rtc-rs5c313.c: add error handling to avoid hardware hangup

Add error processing.  Hanging up by an infinite loop is evaded.

Signed-off-by: kogiidena <kogiidena@eggplant.ddo.jp>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/rtc/rtc-rs5c313.c b/drivers/rtc/rtc-rs5c313.c
index f964d1d33c04..66eb133bf5fd 100644
--- a/drivers/rtc/rtc-rs5c313.c
+++ b/drivers/rtc/rtc-rs5c313.c
@@ -212,7 +212,9 @@ static inline void rs5c313_write_intintvreg(unsigned char data)
 static int rs5c313_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
         int data;
+        int cnt;
 
+        cnt = 0;
         while (1) {
                 RS5C313_CEENABLE;       /* CE:H */
 
@@ -225,6 +227,10 @@ static int rs5c313_rtc_read_time(struct device *dev, struct rtc_time *tm)
                 RS5C313_CEDISABLE;
                 ndelay(700);    /* CE:L */
 
+                if (cnt++ > 100) {
+                        dev_err(dev, "%s: timeout error\n", __FUNCTION__);
+                        return -EIO;
+                }
         }
 
         data = rs5c313_read_reg(RS5C313_ADDR_SEC);
@@ -266,7 +272,9 @@ static int rs5c313_rtc_read_time(struct device *dev, struct rtc_time *tm)
 static int rs5c313_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
         int data;
+        int cnt;
 
+        cnt = 0;
         /* busy check. */
         while (1) {
                 RS5C313_CEENABLE;       /* CE:H */
@@ -279,6 +287,11 @@ static int rs5c313_rtc_set_time(struct device *dev, struct rtc_time *tm)
                 RS5C313_MISCOP;
                 RS5C313_CEDISABLE;
                 ndelay(700);    /* CE:L */
+
+                if (cnt++ > 100) {
+                        dev_err(dev, "%s: timeout error\n", __FUNCTION__);
+                        return -EIO;
+                }
         }
 
         data = BIN2BCD(tm->tm_sec);
@@ -317,6 +330,7 @@ static int rs5c313_rtc_set_time(struct device *dev, struct rtc_time *tm)
 static void rs5c313_check_xstp_bit(void)
 {
         struct rtc_time tm;
+        int cnt;
 
         RS5C313_CEENABLE;       /* CE:H */
         if (rs5c313_read_cntreg() & RS5C313_CNTREG_WTEN_XSTP) {
@@ -326,8 +340,11 @@ static void rs5c313_check_xstp_bit(void)
                 rs5c313_write_cntreg(0x07);
 
                 /* busy check. */
-                while (rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY)
+                for (cnt = 0; cnt < 100; cnt++) {
+                        if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
+                                break;
                         RS5C313_MISCOP;
+                }
 
                 memset(&tm, 0, sizeof(struct rtc_time));
                 tm.tm_mday      = 1;