hwmon: do not init sensors on startup

The U-Boot Design Principles[1] clearly say:

  Initialize devices only when they are needed within U-Boot, i.e. don't
  initialize the Ethernet interface(s) unless U-Boot performs a download
  over Ethernet; don't initialize any IDE or USB devices unless U-Boot
  actually tries to load files from these, etc. (and don't forget to
  shut down these devices after using them - otherwise nasty things may
  happen when you try to boot your OS).

So, do not initialize and read the sensors on startup.

Signed-off-by: Heiko Schocher <hs@denx.de>
cc: Wolfgang Denk <wd@denx.de>
cc: Holger Brunck <holger.brunck@keymile.com>

arch/powerpc/lib/board.c

@@ -944,9 +944,6 @@ void board_init_r (gd_t *id, ulong dest_addr)
 
 	WATCHDOG_RESET ();
 
-#if defined(CONFIG_DTT)		/* Digital Thermometers and Thermostats */
-	dtt_init ();
-#endif
 #if defined(CONFIG_CMD_SCSI)
 	WATCHDOG_RESET ();
 	puts ("SCSI:  ");

common/cmd_dtt.c

@@ -28,12 +28,16 @@
 #include <dtt.h>
 #include <i2c.h>
 
+static unsigned long sensor_initialized;
+
 int do_dtt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;
 	unsigned char sensors[] = CONFIG_DTT_SENSORS;
 	int old_bus;
 
+	/* Force a compilation error, if there are more then 32 sensors */
+	BUILD_BUG_ON(sizeof(sensors) > 32);
 	/* switch to correct I2C bus */
 	old_bus = I2C_GET_BUS();
 	I2C_SET_BUS(CONFIG_SYS_DTT_BUS_NUM);
@@ -42,8 +46,16 @@ int do_dtt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 	 * Loop through sensors, read
 	 * temperature, and output it.
 	 */
-	for (i = 0; i < sizeof (sensors); i++)
-		printf ("DTT%d: %i C\n", i + 1, dtt_get_temp (sensors[i]));
+	for (i = 0; i < sizeof(sensors); i++) {
+		if ((sensor_initialized & (1 << i)) == 0) {
+			if (dtt_init_one(sensors[i]) != 0) {
+				printf("DTT%d: Failed init!\n", i);
+				continue;
+			}
+			sensor_initialized |= (1 << i);
+		}
+		printf("DTT%d: %i C\n", i + 1, dtt_get_temp(sensors[i]));
+	}
 
 	/* switch back to original I2C bus */
 	I2C_SET_BUS(old_bus);

drivers/hwmon/adm1021.c

@@ -109,8 +109,8 @@ dtt_write (int sensor, int reg, int val)
 	return 0;
 } /* dtt_write() */
 
-static int
-_dtt_init (int sensor)
+int
+dtt_init_one(int sensor)
 {
 	dtt_cfg_t *dcp = &dttcfg[sensor >> 1];
 	int reg, val;
@@ -164,28 +164,7 @@ _dtt_init (int sensor)
 		return 1;
 
 	return 0;
-} /* _dtt_init() */
-
-int
-dtt_init (void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-	const char *const header = "DTT:   ";
-
-	/* switch to correct I2C bus */
-	I2C_SET_BUS(CONFIG_SYS_DTT_BUS_NUM);
-
-	for (i = 0; i < sizeof(sensors); i++) {
-		if (_dtt_init(sensors[i]) != 0)
-			printf ("%s%d FAILED INIT\n", header, i+1);
-		else
-			printf ("%s%d is %i C\n", header, i+1,
-				dtt_get_temp(sensors[i]));
-	}
-
-	return (0);
-} /* dtt_init() */
+} /* dtt_init_one() */
 
 int
 dtt_get_temp (int sensor)

drivers/hwmon/adt7460.c

@@ -50,7 +50,7 @@ int dtt_write(int sensor, int reg, int val)
 	return 0;
 }
 
-int dtt_init(void)
+int dtt_init_one(int sensor)
 {
 	printf("ADT7460 at I2C address 0x%2x\n", ADT7460_ADDRESS);
 

drivers/hwmon/ds1621.c

@@ -126,7 +126,7 @@ int dtt_write(int sensor, int reg, int val)
 }
 
 
-static int _dtt_init(int sensor)
+int dtt_init_one(int sensor)
 {
 	int val;
 
@@ -155,23 +155,6 @@ static int _dtt_init(int sensor)
 	return 0;
 }
 
-
-int dtt_init (void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-
-	for (i = 0; i < sizeof(sensors); i++) {
-		if (_dtt_init(sensors[i]) != 0)
-			printf("DTT%d:  FAILED\n", i + 1);
-		else
-			printf("DTT%d:  %i C\n", i + 1, dtt_get_temp(sensors[i]));
-	}
-
-	return (0);
-}
-
-
 int dtt_get_temp(int sensor)
 {
 	int i;

drivers/hwmon/ds1775.c

@@ -98,7 +98,7 @@ int dtt_write(int sensor, int reg, int val)
 }
 
 
-static int _dtt_init(int sensor)
+int dtt_init_one(int sensor)
 {
 	int val;
 
