u-boot/common/cmd_dtt.c
Heiko Schocher 780f13a9e1 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>
2011-08-04 23:30:38 +02:00

72 lines
1.9 KiB
C

/*
* (C) Copyright 2001
* Erik Theisen, Wave 7 Optics, etheisen@mindspring.com
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <config.h>
#include <command.h>
#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);
/*
* Loop through sensors, read
* temperature, and output it.
*/
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);
return 0;
} /* do_dtt() */
/***************************************************/
U_BOOT_CMD(
dtt, 1, 1, do_dtt,
"Read temperature from Digital Thermometer and Thermostat",
""
);