arch/arm/mach-imx/imx9/soc.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2022 NXP
 *
 * Peng Fan <peng.fan@nxp.com>
 */

#include <common.h>
#include <cpu_func.h>
#include <init.h>
#include <log.h>
#include <asm/arch/imx-regs.h>
#include <asm/global_data.h>
#include <asm/io.h>
#include <asm/arch/clock.h>
#include <asm/arch/ccm_regs.h>
#include <asm/arch/sys_proto.h>
#include <asm/arch/trdc.h>
#include <asm/mach-imx/boot_mode.h>
#include <asm/mach-imx/syscounter.h>
#include <asm/armv8/mmu.h>
#include <dm/device.h>
#include <dm/device_compat.h>
#include <dm/uclass.h>
#include <env.h>
#include <env_internal.h>
#include <errno.h>
#include <fdt_support.h>
#include <imx_thermal.h>
#include <linux/bitops.h>
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <thermal.h>
#include <asm/setup.h>
#include <asm/bootm.h>
#include <asm/arch-imx/cpu.h>
#include <asm/mach-imx/s400_api.h>
#include <fuse.h>

DECLARE_GLOBAL_DATA_PTR;

struct rom_api *g_rom_api = (struct rom_api *)0x1980;

#ifdef CONFIG_ENV_IS_IN_MMC
__weak int board_mmc_get_env_dev(int devno)
{
	return devno; }

int mmc_get_env_dev(void)
{
	volatile gd_t *pgd = gd;
	int ret;
	u32 boot;
	u16 boot_type;
	u8 boot_instance;

	ret = g_rom_api->query_boot_infor(QUERY_BT_DEV, &boot,
					  ((uintptr_t)&boot) ^ QUERY_BT_DEV);
	set_gd(pgd);

	if (ret != ROM_API_OKAY) {
		puts("ROMAPI: failure at query_boot_info\n");
		return CONFIG_SYS_MMC_ENV_DEV;
	}

	boot_type = boot >> 16;
	boot_instance = (boot >> 8) & 0xff;

	debug("boot_type %d, instance %d\n", boot_type, boot_instance);

	/* If not boot from sd/mmc, use default value */
	if (boot_type != BOOT_TYPE_SD && boot_type != BOOT_TYPE_MMC)
		return env_get_ulong("mmcdev", 10, CONFIG_SYS_MMC_ENV_DEV);

	return board_mmc_get_env_dev(boot_instance);
}
#endif

/*
 * SPEED_GRADE[5:4]    SPEED_GRADE[3:0]    MHz
 * xx                  0000                2300
 * xx                  0001                2200
 * xx                  0010                2100
 * xx                  0011                2000
 * xx                  0100                1900
 * xx                  0101                1800
 * xx                  0110                1700
 * xx                  0111                1600
 * xx                  1000                1500
 * xx                  1001                1400
 * xx                  1010                1300
 * xx                  1011                1200
 * xx                  1100                1100
 * xx                  1101                1000
 * xx                  1110                900
 * xx                  1111                800
 */
u32 get_cpu_speed_grade_hz(void)
{
	u32 speed, max_speed;
	u32 val;

	fuse_read(2, 3, &val);
	val = FIELD_GET(SPEED_GRADING_MASK, val) & 0xF;

	speed = MHZ(2300) - val * MHZ(100);

	if (is_imx93())
		max_speed = MHZ(1700);

	/* In case the fuse of speed grade not programmed */
	if (speed > max_speed)
		speed = max_speed;

	return speed;
}

/*
 * `00` - Consumer 0C to 95C
 * `01` - Ext. Consumer -20C to 105C
 * `10` - Industrial -40C to 105C
 * `11` - Automotive -40C to 125C
 */
u32 get_cpu_temp_grade(int *minc, int *maxc)
{
	u32 val;

	fuse_read(2, 3, &val);
	val = FIELD_GET(MARKETING_GRADING_MASK, val);

	if (minc && maxc) {
		if (val == TEMP_AUTOMOTIVE) {
			*minc = -40;
			*maxc = 125;
		} else if (val == TEMP_INDUSTRIAL) {
			*minc = -40;
			*maxc = 105;
		} else if (val == TEMP_EXTCOMMERCIAL) {
			if (is_imx93()) {
				/* imx93 only has extended industrial*/
				*minc = -40;
				*maxc = 125;
			} else {
				*minc = -20;
				*maxc = 105;
			}
		} else {
			*minc = 0;
			*maxc = 95;
		}
	}
	return val;
}

