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: 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>
diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
index e36b18b..9709b8b 100644
--- a/drivers/w1/masters/w1-gpio.c
+++ b/drivers/w1/masters/w1-gpio.c
@@ -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 @@
} 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);
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index 5a98649..590bd8a 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -117,18 +117,6 @@
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);
diff --git a/include/linux/w1-gpio.h b/include/linux/w1-gpio.h
index 065e3ae..d58594a 100644
--- a/include/linux/w1-gpio.h
+++ b/include/linux/w1-gpio.h
@@ -20,6 +20,7 @@
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 */