Preserve PSRAM QMI interface around flash ops

The flash ROM routines seem to overwrite the QMI configuration we set for
PSRAM, rendering it unreadable after any erase or write or ID command.

Wrap the 4 flash control functions to preserve the QMI state on the
RP2350.  On the RP2040, simply pass through the call.

Fixes #2537

Author: earlephilhower

cores/rp2040/flash_wrapper.cpp

@@ -0,0 +1,73 @@
+/*
+    Flash wrappers to protect PSRAM access on the RP2350
+
+    Copyright (c) 2024 Earle F. Philhower, III <[email protected]>
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifdef PICO_RP2350
+#include <hardware/structs/qmi.h>
+#endif
+
+extern "C" {
+    extern void __real_flash_range_erase(uint32_t flash_offs, size_t count);
+    void __wrap_flash_range_erase(uint32_t flash_offs, size_t count) {
+#ifdef PICO_RP2350
+        auto s = qmi_hw->m[1];
+#endif
+        __real_flash_range_erase(flash_offs, count);
+#ifdef PICO_RP2350
+        qmi_hw->m[1] = s;
+        __compiler_memory_barrier();
+#endif
+    }
+
+    extern void __real_flash_range_program(uint32_t flash_offs, const uint8_t *data, size_t count);
+    void __wrap_flash_range_program(uint32_t flash_offs, const uint8_t *data, size_t count) {
+#ifdef PICO_RP2350
+        auto s = qmi_hw->m[1];
+#endif
+        __real_flash_range_program(flash_offs, data, count);
+#ifdef PICO_RP2350
+        qmi_hw->m[1] = s;
+        __compiler_memory_barrier();
+#endif
+    }
+
+    extern void __real_flash_get_unique_id(uint8_t *id_out);
+    void __wrap_flash_get_unique_id(uint8_t *id_out) {
+#ifdef PICO_RP2350
+        auto s = qmi_hw->m[1];
+#endif
+        __real_flash_get_unique_id(id_out);
+#ifdef PICO_RP2350
+        qmi_hw->m[1] = s;
+        __compiler_memory_barrier();
+#endif
+    }
+
+    extern void __real_flash_do_cmd(const uint8_t *txbuf, uint8_t *rxbuf, size_t count);
+    void __wrap_flash_do_cmd(const uint8_t *txbuf, uint8_t *rxbuf, size_t count) {
+#ifdef PICO_RP2350
+        auto s = qmi_hw->m[1];
+#endif
+        __real_flash_do_cmd(txbuf, rxbuf, count);
+#ifdef PICO_RP2350
+        qmi_hw->m[1] = s;
+        __compiler_memory_barrier();
+#endif
+    }
+};

lib/core_wrap.txt

@@ -67,3 +67,8 @@
 -Wl,--wrap=cyw43_tcpip_link_status
 -Wl,--wrap=cyw43_cb_tcpip_init
 -Wl,--wrap=cyw43_cb_tcpip_deinit
+
+-Wl,--wrap=flash_range_erase
+-Wl,--wrap=flash_range_program
+-Wl,--wrap=flash_get_unique_id
+-Wl,--wrap=flash_do_cmd