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

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

Signed-off-by: Evgeny Boger <boger@contactless.ru>
Cc: Greg KH <greg@kroah.com>
Acked-by: David Fries <david@fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Evgeny Boger
2014-01-23 15:56:18 -08:00
committed by Linus Torvalds
parent 63509beaf7
commit 3089a4c8d3
3 changed files with 23 additions and 12 deletions
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22
drivers/w1/masters/w1-gpio.c
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@@ -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);