iio: ltr501: Add interrupt rate control support

Added rate control support for ALS and proximity
threshold interrupts.Also, Added support to modify
and read ALS & proximity sensor sampling frequency.

LTR-501 supports interrupt rate control using persistence
register settings. Writing <n> to persistence register
would generate interrupt only if there are <n> consecutive
data values outside the threshold range.

Since we don't have any existing ABI's to directly
control the persistence register count, we have implemented
the rate control using IIO_EV_INFO_PERIOD. _period event
attribute represents the amount of time in seconds an
event should be true for the device to generate the
interrupt. So using _period value and device frequency,
persistence count is calculated in driver using following
logic.

count =  period / measurement_rate

If the given period is not a multiple of measurement rate then
we round up the value to next multiple.

This patch also handles change to persistence count whenever
there is change in frequency.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/light/ltr501.c b/drivers/iio/light/ltr501.c
index 593dbb11ec38058bca0e90d6c196c93632892e87..d9b4536f006728c0ffa58f96805b3a6898c46d1c 100644 (file)
--- a/drivers/iio/light/ltr501.c
+++ b/drivers/iio/light/ltr501.c
@@ -9,7 +9,7 @@
  *
  * 7-bit I2C slave address 0x23
  *
- * TODO: measurement rate, IR LED characteristics
+ * TODO: IR LED characteristics
  */
 
 #include <linux/module.h>
@@ -29,6 +29,7 @@
 
 #define LTR501_ALS_CONTR 0x80 /* ALS operation mode, SW reset */
 #define LTR501_PS_CONTR 0x81 /* PS operation mode */
+#define LTR501_PS_MEAS_RATE 0x84 /* measurement rate*/
 #define LTR501_ALS_MEAS_RATE 0x85 /* ALS integ time, measurement rate*/
 #define LTR501_PART_ID 0x86
 #define LTR501_MANUFAC_ID 0x87
@@ -41,6 +42,7 @@
 #define LTR501_PS_THRESH_LOW 0x92 /* 11 bit, ps lower threshold */
 #define LTR501_ALS_THRESH_UP 0x97 /* 16 bit, ALS upper threshold */
 #define LTR501_ALS_THRESH_LOW 0x99 /* 16 bit, ALS lower threshold */
+#define LTR501_INTR_PRST 0x9e /* ps thresh, als thresh */
 #define LTR501_MAX_REG 0x9f
 
 #define LTR501_ALS_CONTR_SW_RESET BIT(2)
@@ -58,6 +60,9 @@
 #define LTR501_PS_THRESH_MASK 0x7ff
 #define LTR501_ALS_THRESH_MASK 0xffff
 
+#define LTR501_ALS_DEF_PERIOD 500000
+#define LTR501_PS_DEF_PERIOD 100000
+
 #define LTR501_REGMAP_NAME "ltr501_regmap"
 
 static const int int_time_mapping[] = {100000, 50000, 200000, 400000};
@@ -68,17 +73,171 @@ static const struct reg_field reg_field_als_intr =
                                REG_FIELD(LTR501_INTR, 0, 0);
 static const struct reg_field reg_field_ps_intr =
                                REG_FIELD(LTR501_INTR, 1, 1);
+static const struct reg_field reg_field_als_rate =
+                               REG_FIELD(LTR501_ALS_MEAS_RATE, 0, 2);
+static const struct reg_field reg_field_ps_rate =
+                               REG_FIELD(LTR501_PS_MEAS_RATE, 0, 3);
+static const struct reg_field reg_field_als_prst =
+                               REG_FIELD(LTR501_INTR_PRST, 0, 3);
+static const struct reg_field reg_field_ps_prst =
+                               REG_FIELD(LTR501_INTR_PRST, 4, 7);
+
+struct ltr501_samp_table {
+       int freq_val;  /* repetition frequency in micro HZ*/
+       int time_val; /* repetition rate in micro seconds */
+};
 
 struct ltr501_data {
        struct i2c_client *client;
        struct mutex lock_als, lock_ps;
        u8 als_contr, ps_contr;
+       int als_period, ps_period; /* period in micro seconds */
        struct regmap *regmap;
        struct regmap_field *reg_it;
        struct regmap_field *reg_als_intr;
        struct regmap_field *reg_ps_intr;
+       struct regmap_field *reg_als_rate;
+       struct regmap_field *reg_ps_rate;
+       struct regmap_field *reg_als_prst;
+       struct regmap_field *reg_ps_prst;
+};
+
+static const struct ltr501_samp_table ltr501_als_samp_table[] = {
+                       {20000000, 50000}, {10000000, 100000},
+                       {5000000, 200000}, {2000000, 500000},
+                       {1000000, 1000000}, {500000, 2000000},
+                       {500000, 2000000}, {500000, 2000000}
 };
 
