soc/intel/apollolake: Disable XHCI LFPS power management

Provide the option to disable XHCI LFPS power management.
If the option is set in the devicetree, the bits[7:4] in
XHCI MMIO BAR + offset 0x80A4 (PMCTRL_REG) will be updated
from default 9 to 0.

BUG=b:146768983
BRANCH=None
TEST=build coreboot with DisableXhciLfpsPM being set to 1 and flash
     the image to the device. Run following command to check if
     bits[7:4] is set 0:
     >iotools mmio_read32 "XHCI MMIO BAR + 0x80A4"

Signed-off-by: Marx Wang <marx.wang@intel.com>
Change-Id: Ic603e3b919d8b443c6ede8bb5e46e2de07fcb856
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40255
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

2 files changed, 39 insertions, 0 deletions

diff --git a/src/soc/intel/apollolake/chip.c b/src/soc/intel/apollolake/chip.c
index 1075642517..c4e068d41f 100644
--- a/src/soc/intel/apollolake/chip.c
+++ b/src/soc/intel/apollolake/chip.c
@@ -99,6 +99,10 @@
 /* IOSF Gasket Backbone Local Clock Gating Enable */
 #define IOSFGBLCGE		(1 << 0)
 
+#define CFG_XHCPMCTRL		0x80a4
+/* BIT[7:4] LFPS periodic sampling for USB3 Ports */
+#define LFPS_PM_DISABLE_MASK    0xFFFFFF0F
+
 const char *soc_acpi_name(const struct device *dev)
 {
 	if (dev->path.type == DEVICE_PATH_DOMAIN)
@@ -829,6 +833,30 @@ static int check_xdci_enable(void)
 	return !!dev->enabled;
 }
 
+static void disable_xhci_lfps_pm(void)
+{
+	struct soc_intel_apollolake_config *cfg;
+
+	cfg = config_of_soc();
+
+	if (cfg->disable_xhci_lfps_pm) {
+		void *addr;
+		const struct resource *res;
+		uint32_t reg;
+		struct device *xhci_dev = PCH_DEV_XHCI;
+
+		res = find_resource(xhci_dev, PCI_BASE_ADDRESS_0);
+		addr = (void *)(uintptr_t)(res->base + CFG_XHCPMCTRL);
+		reg = read32(addr);
+		printk(BIOS_DEBUG, "XHCI PM: control reg=0x%x.\n", reg);
+		if (reg) {
+			reg &= LFPS_PM_DISABLE_MASK;
+			write32(addr, reg);
+			printk(BIOS_INFO, "XHCI PM: Disable xHCI LFPS as configured in devicetree.\n");
+		}
+	}
+}
+
 void platform_fsp_notify_status(enum fsp_notify_phase phase)
 {
 	if (phase == END_OF_FIRMWARE) {
@@ -876,6 +904,9 @@ void platform_fsp_notify_status(enum fsp_notify_phase phase)
 				IOSFGBLCGE;
 			write32(cfg, reg);
 		}
+
+		/* Disable XHCI LFPS power management if the option in dev tree is set. */
+		disable_xhci_lfps_pm();
 	}
 }
 
diff --git a/src/soc/intel/apollolake/chip.h b/src/soc/intel/apollolake/chip.h
index c7974a6cd5..ac36b702ab 100644
--- a/src/soc/intel/apollolake/chip.h
+++ b/src/soc/intel/apollolake/chip.h
@@ -184,6 +184,14 @@ struct soc_intel_apollolake_config {
 	 * the Upd parameter VtdEnable.
 	 */
 	uint8_t enable_vtd;
+
+	/* Options to disable the LFPS periodic sampling for USB3 Ports.
+	 * Default value of PMCTRL_REG bits[7:4] is 9 which means periodic sampling
+	 * interval is 9ms.
+	 * Set 1 to update XHCI host MMIO BAR + PMCTRL_REG (0x80A4 bits[7:4]) to 0
+	 * 0:Enable (default), 1:Disable.
+	 */
+	uint8_t disable_xhci_lfps_pm;
 };
 
 typedef struct soc_intel_apollolake_config config_t;