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| author | Daniel Mack <daniel@caiaq.de> | 2009-06-17 16:28:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-18 13:03:58 -0700 |
| commit | c8a06c1ef0bc45915fc45a170c7c60426971304c (patch) | |
| tree | 9e8f5d3890766bca481c15aac69ef96f52612874 | |
| parent | 9916219579d078c80377dd3988c2cc213536d868 (diff) | |
| download | linux-c8a06c1ef0bc45915fc45a170c7c60426971304c.tar.gz linux-c8a06c1ef0bc45915fc45a170c7c60426971304c.tar.bz2 linux-c8a06c1ef0bc45915fc45a170c7c60426971304c.zip | |
w1-gpio: add external pull-up enable callback
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>
Acked-by: Ville Syrjala <syrjala@sci.fi>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/w1/masters/w1-gpio.c | 35 | ||||
| -rw-r--r-- | 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 a411702413d6..6f8866d6a905 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 9797fec7748a..3adeff82212f 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 */ |