soc/amd/cezanne: Factor out common GPP clk req code

Factor out the `gpp_dxio_update_clk_req_config` function as it will be
useful for other AMD SoCs.

BUG=b:250009974
TEST=Ran on nipperkin device, verified clk req settings match enabled
devices

Change-Id: I9a4c72d8e980993c76a1b128f17b65b0db972a03
Signed-off-by: Robert Zieba <robertzieba@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68138
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

4 files changed, 121 insertions, 0 deletions

diff --git a/src/soc/amd/common/block/include/amdblocks/pci_clk_req.h b/src/soc/amd/common/block/include/amdblocks/pci_clk_req.h
new file mode 100644
index 0000000000..32dadf45b2
--- /dev/null
+++ b/src/soc/amd/common/block/include/amdblocks/pci_clk_req.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef AMD_BLOCK_PCI_GPP_H
+#define AMD_BLOCK_PCI_GPP_H
+
+#include <soc/platform_descriptors.h>
+
+enum gpp_clk_req {
+	GPP_CLK_ON,  /* GPP clock always on; default */
+	GPP_CLK_REQ, /* GPP clock controlled by corresponding #CLK_REQx pin */
+	GPP_CLK_OFF, /* GPP clk off */
+};
+
+void pcie_gpp_dxio_update_clk_req_config(enum gpp_clk_req *gpp_clk_config,
+					 size_t gpp_clk_config_num);
+
+#endif
diff --git a/src/soc/amd/common/block/pci/Kconfig b/src/soc/amd/common/block/pci/Kconfig
index 302a6b8497..1c21833bd2 100644
--- a/src/soc/amd/common/block/pci/Kconfig
+++ b/src/soc/amd/common/block/pci/Kconfig
@@ -16,3 +16,10 @@ config SOC_AMD_COMMON_BLOCK_PCIE_GPP_DRIVER
 	depends on SOC_AMD_COMMON_BLOCK_PCI
 	help
 	  Select this option to use AMD common PCIe GPP driver.
+
+config SOC_AMD_COMMON_BLOCK_PCIE_CLK_REQ
+	bool
+	depends on SOC_AMD_COMMON_BLOCK_PCIE_GPP_DRIVER
+	help
+	  This option includes code to disable PCIe clock request if the corresponding
+	  PCIe device is disabled.
diff --git a/src/soc/amd/common/block/pci/Makefile.inc b/src/soc/amd/common/block/pci/Makefile.inc
index e013777acc..03958c7543 100644
--- a/src/soc/amd/common/block/pci/Makefile.inc
+++ b/src/soc/amd/common/block/pci/Makefile.inc
@@ -4,6 +4,7 @@ ramstage-y += amd_pci_util.c
 ramstage-y += pci_routing_info.c
 ramstage-$(CONFIG_HAVE_ACPI_TABLES) += acpi_prt.c
 ramstage-$(CONFIG_SOC_AMD_COMMON_BLOCK_PCIE_GPP_DRIVER) += pcie_gpp.c
+ramstage-$(CONFIG_SOC_AMD_COMMON_BLOCK_PCIE_CLK_REQ) += pcie_clk_req.c
 
