diff options
| author | Daniel Mack <daniel@caiaq.de> | 2009-06-18 01:28:15 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-18 22:03:58 +0200 |
| commit | c8a06c1ef0bc45915fc45a170c7c60426971304c (patch) | |
| tree | 9e8f5d3890766bca481c15aac69ef96f52612874 /drivers/w1 | |
| parent | dma-mapping: ia64: add CONFIG_DMA_API_DEBUG support (diff) | |
| download | linux-c8a06c1ef0bc45915fc45a170c7c60426971304c.tar.xz 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>
Diffstat (limited to 'drivers/w1')
| -rw-r--r-- | drivers/w1/masters/w1-gpio.c | 35 |
1 files changed, 35 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) |