ab8500-bm: Add usb power path support

AB8540 supports power path function in USB charging mode for fast
power up with dead and weak battery, and it could extend
the battery age.

When USB charging starts, if the Vbattrue is below than SW cut off
voltage, power path and pre-charge should be enabled. If Vbattrue
is higher than SW cut off voltage, power path and pre-charge should
be disabled. This is to make sure full current to battery charge.
At the end of charge, power path should be enable again to reduce
charging the battery again.

Signed-off-by: Lee Jones <lee.jones@linaro.org>

2 files changed, 143 insertions, 0 deletions

diff --git a/drivers/power/ab8500_charger.c b/drivers/power/ab8500_charger.c
index 6fea4fdf8701..f249a65b02e1 100644
--- a/drivers/power/ab8500_charger.c
+++ b/drivers/power/ab8500_charger.c
@@ -1925,6 +1925,67 @@ static int ab8500_charger_update_charger_current(struct ux500_charger *charger,
         return ret;
 }
 
+/**
+ * ab8540_charger_power_path_enable() - enable usb power path mode
+ * @charger:    pointer to the ux500_charger structure
+ * @enable:     enable/disable flag
+ *
+ * Enable or disable the power path for usb mode
+ * Returns error code in case of failure else 0(on success)
+ */
+static int ab8540_charger_power_path_enable(struct ux500_charger *charger,
+                bool enable)
+{
+        int ret;
+        struct ab8500_charger *di;
+
+        if (charger->psy.type == POWER_SUPPLY_TYPE_USB)
+                di = to_ab8500_charger_usb_device_info(charger);
+        else
+                return -ENXIO;
+
+        ret = abx500_mask_and_set_register_interruptible(di->dev,
+                                AB8500_CHARGER, AB8540_USB_PP_MODE_REG,
+                                BUS_POWER_PATH_MODE_ENA, enable);
+        if (ret) {
+                dev_err(di->dev, "%s write failed\n", __func__);
+                return ret;
+        }
+
+        return ret;
+}
+
+
+/**
+ * ab8540_charger_usb_pre_chg_enable() - enable usb pre change
+ * @charger:    pointer to the ux500_charger structure
+ * @enable:     enable/disable flag
+ *
+ * Enable or disable the pre-chage for usb mode
+ * Returns error code in case of failure else 0(on success)
+ */
+static int ab8540_charger_usb_pre_chg_enable(struct ux500_charger *charger,
+                bool enable)
+{
+        int ret;
+        struct ab8500_charger *di;
+
+        if (charger->psy.type == POWER_SUPPLY_TYPE_USB)
+                di = to_ab8500_charger_usb_device_info(charger);
+        else
+                return -ENXIO;
+
+        ret = abx500_mask_and_set_register_interruptible(di->dev,
+                                AB8500_CHARGER, AB8540_USB_PP_CHR_REG,
+                                BUS_POWER_PATH_PRECHG_ENA, enable);
+        if (ret) {
+                dev_err(di->dev, "%s write failed\n", __func__);
+                return ret;
+        }
+
+        return ret;
+}
+
 static int ab8500_charger_get_ext_psy_data(struct device *dev, void *data)
 {
         struct power_supply *psy;
@@ -3201,6 +3262,23 @@ static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
         if (ret < 0)
                 dev_err(di->dev, "%s mask and set failed\n", __func__);
 
+        if (is_ab8540(di->parent)) {
+                ret = abx500_mask_and_set_register_interruptible(di->dev,
+                        AB8500_CHARGER, AB8540_USB_PP_MODE_REG,
+                        BUS_VSYS_VOL_SELECT_MASK, BUS_VSYS_VOL_SELECT_3P6V);
+                if (ret) {
+                        dev_err(di->dev, "failed to setup usb power path vsys voltage\n");
+                        goto out;
+                }
+                ret = abx500_mask_and_set_register_interruptible(di->dev,
+                        AB8500_CHARGER, AB8540_USB_PP_CHR_REG,
+                        BUS_PP_PRECHG_CURRENT_MASK, 0);
+                if (ret) {
+                        dev_err(di->dev, "failed to setup usb power path prechage current\n");
+                        goto out;
+                }
+        }
+
 out:
         return ret;
 }
@@ -3484,6 +3562,8 @@ static int ab8500_charger_probe(struct platform_device *pdev)
         di->usb_chg.ops.check_enable = &ab8500_charger_usb_check_enable;
         di->usb_chg.ops.kick_wd = &ab8500_charger_watchdog_kick;
         di->usb_chg.ops.update_curr = &ab8500_charger_update_charger_current;
+        di->usb_chg.ops.pp_enable = &ab8540_charger_power_path_enable;
+        di->usb_chg.ops.pre_chg_enable = &ab8540_charger_usb_pre_chg_enable;
         di->usb_chg.max_out_volt = ab8500_charger_voltage_map[
                 ARRAY_SIZE(ab8500_charger_voltage_map) - 1];
         di->usb_chg.max_out_curr = ab8500_charger_current_map[
@@ -3491,6 +3571,7 @@ static int ab8500_charger_probe(struct platform_device *pdev)
         di->usb_chg.wdt_refresh = CHG_WD_INTERVAL;
         di->usb_chg.enabled = di->bm->usb_enabled;
         di->usb_chg.external = false;
+        di->usb_chg.power_path = di->bm->usb_power_path;
         di->usb_state.usb_current = -1;
 
