On Thu, Nov 6, 2014 at 7:02 AM, Srinivas Pandruvada
<srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote:
> On Wed, 2014-11-05 at 14:10 -0800, Gwendal Grignou wrote:
>> For each type of compass supported (AK8975 and AK8963),
>> add a definition structure for register masks, important registers,
>> raw data interpretation.
>> This change will make integrating new type of devices easier.
>>
>> Remove i2c register cache. It is only used for one single register.
>>
>> Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
>> ---
>> drivers/iio/magnetometer/ak8975.c | 279 +++++++++++++++++++++++++-------------
>> 1 file changed, 184 insertions(+), 95 deletions(-)
>>
>> diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
>> index 12f0b00..b170654 100644
>> --- a/drivers/iio/magnetometer/ak8975.c
>> +++ b/drivers/iio/magnetometer/ak8975.c
>> @@ -86,13 +86,153 @@
>> #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)
>> +
>> +/*
>> + * 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().
>> + *
>> + * Given we use IIO_VAL_INT_PLUS_MICRO bit when displaying the scale, we
>> + * multiply the stored scale value by 1e6.
>> + */
>> +long ak8975_raw_to_gauss(u16 data)
> What about inline?
>> +{
>> + return (((long)data + 128) * 3000) / 256;
>> +}
>> +
>> +/*
>> + * For AK8963, same calculation, but the device is less sensitive:
>> + *
>> + * H is in the range of +-8190. The magnetometer has a range of
>> + * +-4912uT. To go from the raw value to uT is:
>> + *
>> + * HuT = H * 4912/8190, or roughly, 6/10, instead of 3/10.
>> + */
>> +long ak8963_raw_to_gauss(u16 data)
> What about inline?
1 - This function is only used at setup time, so we don't have to inline them.
2 - Given the functions are use through pointer, in-lining does not
bring any performance improvement anyway.
>> +{
>> + return (((long)data + 128) * 6000) / 256;
>> +}
>>
>> /* Compatible Asahi Kasei Compass parts */
>> enum asahi_compass_chipset {
>> AK8975,
>> AK8963,
>> + AK_MAX_TYPE
>> +};
>> +
>> +enum ak_ctrl_reg_addr {
>> + ST1,
>> + ST2,
>> + CNTL,
>> + ASA_BASE,
>> + MAX_REGS,
>> + REGS_END,
>> +};
>> +
>> +enum ak_ctrl_reg_mask {
>> + ST1_DRDY,
>> + ST2_HOFL,
>> + ST2_DERR,
>> + CNTL_MODE,
>> + MASK_END,
>> +};
>> +
>> +enum ak_ctrl_mode {
>> + POWER_DOWN,
>> + MODE_ONCE,
>> + SELF_TEST,
>> + FUSE_ROM,
>> + MODE_END,
>> +};
>> +
>> +struct ak_def {
>> + enum asahi_compass_chipset type;
>> + long (*raw_to_gauss)(u16 data);
>> + u16 range;
>> + u8 ctrl_regs[REGS_END];
>> + u8 ctrl_masks[MASK_END];
>> + u8 ctrl_modes[MODE_END];
>> + u8 data_regs[3];
>> +} ak_def_array[AK_MAX_TYPE] = {
>> +{
>> + .type = AK8975,
>> + .raw_to_gauss = ak8975_raw_to_gauss,
>> + .range = 4096,
>> + .ctrl_regs = {
>> + AK8975_REG_ST1,
>> + AK8975_REG_ST2,
>> + AK8975_REG_CNTL,
>> + AK8975_REG_ASAX,
>> + AK8975_MAX_REGS},
>> + .ctrl_masks = {
>> + AK8975_REG_ST1_DRDY_MASK,
>> + AK8975_REG_ST2_HOFL_MASK,
>> + AK8975_REG_ST2_DERR_MASK,
>> + AK8975_REG_CNTL_MODE_MASK},
>> + .ctrl_modes = {
>> + AK8975_REG_CNTL_MODE_POWER_DOWN,
>> + AK8975_REG_CNTL_MODE_ONCE,
>> + AK8975_REG_CNTL_MODE_SELF_TEST,
