From d5d8f49b634520a98337fd413eef86da4e63e4fd Mon Sep 17 00:00:00 2001 From: Crestez Dan Leonard Date: Mon, 18 Apr 2016 17:31:56 +0300 Subject: [PATCH] max44000: Expose ambient sensor scaling This patch exposes ALSTIM as illuminance_integration_time and ALSPGA as illuminance_scale. Changing ALSTIM also changes the number of bits available in the data register. This is handled inside raw value reading because: * It's very easy to shift a few bits * It allows SCALE and INT_TIME to be completely independent controls * Buffer support requires constant scan_type.realbits per-channel Signed-off-by: Crestez Dan Leonard Signed-off-by: Jonathan Cameron --- drivers/iio/light/max44000.c | 167 +++++++++++++++++++++++++++++++++-- 1 file changed, 162 insertions(+), 5 deletions(-) diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c index f0f1a8a6c615..05e11698201a 100644 --- a/drivers/iio/light/max44000.c +++ b/drivers/iio/light/max44000.c @@ -59,6 +59,12 @@ */ #define MAX44000_REG_CFG_RX_DEFAULT 0xf0 +/* REG_RX bits */ +#define MAX44000_CFG_RX_ALSTIM_MASK 0x0c +#define MAX44000_CFG_RX_ALSTIM_SHIFT 2 +#define MAX44000_CFG_RX_ALSPGA_MASK 0x03 +#define MAX44000_CFG_RX_ALSPGA_SHIFT 0 + /* REG_TX bits */ #define MAX44000_LED_CURRENT_MASK 0xf #define MAX44000_LED_CURRENT_MAX 11 @@ -74,11 +80,57 @@ struct max44000_data { /* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */ #define MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2 5 +/* Scale can be multiplied by up to 128x via ALSPGA for measurement gain */ +static const int max44000_alspga_shift[] = {0, 2, 4, 7}; +#define MAX44000_ALSPGA_MAX_SHIFT 7 + +/* + * Scale can be multiplied by up to 64x via ALSTIM because of lost resolution + * + * This scaling factor is hidden from userspace and instead accounted for when + * reading raw values from the device. + * + * This makes it possible to cleanly expose ALSPGA as IIO_CHAN_INFO_SCALE and + * ALSTIM as IIO_CHAN_INFO_INT_TIME without the values affecting each other. + * + * Handling this internally is also required for buffer support because the + * channel's scan_type can't be modified dynamically. + */ +static const int max44000_alstim_shift[] = {0, 2, 4, 6}; +#define MAX44000_ALSTIM_SHIFT(alstim) (2 * (alstim)) + +/* Available integration times with pretty manual alignment: */ +static const int max44000_int_time_avail_ns_array[] = { + 100000000, + 25000000, + 6250000, + 1562500, +}; +static const char max44000_int_time_avail_str[] = + "0.100 " + "0.025 " + "0.00625 " + "0.001625"; + +/* Available scales (internal to ulux) with pretty manual alignment: */ +static const int max44000_scale_avail_ulux_array[] = { + 31250, + 125000, + 500000, + 4000000, +}; +static const char max44000_scale_avail_str[] = + "0.03125 " + "0.125 " + "0.5 " + "4"; + static const struct iio_chan_spec max44000_channels[] = { { .type = IIO_LIGHT, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), - .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | + BIT(IIO_CHAN_INFO_INT_TIME), }, { .type = IIO_PROXIMITY, @@ -94,15 +146,54 @@ static const struct iio_chan_spec max44000_channels[] = { }, }; +static int max44000_read_alstim(struct max44000_data *data) +{ + unsigned int val; + int ret; + + ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val); + if (ret < 0) + return ret; + return (val & MAX44000_CFG_RX_ALSTIM_MASK) >> MAX44000_CFG_RX_ALSTIM_SHIFT; +} + +static int max44000_write_alstim(struct max44000_data *data, int val) +{ + return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX, + MAX44000_CFG_RX_ALSTIM_MASK, + val << MAX44000_CFG_RX_ALSTIM_SHIFT); +} + +static int max44000_read_alspga(struct max44000_data *data) +{ + unsigned int val; + int ret; + + ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val); + if (ret < 0) + return ret; + return (val & MAX44000_CFG_RX_ALSPGA_MASK) >> MAX44000_CFG_RX_ALSPGA_SHIFT; +} + +static