[PATCH v2 9/9] hwmon: adm1275: Support ROHM BD12790

From: Matti Vaittinen

Date: Fri Jun 26 2026 - 03:26:52 EST

From: Matti Vaittinen <mazziesaccount@xxxxxxxxx>

Add support for ROHM BD12790 hot-swap controller which is largely
similar to Analog Devices adm1272.

The BD12790 uses the same selectable 60V/100V voltage ranges and
15mV/30mV current-sense ranges as the ADM1272, and the same VRANGE
(bit 5) and IRANGE (bit 0) layout in PMON_CONFIG. It therefore uses
a dedicated coefficient table that mirrors adm1272_coefficients, with
the following differences derived from BD12790 datasheet Table 1 (p.18):
- power 60V/30mV: m=17560 (vs. 17561)
- power 100V/30mV: m=10536 (vs. 10535)
- temperature: b=31880 (vs. 31871, reflecting T[11:0] = 4.2*T + 3188)

Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
Assisted-by: GitHub Copilot:claude-sonnet-4.6

---
Revision history:
v1 => v2: Changes mostly based on the review by Guenter:
- Add own 'case' for the bd12790.
- Don't use wildcard in the macro name.
- Fix the coefficient computation comment for power to take the
shunt-resistor scale into account.
---
drivers/hwmon/pmbus/Kconfig | 4 +-
drivers/hwmon/pmbus/adm1275.c | 79 +++++++++++++++++++++++++++++++++--
2 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index b3c27f3b2712..6ebc01e26db3 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -52,8 +52,8 @@ config SENSORS_ADM1275
help
If you say yes here you get hardware monitoring support for Analog
Devices ADM1075, ADM1272, ADM1273, ADM1275, ADM1276, ADM1278, ADM1281,
- ADM1293, ADM1294, ROHM BD12780, and SQ24905C Hot-Swap Controller and
- Digital Power Monitors.
+ ADM1293, ADM1294, ROHM BD12780, ROHM BD12790, and SQ24905C
+ Hot-Swap Controller and Digital Power Monitors.

This driver can also be built as a module. If so, the module will
be called adm1275.
diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
index 81c50fab7687..406b44852376 100644
--- a/drivers/hwmon/pmbus/adm1275.c
+++ b/drivers/hwmon/pmbus/adm1275.c
@@ -19,7 +19,7 @@
#include "pmbus.h"

enum chips { adm1075, adm1272, adm1273, adm1275, adm1276, adm1278, adm1281,
- adm1293, adm1294, bd12780, sq24905c };
+ adm1293, adm1294, bd12780, bd12790, sq24905c };

#define ADM1275_MFR_STATUS_IOUT_WARN2 BIT(0)
#define ADM1293_MFR_STATUS_VAUX_UV_WARN BIT(5)
@@ -47,7 +47,7 @@ enum chips { adm1075, adm1272, adm1273, adm1275, adm1276, adm1278, adm1281,
#define ADM1278_VOUT_EN BIT(1)

#define ADM1278_PMON_DEFCONFIG (ADM1278_VOUT_EN | ADM1278_TEMP1_EN | ADM1278_TSFILT)
-/* The BD12780 data sheets mark TSFILT bit as reserved. */
+/* The BD127[89]0 data sheets mark TSFILT bit as reserved. */
#define BD12780_PMON_DEFCONFIG (ADM1278_VOUT_EN | ADM1278_TEMP1_EN)

#define ADM1293_IRANGE_25 0
@@ -136,6 +136,30 @@ static const struct coefficients adm1272_coefficients[] = {

};

