Re: [PATCH] i2c driver fixes for 2.6.0

Greg KH
2003-12-30T22:16:39Z

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 <linux/slab.h>
#include <linux/i2c.h>
#include <linux/i2c-sensor.h>
+#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 <mhoffman@lightlink.com>
+
+ 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 <linux/i2c-sensor.h>
+
+/* 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;
+}
+