| /* |
| * 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/err.h> |
| #include <linux/mutex.h> |
| #include <linux/delay.h> |
| |
| #include <linux/gpio.h> |
| |
| #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 <ldewangan@nvidia.com>"); |
| MODULE_DESCRIPTION("AK8975 magnetometer driver"); |
| MODULE_LICENSE("GPL"); |