@@ -133,23 +133,6 @@ static int _dtt_init(int sensor)
 	return 0;
 }
 
-
-int dtt_init (void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-
-	for (i = 0; i < sizeof(sensors); i++) {
-		if (_dtt_init(sensors[i]) != 0)
-			printf("DTT%d:  FAILED\n", i+1);
-		else
-			printf("DTT%d:  %i C\n", i+1, dtt_get_temp(sensors[i]));
-	}
-
-	return (0);
-}
-
-
 int dtt_get_temp(int sensor)
 {
 	return (dtt_read(sensor, DTT_READ_TEMP) / 256);

drivers/hwmon/lm63.c

@@ -101,7 +101,7 @@ static int is_lm64(int sensor)
 	return sensor && (sensor != DTT_I2C_LM63_ADDR);
 }
 
-static int _dtt_init(int sensor)
+int dtt_init_one(int sensor)
 {
 	int i;
 	int val;
@@ -175,20 +175,3 @@ int dtt_get_temp(int sensor)
 	/* Ignore LSB for now, U-Boot only prints natural numbers */
 	return temp >> 8;
 }
-
-int dtt_init(void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-	const char *const header = "DTT:   ";
-
-	for (i = 0; i < sizeof(sensors); i++) {
-		if (_dtt_init(sensors[i]) != 0)
-			printf("%s%d FAILED INIT\n", header, i + 1);
-		else
-			printf("%s%d is %i C\n", header, i + 1,
-			       dtt_get_temp(sensors[i]));
-	}
-
-	return 0;
-}

drivers/hwmon/lm73.c

@@ -112,7 +112,7 @@ int dtt_write(int const sensor, int const reg, int const val)
 			      dlen);
 } /* dtt_write() */
 
-static int _dtt_init(int const sensor)
+int dtt_init_one(int const sensor)
 {
 	int val;
 
@@ -148,23 +148,7 @@ static int _dtt_init(int const sensor)
 
 	dtt_read(sensor, DTT_CONTROL);	/* clear temperature flags */
 	return 0;
-} /* _dtt_init() */
-
-int dtt_init(void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-	const char *const header = "DTT:   ";
-
-	for (i = 0; i < sizeof(sensors); i++) {
-		if (0 != _dtt_init(sensors[i]))
-			printf("%s%d FAILED INIT\n", header, i + 1);
-		else
-			printf("%s%d is %i C\n", header, i + 1,
-			       dtt_get_temp(sensors[i]));
-	}
-	return 0;
-} /* dtt_init() */
+} /* dtt_init_one() */
 
 int dtt_get_temp(int const sensor)
 {

drivers/hwmon/lm75.c

@@ -119,7 +119,7 @@ int dtt_write(int sensor, int reg, int val)
 } /* dtt_write() */
 
 
-static int _dtt_init(int sensor)
+int dtt_init_one(int sensor)
 {
 	int val;
 
@@ -145,32 +145,7 @@ static int _dtt_init(int sensor)
 		return 1;
 
 	return 0;
-} /* _dtt_init() */
-
-
-int dtt_init (void)
-{
-	int i;
-	unsigned char sensors[] = CONFIG_DTT_SENSORS;
-	const char *const header = "DTT:   ";
-	int old_bus;
-
-	/* switch to correct I2C bus */
-	old_bus = I2C_GET_BUS();
-	I2C_SET_BUS(CONFIG_SYS_DTT_BUS_NUM);
-
-	for (i = 0; i < sizeof(sensors); i++) {
-	if (_dtt_init(sensors[i]) != 0)
-		printf("%s%d FAILED INIT\n", header, i+1);
-	else
-		printf("%s%d is %i C\n", header, i+1,
-		dtt_get_temp(sensors[i]));
-	}
-	/* switch back to original I2C bus */
-	I2C_SET_BUS(old_bus);
-
-	return (0);
-} /* dtt_init() */
+} /* dtt_init_one() */
 
 int dtt_get_temp(int sensor)
 {

drivers/hwmon/lm81.c

@@ -89,7 +89,7 @@ int dtt_write(int sensor, int reg, int val)
 #define DTT_CONFIG	0x40
 #define DTT_ADR		0x48
 
-static int _dtt_init(int sensor)
+int dtt_init_one(int sensor)
 {
 	int	man;
 	int	adr;
@@ -111,26 +111,9 @@ static int _dtt_init(int sensor)
 
 	debug ("DTT:   Found LM81@%x Rev: %d\n", adr, rev);
 	return 0;
-} /* _dtt_init() */
+} /* dtt_init_one() */
 
 
-int dtt_init (void)
-{
-    int i;
-    unsigned char sensors[] = CONFIG_DTT_SENSORS;
-    const char *const header = "DTT:   ";
-
-    for (i = 0; i < sizeof(sensors); i++) {
-	if (_dtt_init(sensors[i]) != 0)
-	    printf("%s%d FAILED INIT\n", header, i+1);
-	else
-	    printf("%s%d is %i C\n", header, i+1,
-		   dtt_get_temp(sensors[i]));
-    }
-
-    return (0);
-} /* dtt_init() */
-
 #define TEMP_FROM_REG(temp) \
    ((temp)<256?((((temp)&0x1fe) >> 1) * 10)	 + ((temp) & 1) * 5:  \
 	       ((((temp)&0x1fe) >> 1) -255) * 10 - ((temp) & 1) * 5)  \

include/dtt.h

@@ -52,7 +52,7 @@
 #endif
 #endif /* CONFIG_DTT_ADM1021 */
 
-extern int dtt_init (void);
+extern int dtt_init_one(int);
 extern int dtt_read(int sensor, int reg);
 extern int dtt_write(int sensor, int reg, int val);
 extern int dtt_get_temp(int sensor);