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发表于 2015-3-22 10:59:48
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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/acpi.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)
- #define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256)
- #define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256)
- /* Compatible Asahi Kasei Compass parts */
- enum asahi_compass_chipset {
- AK8975,
- AK8963,
- };
- /*
- * 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;
- enum asahi_compass_chipset chipset;
- };
- 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 = devm_request_irq(&client->dev, 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 * 1/100
- * Hadj = H * ((ASA + 128) * 0.003) / 256
- *
- * Since ASA doesn't change, we cache the resultant scale factor into the
- * device context in ak8975_setup().
- */
- if (data->chipset == AK8963) {
- /*
- * H range is +-8190 and magnetometer range is +-4912.
- * So HuT using the above explanation for 8975,
- * 4912/8190 = ~ 6/10.
- * So the Hadj should use 6/10 instead of 3/10.
- */
- data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]);
- data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]);
- data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]);
- } else {
- data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]);
- data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]);
- data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]);
- }
- 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 < 0)
- dev_err(&client->dev, "Error in reading ST1\n");
- return ret;
- }
- static int wait_conversion_complete_polled(struct ak8975_data *data)
- {
- struct i2c_client *client = data->client;
- u8 read_status;
- u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
- int ret;
- /* Wait for the conversion to complete. */
- while (timeout_ms) {
- msleep(AK8975_CONVERSION_DONE_POLL_TIME);
- ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
- if (ret < 0) {
- dev_err(&client->dev, "Error in reading ST1\n");
- return ret;
- }
- read_status = ret;
- if (read_status)
- break;
- timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
- }
- if (!timeout_ms) {
- dev_err(&client->dev, "Conversion timeout happened\n");
- return -EINVAL;
- }
- return read_status;
- }
- /* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
- static int wait_conversion_complete_interrupt(struct ak8975_data *data)
- {
- int ret;
- ret = wait_event_timeout(data->data_ready_queue,
- test_bit(0, &data->flags),
- AK8975_DATA_READY_TIMEOUT);
- clear_bit(0, &data->flags);
- return ret > 0 ? 0 : -ETIME;
- }
- /*
- * Emits the raw flux value for the x, y, or z axis.
- */
- static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
- {
- struct ak8975_data *data = iio_priv(indio_dev);
- struct i2c_client *client = data->client;
- int ret;
- mutex_lock(&data->lock);
- /* 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. */
- if (data->eoc_irq)
- ret = wait_conversion_complete_interrupt(data);
- else if (gpio_is_valid(data->eoc_gpio))
- ret = wait_conversion_complete_gpio(data);
- else
- ret = wait_conversion_complete_polled(data);
- if (ret < 0)
- goto exit;
- /* This will be executed only for non-interrupt based waiting case */
- if (ret & AK8975_REG_ST1_DRDY_MASK) {
- ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
- if (ret < 0) {
- dev_err(&client->dev, "Error in reading ST2\n");
- goto exit;
- }
- if (ret & (AK8975_REG_ST2_DERR_MASK |
- AK8975_REG_ST2_HOFL_MASK)) {
- dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
- ret = -EINVAL;
- goto exit;
- }
- }
- /* Read the flux value from the appropriate register
- (the register is specified in the iio device attributes). */
- ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
- if (ret < 0) {
- dev_err(&client->dev, "Read axis data fails\n");
- goto exit;
- }
- mutex_unlock(&data->lock);
- /* Clamp to valid range. */
- *val = clamp_t(s16, ret, -4096, 4095);
- return IIO_VAL_INT;
- exit:
- mutex_unlock(&data->lock);
- return ret;
- }
- static int ak8975_read_raw(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- int *val, int *val2,
- long mask)
- {
- struct ak8975_data *data = iio_priv(indio_dev);
- switch (mask) {
- case IIO_CHAN_INFO_RAW:
- return ak8975_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 AK8975_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 ak8975_channels[] = {
- AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
- };
- static const struct iio_info ak8975_info = {
- .read_raw = &ak8975_read_raw,
- .driver_module = THIS_MODULE,
- };
- static const struct acpi_device_id ak_acpi_match[] = {
- {"AK8975", AK8975},
- {"AK8963", AK8963},
- {"INVN6500", AK8963},
- { },
- };
- MODULE_DEVICE_TABLE(acpi, ak_acpi_match);
- static const char *ak8975_match_acpi_device(struct device *dev,
- enum asahi_compass_chipset *chipset)
- {
- const struct acpi_device_id *id;
- id = acpi_match_device(dev->driver->acpi_match_table, dev);
- if (!id)
- return NULL;
- *chipset = (int)id->driver_data;
- return dev_name(dev);
- }
- static int ak8975_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
- {
- struct ak8975_data *data;
- struct iio_dev *indio_dev;
- int eoc_gpio;
- int err;
- const char *name = NULL;
- /* Grab and set up the supplied GPIO. */
- if (client->dev.platform_data)
- eoc_gpio = *(int *)(client->dev.platform_data);
- else if (client->dev.of_node)
- eoc_gpio = of_get_gpio(client->dev.of_node, 0);
- else
- eoc_gpio = -1;
- if (eoc_gpio == -EPROBE_DEFER)
- return -EPROBE_DEFER;
- /* We may not have a GPIO based IRQ to scan, that is fine, we will
- poll if so */
- if (gpio_is_valid(eoc_gpio)) {
- err = devm_gpio_request_one(&client->dev, eoc_gpio,
- GPIOF_IN, "ak_8975");
- if (err < 0) {
- dev_err(&client->dev,
- "failed to request GPIO %d, error %d\n",
- eoc_gpio, err);
- return err;
- }
- }
- /* Register with IIO */
- 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;
- data->eoc_gpio = eoc_gpio;
- data->eoc_irq = 0;
- /* id will be NULL when enumerated via ACPI */
- if (id) {
- data->chipset =
- (enum asahi_compass_chipset)(id->driver_data);
- name = id->name;
- } else if (ACPI_HANDLE(&client->dev))
- name = ak8975_match_acpi_device(&client->dev, &data->chipset);
- else
- return -ENOSYS;
- dev_dbg(&client->dev, "Asahi compass chip %s\n", name);
- /* 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");
- return err;
- }
- data->client = client;
- mutex_init(&data->lock);
- data->eoc_gpio = eoc_gpio;
- indio_dev->dev.parent = &client->dev;
- indio_dev->channels = ak8975_channels;
- indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
- indio_dev->info = &ak8975_info;
- indio_dev->modes = INDIO_DIRECT_MODE;
- indio_dev->name = name;
- err = devm_iio_device_register(&client->dev, indio_dev);
- if (err < 0)
- return err;
- return 0;
- }
- static const struct i2c_device_id ak8975_id[] = {
- {"ak8975", AK8975},
- {"ak8963", AK8963},
- {}
- };
- MODULE_DEVICE_TABLE(i2c, ak8975_id);
- static const struct of_device_id ak8975_of_match[] = {
- { .compatible = "asahi-kasei,ak8975", },
- { .compatible = "ak8975", },
- { }
- };
- MODULE_DEVICE_TABLE(of, ak8975_of_match);
- static struct i2c_driver ak8975_driver = {
- .driver = {
- .name = "ak8975",
- .of_match_table = ak8975_of_match,
- .acpi_match_table = ACPI_PTR(ak_acpi_match),
- },
- .probe = ak8975_probe,
- .id_table = ak8975_id,
- };
- module_i2c_driver(ak8975_driver);
- MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
- MODULE_DESCRIPTION("AK8975 magnetometer driver");
- MODULE_LICENSE("GPL");
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