Update RP2040 target to use flash memory bank (#392)

* Add RPi Pico flash bank

* Start on linker script changes

* Finish linker script

* Fix license

* It's nice to be on the right side of history

Author: Jamie Smith

targets/TARGET_RASPBERRYPI/TARGET_RP2040/TOOLCHAIN_GCC_ARM/memmap_default_mbed.ld

@@ -22,8 +22,6 @@
     __stack (== StackTop)
 */
 
-#include "../cmsis_nvic.h"
-
 #if !defined(MBED_CONF_TARGET_BOOT_STACK_SIZE)
     /* This value is normally defined by the tools
        to 0x1000 for bare metal and 0x400 for RTOS */
@@ -32,15 +30,24 @@
 
 MEMORY
 {
-    FLASH(rx) : ORIGIN = MBED_ROM_START, LENGTH = MBED_ROM_SIZE
-    RAM(rwx) : ORIGIN =  MBED_RAM_START, LENGTH = MBED_RAM_SIZE
+    FLASH(rx) : ORIGIN = MBED_CONFIGURED_ROM_BANK_QSPI_FLASH_START, LENGTH = MBED_CONFIGURED_ROM_BANK_QSPI_FLASH_SIZE
+    RAM(rwx) : ORIGIN =  MBED_CONFIGURED_RAM_BANK_IRAM1_START, LENGTH = MBED_CONFIGURED_RAM_BANK_IRAM1_SIZE
 
     /*
      * Scratch banks are commonly used for critical data and functions accessed only by one core (when only
      * one core is accessing the RAM bank, there is no opportunity for stalls).
      */
-    SCRATCH_X(rwx) : ORIGIN = 0x20040000, LENGTH = 4k
-    SCRATCH_Y(rwx) : ORIGIN = 0x20041000, LENGTH = 4k
+    SCRATCH_X(rwx) : ORIGIN = MBED_RAM_BANK_SCRATCH_X_START, LENGTH = MBED_RAM_BANK_SCRATCH_X_SIZE
+    SCRATCH_Y(rwx) : ORIGIN = MBED_RAM_BANK_SCRATCH_Y_START, LENGTH = MBED_RAM_BANK_SCRATCH_Y_SIZE
+
+/* If we are at the start of RAM, we are core 0.  Otherwise we are core 1. */
+#if MBED_CONFIGURED_RAM_BANK_IRAM1_START == MBED_RAM_BANK_IRAM1_START
+#define STACK_SCRATCH SCRATCH_X
+#define STACK_SCRATCH_STATIC_END_SYMBOL __scratch_x_end__
+#else
+#define STACK_SCRATCH SCRATCH_Y
+#define STACK_SCRATCH_STATIC_END_SYMBOL __scratch_y_end__
+#endif
 }
 
 ENTRY(_entry_point)
@@ -218,23 +225,23 @@ SECTIONS
         __end__ = .;
         PROVIDE(end = .);
         *(.heap*)
-        . = ORIGIN(RAM) + LENGTH(RAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE;
+        . = ORIGIN(RAM) + LENGTH(RAM);
         __HeapLimit = .;
     } > RAM
 
+    /* Check if data + heap exceeds RAM limit */
+    ASSERT(__end__ < ORIGIN(RAM) + LENGTH(RAM), "region RAM overflowed")
+
     .flash_end : {
         PROVIDE(__flash_binary_end = .);
     } > FLASH
 
-    /* stack limit is poorly named, but historically is maximum heap ptr */
-    __StackTop = ORIGIN(SCRATCH_Y) + LENGTH(SCRATCH_Y);
+    __StackTop = ORIGIN(STACK_SCRATCH) + LENGTH(STACK_SCRATCH);
     __StackLimit = __StackTop - MBED_CONF_TARGET_BOOT_STACK_SIZE;
     __StackBottom = __StackLimit;
+    ASSERT(__StackLimit >= STACK_SCRATCH_STATIC_END_SYMBOL, "stack scratch region overflowed")
     PROVIDE(__stack = __StackTop);
 
-    /* Check if data + heap + stack exceeds RAM limit */
-    ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
-
     ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
     /* todo assert on extra code */
 }

targets/TARGET_RASPBERRYPI/TARGET_RP2040/cmsis_nvic.h

@@ -17,24 +17,5 @@
 #ifndef MBED_CMSIS_NVIC_H
 #define MBED_CMSIS_NVIC_H
 
-#if !defined(MBED_ROM_START)
-#define MBED_ROM_START  0x10000000
-#endif
-
-#if !defined(MBED_ROM_SIZE)
-#if defined(PICO_FLASH_SIZE_BYTES)
-#define MBED_ROM_SIZE PICO_FLASH_SIZE_BYTES
-#else
-#define MBED_ROM_SIZE  (2048*1024)
-#endif
-#endif
-
-#if !defined(MBED_RAM_START)
-#define MBED_RAM_START  0x20000000
-#endif
-
-#if !defined(MBED_RAM_SIZE)
-#define MBED_RAM_SIZE  (256*1024)
-#endif
 
 #endif

targets/TARGET_RASPBERRYPI/TARGET_RP2040/flash_api.c

@@ -1,3 +1,20 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2024, Arm Limited and affiliates.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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
  ******************************************************************************/
@@ -88,7 +105,7 @@ uint32_t flash_get_size(const flash_t *obj)
 {
     (void)(obj);
 
-    return PICO_FLASH_SIZE_BYTES;
+    return MBED_ROM_BANK_QSPI_FLASH_SIZE;
 }
 
 uint32_t flash_get_sector_size(const flash_t *obj, uint32_t address)

targets/TARGET_RASPBERRYPI/TARGET_RP2040/rtc_api.c

@@ -1,3 +1,20 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2024, Arm Limited and affiliates.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ */
+
 #if DEVICE_RTC
 
 #include "mbed_critical.h"
@@ -81,6 +98,8 @@ void rtc_write(time_t t)
     // won't produce the expected result.  I wasn't able to find any errata or anything documenting
     // this behavior, but it's very consistent, and the RTC tests fail if the below block is removed.
     // To fix the error, we just decrease the time by 1 second before writing it to the registers.
+    // Update 2024: This is now a known, if not officially acknowledged, errata:
+    // https://forums.raspberrypi.com/viewtopic.php?t=377876
     if (t >= 1) {
         t -= 1;
     }

targets/targets.json5

@@ -9820,6 +9820,21 @@
             // (so the ADC can never read 100%).
             "default-adc-vref": 3.3
         },
+        "memory_banks": {
+            "QSPI_FLASH": {
+                "access": {
+                    "execute": true,
+                    "peripheral": false,
+                    "read": true,
+                    "secure": false,
+                    "write": false
+                },
+                "default": true,
+                "startup": true,
+                "size": 0x200000, // 2MiB
+                "start": 0x10000000
+            }
+        },
         "image_url": "https://cdn11.bigcommerce.com/s-2fbyfnm8ev/images/stencil/1280x1280/products/1212/4275/Pico3__75642.1611086462.jpg?c=2"
     },
     "RASPBERRY_PI_PICO_SWD": {