         /* Create a work queue for the charger */
diff --git a/drivers/power/abx500_chargalg.c b/drivers/power/abx500_chargalg.c
index a876976678ab..a9b8efdafb8f 100644
--- a/drivers/power/abx500_chargalg.c
+++ b/drivers/power/abx500_chargalg.c
@@ -34,6 +34,9 @@
 /* End-of-charge criteria counter */
 #define EOC_COND_CNT                    10
 
+/* Plus margin for the low battery threshold */
+#define BAT_PLUS_MARGIN                (100)
+
 #define to_abx500_chargalg_device_info(x) container_of((x), \
         struct abx500_chargalg, chargalg_psy);
 
@@ -83,6 +86,7 @@ enum abx500_chargalg_states {
         STATE_HW_TEMP_PROTECT_INIT,
         STATE_HW_TEMP_PROTECT,
         STATE_NORMAL_INIT,
+        STATE_USB_PP_PRE_CHARGE,
         STATE_NORMAL,
         STATE_WAIT_FOR_RECHARGE_INIT,
         STATE_WAIT_FOR_RECHARGE,
@@ -114,6 +118,7 @@ static const char *states[] = {
         "HW_TEMP_PROTECT_INIT",
         "HW_TEMP_PROTECT",
         "NORMAL_INIT",
+        "USB_PP_PRE_CHARGE",
         "NORMAL",
         "WAIT_FOR_RECHARGE_INIT",
         "WAIT_FOR_RECHARGE",
@@ -560,6 +565,37 @@ static int abx500_chargalg_usb_en(struct abx500_chargalg *di, int enable,
         return di->usb_chg->ops.enable(di->usb_chg, enable, vset, iset);
 }
 
+ /**
+ * ab8540_chargalg_usb_pp_en() - Enable/ disable USB power path
+ * @di:                pointer to the abx500_chargalg structure
+ * @enable:    power path enable/disable
+ *
+ * The USB power path will be enable/ disable
+ */
+static int ab8540_chargalg_usb_pp_en(struct abx500_chargalg *di, bool enable)
+{
+        if (!di->usb_chg || !di->usb_chg->ops.pp_enable)
+                return -ENXIO;
+
+        return di->usb_chg->ops.pp_enable(di->usb_chg, enable);
+}
+
+/**
+ * ab8540_chargalg_usb_pre_chg_en() - Enable/ disable USB pre-charge
+ * @di:                pointer to the abx500_chargalg structure
+ * @enable:    USB pre-charge enable/disable
+ *
+ * The USB USB pre-charge will be enable/ disable
+ */
+static int ab8540_chargalg_usb_pre_chg_en(struct abx500_chargalg *di,
+                                          bool enable)
+{
+        if (!di->usb_chg || !di->usb_chg->ops.pre_chg_enable)
+                return -ENXIO;
+
+        return di->usb_chg->ops.pre_chg_enable(di->usb_chg, enable);
+}
+
 /**
  * abx500_chargalg_update_chg_curr() - Update charger current
  * @di:         pointer to the abx500_chargalg structure
@@ -765,6 +801,9 @@ static void abx500_chargalg_end_of_charge(struct abx500_chargalg *di)
                 di->batt_data.avg_curr > 0) {
                 if (++di->eoc_cnt >= EOC_COND_CNT) {
                         di->eoc_cnt = 0;
+                        if ((di->chg_info.charger_type & USB_CHG) &&
+                           (di->usb_chg->power_path))
+                                ab8540_chargalg_usb_pp_en(di, true);
                         di->charge_status = POWER_SUPPLY_STATUS_FULL;
                         di->maintenance_chg = true;
                         dev_dbg(di->dev, "EOC reached!\n");
@@ -1465,6 +1504,22 @@ static void abx500_chargalg_algorithm(struct abx500_chargalg *di)
                 break;
 
         case STATE_NORMAL_INIT:
+                if ((di->chg_info.charger_type & USB_CHG) &&
+                                di->usb_chg->power_path) {
+                        if (di->batt_data.volt >
+                            (di->bm->fg_params->lowbat_threshold +
+                             BAT_PLUS_MARGIN)) {
+                                ab8540_chargalg_usb_pre_chg_en(di, false);
+                                ab8540_chargalg_usb_pp_en(di, false);
+                        } else {
+                                ab8540_chargalg_usb_pp_en(di, true);
+                                ab8540_chargalg_usb_pre_chg_en(di, true);
+                                abx500_chargalg_state_to(di,
+                                        STATE_USB_PP_PRE_CHARGE);
+                                break;
+                        }
+                }
+
                 abx500_chargalg_start_charging(di,
                         di->bm->bat_type[di->bm->batt_id].normal_vol_lvl,
                         di->bm->bat_type[di->bm->batt_id].normal_cur_lvl);
@@ -1479,6 +1534,13 @@ static void abx500_chargalg_algorithm(struct abx500_chargalg *di)
 
                 break;
 
+        case STATE_USB_PP_PRE_CHARGE:
+                if (di->batt_data.volt >
+                        (di->bm->fg_params->lowbat_threshold +
+                        BAT_PLUS_MARGIN))
+                        abx500_chargalg_state_to(di, STATE_NORMAL_INIT);
+                break;
+
         case STATE_NORMAL:
                 handle_maxim_chg_curr(di);
                 if (di->charge_status == POWER_SUPPLY_STATUS_FULL &&