. */ + raw = clamp_t(s16, raw, -4096, 4095); + + return sprintf(buf, "%d\n", raw); + +exit: + mutex_unlock(&data->lock); + return ret; +} + +static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, show_mode, store_mode, 0); +static IIO_DEV_ATTR_MAGN_X_SCALE(S_IRUGO, show_scale, NULL, 0); +static IIO_DEV_ATTR_MAGN_Y_SCALE(S_IRUGO, show_scale, NULL, 1); +static IIO_DEV_ATTR_MAGN_Z_SCALE(S_IRUGO, show_scale, NULL, 2); +static IIO_DEV_ATTR_MAGN_X(show_raw, AK8975_REG_HXL); +static IIO_DEV_ATTR_MAGN_Y(show_raw, AK8975_REG_HYL); +static IIO_DEV_ATTR_MAGN_Z(show_raw, AK8975_REG_HZL); + +static struct attribute *ak8975_attr[] = { + &iio_dev_attr_mode.dev_attr.attr, + &iio_dev_attr_magn_x_scale.dev_attr.attr, + &iio_dev_attr_magn_y_scale.dev_attr.attr, + &iio_dev_attr_magn_z_scale.dev_attr.attr, + &iio_dev_attr_magn_x_raw.dev_attr.attr, + &iio_dev_attr_magn_y_raw.dev_attr.attr, + &iio_dev_attr_magn_z_raw.dev_attr.attr, + NULL +}; + +static struct attribute_group ak8975_attr_group = { + .attrs = ak8975_attr, +}; + +static int ak8975_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct ak8975_data *data; + int err; + + /* Allocate our device context. */ + data = kzalloc(sizeof(struct ak8975_data), GFP_KERNEL); + if (!data) { + dev_err(&client->dev, "Memory allocation fails\n"); + err = -ENOMEM; + goto exit; + } + + i2c_set_clientdata(client, data); + data->client = client; + + mutex_init(&data->lock); + + /* Grab and set up the supplied GPIO. */ + data->eoc_irq = client->irq; + data->eoc_gpio = irq_to_gpio(client->irq); + + if (!data->eoc_gpio) { + dev_err(&client->dev, "failed, no valid GPIO\n"); + err = -EINVAL; + goto exit_free; + } + + err = gpio_request(data->eoc_gpio, "ak_8975"); + if (err < 0) { + dev_err(&client->dev, "failed to request GPIO %d, error %d\n", + data->eoc_gpio, err); + goto exit_free; + } + + err = gpio_direction_input(data->eoc_gpio); + if (err < 0) { + dev_err(&client->dev, "Failed to configure input direction for" + " GPIO %d, error %d\n", data->eoc_gpio, err); + goto exit_gpio; + } + + /* Perform some basic start-of-day setup of the device. */ + err = ak8975_setup(client); + if (err < 0) { + dev_err(&client->dev, "AK8975 initialization fails\n"); + goto exit_gpio; + } + + /* Register with IIO */ + data->indio_dev = iio_allocate_device(); + if (data->indio_dev == NULL) { + err = -ENOMEM; + goto exit_gpio; + } + + data->indio_dev->dev.parent = &client->dev; + data->indio_dev->attrs = &ak8975_attr_group; + data->indio_dev->dev_data = (void *)(data); + data->indio_dev->driver_module = THIS_MODULE; + data->indio_dev->modes = INDIO_DIRECT_MODE; + + err = iio_device_register(data->indio_dev); + if (err < 0) + goto exit_free_iio; + + return 0; + +exit_free_iio: + iio_free_device(data->indio_dev); +exit_gpio: + gpio_free(data->eoc_gpio); +exit_free: + kfree(data); +exit: + return err; +} + +static int ak8975_remove(struct i2c_client *client) +{ + struct ak8975_data *data = i2c_get_clientdata(client); + + iio_device_unregister(data->indio_dev); + iio_free_device(data->indio_dev); + + gpio_free(data->eoc_gpio); + + kfree(data); + + return 0; +} + +static const struct i2c_device_id ak8975_id[] = { + {"ak8975", 0}, + {} +}; + +MODULE_DEVICE_TABLE(i2c, ak8975_id); + +static struct i2c_driver ak8975_driver = { + .driver = { + .name = "ak8975", + }, + .probe = ak8975_probe, + .remove = __devexit_p(ak8975_remove), + .id_table = ak8975_id, +}; + +static int __init ak8975_init(void) +{ + return i2c_add_driver(&ak8975_driver); +} + +static void __exit ak8975_exit(void) +{ + i2c_del_driver(&ak8975_driver); +} + +module_init(ak8975_init); +module_exit(ak8975_exit); + +MODULE_AUTHOR("Laxman Dewangan "); +MODULE_DESCRIPTION("AK8975 magnetometer driver"); +MODULE_LICENSE("GPL");