x86: sysreset: Implement power-off if available

On modern x86 devices we can power the system off using the power-
management features of the PCH. Add an implementation for this.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

drivers/sysreset/sysreset_x86.c

@@ -7,14 +7,75 @@
 
 #include <common.h>
 #include <dm.h>
+#include <efi_loader.h>
+#include <pch.h>
 #include <sysreset.h>
+#include <asm/acpi_s3.h>
 #include <asm/io.h>
 #include <asm/processor.h>
-#include <efi_loader.h>
+
+struct x86_sysreset_platdata {
+	struct udevice *pch;
+};
+
+/*
+ * Power down the machine by using the power management sleep control
+ * of the chipset. This will currently only work on Intel chipsets.
+ * However, adapting it to new chipsets is fairly simple. You will
+ * have to find the IO address of the power management register block
+ * in your southbridge, and look up the appropriate SLP_TYP_S5 value
+ * from your southbridge's data sheet.
+ *
+ * This function never returns.
+ */
+int pch_sysreset_power_off(struct udevice *dev)
+{
+	struct x86_sysreset_platdata *plat = dev_get_platdata(dev);
+	struct pch_pmbase_info pm;
+	u32 reg32;
+	int ret;
+
+	if (!plat->pch)
+		return -ENOENT;
+	ret = pch_ioctl(plat->pch, PCH_REQ_PMBASE_INFO, &pm, sizeof(pm));
+	if (ret)
+		return ret;
+
+	/*
+	 * Mask interrupts or system might stay in a coma, not executing code
+	 * anymore, but not powered off either.
+	 */
+	asm("cli");
+
+	/*
+	 * Avoid any GPI waking the system from S5* or the system might stay in
+	 * a coma
+	 */
+	outl(0x00000000, pm.base + pm.gpio0_en_ofs);
+
+	/* Clear Power Button Status */
+	outw(PWRBTN_STS, pm.base + pm.pm1_sts_ofs);
+
+	/* PMBASE + 4, Bit 10-12, Sleeping Type, * set to 111 -> S5, soft_off */
+	reg32 = inl(pm.base + pm.pm1_cnt_ofs);
+
+	/* Set Sleeping Type to S5 (poweroff) */
+	reg32 &= ~(SLP_EN | SLP_TYP);
+	reg32 |= SLP_TYP_S5;
+	outl(reg32, pm.base + pm.pm1_cnt_ofs);
+
+	/* Now set the Sleep Enable bit */
+	reg32 |= SLP_EN;
+	outl(reg32, pm.base + pm.pm1_cnt_ofs);
+
+	for (;;)
+		asm("hlt");
+}
 
 static int x86_sysreset_request(struct udevice *dev, enum sysreset_t type)
 {
 	int value;
+	int ret;
 
 	switch (type) {
 	case SYSRESET_WARM:
@@ -23,6 +84,11 @@ static int x86_sysreset_request(struct udevice *dev, enum sysreset_t type)
 	case SYSRESET_COLD:
 		value = SYS_RST | RST_CPU | FULL_RST;
 		break;
+	case SYSRESET_POWER_OFF:
+		ret = pch_sysreset_power_off(dev);
+		if (ret)
+			return ret;
+		return -EINPROGRESS;
 	default:
 		return -ENOSYS;
 	}
@@ -57,6 +123,15 @@ void __efi_runtime EFIAPI efi_reset_system(
 }
 #endif
 
+static int x86_sysreset_probe(struct udevice *dev)
+{
+	struct x86_sysreset_platdata *plat = dev_get_platdata(dev);
+
+	/* Locate the PCH if there is one. It isn't essential */
+	uclass_first_device(UCLASS_PCH, &plat->pch);
+
+	return 0;
+}
 
 static const struct udevice_id x86_sysreset_ids[] = {
 	{ .compatible = "x86,reset" },
@@ -72,4 +147,6 @@ U_BOOT_DRIVER(x86_sysreset) = {
 	.id = UCLASS_SYSRESET,
 	.of_match = x86_sysreset_ids,
 	.ops = &x86_sysreset_ops,
+	.probe = x86_sysreset_probe,
+	.platdata_auto_alloc_size	= sizeof(struct x86_sysreset_platdata),
 };