Low power fixups (#2941)

will-v-pi · kilograham · web-flow · commit b44dbd852b89 · 2026-05-16T12:15:16.000-05:00
* Move persistent data reset into C code

Doesn't need to be in crt0, and that is less maintainable anyway

* Fix low power compilation issue with clang

Clang sometimes tries to place persistent_data in a differet region

Fix is to add `&gt; XXX` to the end, to explicitly put it in RAM/XIP_RAM

* Update memmap annotations

* nit of include order

---------

Co-authored-by: Graham Sanderson &lt;graham.sanderson@raspberrypi.com&gt;
diff --git a/src/rp2040/pico_platform/memmap_blocked_ram.ld b/src/rp2040/pico_platform/memmap_blocked_ram.ld
@@ -12,6 +12,7 @@ INCLUDE "memmap_default.incl"
  * └── memmap_default.incl                               rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
  *     ├── memory_flash.incl                             rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2040/pico_platform/memmap_copy_to_ram.ld b/src/rp2040/pico_platform/memmap_copy_to_ram.ld
@@ -9,6 +9,7 @@ INCLUDE "memmap_copy_to_ram.incl"
  * └── memmap_copy_to_ram.incl                           rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
  *     ├── memory_flash.incl                             rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2040/pico_platform/memmap_default.ld b/src/rp2040/pico_platform/memmap_default.ld
@@ -9,6 +9,7 @@ INCLUDE "memmap_default.incl"
  * └── memmap_default.incl                               rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
  *     ├── memory_flash.incl                             rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2040/pico_platform/memmap_no_flash.ld b/src/rp2040/pico_platform/memmap_no_flash.ld
@@ -8,6 +8,7 @@ INCLUDE "memmap_no_flash.incl"
  * memmap_no_flash.ld                                    rp2040/pico_platform
  * └── memmap_no_flash.incl                              rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2350/pico_platform/memmap_copy_to_ram.ld b/src/rp2350/pico_platform/memmap_copy_to_ram.ld
@@ -9,6 +9,7 @@ INCLUDE "memmap_copy_to_ram.incl"
  * └── memmap_copy_to_ram.incl                           rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
  *     ├── memory_flash.incl                             rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2350/pico_platform/memmap_default.ld b/src/rp2350/pico_platform/memmap_default.ld
@@ -9,6 +9,7 @@ INCLUDE "memmap_default.incl"
  * └── memmap_default.incl                               rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
  *     ├── memory_flash.incl                             rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2350/pico_platform/memmap_no_flash.ld b/src/rp2350/pico_platform/memmap_no_flash.ld
@@ -8,6 +8,7 @@ INCLUDE "memmap_no_flash.incl"
  * memmap_no_flash.ld                                    rp2350/pico_platform
  * └── memmap_no_flash.incl                              rp2_common/pico_standard_link
  *     ├── set_memory_locations.incl                     rp2_common/pico_standard_link
+ *     ├── memory_xip_ram.incl                           rp2_common/pico_standard_link
  *     ├── memory_ram.incl                               rp2_common/pico_standard_link
  *     ├── memory_scratch.incl                           rp2_common/pico_standard_link
  *     ├── memory_generated.incl                         rp2_common/pico_standard_link
diff --git a/src/rp2_common/pico_crt0/crt0.S b/src/rp2_common/pico_crt0/crt0.S
@@ -15,10 +15,6 @@
 #include "boot/picobin.h"
 #include "pico/bootrom.h"
 
-#if HAS_POWMAN_TIMER
-#include "hardware/regs/powman.h"
-#endif
-
 // PICO_CONFIG: PICO_CRT0_NEAR_CALLS, Whether calls from crt0 into the binary are near (<16M away) - ignored for PICO_COPY_TO_RAM, default=0, type=bool, group=pico_crt0
 #ifndef PICO_CRT0_NEAR_CALLS
 #define PICO_CRT0_NEAR_CALLS 0
@@ -497,7 +493,6 @@ _call_xip_setup:
     // Zero out the BSS
     ldr r1, =__bss_start__
     ldr r2, =__bss_end__
-1:
     movs r0, #0
     b bss_fill_test
 bss_fill_loop:
@@ -506,27 +501,6 @@ bss_fill_test:
     cmp r1, r2
     bne bss_fill_loop
 