int max44000_write_alspga(struct max44000_data *data, int val) +{ + return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX, + MAX44000_CFG_RX_ALSPGA_MASK, + val << MAX44000_CFG_RX_ALSPGA_SHIFT); +} + static int max44000_read_alsval(struct max44000_data *data) { u16 regval; - int ret; + int alstim, ret; ret = regmap_bulk_read(data->regmap, MAX44000_REG_ALS_DATA_HI, ®val, sizeof(regval)); if (ret < 0) return ret; + alstim = ret = max44000_read_alstim(data); + if (ret < 0) + return ret; regval = be16_to_cpu(regval); @@ -118,7 +209,7 @@ static int max44000_read_alsval(struct max44000_data *data) if (regval & MAX44000_ALSDATA_OVERFLOW) return 0x3FFF; - return regval; + return regval << MAX44000_ALSTIM_SHIFT(alstim); } static int max44000_write_led_current_raw(struct max44000_data *data, int val) @@ -151,6 +242,7 @@ static int max44000_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct max44000_data *data = iio_priv(indio_dev); + int alstim, alspga; unsigned int regval; int ret; @@ -196,14 +288,34 @@ static int max44000_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; case IIO_LIGHT: - *val = 1; - *val2 = MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2; + mutex_lock(&data->lock); + alspga = ret = max44000_read_alspga(data); + mutex_unlock(&data->lock); + if (ret < 0) + return ret; + + /* Avoid negative shifts */ + *val = (1 << MAX44000_ALSPGA_MAX_SHIFT); + *val2 = MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2 + + MAX44000_ALSPGA_MAX_SHIFT + - max44000_alspga_shift[alspga]; return IIO_VAL_FRACTIONAL_LOG2; default: return -EINVAL; } + case IIO_CHAN_INFO_INT_TIME: + mutex_lock(&data->lock); + alstim = ret = max44000_read_alstim(data); + mutex_unlock(&data->lock); + + if (ret < 0) + return ret; + *val = 0; + *val2 = max44000_int_time_avail_ns_array[alstim]; + return IIO_VAL_INT_PLUS_NANO; + default: return -EINVAL; } @@ -221,15 +333,60 @@ static int max44000_write_raw(struct iio_dev *indio_dev, ret = max44000_write_led_current_raw(data, val); mutex_unlock(&data->lock); return ret; + } else if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) { + s64 valns = val * NSEC_PER_SEC + val2; + int alstim = find_closest_descending(valns, + max44000_int_time_avail_ns_array, + ARRAY_SIZE(max44000_int_time_avail_ns_array)); + mutex_lock(&data->lock); + ret = max44000_write_alstim(data, alstim); + mutex_unlock(&data->lock); + return ret; + } else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT) { + s64 valus = val * USEC_PER_SEC + val2; + int alspga = find_closest(valus, + max44000_scale_avail_ulux_array, + ARRAY_SIZE(max44000_scale_avail_ulux_array)); + mutex_lock(&data->lock); + ret = max44000_write_alspga(data, alspga); + mutex_unlock(&data->lock); + return ret; } return -EINVAL; } +static int max44000_write_raw_get_fmt(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + long mask) +{ + if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) + return IIO_VAL_INT_PLUS_NANO; + else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT) + return IIO_VAL_INT_PLUS_MICRO; + else + return IIO_VAL_INT; +} + +static IIO_CONST_ATTR(illuminance_integration_time_available, max44000_int_time_avail_str); +static IIO_CONST_ATTR(illuminance_scale_available, max44000_scale_avail_str); + +static struct attribute *max44000_attributes[] = { + &iio_const_attr_illuminance_integration_time_available.dev_attr.attr, + &iio_const_attr_illuminance_scale_available.dev_attr.attr, + NULL +}; + +static const struct attribute_group max44000_attribute_group = { + .attrs = max44000_attributes, +}; + static const struct iio_info max44000_info = { .driver_module = THIS_MODULE, .read_raw = max44000_read_raw, .write_raw = max44000_write_raw, + .write_raw_get_fmt = max44000_write_raw_get_fmt, + .attrs = &max44000_attribute_group, }; static bool max44000_readable_reg(struct device *dev, unsigned int reg) -- 2.20.1