u-boot/arch/arm/mach-snapdragon/init_sdm845.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Common init part for boards based on SDM845
 *
 * (C) Copyright 2021 Dzmitry Sankouski <dsankouski@gmail.com>
 */

#include <init.h>
#include <env.h>
#include <common.h>
#include <asm/system.h>
#include <asm/gpio.h>
#include <dm.h>

DECLARE_GLOBAL_DATA_PTR;

int dram_init(void)
{
	return fdtdec_setup_mem_size_base();
}

void reset_cpu(void)
{
	psci_system_reset();
}

__weak int board_init(void)
{
	return 0;
}

/* Check for vol- and power buttons */
__weak int misc_init_r(void)
{
	struct udevice *pon;
	struct gpio_desc resin;
	int node, ret;

	ret = uclass_get_device_by_name(UCLASS_GPIO, "pm8998_pon@800", &pon);
	if (ret < 0) {
		printf("Failed to find PMIC pon node. Check device tree\n");
		return 0;
	}

	node = fdt_subnode_offset(gd->fdt_blob, dev_of_offset(pon),
				  "key_vol_down");
	if (node < 0) {
		printf("Failed to find key_vol_down node. Check device tree\n");
		return 0;
	}
	if (gpio_request_by_name_nodev(offset_to_ofnode(node), "gpios", 0,
				       &resin, 0)) {
		printf("Failed to request key_vol_down button.\n");
		return 0;
	}
	if (dm_gpio_get_value(&resin)) {
		env_set("key_vol_down", "1");
		printf("Volume down button pressed\n");
	} else {
		env_set("key_vol_down", "0");
	}

	node = fdt_subnode_offset(gd->fdt_blob, dev_of_offset(pon),
				  "key_power");
	if (node < 0) {
		printf("Failed to find key_power node. Check device tree\n");
		return 0;
	}
	if (gpio_request_by_name_nodev(offset_to_ofnode(node), "gpios", 0,
				       &resin, 0)) {
		printf("Failed to request key_power button.\n");
		return 0;
	}
	if (dm_gpio_get_value(&resin)) {
		env_set("key_power", "1");
		printf("Power button pressed\n");
	} else {
		env_set("key_power", "0");
	}

	return 0;
}