-#if LIB_PICO_LOW_POWER && HAS_POWMAN_TIMER
-    // Check if we're done
-    ldr r6, =__bss_end__
-    cmp r2, r6
-    bne 1f
-    // Zero out persistent_data on non-powman boot
-    ldr r1, =__persistent_data_start__
-    ldr r2, =__persistent_data_end__
-    // Skip if there is no persistent data
-    cmp r1, r2
-    beq 1f
-    // Load previous power state into r6
-    ldr r6, =(POWMAN_BASE+POWMAN_SCRATCH6_OFFSET)
-    ldr r6, [r6]
-    // Check if we should skip zeroing
-    bl persistent_zero_check
-    cmp r0, #0
-    beq 1b
-1:
-#endif
-
 platform_entry: // symbol for stack traces
 #if PICO_CRT0_NEAR_CALLS && !PICO_COPY_TO_RAM
     bl runtime_init
@@ -558,49 +532,6 @@ data_cpy:
     bx lr
 #endif
 
-#if LIB_PICO_LOW_POWER && HAS_POWMAN_TIMER
-persistent_zero_check:
-    // uses r5 and r7 as scratch
-    // uses the powman_power_state in r6
-    // returns in r0
-    mov r0, #0
-    // First check __persistent_data_start__
-    ldr r7, =__persistent_data_start__
-check_r7:
-    ldr r5, =SRAM_BASE
-    cmp r5, r7
-    bgt check_xip_sram
-    ldr r5, =SRAM4_BASE
-    cmp r5, r7
-    bgt check_sram0
-check_sram1:
-    mov r5, #(1 << 0) // POWMAN_POWER_DOMAIN_SRAM_BANK1
-    b do_check
-check_xip_sram:
-    mov r5, #(1 << 2) // POWMAN_POWER_DOMAIN_XIP_CACHE
-    b do_check
-check_sram0:
-    mov r5, #(1 << 1) // POWMAN_POWER_DOMAIN_SRAM_BANK0
-    b do_check
-do_check:
-    and r7, r5, r6
-    cmp r5, r7
-    beq skip
-    b noskip
-skip:
-    cmp r0, #1
-    bne check_end
-    bx lr
-check_end:
-    add r0, #1
-    // If start was skipped, check __persistent_data_end__
-    ldr r7, =__persistent_data_end__
-    b check_r7
-noskip:
-    mov r0, #0
-    bx lr
-#endif
-
 // Note the data copy table is still included for NO_FLASH builds, even though
 // we skip the copy, because it is listed in binary info
 
diff --git a/src/rp2_common/pico_crt0/crt0_riscv.S b/src/rp2_common/pico_crt0/crt0_riscv.S
@@ -12,10 +12,6 @@
 #include "boot/picobin.h"
 #include "pico/bootrom_constants.h"
 
-#if HAS_POWMAN_TIMER
-#include "hardware/regs/powman.h"
-#endif
-
 #ifdef NDEBUG
 #ifndef COLLAPSE_IRQS
 #define COLLAPSE_IRQS
@@ -373,24 +369,6 @@ bss_fill_loop:
 bss_fill_test:
     bne a1, a2, bss_fill_loop
 
-#if LIB_PICO_LOW_POWER && HAS_POWMAN_TIMER
-    // Check if we're done
-    la a6, __bss_end__
-    bne a2, a6, 1f
-    // Zero out persistent_data on non-powman boot
-    la a1, __persistent_data_start__
-    la a2, __persistent_data_end__
-    // Skip if there is no persistent data
-    beq a1, a2, 1f
-    // Load previous power state into r6
-    li a6, POWMAN_BASE+POWMAN_SCRATCH6_OFFSET
-    lw a6, 0(a6)
-    // Check if we should skip zeroing
-    jal persistent_zero_check
-    beqz a0, bss_fill_test
-1:
-#endif
-
 platform_entry: // symbol for stack traces
     // Use `call` pseudo-instruction instead of a bare `jal` so that the
     // linker can use longer sequences if these are out of `jal` range. Will
@@ -417,45 +395,6 @@ data_cpy:
     ret
 #endif
 
