Re: [PATCH] hwmon: (ina3221) Add voltage conversion time settings
From: Guenter Roeck
Date: Wed Apr 17 2019 - 09:46:56 EST
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.
+
/* 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,