powerpc/mpc52xx_lpbfifo: optionally defer fifo transfer start

Currently fifo transfer is started when submitting a transfer
request. Add posibility to defer the fifo transfer and start it
later by calling additional function. This change is backward
compatible, the behaviour of mpc52xx_lpbfifo_submit() is the same
for previous driver users, so there is no need to adapt them.

Signed-off-by: Anatolij Gustschin <agust@denx.de>

2 files changed, 36 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/mpc52xx.h b/arch/powerpc/include/asm/mpc52xx.h
index 1f41382eda38..0acc7c7c28d1 100644
--- a/arch/powerpc/include/asm/mpc52xx.h
+++ b/arch/powerpc/include/asm/mpc52xx.h
@@ -307,6 +307,7 @@ struct mpc52xx_lpbfifo_request {
         size_t size;
         size_t pos;     /* current position of transfer */
         int flags;
+        int defer_xfer_start;
 
         /* What to do when finished */
         void (*callback)(struct mpc52xx_lpbfifo_request *);
@@ -323,6 +324,7 @@ struct mpc52xx_lpbfifo_request {
 extern int mpc52xx_lpbfifo_submit(struct mpc52xx_lpbfifo_request *req);
 extern void mpc52xx_lpbfifo_abort(struct mpc52xx_lpbfifo_request *req);
 extern void mpc52xx_lpbfifo_poll(void);
+extern int mpc52xx_lpbfifo_start_xfer(struct mpc52xx_lpbfifo_request *req);
 
 /* mpc52xx_pic.c */
 extern void mpc52xx_init_irq(void);
diff --git a/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c b/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
index d61fb1c0c1a0..2351f9e0fb6f 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
@@ -170,7 +170,8 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
         out_be32(lpbfifo.regs + LPBFIFO_REG_CONTROL, bit_fields);
 
         /* Kick it off */
-        out_8(lpbfifo.regs + LPBFIFO_REG_PACKET_SIZE, 0x01);
+        if (!lpbfifo.req->defer_xfer_start)
+                out_8(lpbfifo.regs + LPBFIFO_REG_PACKET_SIZE, 0x01);
         if (dma)
                 bcom_enable(lpbfifo.bcom_cur_task);
 }
@@ -421,6 +422,38 @@ int mpc52xx_lpbfifo_submit(struct mpc52xx_lpbfifo_request *req)
 }
 EXPORT_SYMBOL(mpc52xx_lpbfifo_submit);
 
+int mpc52xx_lpbfifo_start_xfer(struct mpc52xx_lpbfifo_request *req)
+{
+        unsigned long flags;
+
+        if (!lpbfifo.regs)
+                return -ENODEV;
+
+        spin_lock_irqsave(&lpbfifo.lock, flags);
+
+        /*
+         * If the req pointer is already set and a transfer was
+         * started on submit, then this transfer is in progress
+         */
+        if (lpbfifo.req && !lpbfifo.req->defer_xfer_start) {
+                spin_unlock_irqrestore(&lpbfifo.lock, flags);
+                return -EBUSY;
+        }
+
+        /*
+         * If the req was previously submitted but not
+         * started, start it now
+         */
+        if (lpbfifo.req && lpbfifo.req == req &&
+            lpbfifo.req->defer_xfer_start) {
+                out_8(lpbfifo.regs + LPBFIFO_REG_PACKET_SIZE, 0x01);
+        }
+
+        spin_unlock_irqrestore(&lpbfifo.lock, flags);
+        return 0;
+}
+EXPORT_SYMBOL(mpc52xx_lpbfifo_start_xfer);
+
 void mpc52xx_lpbfifo_abort(struct mpc52xx_lpbfifo_request *req)
 {
         unsigned long flags;