[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, 28 insertions, 7 deletions

diff --git a/arch/arm/mach-pxa/ssp.c b/arch/arm/mach-pxa/ssp.c
index 93096befd017..1fddfeaa630d 100644
--- a/arch/arm/mach-pxa/ssp.c
+++ b/arch/arm/mach-pxa/ssp.c
@@ -40,6 +40,8 @@
 
 #define PXA_SSP_PORTS   3
 
+#define TIMEOUT 100000
+
 struct ssp_info_ {
         int irq;
         u32 clock;
@@ -92,13 +94,18 @@ 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(struct ssp_dev *dev, u32 data)
 {
-        while (!(SSSR_P(dev->port) & SSSR_TNF))
+        int timeout = TIMEOUT;
+
+        while (!(SSSR_P(dev->port) & SSSR_TNF)) {
+                if (!--timeout)
+                        return -ETIMEDOUT;
                 cpu_relax();
+        }
 
         SSDR_P(dev->port) = data;
 
@@ -117,15 +124,21 @@ int ssp_write_word(struct ssp_dev *dev, u32 data)
  * The caller is expected to perform the necessary locking.
  *
  * Returns:
- *   %-ETIMEDOUT        timeout occurred (for future)
+ *   %-ETIMEDOUT        timeout occurred
  *   32-bit data        success
  */
-int ssp_read_word(struct ssp_dev *dev)
+int ssp_read_word(struct ssp_dev *dev, u32 *data)
 {
-        while (!(SSSR_P(dev->port) & SSSR_RNE))
+        int timeout = TIMEOUT;
+
+        while (!(SSSR_P(dev->port) & SSSR_RNE)) {
+                if (!--timeout)
+                        return -ETIMEDOUT;
                 cpu_relax();
+        }
 
-        return SSDR_P(dev->port);
+        *data = SSDR_P(dev->port);
+        return 0;
 }
 
 /**
@@ -136,13 +149,21 @@ int ssp_read_word(struct ssp_dev *dev)
  *
  * The caller is expected to perform the necessary locking.
  */
-void ssp_flush(struct ssp_dev *dev)
+int ssp_flush(struct ssp_dev *dev)
 {
+        int timeout = TIMEOUT * 2;
+
         do {
                 while (SSSR_P(dev->port) & SSSR_RNE) {
+                        if (!--timeout)
+                                return -ETIMEDOUT;
                         (void) SSDR_P(dev->port);
                 }
+                if (!--timeout)
+                        return -ETIMEDOUT;
         } while (SSSR_P(dev->port) & SSSR_BSY);
+
+        return 0;
 }
 
 /**