skylake: Add support for eSPI SMI events

Add the necessary infrastructure to support eSPI SMI events,
and a mainboard handler to pass control to the EC.

BUG=chrome-os-partner:58666
TEST=tested on eve board with eSPI enabled, verified that lid
close event from the EC during firmware will result in an SMI
and shut down the system.

Change-Id: I6367e233e070a8fca053a7bdd2534c0578d15d12
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/17134
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/skylake/include/soc/pm.h

@@ -46,6 +46,7 @@
 #define SMI_EN			0x30
 #define  XHCI_SMI_EN		(1 << 31)
 #define  ME_SMI_EN		(1 << 30)
+#define  ESPI_SMI_EN		(1 << 28)
 #define  GPIO_UNLOCK_SMI_EN	(1 << 27)
 #define  INTEL_USB2_EN		(1 << 18)
 #define  LEGACY_USB2_EN		(1 << 17)

src/soc/intel/skylake/include/soc/smm.h

@@ -50,6 +50,8 @@ struct smm_relocation_params {
 /* Mainboard handler for GPI SMIs*/
 void mainboard_smi_gpi_handler(const struct gpi_status *sts);
 
+/* Mainboard handler for eSPI SMIs */
+void mainboard_smi_espi_handler(void);
 
 #if IS_ENABLED(CONFIG_HAVE_SMI_HANDLER)
 void smm_relocation_handler(int cpu, uintptr_t curr_smbase,

src/soc/intel/skylake/pmutil.c

@@ -177,7 +177,8 @@ static u32 print_smi_status(u32 smi_sts)
 		[20] = "PCI_EXP_SMI",
 		[21] = "MONITOR",
 		[26] = "SPI",
-		[27] = "GPIO_UNLOCK"
+		[27] = "GPIO_UNLOCK",
+		[28] = "ESPI_SMI",
 	};
 
 	if (!smi_sts)

src/soc/intel/skylake/smi.c

@@ -62,11 +62,12 @@ void southbridge_smm_enable_smi(void)
 	 *  - on APMC writes (io 0xb2)
 	 *  - on writes to SLP_EN (sleep states)
 	 *  - on writes to GBL_RLS (bios commands)
+	 *  - on eSPI events (does nothing on LPC systems)
 	 * No SMIs:
 	 *  - on microcontroller writes (io 0x62/0x66)
 	 *  - on TCO events
 	 */
-	enable_smi(APMC_EN | SLP_SMI_EN | GBL_SMI_EN | EOS);
+	enable_smi(APMC_EN | SLP_SMI_EN | GBL_SMI_EN | ESPI_SMI_EN | EOS);
 }
 
 void southbridge_trigger_smi(void)

src/soc/intel/skylake/smihandler.c

@@ -361,6 +361,12 @@ static void southbridge_smi_gpi(void)
 	gpi_clear_get_smi_status(&smi_sts);
 }
 
+void __attribute__((weak)) mainboard_smi_espi_handler(void) { }
+static void southbridge_smi_espi(void)
+{
+	mainboard_smi_espi_handler();
+}
+
 static void southbridge_smi_mc(void)
 {
 	u32 reg32 = inl(ACPI_BASE_ADDRESS + SMI_EN);
@@ -482,6 +488,7 @@ static smi_handler_t southbridge_smi[SMI_STS_BITS] = {
 	[PM1_STS_BIT] = southbridge_smi_pm1,
 	[GPE0_STS_BIT] = southbridge_smi_gpe0,
 	[GPIO_STS_BIT] = southbridge_smi_gpi,
+	[ESPI_SMI_STS_BIT] = southbridge_smi_espi,
 	[MCSMI_STS_BIT] = southbridge_smi_mc,
 	[TCO_STS_BIT] = southbridge_smi_tco,
 	[PERIODIC_STS_BIT] = southbridge_smi_periodic,