static void set_cpu_info(struct sentinel_get_info_data *info)
{
	gd->arch.soc_rev = info->soc;
	gd->arch.lifecycle = info->lc;
	memcpy((void *)&gd->arch.uid, &info->uid, 4 * sizeof(u32));
}

u32 get_cpu_rev(void)
{
	u32 rev = (gd->arch.soc_rev >> 24) - 0xa0;

	return (MXC_CPU_IMX93 << 12) | (CHIP_REV_1_0 + rev);
}

#define UNLOCK_WORD 0xD928C520 /* unlock word */
#define REFRESH_WORD 0xB480A602 /* refresh word */

static void disable_wdog(void __iomem *wdog_base)
{
	u32 val_cs = readl(wdog_base + 0x00);

	if (!(val_cs & 0x80))
		return;

	/* default is 32bits cmd */
	writel(REFRESH_WORD, (wdog_base + 0x04)); /* Refresh the CNT */

	if (!(val_cs & 0x800)) {
		writel(UNLOCK_WORD, (wdog_base + 0x04));
		while (!(readl(wdog_base + 0x00) & 0x800))
			;
	}
	writel(0x0, (wdog_base + 0x0C)); /* Set WIN to 0 */
	writel(0x400, (wdog_base + 0x08)); /* Set timeout to default 0x400 */
	writel(0x2120, (wdog_base + 0x00)); /* Disable it and set update */

	while (!(readl(wdog_base + 0x00) & 0x400))
		;
}

void init_wdog(void)
{
	u32 src_val;

	disable_wdog((void __iomem *)WDG3_BASE_ADDR);
	disable_wdog((void __iomem *)WDG4_BASE_ADDR);
	disable_wdog((void __iomem *)WDG5_BASE_ADDR);

	src_val = readl(0x54460018); /* reset mask */
	src_val &= ~0x1c;
	writel(src_val, 0x54460018);
}

static struct mm_region imx93_mem_map[] = {
	{
		/* ROM */
		.virt = 0x0UL,
		.phys = 0x0UL,
		.size = 0x100000UL,
		.attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |
			 PTE_BLOCK_OUTER_SHARE
	}, {
		/* TCM */
		.virt = 0x201c0000UL,
		.phys = 0x201c0000UL,
		.size = 0x80000UL,
		.attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |
			 PTE_BLOCK_NON_SHARE |
			 PTE_BLOCK_PXN | PTE_BLOCK_UXN
	}, {
		/* OCRAM */
		.virt = 0x20480000UL,
		.phys = 0x20480000UL,
		.size = 0xA0000UL,
		.attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |
			 PTE_BLOCK_OUTER_SHARE
	}, {
		/* AIPS */
		.virt = 0x40000000UL,
		.phys = 0x40000000UL,
		.size = 0x40000000UL,
		.attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |
			 PTE_BLOCK_NON_SHARE |
			 PTE_BLOCK_PXN | PTE_BLOCK_UXN
	}, {
		/* Flexible Serial Peripheral Interface */
		.virt = 0x28000000UL,
		.phys = 0x28000000UL,
		.size = 0x30000000UL,
		.attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |
			 PTE_BLOCK_NON_SHARE |
			 PTE_BLOCK_PXN | PTE_BLOCK_UXN
	}, {
		/* DRAM1 */
		.virt = 0x80000000UL,
		.phys = 0x80000000UL,
		.size = PHYS_SDRAM_SIZE,
		.attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |
			 PTE_BLOCK_OUTER_SHARE
	}, {
		/* empty entrie to split table entry 5 if needed when TEEs are used */
		0,
	}, {
		/* List terminator */
		0,
	}
};

struct mm_region *mem_map = imx93_mem_map;

static unsigned int imx9_find_dram_entry_in_mem_map(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(imx93_mem_map); i++)
		if (imx93_mem_map[i].phys == CFG_SYS_SDRAM_BASE)
			return i;

