powerpc/qe: add polling timeout to qe_issue_cmd()

The qe_issue_cmd() function (Freescale PowerPC QUICC Engine library) polls
on a register until a status bit changes, but does not include a timeout
to handle the situation if the bit never changes.  Change the code to use
the new spin_event_timeout() macro, which simplifies polling on a register
without a timeout.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/sysdev/qe_lib/qe.c

@@ -112,6 +112,7 @@ int qe_issue_cmd(u32 cmd, u32 device, u8 mcn_protocol, u32 cmd_input)
 {
 	unsigned long flags;
 	u8 mcn_shift = 0, dev_shift = 0;
+	u32 ret;
 
 	spin_lock_irqsave(&qe_lock, flags);
 	if (cmd == QE_RESET) {
@@ -139,11 +140,13 @@ int qe_issue_cmd(u32 cmd, u32 device, u8 mcn_protocol, u32 cmd_input)
 	}
 
 	/* wait for the QE_CR_FLG to clear */
-	while(in_be32(&qe_immr->cp.cecr) & QE_CR_FLG)
-		cpu_relax();
+	ret = spin_event_timeout((in_be32(&qe_immr->cp.cecr) & QE_CR_FLG) == 0,
+			   100, 0);
+	/* On timeout (e.g. failure), the expression will be false (ret == 0),
+	   otherwise it will be true (ret == 1). */
 	spin_unlock_irqrestore(&qe_lock, flags);
 
-	return 0;
+	return ret == 1;
 }
 EXPORT_SYMBOL(qe_issue_cmd);