Some USB devices will share same phy, so make the ->init
and ->shutdown to be protected.
Only first device will initialize the phy, and only last device
can shutdown phy.
Signed-off-by: Chao Xie <chao.xie@xxxxxxxxxxx>
---
drivers/usb/phy/phy.c | 6 ++++++
include/linux/usb/phy.h | 22 ++++++++++++++++++----
2 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/phy/phy.c b/drivers/usb/phy/phy.c
index a9984c7..97dd396 100644
--- a/drivers/usb/phy/phy.c
+++ b/drivers/usb/phy/phy.c
@@ -329,6 +329,9 @@ int usb_add_phy(struct usb_phy *x, enum usb_phy_type type)
return -EINVAL;
}
+ mutex_init(&x->phy_mutex);
+ x->refcount = 0;
+
spin_lock_irqsave(&phy_lock, flags);
list_for_each_entry(phy, &phy_list, head) {
@@ -367,6 +370,9 @@ int usb_add_phy_dev(struct usb_phy *x)
return -EINVAL;
}
+ mutex_init(&x->phy_mutex);
+ x->refcount = 0;
+
spin_lock_irqsave(&phy_lock, flags);
list_for_each_entry(phy_bind, &phy_bind_list, list)
if (!(strcmp(phy_bind->phy_dev_name, dev_name(x->dev))))
diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h
index 6b5978f..b645520 100644
--- a/include/linux/usb/phy.h
+++ b/include/linux/usb/phy.h
@@ -87,6 +87,14 @@ struct usb_phy {
/* to support controllers that have multiple transceivers */
struct list_head head;
+ /*
+ * PHY may be shared by multiple devices.
+ * Being protected by phy_mutex and refcount, PHY is initialized
+ * or shut down only once.
+ */
+ struct mutex phy_mutex;
+ unsigned int refcount;
+
/* initialize/shutdown the OTG controller */
int (*init)(struct usb_phy *x);
void (*shutdown)(struct usb_phy *x);
@@ -150,17 +158,23 @@ static inline int usb_phy_io_write(struct usb_phy *x, u32 val, u32 reg)
static inline int
usb_phy_init(struct usb_phy *x)
{
- if (x->init)
- return x->init(x);
+ int ret = 0;
- return 0;
+ mutex_lock(&x->phy_mutex);
+ if (x->refcount++ == 0 && x->init)
+ ret = x->init(x);
+ mutex_unlock(&x->phy_mutex);
+
+ return ret;
}
static inline void
usb_phy_shutdown(struct usb_phy *x)
{
- if (x->shutdown)
+ mutex_lock(&x->phy_mutex);
+ if (--x->refcount == 0 && x->shutdown)
x->shutdown(x);
+ mutex_unlock(&x->phy_mutex);
}
static inline int
--
1.7.4.1
--
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