+static const struct ltr501_samp_table ltr501_ps_samp_table[] = {
+                       {20000000, 50000}, {14285714, 70000},
+                       {10000000, 100000}, {5000000, 200000},
+                       {2000000, 500000}, {1000000, 1000000},
+                       {500000, 2000000}, {500000, 2000000},
+                       {500000, 2000000}
+};
+
+static unsigned int ltr501_match_samp_freq(const struct ltr501_samp_table *tab,
+                                          int len, int val, int val2)
+{
+       int i, freq;
+
+       freq = val * 1000000 + val2;
+
+       for (i = 0; i < len; i++) {
+               if (tab[i].freq_val == freq)
+                       return i;
+       }
+
+       return -EINVAL;
+}
+
+static int ltr501_als_read_samp_freq(struct ltr501_data *data,
+                                    int *val, int *val2)
+{
+       int ret, i;
+
+       ret = regmap_field_read(data->reg_als_rate, &i);
+       if (ret < 0)
+               return ret;
+
+       if (i < 0 || i >= ARRAY_SIZE(ltr501_als_samp_table))
+               return -EINVAL;
+
+       *val = ltr501_als_samp_table[i].freq_val / 1000000;
+       *val2 = ltr501_als_samp_table[i].freq_val % 1000000;
+
+       return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int ltr501_ps_read_samp_freq(struct ltr501_data *data,
+                                   int *val, int *val2)
+{
+       int ret, i;
+
+       ret = regmap_field_read(data->reg_ps_rate, &i);
+       if (ret < 0)
+               return ret;
+
+       if (i < 0 || i >= ARRAY_SIZE(ltr501_ps_samp_table))
+               return -EINVAL;
+
+       *val = ltr501_ps_samp_table[i].freq_val / 1000000;
+       *val2 = ltr501_ps_samp_table[i].freq_val % 1000000;
+
+       return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int ltr501_als_write_samp_freq(struct ltr501_data *data,
+                                     int val, int val2)
+{
+       int i, ret;
+
+       i = ltr501_match_samp_freq(ltr501_als_samp_table,
+                                  ARRAY_SIZE(ltr501_als_samp_table),
+                                  val, val2);
+
+       if (i < 0)
+               return i;
+
+       mutex_lock(&data->lock_als);
+       ret = regmap_field_write(data->reg_als_rate, i);
+       mutex_unlock(&data->lock_als);
+
+       return ret;
+}
+
+static int ltr501_ps_write_samp_freq(struct ltr501_data *data,
+                                    int val, int val2)
+{
+       int i, ret;
+
+       i = ltr501_match_samp_freq(ltr501_ps_samp_table,
+                                  ARRAY_SIZE(ltr501_ps_samp_table),
+                                  val, val2);
+
+       if (i < 0)
+               return i;
+
+       mutex_lock(&data->lock_ps);
+       ret = regmap_field_write(data->reg_ps_rate, i);
+       mutex_unlock(&data->lock_ps);
+
+       return ret;
+}
+
+static int ltr501_als_read_samp_period(struct ltr501_data *data, int *val)
+{
+       int ret, i;
+
+       ret = regmap_field_read(data->reg_als_rate, &i);
+       if (ret < 0)
+               return ret;
+
+       if (i < 0 || i >= ARRAY_SIZE(ltr501_als_samp_table))
+               return -EINVAL;
+
+       *val = ltr501_als_samp_table[i].time_val;
+
+       return IIO_VAL_INT;
+}
+
+static int ltr501_ps_read_samp_period(struct ltr501_data *data, int *val)
+{
+       int ret, i;
+
+       ret = regmap_field_read(data->reg_ps_rate, &i);
+       if (ret < 0)
+               return ret;
+
+       if (i < 0 || i >= ARRAY_SIZE(ltr501_ps_samp_table))
+               return -EINVAL;
+
+       *val = ltr501_ps_samp_table[i].time_val;
+
+       return IIO_VAL_INT;
+}
+
 static int ltr501_drdy(struct ltr501_data *data, u8 drdy_mask)
 {
        int tries = 100;
@@ -177,6 +336,104 @@ static int ltr501_read_ps(struct ltr501_data *data)
        return status;
 }
 
