[PATCH v3 1/2] hwmon: (pmbus/isl68137) add support for voltage divider on Vout

Grant Peltier
2024-10-23T20:53:16Z

Some applications require Vout to be higher than the detectable voltage
range of the Vsense pin for a given rail. In such applications, a voltage
divider may be placed between Vout and the Vsense pin, but this results
in erroneous telemetry being read back from the part. This change adds
support for a voltage divider to be defined in the devicetree for a (or
multiple) specific rail(s) for a supported digital multiphase device and
for the applicable Vout telemetry to be scaled based on the voltage
divider configuration.

Signed-off-by: Grant Peltier <grantpeltier93@gmail.com>
---
drivers/hwmon/pmbus/isl68137.c | 204 ++++++++++++++++++++++++++++++++-
1 file changed, 199 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/pmbus/isl68137.c b/drivers/hwmon/pmbus/isl68137.c
index 7e53fb1d5ea3..24b5adffb526 100644
--- a/drivers/hwmon/pmbus/isl68137.c
+++ b/drivers/hwmon/pmbus/isl68137.c
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/of.h>
#include <linux/string.h>
#include <linux/sysfs.h>

@@ -20,6 +21,7 @@

#define ISL68137_VOUT_AVS 0x30
#define RAA_DMPVR2_READ_VMON 0xc8
+#define MAX_CHANNELS 4

enum chips {
isl68137,
@@ -72,6 +74,17 @@ enum variants {
raa_dmpvr2_hv,
};

+struct isl68137_channel {
+ u32 vout_voltage_divider[2];
+};
+
+struct isl68137_data {
+ struct pmbus_driver_info info;
+ struct isl68137_channel channel[MAX_CHANNELS];
+};
+
+#define to_isl68137_data(x) container_of(x, struct isl68137_data, info)
+
static const struct i2c_device_id raa_dmpvr_id[];

static ssize_t isl68137_avs_enable_show_page(struct i2c_client *client,
@@ -163,6 +176,8 @@ static const struct attribute_group *isl68137_attribute_groups[] = {
static int raa_dmpvr2_read_word_data(struct i2c_client *client, int page,
int phase, int reg)
{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ const struct isl68137_data *data = to_isl68137_data(info);
int ret;

switch (reg) {
@@ -170,6 +185,25 @@ static int raa_dmpvr2_read_word_data(struct i2c_client *client, int page,
ret = pmbus_read_word_data(client, page, phase,
RAA_DMPVR2_READ_VMON);
break;
+ case PMBUS_READ_POUT:
+ /*
+ * In cases where a voltage divider is attached to the target
+ * rail between Vout and the Vsense pin, both Vout and Pout
+ * should be scaled by the voltage divider scaling factor.
+ * I.e. Vout = Vsense * (R1 + R2) / R2
+ */
+ fallthrough;
+ case PMBUS_READ_VOUT:
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret > 0 && data->channel[page].vout_voltage_divider[0]
+ && data->channel[page].vout_voltage_divider[1]) {
+ u64 temp = DIV_U64_ROUND_CLOSEST((u64)ret *
+ ((u64)data->channel[page].vout_voltage_divider[0]
+ + data->channel[page].vout_voltage_divider[1]),
+ data->channel[page].vout_voltage_divider[1]);
+ ret = clamp_val(temp, 0, 0xffff);
+ }
+ break;
default:
ret = -ENODATA;
break;
@@ -178,6 +212,50 @@ static int raa_dmpvr2_read_word_data(struct i2c_client *client, int page,
return ret;
}

+static int raa_dmpvr2_write_word_data(struct i2c_client *client, int page,
+ int reg, u16 word)
+{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ const struct isl68137_data *data = to_isl68137_data(info);
+ int ret;
+
+ switch (reg) {
+ case PMBUS_VOUT_MAX:
+ /*
+ * In cases where a voltage divider is attached to the target
+ * rail between Vout and the Vsense pin, Vout related PMBus
+ * commands should be scaled based on the expected voltage
+ * at the Vsense pin.
+ * I.e. Vsense = Vout * R2 / (R1 + R2)
+ */
+ fallthrough;
+ case PMBUS_VOUT_MARGIN_HIGH:
+ fallthrough;
+ case PMBUS_VOUT_MARGIN_LOW:
+ fallthrough;
+ case PMBUS_VOUT_OV_FAULT_LIMIT:
+ fallthrough;
+ case PMBUS_VOUT_UV_FAULT_LIMIT:
+ fallthrough;
+ case PMBUS_VOUT_COMMAND:
+ if (data->channel[page].vout_voltage_divider[0]
+ && data->channel[page].vout_voltage_divider[1]) {
+ u64 temp = DIV64_U64_ROUND_CLOSEST((u64)word *
+ data->channel[page].vout_voltage_divider[1],
+ ((u64)data->channel[page].vout_voltage_divider[0]
+ + data->channel[page].vout_voltage_divider[1]));
+ ret = clamp_val(temp, 0, 0xffff);
+ } else {
+ ret = -ENODATA;
+ }
+ break;
+ default:
+ ret = -ENODATA;
+ break;
+ }
+ return ret;
+}
+
static struct pmbus_driver_info raa_dmpvr_info = {
.pages = 3,
.format[PSC_VOLTAGE_IN] = direct,
@@ -220,14 +298,72 @@ static struct pmbus_driver_info raa_dmpvr_info = {
| PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_POUT,
};

