Re: [PATCH 4/6] iio: accel: kxcjk-1013: Set adjustable range

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On 07/20/2014 08:45 AM, Jonathan Cameron wrote:
On 17/07/14 01:42, Srinivas Pandruvada wrote:
This chip can support 3 different ranges. Allowing range specification.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
A few minor suggestions.  Basically fine though.
---
drivers/iio/accel/kxcjk-1013.c | 80 +++++++++++++++++++++++++++++++++++++++++-
  1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
index 4912143..975f8a6 100644
--- a/drivers/iio/accel/kxcjk-1013.c
+++ b/drivers/iio/accel/kxcjk-1013.c
@@ -70,6 +70,10 @@
  #define KXCJK1013_REG_INT_REG1_BIT_IEA    BIT(4)
  #define KXCJK1013_REG_INT_REG1_BIT_IEN    BIT(5)

+#define KXCJK1013_RANGE_2G        0x00
+#define KXCJK1013_RANGE_4G        0x01
+#define KXCJK1013_RANGE_8G        0x02
These are effectively used as an enum?  Hence I'd make them one.

+
  #define KXCJK1013_DATA_MASK_12_BIT    0x0FFF
  #define KXCJK1013_MAX_STARTUP_TIME_US    100000

@@ -86,6 +90,7 @@ struct kxcjk1013_data {
      struct mutex mutex;
      s16 buffer[8];
      u8 odr_bits;
+    u8 range;
with an enum above this becomes a little more obvious too.
      bool active_high_intr;
      bool trigger_on;
  };
@@ -120,6 +125,14 @@ static const struct {
                 {0x02, 21000}, {0x03, 11000}, {0x04, 6400},
                 {0x05, 3900}, {0x06, 2700}, {0x07, 2100} };

+static const struct {
+    u16 scale;
+    u8 gsel_0;
+    u8 gsel_1;
Could use a bitfield to make it clear these are single bits..
I thought bit fields is not recommended for portability concerns in kernel.
Hence avoided using bit fields.

Thanks,
Srinivas

+} KXCJK1013_scale_table[] = { {9582, 0, 0},
+                  {19163, 0, 1},
+                  {38326, 1, 0} };
+
Once the _4G etc defines are an enum, you can explicitly set the values
in the table using [KXCJK1013_RANGE_2G] = etc

  static int kxcjk1013_set_mode(struct kxcjk1013_data *data,
                    enum kxcjk1013_mode mode)
  {
@@ -190,6 +203,7 @@ static int kxcjk1013_chip_init(struct kxcjk1013_data *data)
      /* Setting range to 4G */
      ret |= KXCJK1013_REG_CTRL1_BIT_GSEL0;
      ret &= ~KXCJK1013_REG_CTRL1_BIT_GSEL1;
+    data->range = KXCJK1013_RANGE_4G;
I'd almost be tempted to call the set function here instead of hand coding
this case.  I know it will involve more hardware writes, but it will give
slightly more obviously correct code (one path to set it rather than two).

      /* Set 12 bit mode */
      ret |= KXCJK1013_REG_CTRL1_BIT_RES;
@@ -422,6 +436,59 @@ static int kxcjk1013_get_startup_times(struct kxcjk1013_data *data)
      return KXCJK1013_MAX_STARTUP_TIME_US;
  }

+static int kxcjk1013_set_scale(struct kxcjk1013_data *data, int val)
+{
+    int ret, i;
+    enum kxcjk1013_mode store_mode;
+
+
+    for (i = 0; i < ARRAY_SIZE(KXCJK1013_scale_table); ++i) {
+        if (KXCJK1013_scale_table[i].scale == val) {
+
+            ret = kxcjk1013_get_mode(data, &store_mode);
+            if (ret < 0)
+                return ret;
+
+            ret = kxcjk1013_set_mode(data, STANDBY);
+            if (ret < 0)
+                return ret;
+
+            ret = i2c_smbus_read_byte_data(data->client,
+                               KXCJK1013_REG_CTRL1);
+            if (ret < 0) {
+                dev_err(&data->client->dev,
+                        "Error reading reg_ctrl1\n");
+                return ret;
+            }
+
+            ret |= (KXCJK1013_scale_table[i].gsel_0 << 3);
+            ret |= (KXCJK1013_scale_table[i].gsel_1 << 4);
+
+            ret = i2c_smbus_write_byte_data(data->client,
+                            KXCJK1013_REG_CTRL1,
+                            ret);
+            if (ret < 0) {
+                dev_err(&data->client->dev,
+                    "Error writing reg_ctrl1\n");
+                return ret;
+            }
+
+            data->range = i;
+            dev_dbg(&data->client->dev, "New Scale range %d\n", i);
+
+            if (store_mode == OPERATION) {
+                ret = kxcjk1013_set_mode(data, OPERATION);
+                if (ret)
+                    return ret;
+            }
+
+            return 0;
+        }
+    }
+
+    return -EINVAL;
+}
+
  static int kxcjk1013_read_raw(struct iio_dev *indio_dev,
                    struct iio_chan_spec const *chan, int *val,
                    int *val2, long mask)
@@ -458,7 +525,7 @@ static int kxcjk1013_read_raw(struct iio_dev *indio_dev,

      case IIO_CHAN_INFO_SCALE:
          *val = 0;
-        *val2 = 19163; /* range +-4g (4/2047*9.806650) */
+        *val2 = KXCJK1013_scale_table[data->range].scale;
          return IIO_VAL_INT_PLUS_MICRO;

      case IIO_CHAN_INFO_SAMP_FREQ:
@@ -485,6 +552,14 @@ static int kxcjk1013_write_raw(struct iio_dev *indio_dev,
          ret = kxcjk1013_set_odr(data, val, val2);
          mutex_unlock(&data->mutex);
          break;
+    case IIO_CHAN_INFO_SCALE:
+        if (val)
+            return -EINVAL;
+
+        mutex_lock(&data->mutex);
+        ret = kxcjk1013_set_scale(data, val2);
+        mutex_unlock(&data->mutex);
+        break;
      default:
          ret = -EINVAL;
      }
@@ -506,8 +581,11 @@ static int kxcjk1013_validate_trigger(struct iio_dev *indio_dev,
  static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
"0.781000 1.563000 3.125000 6.250000 12.500000 25 50 100 200 400 800 1600");

+static IIO_CONST_ATTR(in_accel_scale_available, "0.009582 0.019163 0.038326");
+
  static struct attribute *kxcjk1013_attributes[] = {
&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+    &iio_const_attr_in_accel_scale_available.dev_attr.attr,
      NULL,
  };





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