+static int ltr501_read_intr_prst(struct ltr501_data *data,
+                                enum iio_chan_type type,
+                                int *val2)
+{
+       int ret, samp_period, prst;
+
+       switch (type) {
+       case IIO_INTENSITY:
+               ret = regmap_field_read(data->reg_als_prst, &prst);
+               if (ret < 0)
+                       return ret;
+
+               ret = ltr501_als_read_samp_period(data, &samp_period);
+
+               if (ret < 0)
+                       return ret;
+               *val2 = samp_period * prst;
+               return IIO_VAL_INT_PLUS_MICRO;
+       case IIO_PROXIMITY:
+               ret = regmap_field_read(data->reg_ps_prst, &prst);
+               if (ret < 0)
+                       return ret;
+
+               ret = ltr501_ps_read_samp_period(data, &samp_period);
+
+               if (ret < 0)
+                       return ret;
+
+               *val2 = samp_period * prst;
+               return IIO_VAL_INT_PLUS_MICRO;
+       default:
+               return -EINVAL;
+       }
+
+       return -EINVAL;
+}
+
+static int ltr501_write_intr_prst(struct ltr501_data *data,
+                                 enum iio_chan_type type,
+                                 int val, int val2)
+{
+       int ret, samp_period, new_val;
+       unsigned long period;
+
+       if (val < 0 || val2 < 0)
+               return -EINVAL;
+
+       /* period in microseconds */
+       period = ((val * 1000000) + val2);
+
+       switch (type) {
+       case IIO_INTENSITY:
+               ret = ltr501_als_read_samp_period(data, &samp_period);
+               if (ret < 0)
+                       return ret;
+
+               /* period should be atleast equal to sampling period */
+               if (period < samp_period)
+                       return -EINVAL;
+
+               new_val = DIV_ROUND_UP(period, samp_period);
+               if (new_val < 0 || new_val > 0x0f)
+                       return -EINVAL;
+
+               mutex_lock(&data->lock_als);
+               ret = regmap_field_write(data->reg_als_prst, new_val);
+               mutex_unlock(&data->lock_als);
+               if (ret >= 0)
+                       data->als_period = period;
+
+               return ret;
+       case IIO_PROXIMITY:
+               ret = ltr501_ps_read_samp_period(data, &samp_period);
+               if (ret < 0)
+                       return ret;
+
+               /* period should be atleast equal to rate */
+               if (period < samp_period)
+                       return -EINVAL;
+
+               new_val = DIV_ROUND_UP(period, samp_period);
+               if (new_val < 0 || new_val > 0x0f)
+                       return -EINVAL;
+
+               mutex_lock(&data->lock_ps);
+               ret = regmap_field_write(data->reg_ps_prst, new_val);
+               mutex_unlock(&data->lock_ps);
+               if (ret >= 0)
+                       data->ps_period = period;
+
+               return ret;
+       default:
+               return -EINVAL;
+       }
+
+       return -EINVAL;
+}
+
 static const struct iio_event_spec ltr501_als_event_spec[] = {
        {
                .type = IIO_EV_TYPE_THRESH,
@@ -189,7 +446,8 @@ static const struct iio_event_spec ltr501_als_event_spec[] = {
        }, {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_EITHER,
-               .mask_separate = BIT(IIO_EV_INFO_ENABLE),
+               .mask_separate = BIT(IIO_EV_INFO_ENABLE) |
+                                BIT(IIO_EV_INFO_PERIOD),
        },
 
 };
@@ -206,7 +464,8 @@ static const struct iio_event_spec ltr501_pxs_event_spec[] = {
        }, {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_EITHER,
-               .mask_separate = BIT(IIO_EV_INFO_ENABLE),
+               .mask_separate = BIT(IIO_EV_INFO_ENABLE) |
+                                BIT(IIO_EV_INFO_PERIOD),
        },
 };
 