+/*
+ * BD12790 coefficients derived from preliminary datasheet, Table 1 (p.18)
+ * and the PMBus direct-format relationship X = (Y * 10^(-R) - b) / m.
+ *
+ * Voltage: V[V] = 14.77e-3 * code (60V) / 24.62e-3 * code (100V)
+ * -> m = 6770, R=-2 / m = 4062, R=-2
+ * Current: code = I[A] * RS * 132802.1 + 2048 (15mV) / * 66401.06 + 2048 (30mV)
+ * -> m = 1328, b = 2048 * 10^(-R) = 20480, R=-1 / m = 664, same b and R
+ * Power: code = k * RS * PIN, k = 35119.94 / 17559.97 / 21071.44 / 10535.72
+ * -> m = round(k / 10^(-3-R)), R=-2 for 60V/15mV, R=-3 for the other three
+ * Temperature: code = 4.2 * T + 3188 -> m = 42, b = 3188 * 10 = 31880, R=-1
+ */
+static const struct coefficients bd12790_coefficients[] = {
+ [0] = { 6770, 0, -2 }, /* voltage, vrange 60V */
+ [1] = { 4062, 0, -2 }, /* voltage, vrange 100V */
+ [2] = { 1328, 20480, -1 }, /* current, vsense range 15mV */
+ [3] = { 664, 20480, -1 }, /* current, vsense range 30mV */
+ [4] = { 3512, 0, -2 }, /* power, vrange 60V, irange 15mV */
+ [5] = { 21071, 0, -3 }, /* power, vrange 100V, irange 15mV */
+ [6] = { 17560, 0, -3 }, /* power, vrange 60V, irange 30mV */
+ [7] = { 10536, 0, -3 }, /* power, vrange 100V, irange 30mV */
+ [8] = { 42, 31880, -1 }, /* temperature */
+};
+
static const struct coefficients adm1275_coefficients[] = {
[0] = { 19199, 0, -2 }, /* voltage, vrange set */
[1] = { 6720, 0, -1 }, /* voltage, vrange not set */
@@ -490,6 +514,7 @@ static const struct i2c_device_id adm1275_id[] = {
{ "adm1293", adm1293 },
{ "adm1294", adm1294 },
{ "bd12780", bd12780 },
+ { "bd12790", bd12790 },
{ "mc09c", sq24905c },
{ }
};
@@ -567,7 +592,8 @@ static int adm1275_probe(struct i2c_client *client)
if (mid->driver_data == adm1272 || mid->driver_data == adm1273 ||
mid->driver_data == adm1278 || mid->driver_data == adm1281 ||
mid->driver_data == adm1293 || mid->driver_data == adm1294 ||
- mid->driver_data == bd12780 || mid->driver_data == sq24905c)
+ mid->driver_data == bd12780 || mid->driver_data == bd12790 ||
+ mid->driver_data == sq24905c)
config_read_fn = i2c_smbus_read_word_data;
else
config_read_fn = i2c_smbus_read_byte_data;
@@ -647,6 +673,7 @@ static int adm1275_probe(struct i2c_client *client)
data->have_power_sampling = true;

coefficients = adm1272_coefficients;
+
vindex = (config & ADM1275_VRANGE) ? 1 : 0;
cindex = (config & ADM1272_IRANGE) ? 3 : 2;
/* pindex depends on the combination of the above */
@@ -679,6 +706,51 @@ static int adm1275_probe(struct i2c_client *client)
if (config & ADM1278_VIN_EN)
info->func[0] |= PMBUS_HAVE_VIN;
break;
+
+ /*
+ * The BD12790 is almost identical to the adm1272. Only the defconfig
+ * and coefficients have minor differences.
+ */
+ case bd12790:
+ data->have_vout = true;
+ data->have_pin_max = true;
+ data->have_temp_max = true;
+ data->have_power_sampling = true;
+
+ coefficients = bd12790_coefficients;
+
+ vindex = (config & ADM1275_VRANGE) ? 1 : 0;
+ cindex = (config & ADM1272_IRANGE) ? 3 : 2;
+ /* pindex depends on the combination of the above */
+ switch (config & (ADM1275_VRANGE | ADM1272_IRANGE)) {
+ case 0:
+ default:
+ pindex = 4;
+ break;
+ case ADM1275_VRANGE:
+ pindex = 5;
+ break;
+ case ADM1272_IRANGE:
+ pindex = 6;
+ break;
+ case ADM1275_VRANGE | ADM1272_IRANGE:
+ pindex = 7;
+ break;
+ }
+ tindex = 8;
+
+ info->func[0] |= PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |
+ PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+ PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
+
+ ret = adm1275_enable_vout_temp(data, client, config,
+ BD12780_PMON_DEFCONFIG);
+ if (ret)
+ return ret;
+
+ if (config & ADM1278_VIN_EN)
+ info->func[0] |= PMBUS_HAVE_VIN;
+ break;
case adm1275:
if (device_config & ADM1275_IOUT_WARN2_SELECT)
data->have_oc_fault = true;
@@ -919,6 +991,7 @@ static const struct of_device_id adm1275_of_match[] = {
{ .compatible = "adi,adm1293", },
{ .compatible = "adi,adm1294", },
{ .compatible = "rohm,bd12780", },
+ { .compatible = "rohm,bd12790", },
{ .compatible = "silergy,mc09c", },
{ }
};
--
2.54.0

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