Re: [PATCH] power_supply: change the way how wm97xx-bat driver is registered

Anton Vorontsov
2008-11-03T15:12:05Z

On Wed, Oct 29, 2008 at 12:04:10PM +0300, Dmitry Baryshkov wrote:
> Do register the driver from wm97xx_bat_set_pdata instead of module init.
> This has several positive outcome points:
> 1) This driver for wm97xx-battery is now registered on demand, thus allowing
> other driver (e.g. tosa-battery) to claim the battery.
> 2) After dropping __init from wm97xx_bat_set_pdata(), the wm97xx_bat driver
> can be correctly built as a module. Then one can request it and set the
> battery data.
>
> Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
> Cc: Marek Vasut <marek.vasut@gmail.com>
> ---
> drivers/power/Kconfig | 4 ++--
> drivers/power/wm97xx_battery.c | 12 +++++-------
> include/linux/wm97xx_batt.h | 7 +++++--
> 3 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index 8e0c2b4..053f20b 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -57,8 +57,8 @@ config BATTERY_TOSA
> SL-6000 (tosa) models.
>
> config BATTERY_WM97XX
> - bool "WM97xx generic battery driver"
> - depends on TOUCHSCREEN_WM97XX=y
> + tristate "WM97xx generic battery driver"
> + depends on TOUCHSCREEN_WM97XX
> help
> Say Y to enable support for battery measured by WM97xx aux port.
>
> diff --git a/drivers/power/wm97xx_battery.c b/drivers/power/wm97xx_battery.c
> index 8bde921..94727dc 100644
> --- a/drivers/power/wm97xx_battery.c
> +++ b/drivers/power/wm97xx_battery.c
> @@ -248,23 +248,21 @@ static struct platform_driver wm97xx_bat_driver = {
> .resume = wm97xx_bat_resume,
> };
>
> -static int __init wm97xx_bat_init(void)
> -{
> - return platform_driver_register(&wm97xx_bat_driver);
> -}
> -
> static void __exit wm97xx_bat_exit(void)
> {
> platform_driver_unregister(&wm97xx_bat_driver);
> }
>
> -void __init wm97xx_bat_set_pdata(struct wm97xx_batt_info *data)
> +int wm97xx_bat_set_pdata(struct wm97xx_batt_info *data)
> {
> + if (pdata)
> + return -EEXIST;
> +
> pdata = data;
> + return platform_driver_register(&wm97xx_bat_driver);
> }
> EXPORT_SYMBOL_GPL(wm97xx_bat_set_pdata);
>
> -module_init(wm97xx_bat_init);
> module_exit(wm97xx_bat_exit);
>
> MODULE_LICENSE("GPL");
> diff --git a/include/linux/wm97xx_batt.h b/include/linux/wm97xx_batt.h
> index 9681d1a..3e42526 100644
> --- a/include/linux/wm97xx_batt.h
> +++ b/include/linux/wm97xx_batt.h
> @@ -18,9 +18,12 @@ struct wm97xx_batt_info {
> };
>
> #ifdef CONFIG_BATTERY_WM97XX
> -void __init wm97xx_bat_set_pdata(struct wm97xx_batt_info *data);
> +int wm97xx_bat_set_pdata(struct wm97xx_batt_info *data);
> #else
> -static inline void wm97xx_bat_set_pdata(struct wm97xx_batt_info *data) {}
> +static inline int wm97xx_bat_set_pdata(struct wm97xx_batt_info *data)
> +{
> + return -ENODEV;
> +}
> #endif

How that supposed to work when BATTERY_WM97XX is a module?
#ifdef CONFIG_BATTERY_WM97XX will evaluate to false, and you'll have
dummy wm97xx_bat_set_pdata() that returns -ENODEV...

The whole wm97xx stuff is broken wrt device-driver model... Yeah,
I know why -- we don't have the ADC API/Subsystem. It would be great
if somebody could find time to forward-port the subsystem from the
handhelds.org tree...

I don't know what happened to the industrialio subsystem though
(http://lkml.org/lkml/2008/7/23/163), but it looked needlessly
complicated, and probably Jonathan gave up on it... :-/

--
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2