soc/intel/alderlake: Factor out A0 stepping workaround

Move the `configure_pmc_descriptor()` function to SoC scope instead of
having two identical copies in mainboard scope. Add a Kconfig option to
allow mainboards to decide whether to implement this workaround.

Change-Id: Ib99073d8da91a93fae9c0cebdfd73e39456cdaa8
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60940
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sheng Lean Tan <sheng.tan@9elements.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

5 files changed, 104 insertions, 0 deletions

diff --git a/src/soc/intel/alderlake/Kconfig b/src/soc/intel/alderlake/Kconfig
index 50c0c0b3e5..74c14a5ef6 100644
--- a/src/soc/intel/alderlake/Kconfig
+++ b/src/soc/intel/alderlake/Kconfig
@@ -102,6 +102,15 @@ config CPU_SPECIFIC_OPTIONS
 	select UDK_202005_BINDING
 	select DISPLAY_FSP_VERSION_INFO
 
+config ALDERLAKE_A0_CONFIGURE_PMC_DESCRIPTOR
+	bool
+	help
+	  Alder Lake stepping A0 needs a different value for a PMC setting in
+	  the IFD. When this option is selected, coreboot will update the IFD
+	  value at runtime, which allows using an IFD with the new value with
+	  any CPU stepping. To apply this workaround, the IFD region needs to
+	  be writable by the host.
+
 config ALDERLAKE_CAR_ENHANCED_NEM
 	bool
 	default y if !INTEL_CAR_NEM
diff --git a/src/soc/intel/alderlake/Makefile.inc b/src/soc/intel/alderlake/Makefile.inc
index d2c48b74c8..095d2100f2 100644
--- a/src/soc/intel/alderlake/Makefile.inc
+++ b/src/soc/intel/alderlake/Makefile.inc
@@ -16,6 +16,7 @@ bootblock-y += bootblock/report_platform.c
 bootblock-y += espi.c
 bootblock-y += gpio.c
 bootblock-y += p2sb.c
+bootblock-$(CONFIG_ALDERLAKE_A0_CONFIGURE_PMC_DESCRIPTOR) += bootblock/pmc_descriptor.c
 
 romstage-y += espi.c
 romstage-y += gpio.c
diff --git a/src/soc/intel/alderlake/bootblock/bootblock.c b/src/soc/intel/alderlake/bootblock/bootblock.c
index b8086a42ab..e209ae24d7 100644
--- a/src/soc/intel/alderlake/bootblock/bootblock.c
+++ b/src/soc/intel/alderlake/bootblock/bootblock.c
@@ -25,6 +25,9 @@ void bootblock_soc_early_init(void)
 
 void bootblock_soc_init(void)
 {
+	if (CONFIG(ALDERLAKE_A0_CONFIGURE_PMC_DESCRIPTOR))
+		configure_pmc_descriptor();
+
 	report_platform_info();
 	bootblock_pch_init();
 
diff --git a/src/soc/intel/alderlake/bootblock/pmc_descriptor.c b/src/soc/intel/alderlake/bootblock/pmc_descriptor.c
new file mode 100644
index 0000000000..4e8095750a
--- /dev/null
+++ b/src/soc/intel/alderlake/bootblock/pmc_descriptor.c
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <arch/cpu.h>
+#include <arch/mmio.h>
+#include <cf9_reset.h>
+#include <commonlib/region.h>
+#include <console/console.h>
+#include <cpu/intel/cpu_ids.h>
+#include <fmap.h>
+#include <intelblocks/pmclib.h>
+#include <soc/bootblock.h>
+#include <types.h>
+
+#define SI_DESC_REGION		"SI_DESC"
+#define SI_DESC_REGION_SZ	4096
+#define PMC_DESC_7_BYTE3	0xc32
+
+/* Flash Master 1 : HOST/BIOS */
+#define FLMSTR1			0x80
+
+/* Flash signature Offset */
+#define FLASH_SIGN_OFFSET	0x10
+#define FLMSTR_WR_SHIFT_V2	20
+#define FLASH_VAL_SIGN		0xFF0A55A
+
+/* It checks whether host(Flash Master 1) has write access to the Descriptor Region or not */
+static int is_descriptor_writeable(uint8_t *desc)
+{
+	/* Check flash has valid signature */
+	if (read32((void *)(desc + FLASH_SIGN_OFFSET)) != FLASH_VAL_SIGN) {
+		printk(BIOS_DEBUG, "Flash Descriptor is not valid\n");
+		return 0;
+	}
+
+	/* Check host has write access to the Descriptor Region */
+	if (!((read32((void *)(desc + FLMSTR1)) >> FLMSTR_WR_SHIFT_V2) & BIT(0))) {
+		printk(BIOS_DEBUG, "Host doesn't have write access to Descriptor Region\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+/* It updates PMC Descriptor in the Descriptor Region */
+void configure_pmc_descriptor(void)
+{
+	uint8_t si_desc_buf[SI_DESC_REGION_SZ];
+	struct region_device desc_rdev;
+
+	if (cpu_get_cpuid() != CPUID_ALDERLAKE_A0)
+		return;
+
+	if (fmap_locate_area_as_rdev_rw(SI_DESC_REGION, &desc_rdev) < 0) {
+		printk(BIOS_ERR, "Failed to locate %s in the FMAP\n", SI_DESC_REGION);
+		return;
+	}
+
+	if (rdev_readat(&desc_rdev, si_desc_buf, 0, SI_DESC_REGION_SZ) != SI_DESC_REGION_SZ) {
+		printk(BIOS_ERR, "Failed to read Descriptor Region from SPI Flash\n");
+		return;
+	}
+
+	if (!is_descriptor_writeable(si_desc_buf))
+		return;
+
+	if (si_desc_buf[PMC_DESC_7_BYTE3] != 0x40) {
+		printk(BIOS_DEBUG, "Update of PMC Descriptor is not required!\n");
+		return;
+	}
+
+	si_desc_buf[PMC_DESC_7_BYTE3] = 0x44;
+
+	if (rdev_eraseat(&desc_rdev, 0, SI_DESC_REGION_SZ) != SI_DESC_REGION_SZ) {
+		printk(BIOS_ERR, "Failed to erase Descriptor Region area\n");
+		return;
+	}
+
+	if (rdev_writeat(&desc_rdev, si_desc_buf, 0, SI_DESC_REGION_SZ)
+			!= SI_DESC_REGION_SZ) {
+		printk(BIOS_ERR, "Failed to update Descriptor Region\n");
+		return;
+	}
+
+	printk(BIOS_DEBUG, "Update of PMC Descriptor successful, trigger GLOBAL RESET\n");
+
+	pmc_global_reset_enable(true);
+	do_full_reset();
+	die("Failed to trigger GLOBAL RESET\n");
+}
diff --git a/src/soc/intel/alderlake/include/soc/bootblock.h b/src/soc/intel/alderlake/include/soc/bootblock.h
index ce2e42e6b2..e989bdd865 100644
--- a/src/soc/intel/alderlake/include/soc/bootblock.h
+++ b/src/soc/intel/alderlake/include/soc/bootblock.h
@@ -17,4 +17,6 @@ void bootblock_pch_init(void);
 void pch_early_iorange_init(void);
 void report_platform_info(void);
 
+void configure_pmc_descriptor(void);
+
 #endif