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hwmon: (pmbus/isl68137) add support for voltage divider on Vout

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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.

This change copies the implementation of the vout-voltage-divider
devicetree property defined in the maxim,max20730 bindings schema since
it is the best fit for the use case of scaling hwmon PMBus telemetry. The
generic voltage-divider property used by many iio drivers was determined
to be a poor fit because that schema is tied directly to iio and the
isl68137 driver is not an iio driver.

Signed-off-by: Grant Peltier <grantpeltier93@gmail.com>
Message-ID: <8c2d048f87282bcf66313afbf5e923d8fc17b4d7.1731439797.git.grantpeltier93@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Grant Peltier 2024-11-12 14:09:28 -06:00 committed by Guenter Roeck
parent 71d689f60b
commit 3996187f80
1 changed files with 205 additions and 5 deletions
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210
drivers/hwmon/pmbus/isl68137.c
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@ -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,
@ -163,13 +176,32 @@ 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;
u64 temp;
switch (reg) {
case PMBUS_VIRT_READ_VMON:
ret = pmbus_read_word_data(client, page, phase,
RAA_DMPVR2_READ_VMON);
break;
case PMBUS_READ_POUT:
case PMBUS_READ_VOUT:
/*
* 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 * Rtotal / Rout
*/
ret = pmbus_read_word_data(client, page, phase, reg);
if (ret > 0) {
temp = DIV_U64_ROUND_CLOSEST((u64)ret *
data->channel[page].vout_voltage_divider[1],
data->channel[page].vout_voltage_divider[0]);
ret = clamp_val(temp, 0, 0xffff);
}
break;
default:
ret = -ENODATA;
break;
@ -178,6 +210,40 @@ 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;
u64 temp;
switch (reg) {
case PMBUS_VOUT_MAX:
case PMBUS_VOUT_MARGIN_HIGH:
case PMBUS_VOUT_MARGIN_LOW:
case PMBUS_VOUT_OV_FAULT_LIMIT:
case PMBUS_VOUT_UV_FAULT_LIMIT:
case PMBUS_VOUT_COMMAND:
/*
* 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 * Rout / Rtotal
*/
temp = DIV_U64_ROUND_CLOSEST((u64)word *
data->channel[page].vout_voltage_divider[0],
data->channel[page].vout_voltage_divider[1]);
ret = clamp_val(temp, 0, 0xffff);
break;
default:
ret = -ENODATA;
break;
}
return ret;
}
static struct pmbus_driver_info raa_dmpvr_info = {
.pages = 3,
.format[PSC_VOLTAGE_IN] = direct,
@ -220,14 +286,90 @@ 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, rout, rtotal;
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 >= data->info.pages) {
dev_err(dev, "invalid reg %d of %pOFn\n", channel, child);
return -EINVAL;
}
err = of_property_read_u32_array(child, "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 vout-voltage-divider value for channel %d\n",
channel);
return err;
}
rout = data->channel[channel].vout_voltage_divider[0];
rtotal = data->channel[channel].vout_voltage_divider[1];
if (rout == 0) {
dev_err(dev,
"Voltage divider output resistance must be greater than 0\n");
return -EINVAL;
}
if (rtotal < rout) {
dev_err(dev,
"Voltage divider total resistance is less than output resistance\n");
return -EINVAL;
}
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));
/*
* Initialize all voltage dividers to Rout=1 and Rtotal=1 to simplify
* logic in PMBus word read/write functions
*/
for (i = 0; i < MAX_CHANNELS; i++)
memset(data->channel[i].vout_voltage_divider,
1,
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:
@ -237,11 +379,14 @@ static int isl68137_probe(struct i2c_client *client)
info->func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
| PMBUS_HAVE_POUT;
info->read_word_data = raa_dmpvr2_read_word_data;
info->write_word_data = raa_dmpvr2_write_word_data;
info->groups = isl68137_attribute_groups;
break;
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 +395,11 @@ 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 +410,16 @@ 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;
}
err = isl68137_probe_from_dt(dev, data);
if (err)
return err;
return pmbus_do_probe(client, info);
}
@ -318,11 +470,59 @@ 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 = "isil,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 = "isil,isl69260", .data = (void *)raa_dmpvr2_2rail },
{ .compatible = "renesas,isl69268", .data = (void *)raa_dmpvr2_2rail },
{ .compatible = "isil,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,
};