	hang();	/* Entry not found, this must never happen. */
}

void enable_caches(void)
{
	/* If OPTEE runs, remove OPTEE memory from MMU table to avoid speculative prefetch
	 * If OPTEE does not run, still update the MMU table according to dram banks structure
	 * to set correct dram size from board_phys_sdram_size
	 */
	int i = 0;
	/*
	 * please make sure that entry initial value matches
	 * imx93_mem_map for DRAM1
	 */
	int entry = imx9_find_dram_entry_in_mem_map();
	u64 attrs = imx93_mem_map[entry].attrs;

	while (i < CONFIG_NR_DRAM_BANKS &&
	       entry < ARRAY_SIZE(imx93_mem_map)) {
		if (gd->bd->bi_dram[i].start == 0)
			break;
		imx93_mem_map[entry].phys = gd->bd->bi_dram[i].start;
		imx93_mem_map[entry].virt = gd->bd->bi_dram[i].start;
		imx93_mem_map[entry].size = gd->bd->bi_dram[i].size;
		imx93_mem_map[entry].attrs = attrs;
		debug("Added memory mapping (%d): %llx %llx\n", entry,
		      imx93_mem_map[entry].phys, imx93_mem_map[entry].size);
		i++; entry++;
	}

	icache_enable();
	dcache_enable();
}

__weak int board_phys_sdram_size(phys_size_t *size)
{
	if (!size)
		return -EINVAL;

	*size = PHYS_SDRAM_SIZE;

#ifdef PHYS_SDRAM_2_SIZE
	*size += PHYS_SDRAM_2_SIZE;
#endif
	return 0;
}

int dram_init(void)
{
	phys_size_t sdram_size;
	int ret;

	ret = board_phys_sdram_size(&sdram_size);
	if (ret)
		return ret;

	/* rom_pointer[1] contains the size of TEE occupies */
	if (rom_pointer[1])
		gd->ram_size = sdram_size - rom_pointer[1];
	else
		gd->ram_size = sdram_size;

	return 0;
}

int dram_init_banksize(void)
{
	int bank = 0;
	int ret;
	phys_size_t sdram_size;
	phys_size_t sdram_b1_size, sdram_b2_size;

	ret = board_phys_sdram_size(&sdram_size);
	if (ret)
		return ret;

	/* Bank 1 can't cross over 4GB space */
	if (sdram_size > 0x80000000) {
		sdram_b1_size = 0x80000000;
		sdram_b2_size = sdram_size - 0x80000000;
	} else {
		sdram_b1_size = sdram_size;
		sdram_b2_size = 0;
	}

	gd->bd->bi_dram[bank].start = PHYS_SDRAM;
	if (rom_pointer[1]) {
		phys_addr_t optee_start = (phys_addr_t)rom_pointer[0];
		phys_size_t optee_size = (size_t)rom_pointer[1];

		gd->bd->bi_dram[bank].size = optee_start - gd->bd->bi_dram[bank].start;
		if ((optee_start + optee_size) < (PHYS_SDRAM + sdram_b1_size)) {
			if (++bank >= CONFIG_NR_DRAM_BANKS) {
				puts("CONFIG_NR_DRAM_BANKS is not enough\n");
				return -1;
			}

			gd->bd->bi_dram[bank].start = optee_start + optee_size;
			gd->bd->bi_dram[bank].size = PHYS_SDRAM +
				sdram_b1_size - gd->bd->bi_dram[bank].start;
		}
	} else {
		gd->bd->bi_dram[bank].size = sdram_b1_size;
	}

	if (sdram_b2_size) {
		if (++bank >= CONFIG_NR_DRAM_BANKS) {
			puts("CONFIG_NR_DRAM_BANKS is not enough for SDRAM_2\n");
			return -1;
		}
		gd->bd->bi_dram[bank].start = 0x100000000UL;
		gd->bd->bi_dram[bank].size = sdram_b2_size;
	}

	return 0;
}

phys_size_t get_effective_memsize(void)
{
	int ret;
	phys_size_t sdram_size;
	phys_size_t sdram_b1_size;

	ret = board_phys_sdram_size(&sdram_size);
	if (!ret) {
		/* Bank 1 can't cross over 4GB space */
		if (sdram_size > 0x80000000)
			sdram_b1_size = 0x80000000;
		else
			sdram_b1_size = sdram_size;

