original_kernel/arch/x86/kernel/reboot_fixups_32.c

/*
 * This is a good place to put board specific reboot fixups.
 *
 * List of supported fixups:
 * geode-gx1/cs5530a - Jaya Kumar <jayalk@intworks.biz>
 * geode-gx/lx/cs5536 - Andres Salomon <dilinger@debian.org>
 *
 */

#include <asm/delay.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <asm/reboot_fixups.h>
#include <asm/msr.h>

static void cs5530a_warm_reset(struct pci_dev *dev)
{
	/* writing 1 to the reset control register, 0x44 causes the
	cs5530a to perform a system warm reset */
	pci_write_config_byte(dev, 0x44, 0x1);
	udelay(50); /* shouldn't get here but be safe and spin-a-while */
	return;
}

static void cs5536_warm_reset(struct pci_dev *dev)
{
	/*
	 * 6.6.2.12 Soft Reset (DIVIL_SOFT_RESET)
	 * writing 1 to the LSB of this MSR causes a hard reset.
	 */
	wrmsrl(0x51400017, 1ULL);
	udelay(50); /* shouldn't get here but be safe and spin a while */
}

struct device_fixup {
	unsigned int vendor;
	unsigned int device;
	void (*reboot_fixup)(struct pci_dev *);
};

static struct device_fixup fixups_table[] = {
{ PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY, cs5530a_warm_reset },
{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, cs5536_warm_reset },
};

/*
 * we see if any fixup is available for our current hardware. if there
 * is a fixup, we call it and we expect to never return from it. if we
 * do return, we keep looking and then eventually fall back to the
 * standard mach_reboot on return.
 */
void mach_reboot_fixups(void)
{
	struct device_fixup *cur;
	struct pci_dev *dev;
	int i;

	/* we can be called from sysrq-B code. In such a case it is
	 * prohibited to dig PCI */
	if (in_interrupt())
		return;

	for (i=0; i < ARRAY_SIZE(fixups_table); i++) {
		cur = &(fixups_table[i]);
		dev = pci_get_device(cur->vendor, cur->device, NULL);
		if (!dev)
			continue;

		cur->reboot_fixup(dev);
	}
}