Re: [PATCH] hwmon: (ina3221) Add voltage conversion time settings

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 4/17/19 6:46 AM, Guenter Roeck wrote:
On 4/16/19 4:55 PM, Nicolin Chen wrote:
The CONFIG register has two 3-bit fields for conversion time
settings of Bus-voltage and Shunt-voltage, respectively. The
conversion settings, along with averaging mode, allow users
to optimize available timing requirement.

This patch adds an 'update_interval' sysfs node through the
hwmon_chip_info of hwmon core. It reflects a total hardware
conversion time:
     samples * channels * (Bus + Shunt conversion times)

Though INA3221 supports different conversion time setups for
Bus and Shunt voltages, this patch only adds the support of
a unified setting for both conversion times, by dividing the
conversion time into two equal values.

Signed-off-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx>
---

Hi Guenter,

I am not quite sure if this update_interval is the best way to
implement the conversion time settings but I can't find another
common approach. This implementation certainly has drawbacks:
  1) It can't configure Bus and Shunt conversion times separately
     (Not crucial for me at this point as I set them equally)
  2) Users need to calculate for the settings of conversion time
  3) The ABI defines update_interval in msec while the hardware
     and datasheet does in usec, and that generates rounding diff
  4) The update_interval value would be spontaneously modified
     everytime number of samples or number of enabled channels
     gets changed. This might confuses users who tries to have
     a fixed update_interval other than really merely setting
     conversion time.

I see IIO subsystem have something like IIO_CHAN_INFO_INT_TIME
for conversion time setting exclusively. Do we have something
similar under hwmon?


No. I think what you have should be good enough for now.
Please see comments below.

Thanks,
Guenter

Thanks

  Documentation/hwmon/ina3221 |  9 +++++
  drivers/hwmon/ina3221.c     | 65 ++++++++++++++++++++++++++++++++-----
  2 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/Documentation/hwmon/ina3221 b/Documentation/hwmon/ina3221
index ed3f22769d4b..3b05170112f0 100644
--- a/Documentation/hwmon/ina3221
+++ b/Documentation/hwmon/ina3221
@@ -38,3 +38,12 @@ in[456]_input           Shunt voltage(uV) for channels 1, 2, and 3 respectively
  samples                 Number of samples using in the averaging mode.
                            Supports the list of number of samples:
                            1, 4, 16, 64, 128, 256, 512, 1024
+update_interval         Data conversion time in millisecond, following:
+                          update_interval = C x S x (BC + SC)
+                              C: number of enabled channels
+                              S: number of samples
+                             BC: bus-voltage conversion time in millisecond
+                             SC: shunt-voltage conversion time in millisecond
+                          Affects both Bus- and Shunt-voltage conversion time.
+                          Note that setting update_interval to 0ms sets both BC
+                          and SC to 140 us (minimum conversion time).
diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index 74d39d212931..af4ab8ddddce 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -144,19 +144,37 @@ static const int ina3221_avg_samples[] = {
      1, 4, 16, 64, 128, 256, 512, 1024,
  };
-static inline int ina3221_wait_for_data(struct ina3221_data *ina)
+/* Converting update_interval in msec to conversion time in usec */
+static inline u32 ina3221_interval_ms_to_conv_time(u16 config, int interval)
  {
-    u32 channels = hweight16(ina->reg_config & INA3221_CONFIG_CHs_EN_MASK);
-    u32 vbus_ct_idx = INA3221_CONFIG_VBUS_CT(ina->reg_config);
-    u32 vsh_ct_idx = INA3221_CONFIG_VSH_CT(ina->reg_config);
-    u32 samples_idx = INA3221_CONFIG_AVG(ina->reg_config);
+    u32 channels = hweight16(config & INA3221_CONFIG_CHs_EN_MASK);
+    u32 samples_idx = INA3221_CONFIG_AVG(config);
+    u32 samples = ina3221_avg_samples[samples_idx];
+
+    /* Bisect the result to Bus and Shunt conversion times */
+    return DIV_ROUND_CLOSEST(interval * 1000 / 2, channels * samples);
+}
+
+/* Converting CONFIG register value to update_interval in usec */
+static inline u32 ina3221_reg_to_interval_us(u16 config)
+{
+    u32 channels = hweight16(config & INA3221_CONFIG_CHs_EN_MASK);
+    u32 vbus_ct_idx = INA3221_CONFIG_VBUS_CT(config);
+    u32 vsh_ct_idx = INA3221_CONFIG_VSH_CT(config);
+    u32 samples_idx = INA3221_CONFIG_AVG(config);
      u32 samples = ina3221_avg_samples[samples_idx];
      u32 vbus_ct = ina3221_conv_time[vbus_ct_idx];
      u32 vsh_ct = ina3221_conv_time[vsh_ct_idx];
-    u32 wait, cvrf;
      /* Calculate total conversion time */
-    wait = channels * (vbus_ct + vsh_ct) * samples;
+    return channels * (vbus_ct + vsh_ct) * samples;
+}
+
+static inline int ina3221_wait_for_data(struct ina3221_data *ina)
+{
+    u32 wait, cvrf;
+
+    wait = ina3221_reg_to_interval_us(ina->reg_config);
      /* Polling the CVRF bit to make sure read data is ready */
      return regmap_field_read_poll_timeout(ina->fields[F_CVRF],
@@ -197,6 +215,11 @@ static int ina3221_read_chip(struct device *dev, u32 attr, long *val)
          regval = INA3221_CONFIG_AVG(ina->reg_config);
          *val = ina3221_avg_samples[regval];
          return 0;
+    case hwmon_chip_update_interval:
+        /* Return in msec */
+        *val = ina3221_reg_to_interval_us(ina->reg_config);
+        *val = DIV_ROUND_CLOSEST(*val, 1000);
+        return 0;
      default:
          return -EOPNOTSUPP;
      }
@@ -308,7 +331,7 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
  static int ina3221_write_chip(struct device *dev, u32 attr, long val)
  {
      struct ina3221_data *ina = dev_get_drvdata(dev);
-    int ret, idx;
+    int ret, idx, tmp;
      switch (attr) {
      case hwmon_chip_samples:
@@ -321,6 +344,28 @@ static int ina3221_write_chip(struct device *dev, u32 attr, long val)
          if (ret)
              return ret;
+        /* Update reg_config accordingly */
+        return regmap_read(ina->regmap, INA3221_CONFIG,
+                   &ina->reg_config);
+    case hwmon_chip_update_interval:
+        tmp = ina3221_interval_ms_to_conv_time(ina->reg_config, val);
+        idx = find_closest(tmp, ina3221_conv_time,
+                   ARRAY_SIZE(ina3221_conv_time));
+
+        /* Update Bus-voltage conversion time */
+        ret = regmap_update_bits(ina->regmap, INA3221_CONFIG,
+                     INA3221_CONFIG_VBUS_CT_MASK,
+                     idx << INA3221_CONFIG_VBUS_CT_SHIFT);
+        if (ret)
+            return ret;
+
+        /* Update Shunt-voltage conversion time */
+        ret = regmap_update_bits(ina->regmap, INA3221_CONFIG,
+                     INA3221_CONFIG_VSH_CT_MASK,
+                     idx << INA3221_CONFIG_VSH_CT_SHIFT);
+        if (ret)
+            return ret;

