hwmon: (pmbus) Introduce and use cached vout margins

When setting a new voltage the voltage boundaries are read every time to
check that the new voltage is within the proper range. Checking these
voltage boundaries consists of reading one of PMBUS_MFR_VOUT_MIN/
PMBUS_VOUT_MARGIN_LOW registers and then PMBUS_MFR_VOUT_MAX/
PMBUS_VOUT_MARGIN_HIGH together with writing the PMBUS_CLEAR_FAULTS
register.

Since these boundaries are never being changed, it can be cached and
thus saving unnecessary smbus transmissions.

Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Link: https://lore.kernel.org/r/20220614093856.3470672-2-marten.lindahl@axis.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 4187dc20d2aadb30f36c34ebe5c565183c17034c..8c6f44988ba5adbd47ab41377cf9f58e840498df 100644 (file)
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -104,6 +104,9 @@ struct pmbus_data {
 
        s16 currpage;   /* current page, -1 for unknown/unset */
        s16 currphase;  /* current phase, 0xff for all, -1 for unknown/unset */
+
+       int vout_low[PMBUS_PAGES];      /* voltage low margin */
+       int vout_high[PMBUS_PAGES];     /* voltage high margin */
 };
 
 struct pmbus_debugfs_entry {
@@ -2848,6 +2851,58 @@ static int pmbus_regulator_get_error_flags(struct regulator_dev *rdev, unsigned
        return 0;
 }
 
+static int pmbus_regulator_get_low_margin(struct i2c_client *client, int page)
+{
+       struct pmbus_data *data = i2c_get_clientdata(client);
+       struct pmbus_sensor s = {
+               .page = page,
+               .class = PSC_VOLTAGE_OUT,
+               .convert = true,
+               .data = -1,
+       };
+
+       if (!data->vout_low[page]) {
+               if (pmbus_check_word_register(client, page, PMBUS_MFR_VOUT_MIN))
+                       s.data = _pmbus_read_word_data(client, page, 0xff,
+                                                      PMBUS_MFR_VOUT_MIN);
+               if (s.data < 0) {
+                       s.data = _pmbus_read_word_data(client, page, 0xff,
+                                                      PMBUS_VOUT_MARGIN_LOW);
+                       if (s.data < 0)
+                               return s.data;
+               }
+               data->vout_low[page] = pmbus_reg2data(data, &s);
+       }
+
+       return data->vout_low[page];
+}
+
+static int pmbus_regulator_get_high_margin(struct i2c_client *client, int page)
+{
+       struct pmbus_data *data = i2c_get_clientdata(client);
+       struct pmbus_sensor s = {
+               .page = page,
+               .class = PSC_VOLTAGE_OUT,
+               .convert = true,
+               .data = -1,
+       };
+
+       if (!data->vout_high[page]) {
+               if (pmbus_check_word_register(client, page, PMBUS_MFR_VOUT_MAX))
+                       s.data = _pmbus_read_word_data(client, page, 0xff,
+                                                      PMBUS_MFR_VOUT_MAX);
+               if (s.data < 0) {
+                       s.data = _pmbus_read_word_data(client, page, 0xff,
+                                                      PMBUS_VOUT_MARGIN_HIGH);
+                       if (s.data < 0)
+                               return s.data;
+               }
+               data->vout_high[page] = pmbus_reg2data(data, &s);
+       }
+
+       return data->vout_high[page];
+}
+
 static int pmbus_regulator_get_voltage(struct regulator_dev *rdev)
 {
        struct device *dev = rdev_get_dev(rdev);
@@ -2883,24 +2938,13 @@ static int pmbus_regulator_set_voltage(struct regulator_dev *rdev, int min_uv,
 
        *selector = 0;
 
-       if (pmbus_check_word_register(client, s.page, PMBUS_MFR_VOUT_MIN))
-               s.data = _pmbus_read_word_data(client, s.page, 0xff, PMBUS_MFR_VOUT_MIN);
-       if (s.data < 0) {
-               s.data = _pmbus_read_word_data(client, s.page, 0xff, PMBUS_VOUT_MARGIN_LOW);
-               if (s.data < 0)
-                       return s.data;
-       }
-       low = pmbus_reg2data(data, &s);
+       low = pmbus_regulator_get_low_margin(client, s.page);
+       if (low < 0)
+               return low;
 
-       s.data = -1;
-       if (pmbus_check_word_register(client, s.page, PMBUS_MFR_VOUT_MAX))
-               s.data = _pmbus_read_word_data(client, s.page, 0xff, PMBUS_MFR_VOUT_MAX);
-       if (s.data < 0) {
-               s.data = _pmbus_read_word_data(client, s.page, 0xff, PMBUS_VOUT_MARGIN_HIGH);
-               if (s.data < 0)
-                       return s.data;
-       }
-       high = pmbus_reg2data(data, &s);
+       high = pmbus_regulator_get_high_margin(client, s.page);
+       if (high < 0)
+               return high;
 
        /* Make sure we are within margins */
        if (low > val)