SMCCC/PCI: Handle std svc boilerplate

Add SMC wrappers for handshaking the existence
and basic parameter validation for the SMCCC/PCI
API. The actual read/write/segment validation is
implemented by a given platform which will enable
the API by defining SMC_PCI_SUPPORT.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Change-Id: I4485ad0fe6003cec6f5eedef688914d100513c21

bl31/bl31.mk

@@ -95,6 +95,10 @@ BL31_SOURCES		+=	lib/cpus/aarch64/wa_cve_2017_5715_bpiall.S	\
 				lib/cpus/aarch64/wa_cve_2017_5715_mmu.S
 endif
 
+ifeq ($(SMC_PCI_SUPPORT),1)
+BL31_SOURCES		+=	services/std_svc/pci_svc.c
+endif
+
 BL31_LINKERFILE		:=	bl31/bl31.ld.S
 
 # Flag used to indicate if Crash reporting via console should be included

services/std_svc/pci_svc.c

@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include <common/debug.h>
+#include <common/runtime_svc.h>
+#include <services/pci_svc.h>
+#include <services/std_svc.h>
+#include <smccc_helpers.h>
+
+static uint64_t validate_rw_addr_sz(uint32_t addr, uint64_t off, uint64_t sz)
+{
+	uint32_t nseg;
+	uint32_t ret;
+	uint32_t start_end_bus;
+
+	ret = pci_get_bus_for_seg(PCI_ADDR_SEG(addr), &start_end_bus, &nseg);
+
+	if (ret != SMC_PCI_CALL_SUCCESS) {
+		return SMC_PCI_CALL_INVAL_PARAM;
+	}
+	switch (sz) {
+	case SMC_PCI_SZ_8BIT:
+	case SMC_PCI_SZ_16BIT:
+	case SMC_PCI_SZ_32BIT:
+		break;
+	default:
+		return SMC_PCI_CALL_INVAL_PARAM;
+	}
+	if ((off + sz) > (PCI_OFFSET_MASK + 1U)) {
+		return SMC_PCI_CALL_INVAL_PARAM;
+	}
+	return SMC_PCI_CALL_SUCCESS;
+}
+
+uint64_t pci_smc_handler(uint32_t smc_fid,
+			     u_register_t x1,
+			     u_register_t x2,
+			     u_register_t x3,
+			     u_register_t x4,
+			     void *cookie,
+			     void *handle,
+			     u_register_t flags)
+{
+	switch (smc_fid) {
+	case SMC_PCI_VERSION: {
+		pcie_version ver;
+
+		ver.major = 1U;
+		ver.minor = 0U;
+		SMC_RET4(handle, ver.val, 0U, 0U, 0U);
+	}
+	case SMC_PCI_FEATURES:
+		switch (x1) {
+		case SMC_PCI_VERSION:
+		case SMC_PCI_FEATURES:
+		case SMC_PCI_READ:
+		case SMC_PCI_WRITE:
+		case SMC_PCI_SEG_INFO:
+			SMC_RET1(handle, SMC_PCI_CALL_SUCCESS);
+		default:
+			SMC_RET1(handle, SMC_PCI_CALL_NOT_SUPPORTED);
+		}
+		break;
+	case SMC_PCI_READ: {
+		uint32_t ret;
+
+		if (validate_rw_addr_sz(x1, x2, x3) != SMC_PCI_CALL_SUCCESS) {
+			SMC_RET2(handle, SMC_PCI_CALL_INVAL_PARAM, 0U);
+		}
+		if (x4 != 0U) {
+			SMC_RET2(handle, SMC_PCI_CALL_INVAL_PARAM, 0U);
+		}
+		if (pci_read_config(x1, x2, x3, &ret) != 0U) {
+			SMC_RET2(handle, SMC_PCI_CALL_INVAL_PARAM, 0U);
+		} else {
+			SMC_RET2(handle, SMC_PCI_CALL_SUCCESS, ret);
+		}
+		break;
+	}
+	case SMC_PCI_WRITE: {
+		uint32_t ret;
+
+		if (validate_rw_addr_sz(x1, x2, x3) != SMC_PCI_CALL_SUCCESS) {
+			SMC_RET1(handle, SMC_PCI_CALL_INVAL_PARAM);
+		}
+		ret = pci_write_config(x1, x2, x3, x4);
+		SMC_RET1(handle, ret);
+		break;
+	}
+	case SMC_PCI_SEG_INFO: {
+		uint32_t nseg;
+		uint32_t ret;
+		uint32_t start_end_bus;
+
+		if ((x2 != 0U) || (x3 != 0U) || (x4 != 0U)) {
+		    SMC_RET3(handle, SMC_PCI_CALL_INVAL_PARAM, 0U, 0U);
+		}
+		ret = pci_get_bus_for_seg(x1, &start_end_bus, &nseg);
+		SMC_RET3(handle, ret, start_end_bus, nseg);
+		break;
+	}
+	default:
+		/* should be unreachable */
+		WARN("Unimplemented PCI Service Call: 0x%x\n", smc_fid);
+		SMC_RET1(handle, SMC_PCI_CALL_NOT_SUPPORTED);
+	}
+}

services/std_svc/std_svc_setup.c

@@ -13,6 +13,7 @@
 #include <lib/pmf/pmf.h>
 #include <lib/psci/psci.h>
 #include <lib/runtime_instr.h>
+#include <services/pci_svc.h>
 #include <services/sdei.h>
 #include <services/spm_mm_svc.h>
 #include <services/spmd_svc.h>
@@ -158,6 +159,13 @@ static uintptr_t std_svc_smc_handler(uint32_t smc_fid,
 	}
 #endif
 
+#if SMC_PCI_SUPPORT
+	if (is_pci_fid(smc_fid)) {
+		return pci_smc_handler(smc_fid, x1, x2, x3, x4, cookie, handle,
+				       flags);
+	}
+#endif
+
 	switch (smc_fid) {
 	case ARM_STD_SVC_CALL_COUNT:
 		/*