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// SPDX-License-Identifier: GPL-2.0-only
/*
* Shared library for Kinetic's ExpressWire protocol.
* This protocol works by pulsing the ExpressWire IC's control GPIO.
* ktd2692 and ktd2801 are known to use this protocol.
*/
#include <linux/bits.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/gpio/consumer.h>
#include <linux/irqflags.h>
#include <linux/types.h>
#include <linux/leds-expresswire.h>
void expresswire_power_off(struct expresswire_common_props *props)
{
gpiod_set_value_cansleep(props->ctrl_gpio, 0);
fsleep(props->timing.poweroff_us);
}
EXPORT_SYMBOL_NS_GPL(expresswire_power_off, "EXPRESSWIRE");
void expresswire_enable(struct expresswire_common_props *props)
{
unsigned long flags;
local_irq_save(flags);
gpiod_set_value(props->ctrl_gpio, 1);
udelay(props->timing.detect_delay_us);
gpiod_set_value(props->ctrl_gpio, 0);
udelay(props->timing.detect_us);
gpiod_set_value(props->ctrl_gpio, 1);
local_irq_restore(flags);
}
EXPORT_SYMBOL_NS_GPL(expresswire_enable, "EXPRESSWIRE");
static void expresswire_start(struct expresswire_common_props *props)
{
gpiod_set_value(props->ctrl_gpio, 1);
udelay(props->timing.data_start_us);
}
static void expresswire_end(struct expresswire_common_props *props)
{
gpiod_set_value(props->ctrl_gpio, 0);
udelay(props->timing.end_of_data_low_us);
gpiod_set_value(props->ctrl_gpio, 1);
udelay(props->timing.end_of_data_high_us);
}
static void expresswire_set_bit(struct expresswire_common_props *props, bool bit)
{
if (bit) {
gpiod_set_value(props->ctrl_gpio, 0);
udelay(props->timing.short_bitset_us);
gpiod_set_value(props->ctrl_gpio, 1);
udelay(props->timing.long_bitset_us);
} else {
gpiod_set_value(props->ctrl_gpio, 0);
udelay(props->timing.long_bitset_us);
gpiod_set_value(props->ctrl_gpio, 1);
udelay(props->timing.short_bitset_us);
}
}
void expresswire_write_u8(struct expresswire_common_props *props, u8 val)
{
unsigned long flags;
local_irq_save(flags);
expresswire_start(props);
for (int i = 7; i >= 0; i--)
expresswire_set_bit(props, val & BIT(i));
expresswire_end(props);
local_irq_restore(flags);
}
EXPORT_SYMBOL_NS_GPL(expresswire_write_u8, "EXPRESSWIRE");
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