lkml.org 
[lkml]   [2009]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] w1-gpio: add external pull-up enable callback
(cc Evgeniy Polyakov)

Evgeniy, could you give some feedback on this? Ville Syrjala gave his
Acked-by already.

Thanks,
Daniel


On Tue, May 05, 2009 at 02:43:33PM +0200, Daniel Mack wrote:
> On embedded devices, sleep mode conditions can be tricky to handle,
> Especially when processors tend to pull-down the w1 bus during sleep.
> Bus slaves (such as the ds2760) may interpret this as a reason for
> power-down conditions and entirely switch off the device.
>
> This patch adds a callback function pointer to let users switch on and
> off the external pull-up resistor. This lets the outside world know
> whether the processor is currently actively driving the bus or not.
>
> When this callback is not provided, the code behaviour won't change.
>
> Signed-off-by: Daniel Mack <daniel@caiaq.de>
> Cc: Ville Syrjala <syrjala@sci.fi>
> ---
> drivers/w1/masters/w1-gpio.c | 35 +++++++++++++++++++++++++++++++++++
> include/linux/w1-gpio.h | 1 +
> 2 files changed, 36 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
> index a411702..6f8866d 100644
> --- a/drivers/w1/masters/w1-gpio.c
> +++ b/drivers/w1/masters/w1-gpio.c
> @@ -74,6 +74,9 @@ static int __init w1_gpio_probe(struct platform_device *pdev)
> if (err)
> goto free_gpio;
>
> + if (pdata->enable_external_pullup)
> + pdata->enable_external_pullup(1);
> +
> platform_set_drvdata(pdev, master);
>
> return 0;
> @@ -91,6 +94,9 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
> struct w1_bus_master *master = platform_get_drvdata(pdev);
> struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
>
> + if (pdata->enable_external_pullup)
> + pdata->enable_external_pullup(0);
> +
> w1_remove_master_device(master);
> gpio_free(pdata->pin);
> kfree(master);
> @@ -98,12 +104,41 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
> return 0;
> }
>
> +#ifdef CONFIG_PM
> +
> +static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> + struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
> +
> + if (pdata->enable_external_pullup)
> + pdata->enable_external_pullup(0);
> +
> + return 0;
> +}
> +
> +static int w1_gpio_resume(struct platform_device *pdev)
> +{
> + struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
> +
> + if (pdata->enable_external_pullup)
> + pdata->enable_external_pullup(1);
> +
> + return 0;
> +}
> +
> +#else
> +#define w1_gpio_suspend NULL
> +#define w1_gpio_resume NULL
> +#endif
> +
> static struct platform_driver w1_gpio_driver = {
> .driver = {
> .name = "w1-gpio",
> .owner = THIS_MODULE,
> },
> .remove = __exit_p(w1_gpio_remove),
> + .suspend = w1_gpio_suspend,
> + .resume = w1_gpio_resume,
> };
>
> static int __init w1_gpio_init(void)
> diff --git a/include/linux/w1-gpio.h b/include/linux/w1-gpio.h
> index 9797fec..3adeff8 100644
> --- a/include/linux/w1-gpio.h
> +++ b/include/linux/w1-gpio.h
> @@ -18,6 +18,7 @@
> struct w1_gpio_platform_data {
> unsigned int pin;
> unsigned int is_open_drain:1;
> + void (*enable_external_pullup)(int enable);
> };
>
> #endif /* _LINUX_W1_GPIO_H */
> --
> 1.6.2.1
>


\
 
 \ /
  Last update: 2009-05-08 22:15    [W:0.088 / U:4.920 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site