linux-kernel - Re: [PATCH 1/5] adt7462: New hwmon driver

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Message-Id: <20081107111808.851dad3b.akpm@linux-foundation.org>
Date:	Fri, 7 Nov 2008 11:18:08 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	"Darrick J. Wong" <djwong@...ibm.com>
Cc:	djwong@...ibm.com, khali@...ux-fr.org,
	linux-kernel@...r.kernel.org, lm-sensors@...sensors.org
Subject: Re: [PATCH 1/5] adt7462: New hwmon driver

On Fri, 07 Nov 2008 10:56:26 -0800
"Darrick J. Wong" <djwong@...ibm.com> wrote:

> 
> New driver to play with.  As Jean mentioned a couple of years ago, this
> chip is a beast with odd combinations of 8 fans, 4 temperatures, and 
> 13 voltage sensors.  This driver has been tested on an IntelliStation
> Z30.
> 
> ...
>
> + * 9. Vbatt/FSB_Vtt (pin 26)
> + * A. +3.3V/+1.2V1 (pin 25)
> + * B. Vccp2/+2.5V/+1.8V/+1.5V (pin 24)
> + * C. +1.5V ICH (only if BOTH pin 28/29 are set to +1.5V)
> + * D. +1.5V 3GPIO (only if BOTH pin 28/29 are set to +1.5V)
> + *
> + * Each of these 13 has a factor to convert raw to voltage.  Even better,
> + * the pins can be connected to other sensors (tach/gpio/hot/etc), which
> + * makes the bookkeeping tricky.
> + *
> + * Some, but not all, of these voltages have low/high limits.
> + */
> +#define ADT7462_VOLT_COUNT	12
> +
> +#define ADT7462_VENDOR		0x41
> +#define ADT7462_DEVICE		0x62
> +/* datasheet only mentions a revision 4 */
> +#define ADT7462_REVISION	0x04
> +
> +/* How often do we reread sensors values? (In jiffies) */
> +#define SENSOR_REFRESH_INTERVAL	(2 * HZ)
> +
> +/* How often do we reread sensor limit values? (In jiffies) */
> +#define LIMIT_REFRESH_INTERVAL	(60 * HZ)
> +
> +/* datasheet says to divide this number by the fan reading to get fan rpm */
> +#define FAN_PERIOD_TO_RPM(x)	((90000 * 60) / (x))
> +#define FAN_RPM_TO_PERIOD	FAN_PERIOD_TO_RPM
> +#define FAN_PERIOD_INVALID	65535
> +#define FAN_DATA_VALID(x)	((x) && (x) != FAN_PERIOD_INVALID)

A macro which evaluates its args more than once is a bit naughty.

> +#define MASK_AND_SHIFT(value, prefix)	\
> +	(((value) & prefix##_MASK) >> prefix##_SHIFT)
> +
> +#define ROUND_DIV(x, divisor)  (((x) + ((divisor) / 2)) / (divisor))

hm, ok.

That evaluates `divisor' twice, too.

argh.  ALIGN() has the same problem.  Something like this...

--- a/include/linux/kernel.h~a
+++ a/include/linux/kernel.h
@@ -39,7 +39,12 @@ extern const char linux_proc_banner[];
 #define STACK_MAGIC	0xdeadbeef
 
 #define ALIGN(x,a)		__ALIGN_MASK(x,(typeof(x))(a)-1)
-#define __ALIGN_MASK(x,mask)	(((x)+(mask))&~(mask))
+
+#define __ALIGN_MASK(x,mask)	({		\
+	typeof(mask) __mask = mask;		\
+	(((x) + __mask) & ~__mask);		\
+})
+
 #define PTR_ALIGN(p, a)		((typeof(p))ALIGN((unsigned long)(p), (a)))
 #define IS_ALIGNED(x, a)		(((x) & ((typeof(x))(a) - 1)) == 0)
 
_

Looks good to my untrained eye.  Quite a large driver.
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