1 files changed, 61 insertions, 6 deletions

diff --git a/drivers/power/twl4030_charger.c b/drivers/power/twl4030_charger.c
index 68117ad23564..2c537ee11bbe 100644
--- a/drivers/power/twl4030_charger.c
+++ b/drivers/power/twl4030_charger.c
@@ -119,6 +119,18 @@ struct twl4030_bci {
 #define CHARGE_AUTO     1
 #define CHARGE_LINEAR   2
 
+        /* When setting the USB current we slowly increase the
+         * requested current until target is reached or the voltage
+         * drops below 4.75V.  In the latter case we step back one
+         * step.
+         */
+        unsigned int            usb_cur_target;
+        struct delayed_work     current_worker;
+#define USB_CUR_STEP    20000   /* 20mA at a time */
+#define USB_MIN_VOLT    4750000 /* 4.75V */
+#define USB_CUR_DELAY   msecs_to_jiffies(100)
+#define USB_MAX_CURRENT 1700000 /* TWL4030 caps at 1.7A */
+
         unsigned long           event;
 };
 
@@ -257,6 +269,12 @@ static int twl4030_charger_update_current(struct twl4030_bci *bci)
         } else {
                 cur = bci->usb_cur;
                 bci->ac_is_active = false;
+                if (cur > bci->usb_cur_target) {
+                        cur = bci->usb_cur_target;
+                        bci->usb_cur = cur;
+                }
+                if (cur < bci->usb_cur_target)
+                        schedule_delayed_work(&bci->current_worker, USB_CUR_DELAY);
         }
 
         /* First, check thresholds and see if cgain is needed */
@@ -391,6 +409,41 @@ static int twl4030_charger_update_current(struct twl4030_bci *bci)
         return 0;
 }
 
+static int twl4030_charger_get_current(void);
+
+static void twl4030_current_worker(struct work_struct *data)
+{
+        int v, curr;
+        int res;
+        struct twl4030_bci *bci = container_of(data, struct twl4030_bci,
+                                               current_worker.work);
+
+        res = twl4030bci_read_adc_val(TWL4030_BCIVBUS);
+        if (res < 0)
+                v = 0;
+        else
+                /* BCIVBUS uses ADCIN8, 7/1023 V/step */
+                v = res * 6843;
+        curr = twl4030_charger_get_current();
+
+        dev_dbg(bci->dev, "v=%d cur=%d limit=%d target=%d\n", v, curr,
+                bci->usb_cur, bci->usb_cur_target);
+
+        if (v < USB_MIN_VOLT) {
+                /* Back up and stop adjusting. */
+                bci->usb_cur -= USB_CUR_STEP;
+                bci->usb_cur_target = bci->usb_cur;
+        } else if (bci->usb_cur >= bci->usb_cur_target ||
+                   bci->usb_cur + USB_CUR_STEP > USB_MAX_CURRENT) {
+                /* Reached target and voltage is OK - stop */
+                return;
+        } else {
+                bci->usb_cur += USB_CUR_STEP;
+                schedule_delayed_work(&bci->current_worker, USB_CUR_DELAY);
+        }
+        twl4030_charger_update_current(bci);
+}
+
 /*
  * Enable/Disable USB Charge functionality.
  */
@@ -451,6 +504,7 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
                         pm_runtime_put_autosuspend(bci->transceiver->dev);
                         bci->usb_enabled = 0;
                 }
+                bci->usb_cur = 0;
         }
 
         return ret;
@@ -599,7 +653,7 @@ twl4030_bci_max_current_store(struct device *dev, struct device_attribute *attr,
         if (dev == &bci->ac->dev)
                 bci->ac_cur = cur;
         else
-                bci->usb_cur = cur;
+                bci->usb_cur_target = cur;
 
         twl4030_charger_update_current(bci);
         return n;
@@ -621,7 +675,7 @@ static ssize_t twl4030_bci_max_current_show(struct device *dev,
                         cur = bci->ac_cur;
         } else {
                 if (bci->ac_is_active)
-                        cur = bci->usb_cur;
+                        cur = bci->usb_cur_target;
         }
         if (cur < 0) {
                 cur = twl4030bci_read_adc_val(TWL4030_BCIIREF1);
@@ -662,9 +716,9 @@ static int twl4030_bci_usb_ncb(struct notifier_block *nb, unsigned long val,
 
         /* reset current on each 'plug' event */
         if (allow_usb)
-                bci->usb_cur = 500000;
+                bci->usb_cur_target = 500000;
         else
-                bci->usb_cur = 100000;
+                bci->usb_cur_target = 100000;
 
         bci->event = val;
         schedule_work(&bci->work);
@@ -927,9 +981,9 @@ static int twl4030_bci_probe(struct platform_device *pdev)
         bci->ichg_hi = 500000; /* High threshold */
         bci->ac_cur = 500000; /* 500mA */
         if (allow_usb)
-                bci->usb_cur = 500000;  /* 500mA */
+                bci->usb_cur_target = 500000;  /* 500mA */
         else
-                bci->usb_cur = 100000;  /* 100mA */
+                bci->usb_cur_target = 100000;  /* 100mA */
         bci->usb_mode = CHARGE_AUTO;
         bci->ac_mode = CHARGE_AUTO;
 
@@ -980,6 +1034,7 @@ static int twl4030_bci_probe(struct platform_device *pdev)
         }
 
         INIT_WORK(&bci->work, twl4030_bci_usb_work);
+        INIT_DELAYED_WORK(&bci->current_worker, twl4030_current_worker);
 
         bci->usb_nb.notifier_call = twl4030_bci_usb_ncb;
         if (bci->dev->of_node) {