On Wed, Jan 19, 2005 at 05:27:53PM +0100, Aur?lien Jarno wrote:
> I have looked to the datasheet to find a way to detect the DS1621 chip.
> Here is my proposal:
>
> 1) Verify that the 7 lowest bits of the TL register are 0. This is
> basically what you proposed. It is specified in the datasheet that's
> these bit are always 0, and I doubt it will change in the future
> (because in that case a lot of existing design won't work anymore).
>
> 2) Verify that bit 4 of the config register is 0. It means that the chip
> is not currently writing to its EEPROM, or that no EEPROM write has been
> requested in the last 10ms. I think we could safely say that it is
> always the case with the kernel driver.
>
> 3) Issue a "stop conversion T" (= sending 0x22 to the chip), and verify
> that the bit 7 of the config register is set to 1 (no conversion in
> progress).
The 3) doesn't work, because the bit is actually "conversion done", so
on power-up this bit is set to 0. Anyway, starting a conversion toggle
this bit to 0 during 500ms to 1s so if we read it shortly after sending
such a command, it should be 0.
I have attached a patch for the 2.6 kernel as well for lm_sensors CVS. I
have tested the 2.6 module, and it works as expected. For the 2.4
module I only built it as I don't have a 2.4 kernel. Note that I also
improved the detection routine by backporting the 1) from the 2.6
kernel.
If everybody agrees, I'll send the 2.6 patch to Greg.
Bye,
Aurelien
--
.''`. Aurelien Jarno GPG: 1024D/F1BCDB73
: :' : Debian GNU/Linux developer | Electrical Engineer
`. `' aurel32 at debian.org | aurelien at aurel32.net
`- people.debian.org/~aurel32 | www.aurel32.net
-------------- next part --------------
Index: kernel/chips/ds1621.c
===================================================================
RCS file: /home/cvs/lm_sensors2/kernel/chips/ds1621.c,v
retrieving revision 1.16
diff -u -1 -b -p -r1.16 ds1621.c
--- kernel/chips/ds1621.c 4 Dec 2004 21:18:34 -0000 1.16
+++ kernel/chips/ds1621.c 19 Jan 2005 17:58:36 -0000
@@ -45,5 +45,4 @@ SENSORS_INSMOD_1(ds1621);
/* 7 6 5 4 3 2 1 0 */
-/* |Done|THF |TLF |NVB | 1 | 0 |POL |1SHOT| */
-#define DS1621_REG_CONFIG_MASK 0x0C
-#define DS1621_REG_CONFIG_VAL 0x08
+/* |Done|THF |TLF |NVB | X | X |POL |1SHOT| */
+#define DS1621_REG_CONFIG_NVB 0x10
#define DS1621_REG_CONFIG_POLARITY 0x02
@@ -167,3 +166,3 @@ int ds1621_detect(struct i2c_adapter *ad
{
- int i, conf;
+ int i, conf, temp;
struct i2c_client *new_client;
@@ -205,7 +204,33 @@ int ds1621_detect(struct i2c_adapter *ad
if (kind < 0) {
+ /* The NVB bit should be low if no EEPROM write has been
+ requested during the latest 10ms, which is highly
+ improbable in our case. */
conf = i2c_smbus_read_byte_data(new_client,
DS1621_REG_CONF);
- if ((conf & DS1621_REG_CONFIG_MASK)
- != DS1621_REG_CONFIG_VAL)
+ if (conf & DS1621_REG_CONFIG_NVB)
goto ERROR1;
+ /* The 7 lowest bits of a temperature should always be 0. */
+ temp = ds1621_read_value(new_client,
+ DS1621_REG_TEMP);
+ if (temp & 0x007f)
+ goto ERROR1;
+ temp = ds1621_read_value(new_client,
+ DS1621_REG_TEMP_OVER);
+ if (temp & 0x007f)
+ goto ERROR1;
+ temp = ds1621_read_value(new_client,
+ DS1621_REG_TEMP_HYST);
+ if (temp & 0x007f)
+ goto ERROR1;
+ /* Start conversion. DONE should go to low. */
+ i2c_smbus_write_byte(new_client,
+ DS1621_COM_START);
+ conf = i2c_smbus_read_byte_data(new_client,
+ DS1621_REG_CONF);
+ if (conf & DS1621_REG_CONFIG_DONE)
+ goto ERROR1;
+ /* Stop conversion. */
+ i2c_smbus_write_byte(new_client,
+ DS1621_COM_STOP);
+
}
-------------- next part --------------
diff -urN linux-2.6.11-rc1.orig/drivers/i2c/chips/ds1621.c linux-2.6.11-rc1/drivers/i2c/chips/ds1621.c
--- linux-2.6.11-rc1.orig/drivers/i2c/chips/ds1621.c 2004-12-24 22:35:40.000000000 +0100
+++ linux-2.6.11-rc1/drivers/i2c/chips/ds1621.c 2005-01-19 18:39:23.000000000 +0100
@@ -42,9 +42,8 @@
/* Many DS1621 constants specified below */
/* Config register used for detection */
/* 7 6 5 4 3 2 1 0 */
-/* |Done|THF |TLF |NVB | 1 | 0 |POL |1SHOT| */
-#define DS1621_REG_CONFIG_MASK 0x0C
-#define DS1621_REG_CONFIG_VAL 0x08
+/* |Done|THF |TLF |NVB | X | X |POL |1SHOT| */
+#define DS1621_REG_CONFIG_NVB 0x10
#define DS1621_REG_CONFIG_POLARITY 0x02
#define DS1621_REG_CONFIG_1SHOT 0x01
#define DS1621_REG_CONFIG_DONE 0x80
@@ -55,6 +54,7 @@
#define DS1621_REG_TEMP_MAX 0xA2 /* word, RW */
#define DS1621_REG_CONF 0xAC /* byte, RW */
#define DS1621_COM_START 0xEE /* no data */
+#define DS1621_COM_STOP 0x22 /* no data */
/* The DS1621 configuration register */
#define DS1621_ALARM_TEMP_HIGH 0x40
@@ -212,9 +212,13 @@
/* Now, we do the remaining detection. It is lousy. */
if (kind < 0) {
+ /* The NVB bit should be low if no EEPROM write has been
+ requested during the latest 10ms, which is highly
+ improbable in our case. */
conf = ds1621_read_value(new_client, DS1621_REG_CONF);
- if ((conf & DS1621_REG_CONFIG_MASK) != DS1621_REG_CONFIG_VAL)
+ if (conf & DS1621_REG_CONFIG_NVB)
goto exit_free;
+ /* The 7 lowest bits of a temperature should always be 0. */
temp = ds1621_read_value(new_client, DS1621_REG_TEMP);
if (temp & 0x007f)
goto exit_free;
@@ -224,6 +228,13 @@
temp = ds1621_read_value(new_client, DS1621_REG_TEMP_MAX);
if (temp & 0x007f)
goto exit_free;
+ /* Start conversion. DONE should go to low. */
+ i2c_smbus_write_byte(new_client, DS1621_COM_START);
+ conf = ds1621_read_value(new_client, DS1621_REG_CONF);
+ if (conf & DS1621_REG_CONFIG_DONE)
+ goto exit_free;
+ /* Stop conversion. */
+ i2c_smbus_write_byte(new_client, DS1621_COM_STOP);
}
/* Determine the chip type - only one kind supported! */
