power: supply: axp288_fuel_gauge: Only read PWR_OP_MODE, FG_LOW_CAP_REG regs once

Accessing registers on the AXP288 is quite expensive, so we should avoid
doing unnecessary accesses.

The FG_LOW_CAP_REG never changes underneath us, so we only need to read
it once. Devices with an AXP288 do not have user-replace (let alone
hot-swappable) batteries and the only bit we care about in the
PWR_OP_MODE register is the CHRG_STAT_BAT_PRESENT bit, so we can get
away with only reading the PWR_OP_MODE register once too.

Note that the FG_LOW_CAP_REG is not marked volatile in the regmap, so we
were effectively already reading it once. This change makes this explicit,
this is done as preparation of a further patch which moves all remaining
register accesses in fuel_gauge_get_property() out of that function.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/axp288_fuel_gauge.c b/drivers/power/supply/axp288_fuel_gauge.c
index 1366027..8011628 100644 (file)
--- a/drivers/power/supply/axp288_fuel_gauge.c
+++ b/drivers/power/supply/axp288_fuel_gauge.c
@@ -111,6 +111,8 @@ struct axp288_fg_info {
        struct mutex lock;
        int status;
        int max_volt;
+       int pwr_op;
+       int low_cap;
        struct dentry *debug_file;
 };
 
@@ -336,11 +338,7 @@ static int fuel_gauge_get_property(struct power_supply *ps,
                val->intval = PROP_CURR(value);
                break;
        case POWER_SUPPLY_PROP_PRESENT:
-               ret = fuel_gauge_reg_readb(info, AXP20X_PWR_OP_MODE);
-               if (ret < 0)
-                       goto fuel_gauge_read_err;
-
-               if (ret & CHRG_STAT_BAT_PRESENT)
+               if (info->pwr_op & CHRG_STAT_BAT_PRESENT)
                        val->intval = 1;
                else
                        val->intval = 0;
@@ -355,10 +353,7 @@ static int fuel_gauge_get_property(struct power_supply *ps,
                val->intval = (ret & FG_REP_CAP_VAL_MASK);
                break;
        case POWER_SUPPLY_PROP_CAPACITY_ALERT_MIN:
-               ret = fuel_gauge_reg_readb(info, AXP288_FG_LOW_CAP_REG);
-               if (ret < 0)
-                       goto fuel_gauge_read_err;
-               val->intval = (ret & 0x0f);
+               val->intval = (info->low_cap & 0x0f);
                break;
        case POWER_SUPPLY_PROP_TECHNOLOGY:
                val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
@@ -398,7 +393,7 @@ static int fuel_gauge_set_property(struct power_supply *ps,
                const union power_supply_propval *val)
 {
        struct axp288_fg_info *info = power_supply_get_drvdata(ps);
-       int ret = 0;
+       int new_low_cap, ret = 0;
 
        mutex_lock(&info->lock);
        switch (prop) {
@@ -407,12 +402,12 @@ static int fuel_gauge_set_property(struct power_supply *ps,
                        ret = -EINVAL;
                        break;
                }
-               ret = fuel_gauge_reg_readb(info, AXP288_FG_LOW_CAP_REG);
-               if (ret < 0)
-                       break;
-               ret &= 0xf0;
-               ret |= (val->intval & 0xf);
-               ret = fuel_gauge_reg_writeb(info, AXP288_FG_LOW_CAP_REG, ret);
+               new_low_cap = info->low_cap;
+               new_low_cap &= 0xf0;
+               new_low_cap |= (val->intval & 0xf);
+               ret = fuel_gauge_reg_writeb(info, AXP288_FG_LOW_CAP_REG, new_low_cap);
+               if (ret == 0)
+                       info->low_cap = new_low_cap;
                break;
        default:
                ret = -EINVAL;
@@ -695,6 +690,16 @@ static int axp288_fuel_gauge_probe(struct platform_device *pdev)
                break;
        }
 
+       ret = fuel_gauge_reg_readb(info, AXP20X_PWR_OP_MODE);
+       if (ret < 0)
+               goto out_free_iio_chan;
+       info->pwr_op = ret;
+
+       ret = fuel_gauge_reg_readb(info, AXP288_FG_LOW_CAP_REG);
+       if (ret < 0)
+               goto out_free_iio_chan;
+       info->low_cap = ret;
+
        psy_cfg.drv_data = info;
        info->bat = power_supply_register(&pdev->dev, &fuel_gauge_desc, &psy_cfg);
        if (IS_ERR(info->bat)) {