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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>
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@ -18,10 +18,31 @@
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#include <linux/of_gpio.h>
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#include <linux/err.h>
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#include <linux/of.h>
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#include <linux/delay.h>
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#include "../w1.h"
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#include "../w1_int.h"
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static u8 w1_gpio_set_pullup(void *data, int delay)
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{
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struct w1_gpio_platform_data *pdata = data;
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if (delay) {
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pdata->pullup_duration = delay;
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} else {
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if (pdata->pullup_duration) {
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gpio_direction_output(pdata->pin, 1);
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msleep(pdata->pullup_duration);
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gpio_direction_input(pdata->pin);
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}
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pdata->pullup_duration = 0;
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}
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return 0;
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}
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static void w1_gpio_write_bit_dir(void *data, u8 bit)
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{
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struct w1_gpio_platform_data *pdata = data;
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@ -132,6 +153,7 @@ static int w1_gpio_probe(struct platform_device *pdev)
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} else {
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gpio_direction_input(pdata->pin);
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master->write_bit = w1_gpio_write_bit_dir;
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master->set_pullup = w1_gpio_set_pullup;
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}
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err = w1_add_master_device(master);
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@ -117,18 +117,6 @@ int w1_add_master_device(struct w1_bus_master *master)
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printk(KERN_ERR "w1_add_master_device: invalid function set\n");
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return(-EINVAL);
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}
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/* While it would be electrically possible to make a device that
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* generated a strong pullup in bit bang mode, only hardware that
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* controls 1-wire time frames are even expected to support a strong
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* pullup. w1_io.c would need to support calling set_pullup before
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* the last write_bit operation of a w1_write_8 which it currently
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* doesn't.
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*/
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if (!master->write_byte && !master->touch_bit && master->set_pullup) {
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printk(KERN_ERR "w1_add_master_device: set_pullup requires "
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"write_byte or touch_bit, disabling\n");
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master->set_pullup = NULL;
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}
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/* Lock until the device is added (or not) to w1_masters. */
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mutex_lock(&w1_mlock);
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@ -20,6 +20,7 @@ struct w1_gpio_platform_data {
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unsigned int is_open_drain:1;
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void (*enable_external_pullup)(int enable);
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unsigned int ext_pullup_enable_pin;
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unsigned int pullup_duration;
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};
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#endif /* _LINUX_W1_GPIO_H */
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