@@ -235,7 +494,8 @@ static const struct iio_chan_spec ltr501_channels[] = {
                                 ARRAY_SIZE(ltr501_als_event_spec)),
        LTR501_INTENSITY_CHANNEL(1, LTR501_ALS_DATA1, IIO_MOD_LIGHT_IR,
                                 BIT(IIO_CHAN_INFO_SCALE) |
-                                BIT(IIO_CHAN_INFO_INT_TIME),
+                                BIT(IIO_CHAN_INFO_INT_TIME) |
+                                BIT(IIO_CHAN_INFO_SAMP_FREQ),
                                 NULL, 0),
        {
                .type = IIO_PROXIMITY,
@@ -320,6 +580,15 @@ static int ltr501_read_raw(struct iio_dev *indio_dev,
                default:
                        return -EINVAL;
                }
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               switch (chan->type) {
+               case IIO_INTENSITY:
+                       return ltr501_als_read_samp_freq(data, val, val2);
+               case IIO_PROXIMITY:
+                       return ltr501_ps_read_samp_freq(data, val, val2);
+               default:
+                       return -EINVAL;
+               }
        }
        return -EINVAL;
 }
@@ -340,7 +609,7 @@ static int ltr501_write_raw(struct iio_dev *indio_dev,
                            int val, int val2, long mask)
 {
        struct ltr501_data *data = iio_priv(indio_dev);
-       int i;
+       int i, ret, freq_val, freq_val2;
 
        if (iio_buffer_enabled(indio_dev))
                return -EBUSY;
@@ -382,6 +651,49 @@ static int ltr501_write_raw(struct iio_dev *indio_dev,
                default:
                        return -EINVAL;
                }
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               switch (chan->type) {
+               case IIO_INTENSITY:
+                       ret = ltr501_als_read_samp_freq(data, &freq_val,
+                                                       &freq_val2);
+                       if (ret < 0)
+                               return ret;
+
+                       ret = ltr501_als_write_samp_freq(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+
+                       /* update persistence count when changing frequency */
+                       ret = ltr501_write_intr_prst(data, chan->type,
+                                                    0, data->als_period);
+
+                       if (ret < 0)
+                               return ltr501_als_write_samp_freq(data,
+                                                                 freq_val,
+                                                                 freq_val2);
+                       return ret;
+               case IIO_PROXIMITY:
+                       ret = ltr501_ps_read_samp_freq(data, &freq_val,
+                                                      &freq_val2);
+                       if (ret < 0)
+                               return ret;
+
+                       ret = ltr501_ps_write_samp_freq(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+
+                       /* update persistence count when changing frequency */
+                       ret = ltr501_write_intr_prst(data, chan->type,
+                                                    0, data->ps_period);
+
+                       if (ret < 0)
+                               return ltr501_ps_write_samp_freq(data,
+                                                                freq_val,
+                                                                freq_val2);
+                       return ret;
+               default:
+                       return -EINVAL;
+               }
        }
        return -EINVAL;
 }
@@ -509,6 +821,55 @@ static int ltr501_write_thresh(struct iio_dev *indio_dev,
        return -EINVAL;
 }
 
