Messages in this thread Patch in this message |  | | From | Evgeny Boger <> | Subject | [PATCH 1/1] Add strong pullup emulation to w1-gpio master driver. | Date | Mon, 11 Nov 2013 18:36:54 +0400 |
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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> --- drivers/w1/masters/w1-gpio.c | 22 ++++++++++++++++++++++ drivers/w1/w1_int.c | 12 ------------ 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 f54ece2..cb7f89b 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; @@ -125,6 +146,7 @@ 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 5a98649..590bd8a 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 065e3ae..d58594a 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 */ -- 1.8.1.2
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