soc/intel/cmn/pmc: Perform PM register init for CSE

Before entering FSP-M, AP firmware must ensure the PM1_CNT register
reflects the correct sleep state if a global reset occurred.

This is crucial when Intel CSE has reset the system, as indicated by
the global reset bit and wake status register.

If PM1_CNT doesn't contain a valid sleep state after a CSE reset, AP
firmware must enforce an S5 exit path before handing control to FSP-M
for CSE initialization. This ensures proper system initialization and
avoids potential issues caused by an inconsistent sleep state.

Additionally, clears the PM1 status register (PM1_STS) after retrieving
the power state. This prevents stale status information from persisting
across power cycles, which could lead to confusion during subsequent
boots.

BUG=b:265939425
TEST=Verified that `prev_sleep_state` holds the correct value
(5 for S5) after CSE performs a global reset.

Fixes: Inconsistent sleep state after CSE reset.

Change-Id: Iae9c026da86fef4a3571e06b1bb20504c3d8c9be
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85025
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/src/soc/intel/common/block/pmc/pmclib.c b/src/soc/intel/common/block/pmc/pmclib.c
index 0b3863a0f0..c51a960854 100644
--- a/src/soc/intel/common/block/pmc/pmclib.c
+++ b/src/soc/intel/common/block/pmc/pmclib.c
@@ -430,6 +430,9 @@ static int pmc_prev_sleep_state(const struct chipset_power_state *ps)
 
 		/* Clear SLP_TYP. */
 		pmc_write_pm1_control(ps->pm1_cnt & ~(SLP_TYP));
+
+		/* Clear PM1_STATUS */
+		pmc_clear_pm1_status();
 	}
 
 	prev_sleep_state = soc_prev_sleep_state(ps, prev_sleep_state);
@@ -440,6 +443,34 @@ static int pmc_prev_sleep_state(const struct chipset_power_state *ps)
 	return prev_sleep_state;
 }
 
+static bool pmc_get_global_reset_sts_mmio(void)
+{
+	uint8_t *addr = pmc_mmio_regs();
+
+	return !!(read32p((uintptr_t)(addr + GEN_PMCON_A)) & GBL_RST_STS);
+}
+
+static bool pmc_get_global_reset_sts_pci(void)
+{
+#if defined(__SIMPLE_DEVICE__)
+	pci_devfn_t dev = PCI_DEV(0, PCI_SLOT(PCH_DEVFN_PMC), PCI_FUNC(PCH_DEVFN_PMC));
+#else
+	struct device *dev = pcidev_path_on_root(PCH_DEVFN_PMC);
+	if (!dev)
+		return false;
+#endif
+
+	return !!(pci_read_config32(dev, GEN_PMCON_A) & GBL_RST_STS);
+}
+
+static bool pmc_get_global_reset_sts(void)
+{
+	if (CONFIG(SOC_INTEL_MEM_MAPPED_PM_CONFIGURATION))
+		return pmc_get_global_reset_sts_mmio();
+	else
+		return pmc_get_global_reset_sts_pci();
+}
+
 void pmc_fill_pm_reg_info(struct chipset_power_state *ps)
 {
 	int i;
@@ -450,6 +481,21 @@ void pmc_fill_pm_reg_info(struct chipset_power_state *ps)
 	ps->pm1_en = inw(ACPI_BASE_ADDRESS + PM1_EN);
 	ps->pm1_cnt = pmc_read_pm1_control();
 
+	/*
+	 * Before system memory initialization, AP firmware should check the wake status
+	 * to determine if Intel CSE has reset the system and system sleep state (PM1_CNT)
+	 * holds a valid sleep entry?
+	 *
+	 * If not, then AP FW should force to take a S5 exit path (by programming the PM1_CNT)
+	 * register as per PM register initialization requirement for CSE.
+	 */
+	if (pmc_get_global_reset_sts() && (ps->pm1_sts & WAK_STS) && !(ps->pm1_cnt & SLP_TYP)) {
+		printk(BIOS_DEBUG, "Enforcing the S5 exit path\n");
+		uint32_t pm1_cnt_slp_type = SLP_TYP_S5 << SLP_TYP_SHIFT;
+		ps->pm1_cnt |= pm1_cnt_slp_type;
+		pmc_enable_pm1_control(pm1_cnt_slp_type);
+	}
+
 	printk(BIOS_DEBUG, "pm1_sts: %04x pm1_en: %04x pm1_cnt: %08x\n",
 	       ps->pm1_sts, ps->pm1_en, ps->pm1_cnt);