feat(plat/st): implement platform functions for SMCCC_ARCH_SOC_ID

The JEDEC information for STMicroelectronics is:
JEDEC_ST_MFID U(0x20)
JEDEC_ST_BKID U(0x0)
And rely on platform functions to get chip IP and revision.
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: I4fa4ac8bb5583b1871b768decc9fe08e8966ff54

plat/st/common/include/stm32mp_common.h

@@ -11,6 +11,9 @@
 
 #include <platform_def.h>
 
+#define JEDEC_ST_BKID U(0x0)
+#define JEDEC_ST_MFID U(0x20)
+
 /* Functions to save and get boot context address given by ROM code */
 void stm32mp_save_boot_ctx_address(uintptr_t address);
 uintptr_t stm32mp_get_boot_ctx_address(void);

plat/st/common/stm32mp_common.c

 /*
- * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -12,8 +12,10 @@
 #include <arch_helpers.h>
 #include <common/debug.h>
 #include <drivers/st/stm32mp_clkfunc.h>
+#include <lib/smccc.h>
 #include <lib/xlat_tables/xlat_tables_v2.h>
 #include <plat/common/platform.h>
+#include <services/arm_arch_svc.h>
 
 uintptr_t plat_get_ns_image_entrypoint(void)
 {
@@ -111,3 +113,36 @@ int stm32mp_unmap_ddr(void)
 	return  mmap_remove_dynamic_region(STM32MP_DDR_BASE,
 					   STM32MP_DDR_MAX_SIZE);
 }
+
+/*****************************************************************************
+ * plat_is_smccc_feature_available() - This function checks whether SMCCC
+ *                                     feature is availabile for platform.
+ * @fid: SMCCC function id
+ *
+ * Return SMC_ARCH_CALL_SUCCESS if SMCCC feature is available and
+ * SMC_ARCH_CALL_NOT_SUPPORTED otherwise.
+ *****************************************************************************/
+int32_t plat_is_smccc_feature_available(u_register_t fid)
+{
+	switch (fid) {
+	case SMCCC_ARCH_SOC_ID:
+		return SMC_ARCH_CALL_SUCCESS;
+	default:
+		return SMC_ARCH_CALL_NOT_SUPPORTED;
+	}
+}
+
+/* Get SOC version */
+int32_t plat_get_soc_version(void)
+{
+	uint32_t chip_id = stm32mp_get_chip_dev_id();
+	uint32_t manfid = SOC_ID_SET_JEP_106(JEDEC_ST_BKID, JEDEC_ST_MFID);
+
+	return (int32_t)(manfid | (chip_id & SOC_ID_IMPL_DEF_MASK));
+}
+
+/* Get SOC revision */
+int32_t plat_get_soc_revision(void)
+{
+	return (int32_t)(stm32mp_get_chip_version() & SOC_ID_REV_MASK);
+}