Flash API: Enable Flash api on CM3DS

Implement flash_api.c for CM3DS on MPS2+.
Because MPS2+ board has no physical flash chip, the implementation emulates
flash over SRAM.

targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/flash_api.c

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2017-2018 ARM Limited
+ *
+ * Licensed under the Apache License Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "device.h"
+#include "flash_api.h"
+#include "memory_zones.h"
+
+/* CM3DS is deployed on MPS2 board with an FPGA image (AN511).
+ * It doesn't have physical flash memory,the implementation emulates
+ * flash over SRAM.
+ */
+#define FLASH_PAGE_SIZE   256
+#define FLASH_OFS_START   ZBT_SSRAM1_START
+#define FLASH_SECTOR_SIZE 0x1000
+#define FLASH_OFS_END     (FLASH_OFS_START + FLASH_SIZE)
+
+int32_t flash_init(flash_t *obj)
+{
+    (void)obj;
+
+    return 0;
+}
+
+int32_t flash_free(flash_t *obj)
+{
+    (void)obj;
+
+    return 0;
+}
+
+int32_t flash_erase_sector(flash_t *obj, uint32_t address)
+{
+    (void)obj;
+
+    memset((void *)address, 0xff, FLASH_SECTOR_SIZE);
+
+    return 0;
+}
+
+int32_t flash_read(flash_t *obj, uint32_t address,
+                   uint8_t *data, uint32_t size)
+{
+    (void)obj;
+
+    memcpy(data, (void *)address, size);
+
+    return 0;
+}
+
+int32_t flash_program_page(flash_t *obj, uint32_t address,
+                           const uint8_t *data, uint32_t size)
+{
+    (void)obj;
+
+    memcpy((void *)address, data, size);
+
+    return 0;
+}
+
+uint32_t flash_get_sector_size(const flash_t *obj, uint32_t address)
+{
+    (void)obj;
+
+    if (address < FLASH_OFS_START || address >= FLASH_OFS_END) {
+        return MBED_FLASH_INVALID_SIZE;
+    }
+
+    return FLASH_SECTOR_SIZE;
+}
+
+uint32_t flash_get_page_size(const flash_t *obj)
+{
+    (void)obj;
+
+    return FLASH_PAGE_SIZE;
+}
+
+uint32_t flash_get_start_address(const flash_t *obj)
+{
+    (void)obj;
+
+    return FLASH_OFS_START;
+}
+
+uint32_t flash_get_size(const flash_t *obj)
+{
+    (void)obj;
+
+    return FLASH_SIZE;
+}

targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/objects.h

@@ -70,6 +70,11 @@ struct analogin_s {
     uint16_t ctrl_register;  /* Control bits with the channel identifier */
 };
 
+/* This structure is not used by the HAL implementation. */
+struct flash_s {
+    uint8_t not_used;
+};
+
 /* This TRNG structure is not used by the HAL implementation. */
 struct trng_s {
     uint8_t not_used;

targets/targets.json

@@ -2802,7 +2802,7 @@
         "extra_labels": ["ARM_SSG", "CM3DS_MPS2"],
         "OUTPUT_EXT": "elf",
         "macros": ["CMSDK_CM3DS"],
-        "device_has": ["ANALOGIN", "ETHERNET", "I2C", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "SERIAL", "SPI", "TRNG"],
+        "device_has": ["ANALOGIN", "ETHERNET", "I2C", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "SERIAL", "SPI", "TRNG", "FLASH"],
         "release_versions": ["2", "5"],
         "copy_method": "mps2",
         "reset_method": "reboot.txt"