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

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

drivers/w1/masters/w1-gpio.c

+35 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/w1-gpio.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */