[ARM] 3760/1: This patch adds timeouts while working with SSP registers. Such timeouts were en

Patch from Paul Sokolovsky

This patch adds timeouts while working with SSP registers. Such
timeouts were envisioned by docstrings in ssp.c, but were not
implemented. There were actual lockups while accessing
touchscreen for iPaqs h1910, h4000 due to lack of the timeouts.
This is updated version of previously submitted patch: 3738/1.

Signed-off-by: Paul Sokolovsky <pmiscml@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 38 insertions, 8 deletions

diff --git a/arch/arm/mach-sa1100/ssp.c b/arch/arm/mach-sa1100/ssp.c
index 1604dadf27f..5eba5fbbb56 100644
--- a/arch/arm/mach-sa1100/ssp.c
+++ b/arch/arm/mach-sa1100/ssp.c
@@ -23,6 +23,8 @@
 #include <asm/hardware.h>
 #include <asm/hardware/ssp.h>
 
+#define TIMEOUT 100000
+
 static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 {
         unsigned int status = Ser4SSSR;
@@ -47,18 +49,27 @@ static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  * The caller is expected to perform the necessary locking.
  *
  * Returns:
- *   %-ETIMEDOUT        timeout occurred (for future)
+ *   %-ETIMEDOUT        timeout occurred
  *   0                  success
  */
 int ssp_write_word(u16 data)
 {
-        while (!(Ser4SSSR & SSSR_TNF))
+        int timeout = TIMEOUT;
+
+        while (!(Ser4SSSR & SSSR_TNF)) {
+                if (!--timeout)
+                        return -ETIMEDOUT;
                 cpu_relax();
+        }
 
         Ser4SSDR = data;
 
-        while (!(Ser4SSSR & SSSR_BSY))
+        timeout = TIMEOUT;
+        while (!(Ser4SSSR & SSSR_BSY)) {
+                if (!--timeout)
+                        return -ETIMEDOUT;
                 cpu_relax();
+        }
 
         return 0;
 }
@@ -75,15 +86,22 @@ int ssp_write_word(u16 data)
  * The caller is expected to perform the necessary locking.
  *
  * Returns:
- *   %-ETIMEDOUT        timeout occurred (for future)
+ *   %-ETIMEDOUT        timeout occurred
  *   16-bit data        success
  */
-int ssp_read_word(void)
+int ssp_read_word(u16 *data)
 {
-        while (!(Ser4SSSR & SSSR_RNE))
+        int timeout = TIMEOUT;
+
+        while (!(Ser4SSSR & SSSR_RNE)) {
+                if (!--timeout)
+                        return -ETIMEDOUT;
                 cpu_relax();
+        }
+
+        *data = (u16)Ser4SSDR;
 
-        return Ser4SSDR;
+        return 0;
 }
 
 /**
@@ -93,14 +111,26 @@ int ssp_read_word(void)
  * is empty.
  *
  * The caller is expected to perform the necessary locking.
+ *
+ * Returns:
+ *   %-ETIMEDOUT        timeout occurred
+ *   0                  success
  */
-void ssp_flush(void)
+int ssp_flush(void)
 {
+        int timeout = TIMEOUT * 2;
+
         do {
                 while (Ser4SSSR & SSSR_RNE) {
+                        if (!--timeout)
+                                return -ETIMEDOUT;
                         (void) Ser4SSDR;
                 }
+                if (!--timeout)
+                        return -ETIMEDOUT;
         } while (Ser4SSSR & SSSR_BSY);
+
+        return 0;
 }
 
 /**