1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Shared library for Kinetic's ExpressWire protocol.
4 * This protocol works by pulsing the ExpressWire IC's control GPIO.
5 * ktd2692 and ktd2801 are known to use this protocol.
6 */
7
8#include <linux/bits.h>
9#include <linux/delay.h>
10#include <linux/export.h>
11#include <linux/gpio/consumer.h>
12#include <linux/types.h>
13
14#include <linux/leds-expresswire.h>
15
16void expresswire_power_off(struct expresswire_common_props *props)
17{
18 gpiod_set_value_cansleep(desc: props->ctrl_gpio, value: 0);
19 usleep_range(min: props->timing.poweroff_us, max: props->timing.poweroff_us * 2);
20}
21EXPORT_SYMBOL_NS_GPL(expresswire_power_off, "EXPRESSWIRE");
22
23void expresswire_enable(struct expresswire_common_props *props)
24{
25 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
26 udelay(usec: props->timing.detect_delay_us);
27 gpiod_set_value(desc: props->ctrl_gpio, value: 0);
28 udelay(usec: props->timing.detect_us);
29 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
30}
31EXPORT_SYMBOL_NS_GPL(expresswire_enable, "EXPRESSWIRE");
32
33void expresswire_start(struct expresswire_common_props *props)
34{
35 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
36 udelay(usec: props->timing.data_start_us);
37}
38EXPORT_SYMBOL_NS_GPL(expresswire_start, "EXPRESSWIRE");
39
40void expresswire_end(struct expresswire_common_props *props)
41{
42 gpiod_set_value(desc: props->ctrl_gpio, value: 0);
43 udelay(usec: props->timing.end_of_data_low_us);
44 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
45 udelay(usec: props->timing.end_of_data_high_us);
46}
47EXPORT_SYMBOL_NS_GPL(expresswire_end, "EXPRESSWIRE");
48
49void expresswire_set_bit(struct expresswire_common_props *props, bool bit)
50{
51 if (bit) {
52 gpiod_set_value(desc: props->ctrl_gpio, value: 0);
53 udelay(usec: props->timing.short_bitset_us);
54 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
55 udelay(usec: props->timing.long_bitset_us);
56 } else {
57 gpiod_set_value(desc: props->ctrl_gpio, value: 0);
58 udelay(usec: props->timing.long_bitset_us);
59 gpiod_set_value(desc: props->ctrl_gpio, value: 1);
60 udelay(usec: props->timing.short_bitset_us);
61 }
62}
63EXPORT_SYMBOL_NS_GPL(expresswire_set_bit, "EXPRESSWIRE");
64
65void expresswire_write_u8(struct expresswire_common_props *props, u8 val)
66{
67 expresswire_start(props);
68 for (int i = 7; i >= 0; i--)
69 expresswire_set_bit(props, val & BIT(i));
70 expresswire_end(props);
71}
72EXPORT_SYMBOL_NS_GPL(expresswire_write_u8, "EXPRESSWIRE");
73

source code of linux/drivers/leds/leds-expresswire.c