Commit c8a06c1e authored by Daniel Mack's avatar Daniel Mack Committed by Linus Torvalds

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: default avatarDaniel Mack <daniel@caiaq.de>
Acked-by: default avatarVille Syrjala <syrjala@sci.fi>
Acked-by: default avatarEvgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 99162195
...@@ -74,6 +74,9 @@ static int __init w1_gpio_probe(struct platform_device *pdev) ...@@ -74,6 +74,9 @@ static int __init w1_gpio_probe(struct platform_device *pdev)
if (err) if (err)
goto free_gpio; goto free_gpio;
if (pdata->enable_external_pullup)
pdata->enable_external_pullup(1);
platform_set_drvdata(pdev, master); platform_set_drvdata(pdev, master);
return 0; return 0;
...@@ -91,6 +94,9 @@ static int __exit w1_gpio_remove(struct platform_device *pdev) ...@@ -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_bus_master *master = platform_get_drvdata(pdev);
struct w1_gpio_platform_data *pdata = pdev->dev.platform_data; 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); w1_remove_master_device(master);
gpio_free(pdata->pin); gpio_free(pdata->pin);
kfree(master); kfree(master);
...@@ -98,12 +104,41 @@ static int __exit w1_gpio_remove(struct platform_device *pdev) ...@@ -98,12 +104,41 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
return 0; 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 = { static struct platform_driver w1_gpio_driver = {
.driver = { .driver = {
.name = "w1-gpio", .name = "w1-gpio",
.owner = THIS_MODULE, .owner = THIS_MODULE,
}, },
.remove = __exit_p(w1_gpio_remove), .remove = __exit_p(w1_gpio_remove),
.suspend = w1_gpio_suspend,
.resume = w1_gpio_resume,
}; };
static int __init w1_gpio_init(void) static int __init w1_gpio_init(void)
......
...@@ -18,6 +18,7 @@ ...@@ -18,6 +18,7 @@
struct w1_gpio_platform_data { struct w1_gpio_platform_data {
unsigned int pin; unsigned int pin;
unsigned int is_open_drain:1; unsigned int is_open_drain:1;
void (*enable_external_pullup)(int enable);
}; };
#endif /* _LINUX_W1_GPIO_H */ #endif /* _LINUX_W1_GPIO_H */
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment