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hwmon: (pmbus) Support per-page exponent in linear mode
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Some chips use different exponents for sensors on different pages
or rails. Detect and store exponent per page to support this situation.

This fixes a problem with wrong voltages seen on UCD90120.

Reported-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Tested-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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Guenter Roeck committed Feb 3, 2014
1 parent 38dbfb5 commit daa436e
Showing 1 changed file with 36 additions and 32 deletions.
68 changes: 36 additions & 32 deletions drivers/hwmon/pmbus/pmbus_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,8 @@ struct pmbus_data {

u32 flags; /* from platform data */

int exponent; /* linear mode: exponent for output voltages */
int exponent[PMBUS_PAGES];
/* linear mode: exponent for output voltages */

const struct pmbus_driver_info *info;

Expand Down Expand Up @@ -410,7 +411,7 @@ static long pmbus_reg2data_linear(struct pmbus_data *data,
long val;

if (sensor->class == PSC_VOLTAGE_OUT) { /* LINEAR16 */
exponent = data->exponent;
exponent = data->exponent[sensor->page];
mantissa = (u16) sensor->data;
} else { /* LINEAR11 */
exponent = ((s16)sensor->data) >> 11;
Expand Down Expand Up @@ -516,7 +517,7 @@ static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
#define MIN_MANTISSA (511 * 1000)

static u16 pmbus_data2reg_linear(struct pmbus_data *data,
enum pmbus_sensor_classes class, long val)
struct pmbus_sensor *sensor, long val)
{
s16 exponent = 0, mantissa;
bool negative = false;
Expand All @@ -525,7 +526,7 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
if (val == 0)
return 0;

if (class == PSC_VOLTAGE_OUT) {
if (sensor->class == PSC_VOLTAGE_OUT) {
/* LINEAR16 does not support negative voltages */
if (val < 0)
return 0;
Expand All @@ -534,10 +535,10 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
* For a static exponents, we don't have a choice
* but to adjust the value to it.
*/
if (data->exponent < 0)
val <<= -data->exponent;
if (data->exponent[sensor->page] < 0)
val <<= -data->exponent[sensor->page];
else
val >>= data->exponent;
val >>= data->exponent[sensor->page];
val = DIV_ROUND_CLOSEST(val, 1000);
return val & 0xffff;
}
Expand All @@ -548,14 +549,14 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
}

/* Power is in uW. Convert to mW before converting. */
if (class == PSC_POWER)
if (sensor->class == PSC_POWER)
val = DIV_ROUND_CLOSEST(val, 1000L);

/*
* For simplicity, convert fan data to milli-units
* before calculating the exponent.
*/
if (class == PSC_FAN)
if (sensor->class == PSC_FAN)
val = val * 1000;

/* Reduce large mantissa until it fits into 10 bit */
Expand Down Expand Up @@ -585,22 +586,22 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
}

static u16 pmbus_data2reg_direct(struct pmbus_data *data,
enum pmbus_sensor_classes class, long val)
struct pmbus_sensor *sensor, long val)
{
long m, b, R;

m = data->info->m[class];
b = data->info->b[class];
R = data->info->R[class];
m = data->info->m[sensor->class];
b = data->info->b[sensor->class];
R = data->info->R[sensor->class];

/* Power is in uW. Adjust R and b. */
if (class == PSC_POWER) {
if (sensor->class == PSC_POWER) {
R -= 3;
b *= 1000;
}

/* Calculate Y = (m * X + b) * 10^R */
if (class != PSC_FAN) {
if (sensor->class != PSC_FAN) {
R -= 3; /* Adjust R and b for data in milli-units */
b *= 1000;
}
Expand All @@ -619,28 +620,28 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data,
}

static u16 pmbus_data2reg_vid(struct pmbus_data *data,
enum pmbus_sensor_classes class, long val)
struct pmbus_sensor *sensor, long val)
{
val = clamp_val(val, 500, 1600);

return 2 + DIV_ROUND_CLOSEST((1600 - val) * 100, 625);
}

static u16 pmbus_data2reg(struct pmbus_data *data,
enum pmbus_sensor_classes class, long val)
struct pmbus_sensor *sensor, long val)
{
u16 regval;

switch (data->info->format[class]) {
switch (data->info->format[sensor->class]) {
case direct:
regval = pmbus_data2reg_direct(data, class, val);
regval = pmbus_data2reg_direct(data, sensor, val);
break;
case vid:
regval = pmbus_data2reg_vid(data, class, val);
regval = pmbus_data2reg_vid(data, sensor, val);
break;
case linear:
default:
regval = pmbus_data2reg_linear(data, class, val);
regval = pmbus_data2reg_linear(data, sensor, val);
break;
}
return regval;
Expand Down Expand Up @@ -746,7 +747,7 @@ static ssize_t pmbus_set_sensor(struct device *dev,
return -EINVAL;

mutex_lock(&data->update_lock);
regval = pmbus_data2reg(data, sensor->class, val);
regval = pmbus_data2reg(data, sensor, val);
ret = _pmbus_write_word_data(client, sensor->page, sensor->reg, regval);
if (ret < 0)
rv = ret;
Expand Down Expand Up @@ -1643,12 +1644,13 @@ static int pmbus_find_attributes(struct i2c_client *client,
* This function is called for all chips.
*/
static int pmbus_identify_common(struct i2c_client *client,
struct pmbus_data *data)
struct pmbus_data *data, int page)
{
int vout_mode = -1;

if (pmbus_check_byte_register(client, 0, PMBUS_VOUT_MODE))
vout_mode = _pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE);
if (pmbus_check_byte_register(client, page, PMBUS_VOUT_MODE))
vout_mode = _pmbus_read_byte_data(client, page,
PMBUS_VOUT_MODE);
if (vout_mode >= 0 && vout_mode != 0xff) {
/*
* Not all chips support the VOUT_MODE command,
Expand All @@ -1659,7 +1661,7 @@ static int pmbus_identify_common(struct i2c_client *client,
if (data->info->format[PSC_VOLTAGE_OUT] != linear)
return -ENODEV;

data->exponent = ((s8)(vout_mode << 3)) >> 3;
data->exponent[page] = ((s8)(vout_mode << 3)) >> 3;
break;
case 1: /* VID mode */
if (data->info->format[PSC_VOLTAGE_OUT] != vid)
Expand All @@ -1674,15 +1676,15 @@ static int pmbus_identify_common(struct i2c_client *client,
}
}

pmbus_clear_fault_page(client, 0);
pmbus_clear_fault_page(client, page);
return 0;
}

static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
struct pmbus_driver_info *info)
{
struct device *dev = &client->dev;
int ret;
int page, ret;

/*
* Some PMBus chips don't support PMBUS_STATUS_BYTE, so try
Expand Down Expand Up @@ -1715,10 +1717,12 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
return -ENODEV;
}

ret = pmbus_identify_common(client, data);
if (ret < 0) {
dev_err(dev, "Failed to identify chip capabilities\n");
return ret;
for (page = 0; page < info->pages; page++) {
ret = pmbus_identify_common(client, data, page);
if (ret < 0) {
dev_err(dev, "Failed to identify chip capabilities\n");
return ret;
}
}
return 0;
}
Expand Down

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