+static int ltr501_read_event(struct iio_dev *indio_dev,
+                            const struct iio_chan_spec *chan,
+                            enum iio_event_type type,
+                            enum iio_event_direction dir,
+                            enum iio_event_info info,
+                            int *val, int *val2)
+{
+       int ret;
+
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               return ltr501_read_thresh(indio_dev, chan, type, dir,
+                                         info, val, val2);
+       case IIO_EV_INFO_PERIOD:
+               ret = ltr501_read_intr_prst(iio_priv(indio_dev),
+                                           chan->type, val2);
+               *val = *val2 / 1000000;
+               *val2 = *val2 % 1000000;
+               return ret;
+       default:
+               return -EINVAL;
+       }
+
+       return -EINVAL;
+}
+
+static int ltr501_write_event(struct iio_dev *indio_dev,
+                             const struct iio_chan_spec *chan,
+                             enum iio_event_type type,
+                             enum iio_event_direction dir,
+                             enum iio_event_info info,
+                             int val, int val2)
+{
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               if (val2 != 0)
+                       return -EINVAL;
+               return ltr501_write_thresh(indio_dev, chan, type, dir,
+                                          info, val, val2);
+       case IIO_EV_INFO_PERIOD:
+               return ltr501_write_intr_prst(iio_priv(indio_dev), chan->type,
+                                             val, val2);
+       default:
+               return -EINVAL;
+       }
+
+       return -EINVAL;
+}
+
 static int ltr501_read_event_config(struct iio_dev *indio_dev,
                                    const struct iio_chan_spec *chan,
                                    enum iio_event_type type,
@@ -568,11 +929,13 @@ static int ltr501_write_event_config(struct iio_dev *indio_dev,
 static IIO_CONST_ATTR(in_proximity_scale_available, "1 0.25 0.125 0.0625");
 static IIO_CONST_ATTR(in_intensity_scale_available, "1 0.005");
 static IIO_CONST_ATTR_INT_TIME_AVAIL("0.05 0.1 0.2 0.4");
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("20 10 5 2 1 0.5");
 
 static struct attribute *ltr501_attributes[] = {
        &iio_const_attr_in_proximity_scale_available.dev_attr.attr,
        &iio_const_attr_in_intensity_scale_available.dev_attr.attr,
        &iio_const_attr_integration_time_available.dev_attr.attr,
+       &iio_const_attr_sampling_frequency_available.dev_attr.attr,
        NULL
 };
 
@@ -591,8 +954,8 @@ static const struct iio_info ltr501_info = {
        .read_raw = ltr501_read_raw,
        .write_raw = ltr501_write_raw,
        .attrs = &ltr501_attribute_group,
-       .read_event_value       = &ltr501_read_thresh,
-       .write_event_value      = &ltr501_write_thresh,
+       .read_event_value       = &ltr501_read_event,
+       .write_event_value      = &ltr501_write_event,
        .read_event_config      = &ltr501_read_event_config,
        .write_event_config     = &ltr501_write_event_config,
        .driver_module = THIS_MODULE,
@@ -706,6 +1069,14 @@ static int ltr501_init(struct ltr501_data *data)
 
        data->ps_contr = status | LTR501_CONTR_ACTIVE;
 
+       ret = ltr501_read_intr_prst(data, IIO_INTENSITY, &data->als_period);
+       if (ret < 0)
+               return ret;
+
+       ret = ltr501_read_intr_prst(data, IIO_PROXIMITY, &data->ps_period);
+       if (ret < 0)
+               return ret;
+
        return ltr501_write_contr(data, data->als_contr, data->ps_contr);
 }
 
@@ -783,6 +1154,34 @@ static int ltr501_probe(struct i2c_client *client,
                return PTR_ERR(data->reg_ps_intr);
        }
 
+       data->reg_als_rate = devm_regmap_field_alloc(&client->dev, regmap,
+                                                    reg_field_als_rate);
+       if (IS_ERR(data->reg_als_rate)) {
+               dev_err(&client->dev, "ALS samp rate field init failed.\n");
+               return PTR_ERR(data->reg_als_rate);
+       }
+
+       data->reg_ps_rate = devm_regmap_field_alloc(&client->dev, regmap,
+                                                   reg_field_ps_rate);
+       if (IS_ERR(data->reg_ps_rate)) {
+               dev_err(&client->dev, "PS samp rate field init failed.\n");
+               return PTR_ERR(data->reg_ps_rate);
+       }
+
+       data->reg_als_prst = devm_regmap_field_alloc(&client->dev, regmap,
+                                                    reg_field_als_prst);
+       if (IS_ERR(data->reg_als_prst)) {
+               dev_err(&client->dev, "ALS prst reg field init failed\n");
+               return PTR_ERR(data->reg_als_prst);
+       }
+
+       data->reg_ps_prst = devm_regmap_field_alloc(&client->dev, regmap,
+                                                   reg_field_ps_prst);
+       if (IS_ERR(data->reg_ps_prst)) {
+               dev_err(&client->dev, "PS prst reg field init failed.\n");
+               return PTR_ERR(data->reg_ps_prst);
+       }
+
        ret = regmap_read(data->regmap, LTR501_PART_ID, &partid);
        if (ret < 0)
                return ret;