From 9b20aec24b8ab2860ea41182ba554dfcc444c0c8 Mon Sep 17 00:00:00 2001 From: Chu Lin Date: Sun, 4 Oct 2020 03:14:45 +0000 Subject: [PATCH] hwmon: (pmbus/max20730) adjust the vout reading given voltage divider Problem: We use voltage dividers so that the voltage presented at the voltage sense pins is confusing. We might need to convert these readings to more meaningful readings given the voltage divider. Solution: Read the voltage divider resistance from dts and convert the voltage reading to a more meaningful reading. Testing: max20730 with voltage divider Signed-off-by: Chu Lin Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20201004031445.2321090-3-linchuyuan@google.com [groeck: Return -EINVAL instead of -ENODEV on bad deevicetree data] Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus/max20730.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/hwmon/pmbus/max20730.c b/drivers/hwmon/pmbus/max20730.c index 59907bf..57923d7 100644 --- a/drivers/hwmon/pmbus/max20730.c +++ b/drivers/hwmon/pmbus/max20730.c @@ -53,6 +53,7 @@ struct max20730_data { u16 mfr_devset1; u16 mfr_devset2; u16 mfr_voutmin; + u32 vout_voltage_divider[2]; }; #define to_max20730_data(x) container_of(x, struct max20730_data, info) @@ -468,6 +469,14 @@ static int max20730_read_word_data(struct i2c_client *client, int page, max_c = max_current[data->id][(data->mfr_devset1 >> 5) & 0x3]; ret = val_to_direct(max_c, PSC_CURRENT_OUT, info); break; + case PMBUS_READ_VOUT: + ret = pmbus_read_word_data(client, page, phase, reg); + if (ret > 0 && data->vout_voltage_divider[0] && data->vout_voltage_divider[1]) { + u64 temp = DIV_ROUND_CLOSEST_ULL((u64)ret * data->vout_voltage_divider[1], + data->vout_voltage_divider[0]); + ret = clamp_val(temp, 0, 0xffff); + } + break; default: ret = -ENODATA; break; @@ -717,6 +726,15 @@ static int max20730_probe(struct i2c_client *client) data->id = chip_id; mutex_init(&data->lock); memcpy(&data->info, &max20730_info[chip_id], sizeof(data->info)); + if (of_property_read_u32_array(client->dev.of_node, "vout-voltage-divider", + data->vout_voltage_divider, + ARRAY_SIZE(data->vout_voltage_divider)) != 0) + memset(data->vout_voltage_divider, 0, sizeof(data->vout_voltage_divider)); + if (data->vout_voltage_divider[1] < data->vout_voltage_divider[0]) { + dev_err(dev, + "The total resistance of voltage divider is less than output resistance\n"); + return -EINVAL; + } ret = i2c_smbus_read_word_data(client, MAX20730_MFR_DEVSET1); if (ret < 0) -- 2.7.4