diff options
| author | Evgeny Boger <boger@contactless.ru> | 2014-01-23 15:56:18 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-23 16:37:04 -0800 |
| commit | 3089a4c8d3abc7e2ab105d1d39d415110d1566d6 (patch) | |
| tree | 5064f69853949cb8b5d245c932f65a3202d21219 | |
| parent | 63509beaf7ed7a9dc8c574be61189fce791489f0 (diff) | |
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>
| -rw-r--r-- | drivers/w1/masters/w1-gpio.c | 22 | ||||
| -rw-r--r-- | drivers/w1/w1_int.c | 12 | ||||
| -rw-r--r-- | include/linux/w1-gpio.h | 1 |
3 files changed, 23 insertions, 12 deletions
diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c index e36b18b2817..9709b8b484b 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 @@ 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); diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c index 5a98649f6ab..590bd8a7cd1 100644 --- a/drivers/w1/w1_int.c +++ b/drivers/w1/w1_int.c @@ -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); diff --git a/include/linux/w1-gpio.h b/include/linux/w1-gpio.h index 065e3ae79ab..d58594a3232 100644 --- a/include/linux/w1-gpio.h +++ b/include/linux/w1-gpio.h @@ -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 */ |