ChangeSet 1.1496.8.34, 2003/12/17 16:06:50-08:00, mhoffman@lightlink.com [PATCH] I2C: lm75 chip driver conversion routine fixes This patch is based on the lm_sensors project CVS, from revisions 1.45 and 1.1 of lm75.c and lm75.h, respectively. The patch fixes the conversion routines (according to datasheet) and moves them into a header file - as these conversions can be used by several drivers which emulate LM75s as subclients. Also, temps are now reported in 1/1000 C in sysfs as per documentation. drivers/i2c/chips/lm75.c | 28 ++++++++------------------ drivers/i2c/chips/lm75.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 58 insertions(+), 19 deletions(-) diff -Nru a/drivers/i2c/chips/lm75.c b/drivers/i2c/chips/lm75.c --- a/drivers/i2c/chips/lm75.c Tue Dec 30 12:30:01 2003 +++ b/drivers/i2c/chips/lm75.c Tue Dec 30 12:30:01 2003 @@ -25,6 +25,7 @@ #include #include #include +#include "lm75.h" /* Addresses to scan */ @@ -44,13 +45,6 @@ #define LM75_REG_TEMP_HYST 0x02 #define LM75_REG_TEMP_OS 0x03 -/* Conversions. Rounding and limit checking is only done on the TO_REG - variants. Note that you should be a bit careful with which arguments - these macros are called: arguments may be evaluated more than once. - Fixing this is just not worth it. */ -#define TEMP_FROM_REG(val) ((((val & 0x7fff) >> 7) * 5) | ((val & 0x8000)?-256:0)) -#define TEMP_TO_REG(val) (SENSORS_LIMIT((val<0?(0x200+((val)/5))<<7:(((val) + 2) / 5) << 7),0,0xffff)) - /* Each client has this additional data */ struct lm75_data { struct semaphore update_lock; @@ -83,15 +77,12 @@ static int lm75_id = 0; #define show(value) \ -static ssize_t show_##value(struct device *dev, char *buf) \ -{ \ - struct i2c_client *client = to_i2c_client(dev); \ - struct lm75_data *data = i2c_get_clientdata(client); \ - int temp; \ - \ - lm75_update_client(client); \ - temp = TEMP_FROM_REG(data->value); \ - return sprintf(buf, "%d\n", temp * 100); \ +static ssize_t show_##value(struct device *dev, char *buf) \ +{ \ + struct i2c_client *client = to_i2c_client(dev); \ + struct lm75_data *data = i2c_get_clientdata(client); \ + lm75_update_client(client); \ + return sprintf(buf, "%d\n", LM75_TEMP_FROM_REG(data->value)); \ } show(temp_max); show(temp_hyst); @@ -102,9 +93,8 @@ { \ struct i2c_client *client = to_i2c_client(dev); \ struct lm75_data *data = i2c_get_clientdata(client); \ - int temp = simple_strtoul(buf, NULL, 10) / 100; \ - \ - data->value = TEMP_TO_REG(temp); \ + int temp = simple_strtoul(buf, NULL, 10); \ + data->value = LM75_TEMP_TO_REG(temp); \ lm75_write_value(client, reg, data->value); \ return count; \ } diff -Nru a/drivers/i2c/chips/lm75.h b/drivers/i2c/chips/lm75.h --- /dev/null Wed Dec 31 16:00:00 1969 +++ b/drivers/i2c/chips/lm75.h Tue Dec 30 12:30:01 2003 @@ -0,0 +1,49 @@ +/* + lm75.h - Part of lm_sensors, Linux kernel modules for hardware + monitoring + Copyright (c) 2003 Mark M. Hoffman + + 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., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +/* + This file contains common code for encoding/decoding LM75 type + temperature readings, which are emulated by many of the chips + we support. As the user is unlikely to load more than one driver + which contains this code, we don't worry about the wasted space. +*/ + +#include + +/* straight from the datasheet */ +#define LM75_TEMP_MIN (-55000) +#define LM75_TEMP_MAX 125000 + +/* TEMP: 0.001C/bit (-55C to +125C) + REG: (0.5C/bit, two's complement) << 7 */ +static inline u16 LM75_TEMP_TO_REG(int temp) +{ + int ntemp = SENSORS_LIMIT(temp, LM75_TEMP_MIN, LM75_TEMP_MAX); + ntemp += (ntemp<0 ? -250 : 250); + return (u16)((ntemp / 500) << 7); +} + +static inline int LM75_TEMP_FROM_REG(u16 reg) +{ + /* use integer division instead of equivalent right shift to + guarantee arithmetic shift and preserve the sign */ + return ((s16)reg / 128) * 500; +} +