drivers/leds/leds-expresswire.c

   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);