linux-kernel - Re: [PATCH 1/4] power_supply: Support serial number and ACR in olpc

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Date:	Wed, 30 Apr 2008 14:48:36 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Andres Salomon <dilinger@...ued.net>
Cc:	linux-kernel@...r.kernel.org, cbou@...l.ru, dwmw2@...radead.org
Subject: Re: [PATCH 1/4] power_supply: Support serial number and ACR in
 olpc_battery

On Wed, 30 Apr 2008 16:30:02 -0400
Andres Salomon <dilinger@...ued.net> wrote:

> From: David Woodhouse <dwmw2@...radead.org>
> 
> This adds serial number and accumulated current support to the OLPC
> battery driver.
> 
> Signed-off-by: David Woodhouse <dwmw2@...radead.org>
> Signed-off-by: Andres Salomon <dilinger@...ian.org>
> ---
>  drivers/power/olpc_battery.c       |   23 ++++++++++++++++++++++-
>  drivers/power/power_supply_sysfs.c |    1 +
>  include/linux/power_supply.h       |    1 +
>  3 files changed, 24 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/power/olpc_battery.c b/drivers/power/olpc_battery.c
> index ab1e828..9d9dd09 100644
> --- a/drivers/power/olpc_battery.c
> +++ b/drivers/power/olpc_battery.c
> @@ -19,7 +19,7 @@
>  
>  #define EC_BAT_VOLTAGE	0x10	/* uint16_t,	*9.76/32,    mV   */
>  #define EC_BAT_CURRENT	0x11	/* int16_t,	*15.625/120, mA   */
> -#define EC_BAT_ACR	0x12
> +#define EC_BAT_ACR	0x12	/* int16_t,	*416.667,    __Ah  */
>  #define EC_BAT_TEMP	0x13	/* uint16_t,	*100/256,   __C  */
>  #define EC_AMB_TEMP	0x14	/* uint16_t,	*100/256,   __C  */
>  #define EC_BAT_STATUS	0x15	/* uint8_t,	bitmask */
> @@ -84,6 +84,8 @@ static struct power_supply olpc_ac = {
>  	.get_property = olpc_ac_get_prop,
>  };
>  
> +static char bat_serial[17]; /* Ick */
> +
>  /*********************************************************************
>   *		Battery properties
>   *********************************************************************/
> @@ -94,6 +96,7 @@ static int olpc_bat_get_property(struct power_supply *psy,
>  	int ret = 0;
>  	int16_t ec_word;
>  	uint8_t ec_byte;
> +	uint64_t ser_buf;
>  
>  	ret = olpc_ec_cmd(EC_BAT_STATUS, NULL, 0, &ec_byte, 1);
>  	if (ret)
> @@ -241,6 +244,22 @@ static int olpc_bat_get_property(struct power_supply *psy,
>  		ec_word = be16_to_cpu(ec_word);
>  		val->intval = ec_word * 100 / 256;
>  		break;
> +	case POWER_SUPPLY_PROP_ACCUM_CURRENT:
> +		ret = olpc_ec_cmd(EC_BAT_ACR, NULL, 0, (void *)&ec_word, 2);
> +		if (ret)
> +			return ret;
> +
> +		ec_word = be16_to_cpu(ec_word);
> +		val->intval = ec_word;

It would be cleaner to give ec_word the __be16 type and do

	val->intval = be16_to_cpu(ec_word);

However I suspect that if that conversion were done fully, things would get
rather involved.

It's a shame that we didn't design the endianness suypport in a way which
the compiler could enforce - gcc's handling of small structs is (or was)
suboptimal.  sparse should do it for us, but few run it, I expect.

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