It should be possible to update both conversion times with a single call,
since both calls touch only one register. Something like

         ret = regmap_update_bits(ina->regmap, INA3221_CONFIG
             INA3221_CONFIG_VBUS_CT_MASK | INA3221_CONFIG_VSH_CT_MASK,
             (idx << INA3221_CONFIG_VBUS_CT_SHIFT) | (idx << INA3221_CONFIG_VSH_CT_SHIFT));

Granted, that is a bit long, but it saves an extra i2c write operation.


Thinking about it ... does it even make sense to cache reg_config twice,
or would it be better to just update the local copy and use regmap_write()
to send it to the chip ?

Guenter

+
          /* Update reg_config accordingly */
          return regmap_read(ina->regmap, INA3221_CONFIG,
                     &ina->reg_config);
@@ -482,6 +527,7 @@ static umode_t ina3221_is_visible(const void *drvdata,
      case hwmon_chip:
          switch (attr) {
          case hwmon_chip_samples:
+        case hwmon_chip_update_interval:
              return 0644;
          default:
              return 0;
@@ -527,7 +573,8 @@ static umode_t ina3221_is_visible(const void *drvdata,
  static const struct hwmon_channel_info *ina3221_info[] = {
      HWMON_CHANNEL_INFO(chip,
-               HWMON_C_SAMPLES),
+               HWMON_C_SAMPLES,
+               HWMON_C_UPDATE_INTERVAL),
      HWMON_CHANNEL_INFO(in,
                 /* 0: dummy, skipped in is_visible */
                 HWMON_I_INPUT,







[Index of Archives]     [LM Sensors]     [Linux Sound]     [ALSA Users]     [ALSA Devel]     [Linux Audio Users]     [Linux Media]     [Kernel]     [Gimp]     [Yosemite News]     [Linux Media]

  Powered by Linux