Commit 3089a4c8 authored by Evgeny Boger's avatar Evgeny Boger Committed by Linus Torvalds
Browse files

drivers/w1/masters/w1-gpio.c: add strong pullup emulation 



Strong pullup is emulated by driving pin logic high after write command
when using tri-state push-pull GPIO.

Signed-off-by: default avatarEvgeny Boger <boger@contactless.ru>
Cc: Greg KH <greg@kroah.com>
Acked-by: default avatarDavid Fries <david@fries.net>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 63509bea

drivers/w1/masters/w1-gpio.c

+22 −0
Original line number Diff line number Diff line
@@ -18,10 +18,31 @@ 
#include <linux/of_gpio.h>

#include <linux/err.h>

#include <linux/of.h>

#include <linux/delay.h>



#include "../w1.h"

#include "../w1_int.h"



static u8 w1_gpio_set_pullup(void *data, int delay)

{

	struct w1_gpio_platform_data *pdata = data;



	if (delay) {

		pdata->pullup_duration = delay;

	} else {

		if (pdata->pullup_duration) {

			gpio_direction_output(pdata->pin, 1);



			msleep(pdata->pullup_duration);



			gpio_direction_input(pdata->pin);

		}

		pdata->pullup_duration = 0;

	}



	return 0;

}



static void w1_gpio_write_bit_dir(void *data, u8 bit)

{

	struct w1_gpio_platform_data *pdata = data;
@@ -132,6 +153,7 @@ static int w1_gpio_probe(struct platform_device *pdev) 
	} else {

		gpio_direction_input(pdata->pin);

		master->write_bit = w1_gpio_write_bit_dir;

		master->set_pullup = w1_gpio_set_pullup;

	}



	err = w1_add_master_device(master);

drivers/w1/w1_int.c

+0 −12
Original line number Diff line number Diff line
@@ -117,18 +117,6 @@ int w1_add_master_device(struct w1_bus_master *master) 
		printk(KERN_ERR "w1_add_master_device: invalid function set\n");

		return(-EINVAL);

        }

	/* While it would be electrically possible to make a device that

	 * generated a strong pullup in bit bang mode, only hardware that

	 * controls 1-wire time frames are even expected to support a strong

	 * pullup.  w1_io.c would need to support calling set_pullup before

	 * the last write_bit operation of a w1_write_8 which it currently

	 * doesn't.

	 */

	if (!master->write_byte && !master->touch_bit && master->set_pullup) {

		printk(KERN_ERR "w1_add_master_device: set_pullup requires "

			"write_byte or touch_bit, disabling\n");

		master->set_pullup = NULL;

	}



	/* Lock until the device is added (or not) to w1_masters. */

	mutex_lock(&w1_mlock);

include/linux/w1-gpio.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ struct w1_gpio_platform_data { 
	unsigned int is_open_drain:1;

	void (*enable_external_pullup)(int enable);

	unsigned int ext_pullup_enable_pin;

	unsigned int pullup_duration;

};



#endif /* _LINUX_W1_GPIO_H */

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