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
expresswire_power_off(struct expresswire_common_props * props)16 void expresswire_power_off(struct expresswire_common_props *props)
17 {
18 gpiod_set_value_cansleep(props->ctrl_gpio, 0);
19 usleep_range(props->timing.poweroff_us, props->timing.poweroff_us * 2);
20 }
21 EXPORT_SYMBOL_NS_GPL(expresswire_power_off, EXPRESSWIRE);
22
expresswire_enable(struct expresswire_common_props * props)23 void expresswire_enable(struct expresswire_common_props *props)
24 {
25 gpiod_set_value(props->ctrl_gpio, 1);
26 udelay(props->timing.detect_delay_us);
27 gpiod_set_value(props->ctrl_gpio, 0);
28 udelay(props->timing.detect_us);
29 gpiod_set_value(props->ctrl_gpio, 1);
30 }
31 EXPORT_SYMBOL_NS_GPL(expresswire_enable, EXPRESSWIRE);
32
expresswire_start(struct expresswire_common_props * props)33 void expresswire_start(struct expresswire_common_props *props)
34 {
35 gpiod_set_value(props->ctrl_gpio, 1);
36 udelay(props->timing.data_start_us);
37 }
38 EXPORT_SYMBOL_NS_GPL(expresswire_start, EXPRESSWIRE);
39
expresswire_end(struct expresswire_common_props * props)40 void expresswire_end(struct expresswire_common_props *props)
41 {
42 gpiod_set_value(props->ctrl_gpio, 0);
43 udelay(props->timing.end_of_data_low_us);
44 gpiod_set_value(props->ctrl_gpio, 1);
45 udelay(props->timing.end_of_data_high_us);
46 }
47 EXPORT_SYMBOL_NS_GPL(expresswire_end, EXPRESSWIRE);
48
expresswire_set_bit(struct expresswire_common_props * props,bool bit)49 void expresswire_set_bit(struct expresswire_common_props *props, bool bit)
50 {
51 if (bit) {
52 gpiod_set_value(props->ctrl_gpio, 0);
53 udelay(props->timing.short_bitset_us);
54 gpiod_set_value(props->ctrl_gpio, 1);
55 udelay(props->timing.long_bitset_us);
56 } else {
57 gpiod_set_value(props->ctrl_gpio, 0);
58 udelay(props->timing.long_bitset_us);
59 gpiod_set_value(props->ctrl_gpio, 1);
60 udelay(props->timing.short_bitset_us);
61 }
62 }
63 EXPORT_SYMBOL_NS_GPL(expresswire_set_bit, EXPRESSWIRE);
64
expresswire_write_u8(struct expresswire_common_props * props,u8 val)65 void 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 }
72 EXPORT_SYMBOL_NS_GPL(expresswire_write_u8, EXPRESSWIRE);
73