ELOG: Support GSMI in CPT/PPT southbridge SMI handler

In order to support the GSMI interface the SMI handler needs
to find and use the state save area from the same CPU that
initiated the SMI.  In this case it is a synchronous SMI
resulting form an IO write to port 0xB2.

To find the right CPU state save area iterate over the region
until the "IO Misc Info" field reports the expected value and
then proceed to use that state save area.

This is needed because the coreboot SMI handler only executes on
one core, and that core is non-deterministic.  It is likely that
the core executing the C SMM handler is not the same one that
actually did the IO write to 0xB2 and generated the SMI.

The GSMI parameter buffer is passed as a pointer to EBX in the
tate save area, and the GSMI command is extracted from EAX before
it is used as the return value.

This interface is tested by enabling CONFIG_GOOGLE_GSMI in the
kernel and generating events and verifying that they end up
in the event log.

159 | 2012-06-23 16:22:45 | Kernl Event | Clean Shutdown
184 | 2012-06-23 17:14:05 | Kernl Event | Oops
185 | 2012-06-23 17:14:05 | Kernl Event | Panic

Change-Id: Ic121ea69e9f50c88467c435e095c3e3629989806
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1317
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/southbridge/intel/bd82x6x/smihandler.c

@@ -28,6 +28,7 @@
 #include <cpu/x86/smm.h>
 #include <device/pci_def.h>
 #include <cpu/x86/smm.h>
+#include <elog.h>
 #include "pch.h"
 
 #include "nvs.h"
@@ -405,6 +406,53 @@ static void southbridge_smi_sleep(unsigned int node, smm_state_save_area_t *stat
 	}
 }
 
+#if CONFIG_ELOG_GSMI
+static void southbridge_smi_gsmi(void)
+{
+	em64t101_smm_state_save_area_t *io_smi;
+	u32 base = smi_get_tseg_base() + 0x8000;
+	u32 *ret, *param;
+	u8 sub_command, node;
+
+	/*
+	 * Check for Synchronous IO SMI and use save state from that
+	 * core in case we are not running on the same core that
+	 * initiated the IO transaction.
+	 */
+	for (node = 0; node < CONFIG_MAX_CPUS; node++) {
+		/*
+		 * Look for IO Misc Info:
+		 *  Synchronous bit[0]=1
+		 *  Byte bit[3:1]=1
+		 *  Output bit[7:4]=0
+		 *  APMC port bit[31:16]=0xb2
+		 * RAX[7:0] == 0xEF
+		 */
+		u32 io_want_info = (APM_CNT << 16) | 0x3;
+		io_smi = (em64t101_smm_state_save_area_t *)
+			(base + 0x7d00 - (node * 0x400));
+
+		if (io_smi->io_misc_info == io_want_info &&
+		    ((u8)io_smi->rax == ELOG_GSMI_APM_CNT))
+			break;
+	}
+
+	/* Did not find matching CPU Save State */
+	if (node == CONFIG_MAX_CPUS)
+		return;
+
+	/* Command and return value in EAX */
+	ret = (u32*)&io_smi->rax;
+	sub_command = (u8)(*ret >> 8);
+
+	/* Parameter buffer in EBX */
+	param = (u32*)&io_smi->rbx;
+
+	/* drivers/elog/gsmi.c */
+	*ret = gsmi_exec(sub_command, param);
+}
+#endif
+
 static void southbridge_smi_apmc(unsigned int node, smm_state_save_area_t *state_save)
 {
 	u32 pmctrl;
@@ -452,6 +500,11 @@ static void southbridge_smi_apmc(unsigned int node, smm_state_save_area_t *state
 		smm_initialized = 1;
 		printk(BIOS_DEBUG, "SMI#: Setting up structures to %p, %p, %p\n", gnvs, tcg, smi1);
 		break;
+#if CONFIG_ELOG_GSMI
+	case ELOG_GSMI_APM_CNT:
+		southbridge_smi_gsmi();
+		break;
+#endif
 	}
 
 	tseg_relocate((void **)&mainboard_apmc);