 endif # CONFIG_SOC_AMD_COMMON_BLOCK_PCI
 
diff --git a/src/soc/amd/common/block/pci/pcie_clk_req.c b/src/soc/amd/common/block/pci/pcie_clk_req.c
new file mode 100644
index 0000000000..881c650ed4
--- /dev/null
+++ b/src/soc/amd/common/block/pci/pcie_clk_req.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <amdblocks/pci_clk_req.h>
+#include <console/console.h>
+#include <device/device.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include <soc/platform_descriptors.h>
+
+/* Update gpp glk req config based on DXIO descriptors and enabled devices. */
+void pcie_gpp_dxio_update_clk_req_config(enum gpp_clk_req *gpp_clk_config,
+					 size_t gpp_clk_config_num)
+{
+	const fsp_dxio_descriptor *dxio_descs = NULL;
+	const fsp_ddi_descriptor *ddi_descs = NULL;
+	size_t dxio_num = 0;
+	size_t ddi_num = 0;
+
+	mainboard_get_dxio_ddi_descriptors(&dxio_descs, &dxio_num, &ddi_descs, &ddi_num);
+	if (dxio_descs == NULL) {
+		printk(BIOS_WARNING,
+		       "No DXIO descriptors found, GPP clk req may not reflect enabled devices\n");
+		return;
+	}
+
+	for (int i = 0; i < dxio_num; i++) {
+		const fsp_dxio_descriptor *dxio_desc = &dxio_descs[i];
+
+		/*  Only consider PCIe and unused engine types. */
+		if (dxio_desc->engine_type != PCIE_ENGINE
+		    && dxio_desc->engine_type != UNUSED_ENGINE)
+			continue;
+		enum cpm_clk_req dxio_clk_req = dxio_desc->clk_req;
+
+		/* CLK_DISABLE means there's no corresponding clk req line in use */
+		if (dxio_clk_req == CLK_DISABLE)
+			continue;
+
+		/*
+		 * dxio_clk_req is only 4 bits so having CLK_ENABLE as a value for
+		 * a descriptor should cause a compiler error. 0xF isn't a
+		 * valid clk_req value according to AMD's internal code either.
+		 * This is here to draw attention in case this code is ever used
+		 * in a situation where this has changed.
+		 */
+		if (dxio_clk_req == (CLK_ENABLE & 0xF)) {
+			printk(BIOS_WARNING,
+			       "CLK_ENABLE is an invalid clk_req value for PCIe device %d.%d, DXIO descriptor %d\n",
+			       dxio_desc->device_number, dxio_desc->function_number, i);
+			continue;
+		}
+
+		/* cpm_clk_req 0 is CLK_DISABLE */
+		int gpp_req_index = dxio_clk_req - CLK_REQ0;
+		/* Ensure that our index is valid */
+		if (gpp_req_index < 0 || gpp_req_index >= gpp_clk_config_num) {
+			printk(BIOS_ERR,
+			       "Failed to convert DXIO clk req value %d to GPP clk req index for PCIe device %d.%d, DXIO descriptor %d, clk req settings may be incorrect\n",
+			       dxio_clk_req, dxio_desc->device_number,
+			       dxio_desc->function_number, i);
+			continue;
+		}
+
+		const struct device *pci_device = pcidev_path_on_root(
+			PCI_DEVFN(dxio_desc->device_number, dxio_desc->function_number));
+		if (pci_device == NULL) {
+			gpp_clk_config[gpp_req_index] = GPP_CLK_OFF;
+			printk(BIOS_WARNING,
+			       "Cannot find PCIe device %d.%d, disabling GPP clk req %d, DXIO descriptor %d\n",
+			       dxio_desc->device_number, dxio_desc->function_number, i,
+			       gpp_req_index);
+			continue;
+		}
+
+		/* PCIe devices haven't been fully set up yet, so directly read the vendor id
+		 * and device id to determine if a device is physically present. If a device
+		 * is not present then the id should be 0xffffffff. 0x00000000, 0xffff0000,
+		 * and 0x0000ffff are there to account for any odd failure cases. */
+		u32 id = pci_read_config32(pci_device, PCI_VENDOR_ID);
+		bool enabled = pci_device->enabled && (id != 0xffffffff) && (id != 0x00000000)
+			       && (id != 0x0000ffff) && (id != 0xffff0000);
+
+		/* Inform of possible mismatches between devices and SoC gpp_clk_config. */
+		if (!enabled && gpp_clk_config[gpp_req_index] != GPP_CLK_OFF) {
+			gpp_clk_config[gpp_req_index] = GPP_CLK_OFF;
+			printk(BIOS_INFO,
+			       "PCIe device %d.%d disabled, disabling GPP clk req %d, DXIO descriptor %d\n",
+			       dxio_desc->device_number, dxio_desc->function_number,
+			       gpp_req_index, i);
+		} else if (enabled && gpp_clk_config[gpp_req_index] == GPP_CLK_OFF) {
+			printk(BIOS_INFO,
+			       "PCIe device %d.%d enabled, GPP clk req is off, DXIO descriptor %d\n",
+			       dxio_desc->device_number, dxio_desc->function_number, i);
+		}
+	}
+}