+static int isl68137_probe_child_from_dt(struct device *dev,
+ struct device_node *child,
+ struct isl68137_data *data)
+{
+ u32 channel;
+ int err;
+
+ err = of_property_read_u32(child, "reg", &channel);
+ if (err) {
+ dev_err(dev, "missing reg property of %pOFn\n", child);
+ return err;
+ }
+ if (channel >= MAX_CHANNELS) {
+ dev_err(dev, "invalid reg %d of %pOFn\n", channel, child);
+ return -EINVAL;
+ }
+
+ err = of_property_read_u32_array(child, "renesas,vout-voltage-divider",
+ data->channel[channel].vout_voltage_divider,
+ ARRAY_SIZE(data->channel[channel].vout_voltage_divider));
+ if (err && err != -EINVAL) {
+ dev_err(dev,
+ "malformed renesas,vout-voltage-divider value for channel %d\n",
+ channel);
+ return err;
+ }
+ return 0;
+}
+
+static int isl68137_probe_from_dt(struct device *dev,
+ struct isl68137_data *data)
+{
+ const struct device_node *np = dev->of_node;
+ struct device_node *child;
+ int err;
+
+ for_each_child_of_node(np, child) {
+ if (strcmp(child->name, "channel"))
+ continue;
+
+ err = isl68137_probe_child_from_dt(dev, child, data);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
static int isl68137_probe(struct i2c_client *client)
{
+ struct device *dev = &client->dev;
struct pmbus_driver_info *info;
+ struct isl68137_data *data;
+ int i, err;

- info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
- if (!info)
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
return -ENOMEM;
- memcpy(info, &raa_dmpvr_info, sizeof(*info));
+
+ for (i = 0; i < MAX_CHANNELS; i++)
+ memset(data->channel[i].vout_voltage_divider,
+ 0,
+ sizeof(data->channel[i].vout_voltage_divider));
+
+ memcpy(&data->info, &raa_dmpvr_info, sizeof(data->info));
+ info = &data->info;

switch (i2c_match_id(raa_dmpvr_id, client)->driver_data) {
case raa_dmpvr1_2rail:
@@ -242,6 +378,7 @@ static int isl68137_probe(struct i2c_client *client)
case raa_dmpvr2_1rail:
info->pages = 1;
info->read_word_data = raa_dmpvr2_read_word_data;
+ info->write_word_data = raa_dmpvr2_write_word_data;
break;
case raa_dmpvr2_2rail_nontc:
info->func[0] &= ~PMBUS_HAVE_TEMP3;
@@ -250,9 +387,11 @@ static int isl68137_probe(struct i2c_client *client)
case raa_dmpvr2_2rail:
info->pages = 2;
info->read_word_data = raa_dmpvr2_read_word_data;
+ info->write_word_data = raa_dmpvr2_write_word_data;
break;
case raa_dmpvr2_3rail:
info->read_word_data = raa_dmpvr2_read_word_data;
+ info->write_word_data = raa_dmpvr2_write_word_data;
break;
case raa_dmpvr2_hv:
info->pages = 1;
@@ -263,11 +402,18 @@ static int isl68137_probe(struct i2c_client *client)
info->m[PSC_POWER] = 2;
info->R[PSC_POWER] = -1;
info->read_word_data = raa_dmpvr2_read_word_data;
+ info->write_word_data = raa_dmpvr2_write_word_data;
break;
default:
return -ENODEV;
}

+ if (dev->of_node) {
+ err = isl68137_probe_from_dt(dev, data);
+ if (err)
+ return err;
+ }
+
return pmbus_do_probe(client, info);
}

@@ -318,11 +464,59 @@ static const struct i2c_device_id raa_dmpvr_id[] = {

MODULE_DEVICE_TABLE(i2c, raa_dmpvr_id);

+static const struct of_device_id isl68137_of_match[] = {
+ { .compatible = "renesas,isl68137", .data = (void *)raa_dmpvr1_2rail },
+ { .compatible = "renesas,isl68220", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl68221", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl68222", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl68223", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl68224", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl68225", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl68226", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl68227", .data = (void *)raa_dmpvr2_1rail },
+ { .compatible = "renesas,isl68229", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl68233", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl68239", .data = (void *)raa_dmpvr2_3rail },
+
+ { .compatible = "renesas,isl69222", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69223", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl69224", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69225", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69227", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl69228", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl69234", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69236", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69239", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl69242", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69243", .data = (void *)raa_dmpvr2_1rail },
+ { .compatible = "renesas,isl69247", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69248", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69254", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69255", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69256", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69259", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69260", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69268", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,isl69269", .data = (void *)raa_dmpvr2_3rail },
+ { .compatible = "renesas,isl69298", .data = (void *)raa_dmpvr2_2rail },
+
+ { .compatible = "renesas,raa228000", .data = (void *)raa_dmpvr2_hv },
+ { .compatible = "renesas,raa228004", .data = (void *)raa_dmpvr2_hv },
+ { .compatible = "renesas,raa228006", .data = (void *)raa_dmpvr2_hv },
+ { .compatible = "renesas,raa228228", .data = (void *)raa_dmpvr2_2rail_nontc },
+ { .compatible = "renesas,raa229001", .data = (void *)raa_dmpvr2_2rail },
+ { .compatible = "renesas,raa229004", .data = (void *)raa_dmpvr2_2rail },
+ { },
+};
+
+MODULE_DEVICE_TABLE(of, isl68137_of_match);
+
/* This is the driver that will be inserted */
static struct i2c_driver isl68137_driver = {
.driver = {
- .name = "isl68137",
- },
+ .name = "isl68137",
+ .of_match_table = isl68137_of_match,
+ },
.probe = isl68137_probe,
.id_table = raa_dmpvr_id,
};
--
2.39.5