arch/arm/mach-omap1/reset.c

Source file repositories/reference/linux-study-clean/arch/arm/mach-omap1/reset.c

File Facts

System
Linux kernel
Corpus path
arch/arm/mach-omap1/reset.c
Extension
.c
Size
1700 bytes
Lines
64
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * OMAP1 reset support
 */
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/reboot.h>

#include "hardware.h"
#include "iomap.h"
#include "common.h"

/* ARM_SYSST bit shifts related to SoC reset sources */
#define ARM_SYSST_POR_SHIFT				5
#define ARM_SYSST_EXT_RST_SHIFT				4
#define ARM_SYSST_ARM_WDRST_SHIFT			2
#define ARM_SYSST_GLOB_SWRST_SHIFT			1

/* Standardized reset source bits (across all OMAP SoCs) */
#define OMAP_GLOBAL_COLD_RST_SRC_ID_SHIFT		0
#define OMAP_GLOBAL_WARM_RST_SRC_ID_SHIFT		1
#define OMAP_MPU_WD_RST_SRC_ID_SHIFT			3
#define OMAP_EXTWARM_RST_SRC_ID_SHIFT			5


void omap1_restart(enum reboot_mode mode, const char *cmd)
{
	/*
	 * Workaround for 5912/1611b bug mentioned in sprz209d.pdf p. 28
	 * "Global Software Reset Affects Traffic Controller Frequency".
	 */
	if (cpu_is_omap5912()) {
		omap_writew(omap_readw(DPLL_CTL) & ~(1 << 4), DPLL_CTL);
		omap_writew(0x8, ARM_RSTCT1);
	}

	omap_writew(1, ARM_RSTCT1);
}

/**
 * omap1_get_reset_sources - return the source of the SoC's last reset
 *
 * Returns bits that represent the last reset source for the SoC.  The
 * format is standardized across OMAPs for use by the OMAP watchdog.
 */
u32 omap1_get_reset_sources(void)
{
	u32 ret = 0;
	u16 rs;

	rs = __raw_readw(OMAP1_IO_ADDRESS(ARM_SYSST));

	if (rs & (1 << ARM_SYSST_POR_SHIFT))
		ret |= 1 << OMAP_GLOBAL_COLD_RST_SRC_ID_SHIFT;
	if (rs & (1 << ARM_SYSST_EXT_RST_SHIFT))
		ret |= 1 << OMAP_EXTWARM_RST_SRC_ID_SHIFT;
	if (rs & (1 << ARM_SYSST_ARM_WDRST_SHIFT))
		ret |= 1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT;
	if (rs & (1 << ARM_SYSST_GLOB_SWRST_SHIFT))
		ret |= 1 << OMAP_GLOBAL_WARM_RST_SRC_ID_SHIFT;

	return ret;
}

Annotation

Implementation Notes