usb: chipidea: add wait vbus lower than OTGSC_BSV before role starts

When the gadget role starts, we need to make sure the vbus is lower
than OTGSC_BSV, or there will be an vbus interrupt since we use
B_SESSION_VALID as vbus interrupt to indicate connect and disconnect.
When the host role starts, it may not be useful to wait vbus to lower
than OTGSC_BSV, but it can indicate some hardware problems like the
vbus is still higher than OTGSC_BSV after we disconnect to host some
time later (5000 milliseconds currently), which is obvious not correct.

Tested-by: Marek Vasut <marex@denx.de>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 39 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
index 316036392e11..1c94fc5257f4 100644
--- a/drivers/usb/chipidea/ci.h
+++ b/drivers/usb/chipidea/ci.h
@@ -308,4 +308,7 @@ int hw_port_test_set(struct ci_hdrc *ci, u8 mode);
 
 u8 hw_port_test_get(struct ci_hdrc *ci);
 
+int hw_wait_reg(struct ci_hdrc *ci, enum ci_hw_regs reg, u32 mask,
+                                u32 value, unsigned int timeout_ms);
+
 #endif  /* __DRIVERS_USB_CHIPIDEA_CI_H */
diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
index c95e098fe9db..94626409559a 100644
--- a/drivers/usb/chipidea/core.c
+++ b/drivers/usb/chipidea/core.c
@@ -294,6 +294,38 @@ int hw_device_reset(struct ci_hdrc *ci, u32 mode)
         return 0;
 }
 
+/**
+ * hw_wait_reg: wait the register value
+ *
+ * Sometimes, it needs to wait register value before going on.
+ * Eg, when switch to device mode, the vbus value should be lower
+ * than OTGSC_BSV before connects to host.
+ *
+ * @ci: the controller
+ * @reg: register index
+ * @mask: mast bit
+ * @value: the bit value to wait
+ * @timeout_ms: timeout in millisecond
+ *
+ * This function returns an error code if timeout
+ */
+int hw_wait_reg(struct ci_hdrc *ci, enum ci_hw_regs reg, u32 mask,
+                                u32 value, unsigned int timeout_ms)
+{
+        unsigned long elapse = jiffies + msecs_to_jiffies(timeout_ms);
+
+        while (hw_read(ci, reg, mask) != value) {
+                if (time_after(jiffies, elapse)) {
+                        dev_err(ci->dev, "timeout waiting for %08x in %d\n",
+                                        mask, reg);
+                        return -ETIMEDOUT;
+                }
+                msleep(20);
+        }
+
+        return 0;
+}
+
 static irqreturn_t ci_irq(int irq, void *data)
 {
         struct ci_hdrc *ci = data;
diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
index 7f37484ca362..39bd7ec8bf75 100644
--- a/drivers/usb/chipidea/otg.c
+++ b/drivers/usb/chipidea/otg.c
@@ -52,6 +52,7 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
                 usb_gadget_vbus_disconnect(&ci->gadget);
 }
 
+#define CI_VBUS_STABLE_TIMEOUT_MS 5000
 static void ci_handle_id_switch(struct ci_hdrc *ci)
 {
         enum ci_role role = ci_otg_role(ci);
@@ -61,6 +62,9 @@ static void ci_handle_id_switch(struct ci_hdrc *ci)
                         ci_role(ci)->name, ci->roles[role]->name);
 
                 ci_role_stop(ci);
+                /* wait vbus lower than OTGSC_BSV */
+                hw_wait_reg(ci, OP_OTGSC, OTGSC_BSV, 0,
+                                CI_VBUS_STABLE_TIMEOUT_MS);
                 ci_role_start(ci, role);
         }
 }