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 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 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 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 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 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 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