Rework the 'eeprom erase' path so it's possible to erase an EEPROM that can't be mounted.

Add some bus reset code to the EEPROM read path to maybe help with bus lockup.

apps/systemcmds/eeprom/24xxxx_mtd.c

@@ -138,6 +138,8 @@ struct at24c_dev_s
 
   perf_counter_t        perf_reads;
   perf_counter_t        perf_writes;
+  perf_counter_t        perf_resets;
+  perf_counter_t        perf_read_retries;
 };
 
 /************************************************************************************
@@ -267,6 +269,7 @@ static ssize_t at24c_bread(FAR struct mtd_dev_s *dev, off_t startblock,
 
       for (;;)
         {
+          unsigned tries = 50;
 
           perf_begin(priv->perf_reads);
           ret = I2C_TRANSFER(priv->dev, &msgv[0], 2);
@@ -274,9 +277,20 @@ static ssize_t at24c_bread(FAR struct mtd_dev_s *dev, off_t startblock,
           if (ret >= 0)
             break;
 
-          /* XXX probably want a bus reset in here and an eventual timeout */
           fvdbg("read stall");
           usleep(1000);
+          perf_count(priv->perf_read_retries);
+
+          /*
+           * Kick the bus in case it's stuck.
+           */
+          if (--tries == 0)
+            { 
+              tries = 50;
+              up_i2creset(priv->dev);
+              perf_count(priv->perf_resets);
+            }
+
         }
 
       startblock++;
@@ -480,6 +494,8 @@ FAR struct mtd_dev_s *at24c_initialize(FAR struct i2c_dev_s *dev)
 
       priv->perf_reads = perf_alloc(PC_ELAPSED, "EEPROM read");
       priv->perf_writes = perf_alloc(PC_ELAPSED, "EEPROM write");
+      priv->perf_resets = perf_alloc(PC_COUNT, "EEPROM reset");
+      priv->perf_read_retries = perf_alloc(PC_COUNT, "EEPROM read retries");
     }
 
   /* Return the implementation-specific state structure as the MTD device */

apps/systemcmds/eeprom/eeprom.c

@@ -67,13 +67,16 @@
 
 __EXPORT int eeprom_main(int argc, char *argv[]);
 
+static void	eeprom_attach(void);
 static void	eeprom_start(void);
 static void	eeprom_erase(void);
 static void	eeprom_ioctl(unsigned operation);
 static void	eeprom_save(const char *name);
 static void	eeprom_load(const char *name);
 
+static bool attached = false;
 static bool started = false;
+static struct mtd_dev_s *eeprom_mtd;
 
 int eeprom_main(int argc, char *argv[])
 {
@@ -105,13 +108,8 @@ int eeprom_main(int argc, char *argv[])
 
 
 static void
-eeprom_start(void)
+eeprom_attach(void)
 {
-	int ret;
-
-	if (started)
-		errx(1, "EEPROM service already started");
-
 	/* find the right I2C */
 	struct i2c_dev_s *i2c = up_i2cinitialize(PX4_I2C_BUS_ONBOARD);
 	/* this resets the I2C bus, set correct bus speed again */
@@ -121,16 +119,27 @@ eeprom_start(void)
 		errx(1, "failed to locate I2C bus");
 
 	/* start the MTD driver */
-	struct mtd_dev_s *mtd = at24c_initialize(i2c);
+	eeprom_mtd = at24c_initialize(i2c);
 
-	if (mtd == NULL)
+	if (eeprom_mtd == NULL)
 		errx(1, "failed to initialize EEPROM driver");
 
-	/* driver is started, even if NXFFS fails to mount */
-	started = true;
+	attached = true;
+}
+
+static void
+eeprom_start(void)
+{
+	int ret;
+
+	if (started)
+		errx(1, "EEPROM already mounted");
+
+	if (!attached)
+		eeprom_attach();
 
 	/* start NXFFS */
-	ret = nxffs_initialize(mtd);
+	ret = nxffs_initialize(eeprom_mtd);
 
 	if (ret < 0)
 		errx(1, "failed to initialize NXFFS - erase EEPROM to reformat");
@@ -141,7 +150,9 @@ eeprom_start(void)
 	if (ret < 0)
 		errx(1, "failed to mount /eeprom - erase EEPROM to reformat");
 	
-	errx(0, "mounted EEPROM at /eeprom");
+	started = true;
+	warnx("mounted EEPROM at /eeprom");
+	exit(0);
 }
 
 extern int at24c_nuke(void);
@@ -149,8 +160,8 @@ extern int at24c_nuke(void);
 static void
 eeprom_erase(void)
 {
-	if (!started)
-		errx(1, "must be started first");
+	if (!attached)
+		eeprom_attach();
 
 	if (at24c_nuke())
 		errx(1, "erase failed");