arch/mips/bcm47xx/time.c

Source file repositories/reference/linux-study-clean/arch/mips/bcm47xx/time.c

File Facts

System
Linux kernel
Corpus path
arch/mips/bcm47xx/time.c
Extension
.c
Size
2527 bytes
Lines
82
Domain
Architecture Layer
Bucket
arch/mips
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

#include <linux/init.h>
#include <linux/ssb/ssb.h>
#include <asm/time.h>
#include <bcm47xx.h>
#include <bcm47xx_board.h>

void __init plat_time_init(void)
{
	unsigned long hz = 0;
	u16 chip_id = 0;
	char buf[10];
	int len;
	enum bcm47xx_board board = bcm47xx_board_get();

	/*
	 * Use deterministic values for initial counter interrupt
	 * so that calibrate delay avoids encountering a counter wrap.
	 */
	write_c0_count(0);
	write_c0_compare(0xffff);

	switch (bcm47xx_bus_type) {
#ifdef CONFIG_BCM47XX_SSB
	case BCM47XX_BUS_TYPE_SSB:
		hz = ssb_cpu_clock(&bcm47xx_bus.ssb.mipscore) / 2;
		chip_id = bcm47xx_bus.ssb.chip_id;
		break;
#endif
#ifdef CONFIG_BCM47XX_BCMA
	case BCM47XX_BUS_TYPE_BCMA:
		hz = bcma_cpu_clock(&bcm47xx_bus.bcma.bus.drv_mips) / 2;
		chip_id = bcm47xx_bus.bcma.bus.chipinfo.id;
		break;
#endif
	}

	if (chip_id == 0x5354) {
		len = bcm47xx_nvram_getenv("clkfreq", buf, sizeof(buf));
		if (len >= 0 && !strncmp(buf, "200", 4))
			hz = 100000000;
	}

	switch (board) {
	case BCM47XX_BOARD_ASUS_WL520GC:
	case BCM47XX_BOARD_ASUS_WL520GU:
		hz = 100000000;
		break;
	default:
		break;
	}

	if (!hz)
		hz = 100000000;

	/* Set MIPS counter frequency for fixed_rate_gettimeoffset() */
	mips_hpt_frequency = hz;
}

Annotation

Implementation Notes