2005-01-19 20:27:57

by Aurelien Jarno

Subject: [PATCH 2.6] I2C: Fix DS1621 detection

Hi Greg,

Dallas Semiconductors as recently changed the design of their DS1621
chips, including the bits that were checked in the kernel driver to
detect it.

The patch below fixes the detection by checking an other bit of the
configuration register instead.

Please apply.

Thanks,
Aurelien

Signed-off-by: Aurelien Jarno <[email protected]>


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;

--
.''`. Aurelien Jarno GPG: 1024D/F1BCDB73
: :' : Debian GNU/Linux developer | Electrical Engineer
`. `' [email protected] | [email protected]
`- people.debian.org/~aurel32 | http://www.aurel32.net

2005-01-19 23:27:01

by Greg KH

Subject: Re: [PATCH 2.6] I2C: Fix DS1621 detection

On Wed, Jan 19, 2005 at 09:27:49PM +0100, Aur?lien Jarno wrote:
> Hi Greg,
>
> Dallas Semiconductors as recently changed the design of their DS1621
> chips, including the bits that were checked in the kernel driver to
> detect it.
>
> The patch below fixes the detection by checking an other bit of the
> configuration register instead.
>
> Please apply.

Applied, thanks.

greg k-h