		if (rom_pointer[1]) {
			/* We will relocate u-boot to top of dram1. TEE position has two cases:
			 * 1. At the top of dram1,  Then return the size removed optee size.
			 * 2. In the middle of dram1, return the size of dram1.
			 */
			if ((rom_pointer[0] + rom_pointer[1]) == (PHYS_SDRAM + sdram_b1_size))
				return ((phys_addr_t)rom_pointer[0] - PHYS_SDRAM);
		}

		return sdram_b1_size;
	} else {
		return PHYS_SDRAM_SIZE;
	}
}

void imx_get_mac_from_fuse(int dev_id, unsigned char *mac)
{
	u32 val[2] = {};
	int ret;

	if (dev_id == 0) {
		ret = fuse_read(39, 3, &val[0]);
		if (ret)
			goto err;

		ret = fuse_read(39, 4, &val[1]);
		if (ret)
			goto err;

		mac[0] = val[1] >> 8;
		mac[1] = val[1];
		mac[2] = val[0] >> 24;
		mac[3] = val[0] >> 16;
		mac[4] = val[0] >> 8;
		mac[5] = val[0];

	} else {
		ret = fuse_read(39, 5, &val[0]);
		if (ret)
			goto err;

		ret = fuse_read(39, 4, &val[1]);
		if (ret)
			goto err;

		mac[0] = val[1] >> 24;
		mac[1] = val[1] >> 16;
		mac[2] = val[0] >> 24;
		mac[3] = val[0] >> 16;
		mac[4] = val[0] >> 8;
		mac[5] = val[0];
	}

	debug("%s: MAC%d: %02x.%02x.%02x.%02x.%02x.%02x\n",
	      __func__, dev_id, mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
	return;
err:
	memset(mac, 0, 6);
	printf("%s: fuse read err: %d\n", __func__, ret);
}

int print_cpuinfo(void)
{
	u32 cpurev;

	cpurev = get_cpu_rev();

	printf("CPU:   i.MX93 rev%d.%d\n", (cpurev & 0x000F0) >> 4, (cpurev & 0x0000F) >> 0);

	return 0;
}

int ft_system_setup(void *blob, struct bd_info *bd)
{
	return 0;
}

#if defined(CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG)
void get_board_serial(struct tag_serialnr *serialnr)
{
	printf("UID: 0x%x 0x%x 0x%x 0x%x\n",
	       gd->arch.uid[0], gd->arch.uid[1], gd->arch.uid[2], gd->arch.uid[3]);

	serialnr->low = gd->arch.uid[0];
	serialnr->high = gd->arch.uid[3];
}
#endif

static void save_reset_cause(void)
{
	struct src_general_regs *src = (struct src_general_regs *)SRC_GLOBAL_RBASE;
	u32 srsr = readl(&src->srsr);

	/* clear srsr in sec mode */
	writel(srsr, &src->srsr);

	/* Save value to GPR1 to pass to nonsecure */
	writel(srsr, &src->gpr[0]);
}

int arch_cpu_init(void)
{
	if (IS_ENABLED(CONFIG_SPL_BUILD)) {
		/* Disable wdog */
		init_wdog();

		clock_init();

		trdc_early_init();

		/* Save SRC SRSR to GPR1 and clear it */
		save_reset_cause();
	}

	return 0;
}

int imx9_probe_mu(void *ctx, struct event *event)
{
	struct udevice *devp;
	int node, ret;
	u32 res;
	struct sentinel_get_info_data info;

	node = fdt_node_offset_by_compatible(gd->fdt_blob, -1, "fsl,imx93-mu-s4");

	ret = uclass_get_device_by_of_offset(UCLASS_MISC, node, &devp);
	if (ret)
		return ret;

	if (gd->flags & GD_FLG_RELOC)
		return 0;

	ret = ahab_get_info(&info, &res);
	if (ret)
		return ret;

	set_cpu_info(&info);

	return 0;
}
EVENT_SPY(EVT_DM_POST_INIT_F, imx9_probe_mu);

int timer_init(void)
{
#ifdef CONFIG_SPL_BUILD
	struct sctr_regs *sctr = (struct sctr_regs *)SYSCNT_CTRL_BASE_ADDR;
	unsigned long freq = readl(&sctr->cntfid0);

