usb: phy: replace spinlock with mutex in OTG FSM

OTG Final State Machine calls functions which may sleep.

For example, start_gadget callback implementation can use
usb_gadget_vbus_connect(), whose context: can sleep.

If so, mutex should be used instead of spinlock.

Signed-off-by: Anton Tikhomirov <av.tikhomirov@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/phy/phy-fsl-usb.c

@@ -848,7 +848,7 @@ static int fsl_otg_conf(struct platform_device *pdev)
 		pr_info("Couldn't init OTG timers\n");
 		goto err;
 	}
-	spin_lock_init(&fsl_otg_tc->fsm.lock);
+	mutex_init(&fsl_otg_tc->fsm.lock);
 
 	/* Set OTG state machine operations */
 	fsl_otg_tc->fsm.ops = &fsl_otg_ops;
@@ -1017,10 +1017,9 @@ static int show_fsl_usb2_otg_state(struct device *dev,
 	struct otg_fsm *fsm = &fsl_otg_dev->fsm;
 	char *next = buf;
 	unsigned size = PAGE_SIZE;
-	unsigned long flags;
 	int t;
 
-	spin_lock_irqsave(&fsm->lock, flags);
+	mutex_lock(&fsm->lock);
 
 	/* basic driver infomation */
 	t = scnprintf(next, size,
@@ -1088,7 +1087,7 @@ static int show_fsl_usb2_otg_state(struct device *dev,
 	size -= t;
 	next += t;
 
-	spin_unlock_irqrestore(&fsm->lock, flags);
+	mutex_unlock(&fsm->lock);
 
 	return PAGE_SIZE - size;
 }

drivers/usb/phy/phy-fsm-usb.c

@@ -23,7 +23,7 @@
 
 #include <linux/kernel.h>
 #include <linux/types.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/usb.h>
 #include <linux/usb/gadget.h>
@@ -245,9 +245,8 @@ int otg_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
 int otg_statemachine(struct otg_fsm *fsm)
 {
 	enum usb_otg_state state;
-	unsigned long flags;
 
-	spin_lock_irqsave(&fsm->lock, flags);
+	mutex_lock(&fsm->lock);
 
 	state = fsm->otg->phy->state;
 	state_changed = 0;
@@ -359,7 +358,7 @@ int otg_statemachine(struct otg_fsm *fsm)
 	default:
 		break;
 	}
-	spin_unlock_irqrestore(&fsm->lock, flags);
+	mutex_lock(&fsm->lock);
 
 	VDBG("quit statemachine, changed = %d\n", state_changed);
 	return state_changed;

drivers/usb/phy/phy-fsm-usb.h

@@ -18,7 +18,7 @@
 #ifndef __LINUX_USB_OTG_FSM_H
 #define __LINUX_USB_OTG_FSM_H
 
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/errno.h>
 
 #undef VERBOSE
@@ -116,7 +116,7 @@ struct otg_fsm {
 
 	/* Current usb protocol used: 0:undefine; 1:host; 2:client */
 	int protocol;
-	spinlock_t lock;
+	struct mutex lock;
 };
 
 struct otg_fsm_ops {