i2c_probe: update for use in scripting

Allow the use of an I2C address to test and return success
if one or more devices is found.

This allows device presence to alter the flow of a script.
e.g.
   if i2c probe 0x04 ; then
	echo found Hannstar touch ;
   fi
Signed-off-by: NEric Nelson <eric.nelson@boundarydevices.com>

common/cmd_i2c.c

@@ -605,18 +605,28 @@ mod_i2c_mem(cmd_tbl_t *cmdtp, int incrflag, int flag, int argc, char * const arg
 
 /*
  * Syntax:
- *	i2c probe {addr}{.0, .1, .2}
+ *	i2c probe {addr}
+ *
+ * Returns zero (success) if one or more I2C devices was found
  */
 static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int j;
+	int addr = -1;
+	int found = 0;
 #if defined(CONFIG_SYS_I2C_NOPROBES)
 	int k, skip;
 	uchar bus = GET_BUS_NUM;
 #endif	/* NOPROBES */
 
+	if (argc == 2)
+		addr = simple_strtol(argv[1], 0, 16);
+
 	puts ("Valid chip addresses:");
 	for (j = 0; j < 128; j++) {
+		if ((0 <= addr) && (j != addr))
+			continue;
+
 #if defined(CONFIG_SYS_I2C_NOPROBES)
 		skip = 0;
 		for (k=0; k < NUM_ELEMENTS_NOPROBE; k++) {
@@ -628,8 +638,10 @@ static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv
 		if (skip)
 			continue;
 #endif
-		if (i2c_probe(j) == 0)
+		if (i2c_probe(j) == 0) {
 			printf(" %02X", j);
+			found++;
+		}
 	}
 	putc ('\n');
 
@@ -642,7 +654,7 @@ static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv
 	putc ('\n');
 #endif
 
-	return 0;
+	return (0 == found);
 }
 
 /*
@@ -1380,7 +1392,7 @@ U_BOOT_CMD(
 	"i2c mm chip address[.0, .1, .2] - write to I2C device (auto-incrementing)\n"
 	"i2c mw chip address[.0, .1, .2] value [count] - write to I2C device (fill)\n"
 	"i2c nm chip address[.0, .1, .2] - write to I2C device (constant address)\n"
-	"i2c probe - show devices on the I2C bus\n"
+	"i2c probe [address] - test for and show device(s) on the I2C bus\n"
 	"i2c read chip address[.0, .1, .2] length memaddress - read to memory \n"
 	"i2c write memaddress chip address[.0, .1, .2] length - write memory to i2c\n"
 	"i2c reset - re-init the I2C Controller\n"