>> + AK8975_REG_CNTL_MODE_FUSE_ROM},
>> + .data_regs = {
>> + AK8975_REG_HXL,
>> + AK8975_REG_HYL,
>> + AK8975_REG_HZL},
>> +},
>> +{
>> + .type = AK8963,
>> + .raw_to_gauss = ak8963_raw_to_gauss,
>> + .range = 8190,
>> + .ctrl_regs = {
>> + AK8975_REG_ST1,
>> + AK8975_REG_ST2,
>> + AK8975_REG_CNTL,
>> + AK8975_REG_ASAX,
>> + AK8975_MAX_REGS},
>> + .ctrl_masks = {
>> + AK8975_REG_ST1_DRDY_MASK,
>> + AK8975_REG_ST2_HOFL_MASK,
>> + 0,
>> + AK8975_REG_CNTL_MODE_MASK},
>> + .ctrl_modes = {
>> + AK8975_REG_CNTL_MODE_POWER_DOWN,
>> + AK8975_REG_CNTL_MODE_ONCE,
>> + AK8975_REG_CNTL_MODE_SELF_TEST,
>> + AK8975_REG_CNTL_MODE_FUSE_ROM},
>> + .data_regs = {
>> + AK8975_REG_HXL,
>> + AK8975_REG_HYL,
>> + AK8975_REG_HZL},
>> +},
>> };
>>
>> /*
>> @@ -100,40 +240,36 @@ enum asahi_compass_chipset {
>> */
>> struct ak8975_data {
>> struct i2c_client *client;
>> + struct ak_def *def;
>> 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,
>> + u8 cntl_cache;
>> };
>>
>> /*
>> - * Helper function to write to the I2C device's registers.
>> + * Helper function to write to CNTL register.
>> */
>> -static int ak8975_write_data(struct i2c_client *client,
>> - u8 reg, u8 val, u8 mask, u8 shift)
>> +static int ak8975_set_mode(struct ak8975_data *data, enum ak_ctrl_mode mode)
>> {
>> - 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);
>> + regval = (data->cntl_cache & ~data->def->ctrl_masks[CNTL_MODE]) |
>> + data->def->ctrl_modes[mode];
>> + ret = i2c_smbus_write_byte_data(
>> + data->client, data->def->ctrl_regs[CNTL], regval);
>> if (ret < 0) {
>> - dev_err(&client->dev, "Write to device fails status %x\n", ret);
>> return ret;
>> }
>> - data->reg_cache[reg] = regval;
>> + data->cntl_cache = regval;
>> + /* After mode change wait atleast 100us */
>> + usleep_range(100, 500);
>>
>> return 0;
>> }
>> @@ -207,18 +343,15 @@ static int ak8975_setup(struct i2c_client *client)
>> }
>>
>> /* 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);
>> + ret = ak8975_set_mode(data, FUSE_ROM);
>> 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,
>> + ret = i2c_smbus_read_i2c_block_data(client,
>> + data->def->ctrl_regs[ASA_BASE],
>> 3, data->asa);
>> if (ret < 0) {
>> dev_err(&client->dev, "Not able to read asa data\n");
>> @@ -226,11 +359,7 @@ static int ak8975_setup(struct i2c_client *client)
>> }
>>
>> /* 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);
>> + ret = ak8975_set_mode(data, POWER_DOWN);
>> if (ret < 0) {
>> dev_err(&client->dev, "Error in setting power-down mode\n");
>> return ret;
>> @@ -245,56 +374,9 @@ static int ak8975_setup(struct i2c_client *client)
>> }
>> }
>>
>> -/*
>> - * 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]);
>> - }
>> + data->raw_to_gauss[0] = data->def->raw_to_gauss(data->asa[0]);
>> + data->raw_to_gauss[1] = data->def->raw_to_gauss(data->asa[1]);
>> + data->raw_to_gauss[2] = data->def->raw_to_gauss(data->asa[2]);
>>
>> return 0;
>> }
>> @@ -317,7 +399,7 @@ static int wait_conversion_complete_gpio(struct ak8975_data *data)
>> return -EINVAL;
>> }
>>
>> - ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
>> + ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
>> if (ret < 0)
>> dev_err(&client->dev, "Error in reading ST1\n");
>>
>> @@ -334,7 +416,8 @@ static int wait_conversion_complete_polled(struct ak8975_data *data)
>> /* 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);
>> + ret = i2c_smbus_read_byte_data(
>> + client, data->def->ctrl_regs[ST1]);
>> if (ret < 0) {
>> dev_err(&client->dev, "Error in reading ST1\n");
>> return ret;
>> @@ -377,11 +460,7 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
>> 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);
>> + ret = ak8975_set_mode(data, MODE_ONCE);
>> if (ret < 0) {
>> dev_err(&client->dev, "Error in setting operating mode\n");
>> goto exit;
>> @@ -398,14 +477,15 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
>> 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 & data->def->ctrl_masks[ST1_DRDY]) {
>> + ret = i2c_smbus_read_byte_data(
>> + client, data->def->ctrl_regs[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)) {
>> + if (ret & (data->def->ctrl_masks[ST2_DERR] |
>> + data->def->ctrl_masks[ST2_HOFL])) {
>> dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
>> ret = -EINVAL;
>> goto exit;
>> @@ -414,7 +494,7 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
>>
>> /* 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]);
>> + ret = i2c_smbus_read_word_data(client, data->def->data_regs[index]);
>> if (ret < 0) {
>> dev_err(&client->dev, "Read axis data fails\n");
>> goto exit;
>> @@ -423,7 +503,7 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
>> mutex_unlock(&data->lock);
>>
>> /* Clamp to valid range. */
>> - *val = clamp_t(s16, ret, -4096, 4095);
>> + *val = clamp_t(s16, ret, -data->def->range, data->def->range);
>> return IIO_VAL_INT;
>>
>> exit:
>> @@ -497,6 +577,7 @@ static int ak8975_probe(struct i2c_client *client,
>> int eoc_gpio;
>> int err;
>> const char *name = NULL;
>> + enum asahi_compass_chipset chipset;
>>
>> /* Grab and set up the supplied GPIO. */
>> if (client->dev.platform_data)
>> @@ -536,14 +617,20 @@ static int ak8975_probe(struct i2c_client *client,
>>
>> /* id will be NULL when enumerated via ACPI */
>> if (id) {
>> - data->chipset =
>> - (enum asahi_compass_chipset)(id->driver_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);
>> + name = ak8975_match_acpi_device(&client->dev, &chipset);
>> else
>> return -ENOSYS;
>>
>> + if (chipset >= AK_MAX_TYPE) {
>> + dev_err(&client->dev, "AKM device type unsupported: %d\n",
>> + chipset);
>> + return -ENODEV;
>> + }
>> +
>> + data->def = &ak_def_array[chipset];
>> dev_dbg(&client->dev, "Asahi compass chip %s\n", name);
>>
>> /* Perform some basic start-of-day setup of the device. */
>> @@ -574,7 +661,9 @@ MODULE_DEVICE_TABLE(i2c, ak8975_id);
>> static const struct of_device_id ak8975_of_match[] = {
>> { .compatible = "asahi-kasei,ak8975", },
>> { .compatible = "ak8975", },
>> - { }
>> + { .compatible = "asahi-kasei,ak8963", },
>> + { .compatible = "ak8963", },
>> + {}
>> };
>> MODULE_DEVICE_TABLE(of, ak8975_of_match);
>>
>
>
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