	/* Update with accurate clock frequency */
	asm volatile("msr cntfrq_el0, %0" : : "r" (freq) : "memory");

	clrsetbits_le32(&sctr->cntcr, SC_CNTCR_FREQ0 | SC_CNTCR_FREQ1,
			SC_CNTCR_FREQ0 | SC_CNTCR_ENABLE | SC_CNTCR_HDBG);
#endif

	gd->arch.tbl = 0;
	gd->arch.tbu = 0;

	return 0;
}

enum env_location env_get_location(enum env_operation op, int prio)
{
	enum boot_device dev = get_boot_device();
	enum env_location env_loc = ENVL_UNKNOWN;

	if (prio)
		return env_loc;

	switch (dev) {
#if defined(CONFIG_ENV_IS_IN_SPI_FLASH)
	case QSPI_BOOT:
		env_loc = ENVL_SPI_FLASH;
		break;
#endif
#if defined(CONFIG_ENV_IS_IN_MMC)
	case SD1_BOOT:
	case SD2_BOOT:
	case SD3_BOOT:
	case MMC1_BOOT:
	case MMC2_BOOT:
	case MMC3_BOOT:
		env_loc =  ENVL_MMC;
		break;
#endif
	default:
#if defined(CONFIG_ENV_IS_NOWHERE)
		env_loc = ENVL_NOWHERE;
#endif
		break;
	}

	return env_loc;
}

static int mix_power_init(enum mix_power_domain pd)
{
	enum src_mix_slice_id mix_id;
	enum src_mem_slice_id mem_id;
	struct src_mix_slice_regs *mix_regs;
	struct src_mem_slice_regs *mem_regs;
	struct src_general_regs *global_regs;
	u32 scr, val;

	switch (pd) {
	case MIX_PD_MEDIAMIX:
		mix_id = SRC_MIX_MEDIA;
		mem_id = SRC_MEM_MEDIA;
		scr = BIT(5);

		/* Enable S400 handshake */
		struct blk_ctrl_s_aonmix_regs *s_regs =
			(struct blk_ctrl_s_aonmix_regs *)BLK_CTRL_S_ANOMIX_BASE_ADDR;

		setbits_le32(&s_regs->lp_handshake[0], BIT(13));
		break;
	case MIX_PD_MLMIX:
		mix_id = SRC_MIX_ML;
		mem_id = SRC_MEM_ML;
		scr = BIT(4);
		break;
	case MIX_PD_DDRMIX:
		mix_id = SRC_MIX_DDRMIX;
		mem_id = SRC_MEM_DDRMIX;
		scr = BIT(6);
		break;
	default:
		return -EINVAL;
	}

	mix_regs = (struct src_mix_slice_regs *)(ulong)(SRC_IPS_BASE_ADDR + 0x400 * (mix_id + 1));
	mem_regs =
		(struct src_mem_slice_regs *)(ulong)(SRC_IPS_BASE_ADDR + 0x3800 + 0x400 * mem_id);
	global_regs = (struct src_general_regs *)(ulong)SRC_GLOBAL_RBASE;

	/* Allow NS to set it */
	setbits_le32(&mix_regs->authen_ctrl, BIT(9));

	clrsetbits_le32(&mix_regs->psw_ack_ctrl[0], BIT(28), BIT(29));

	/* mix reset will be held until boot core write this bit to 1 */
	setbits_le32(&global_regs->scr, scr);

	/* Enable mem in Low power auto sequence */
	setbits_le32(&mem_regs->mem_ctrl, BIT(2));

	/* Set the power down state */
	val = readl(&mix_regs->func_stat);
	if (val & SRC_MIX_SLICE_FUNC_STAT_PSW_STAT) {
		/* The mix is default power off, power down it to make PDN_SFT bit
		 *  aligned with FUNC STAT
		 */
		setbits_le32(&mix_regs->slice_sw_ctrl, BIT(31));
		val = readl(&mix_regs->func_stat);

		/* Since PSW_STAT is 1, can't be used for power off status (SW_CTRL BIT31 set)) */
		/* Check the MEM STAT change to ensure SSAR is completed */
		while (!(val & SRC_MIX_SLICE_FUNC_STAT_MEM_STAT))
			val = readl(&mix_regs->func_stat);

		/* wait few ipg clock cycles to ensure FSM done and power off status is correct */
		/* About 5 cycles at 24Mhz, 1us is enough  */
		udelay(1);
	} else {
		/*  The mix is default power on, Do mix power cycle */
		setbits_le32(&mix_regs->slice_sw_ctrl, BIT(31));
		val = readl(&mix_regs->func_stat);
		while (!(val & SRC_MIX_SLICE_FUNC_STAT_PSW_STAT))
			val = readl(&mix_regs->func_stat);
	}

	/* power on */
	clrbits_le32(&mix_regs->slice_sw_ctrl, BIT(31));
	val = readl(&mix_regs->func_stat);
	while (val & SRC_MIX_SLICE_FUNC_STAT_ISO_STAT)
		val = readl(&mix_regs->func_stat);

	return 0;
}

void disable_isolation(void)
{
	struct src_general_regs *global_regs = (struct src_general_regs *)(ulong)SRC_GLOBAL_RBASE;
	/* clear isolation for usbphy, dsi, csi*/
	writel(0x0, &global_regs->sp_iso_ctrl);
}

void soc_power_init(void)
{
	mix_power_init(MIX_PD_MEDIAMIX);
	mix_power_init(MIX_PD_MLMIX);

	disable_isolation();
}

bool m33_is_rom_kicked(void)
{
	struct blk_ctrl_s_aonmix_regs *s_regs =
			(struct blk_ctrl_s_aonmix_regs *)BLK_CTRL_S_ANOMIX_BASE_ADDR;

	if (!(readl(&s_regs->m33_cfg) & BIT(2)))
		return true;

	return false;
}

int m33_prepare(void)
{
	struct src_mix_slice_regs *mix_regs =
		(struct src_mix_slice_regs *)(ulong)(SRC_IPS_BASE_ADDR + 0x400 * (SRC_MIX_CM33 + 1));
	struct src_general_regs *global_regs =
		(struct src_general_regs *)(ulong)SRC_GLOBAL_RBASE;
	struct blk_ctrl_s_aonmix_regs *s_regs =
			(struct blk_ctrl_s_aonmix_regs *)BLK_CTRL_S_ANOMIX_BASE_ADDR;
	u32 val;

	if (m33_is_rom_kicked())
		return -EPERM;

	/* Release reset of M33 */
	setbits_le32(&global_regs->scr, BIT(0));

	/* Check the reset released in M33 MIX func stat */
	val = readl(&mix_regs->func_stat);
	while (!(val & SRC_MIX_SLICE_FUNC_STAT_RST_STAT))
		val = readl(&mix_regs->func_stat);

	/* Release Sentinel TROUT */
	ahab_release_m33_trout();

	/* Mask WDOG1 IRQ from A55, we use it for M33 reset */
	setbits_le32(&s_regs->ca55_irq_mask[1], BIT(6));

	/* Turn on WDOG1 clock */
	ccm_lpcg_on(CCGR_WDG1, 1);

	/* Set sentinel LP handshake for M33 reset */
	setbits_le32(&s_regs->lp_handshake[0], BIT(6));

	/* Clear M33 TCM for ECC */
	memset((void *)(ulong)0x201e0000, 0, 0x40000);

	return 0;
}

int psci_sysreset_get_status(struct udevice *dev, char *buf, int size)
{
	static const char *reset_cause[] = {
		"POR ",
		"JTAG ",
		"IPP USER ",
		"WDOG1 ",
		"WDOG2 ",
		"WDOG3 ",
		"WDOG4 ",
		"WDOG5 ",
		"TEMPSENSE ",
		"CSU ",
		"JTAG_SW ",
		"M33_REQ ",
		"M33_LOCKUP ",
		"UNK ",
		"UNK ",
		"UNK "
	};

	struct src_general_regs *src = (struct src_general_regs *)SRC_GLOBAL_RBASE;
	u32 srsr;
	u32 i;
	int res;

	srsr = readl(&src->gpr[0]);

	for (i = ARRAY_SIZE(reset_cause); i > 0; i--) {
		if (srsr & (BIT(i - 1)))
			break;
	}

	res = snprintf(buf, size, "Reset Status: %s\n", i ? reset_cause[i - 1] : "unknown reset");
	if (res < 0) {
		dev_err(dev, "Could not write reset status message (err = %d)\n", res);
		return -EIO;
	}

	return 0;
}