-#if LIB_PICO_LOW_POWER && HAS_POWMAN_TIMER
-persistent_zero_check:
-    // uses a5 and a7 as scratch
-    // uses the powman_power_state in a6
-    // returns in a0
-    li a0, 0
-    // First check __persistent_data_start__
-    la a7, __persistent_data_start__
-check_a7:
-    li a5, SRAM_BASE
-    bgt a5, a7, check_xip_sram
-    li a5, SRAM4_BASE
-    bgt a5, a7, check_sram0
-check_sram1:
-    li a5, 1 << 0 // POWMAN_POWER_DOMAIN_SRAM_BANK1
-    j do_check
-check_xip_sram:
-    li a5, 1 << 2 // POWMAN_POWER_DOMAIN_XIP_CACHE
-    j do_check
-check_sram0:
-    li a5, 1 << 1 // POWMAN_POWER_DOMAIN_SRAM_BANK0
-    j do_check
-do_check:
-    and a7, a5, a6
-    beq a5, a7, skip
-    j noskip
-skip:
-    beqz a0, check_end
-    ret
-check_end:
-    addi a0, a0, 1
-    // If start was skipped, check __persistent_data_end__
-    la a7, __persistent_data_end__
-    j check_a7
-noskip:
-    li a0, 0
-    ret
-#endif
-
 .align 2
 data_cpy_table:
 #if PICO_RP2350 && PICO_EMBED_XIP_SETUP && !PICO_NO_FLASH
diff --git a/src/rp2_common/pico_low_power/CMakeLists.txt b/src/rp2_common/pico_low_power/CMakeLists.txt
@@ -40,21 +40,24 @@ function(pico_set_persistent_data_loc TARGET PERSISTENT_DATA_LOC)
                 message(FATAL_ERROR "pico_set_persistent_data_loc is not supported on RP2040")
         endif()
 
-        # Configure override section_persistent_data.incl for the target
-        configure_file(${PICO_LOW_POWER_CURRENT_PATH}/section_persistent_data.incl.template ${CMAKE_CURRENT_BINARY_DIR}/${TARGET}/section_persistent_data.incl @ONLY)
-        pico_add_linker_script_override_path(${TARGET} ${CMAKE_CURRENT_BINARY_DIR}/${TARGET})
-
         if (PERSISTENT_DATA_LOC LESS 0x20000000)
                 # XIP_SRAM, so pin the XIP_SRAM
                 target_compile_definitions(${TARGET} PRIVATE PICO_CRT0_PIN_XIP_SRAM=1)
+                set(PERSISTENT_DATA_SECTION "XIP_RAM")
         elseif (PERSISTENT_DATA_LOC LESS 0x20040000)
                 # SRAM0, so heap should come after persistent data
                 pico_set_linker_script_var(${TARGET} HEAP_LOC __persistent_data_end__)
+                set(PERSISTENT_DATA_SECTION "RAM")
         elseif(PERSISTENT_DATA_LOC LESS 0x20080000)
                 # SRAM1, so heap should come before persistent data
                 pico_set_linker_script_var(${TARGET} HEAP_LIMIT ${PERSISTENT_DATA_LOC})
+                set(PERSISTENT_DATA_SECTION "RAM")
         else()
                 # Not supported in scratch, as the linker script will overwrite persistent data with scratch data
                 message(FATAL_ERROR "pico_set_persistent_data_loc only supports persistent data in XIP_SRAM or SRAM0-7")
         endif()
+
+        # Configure override section_persistent_data.incl for the target
+        configure_file(${PICO_LOW_POWER_CURRENT_PATH}/section_persistent_data.incl.template ${CMAKE_CURRENT_BINARY_DIR}/${TARGET}/section_persistent_data.incl @ONLY)
+        pico_add_linker_script_override_path(${TARGET} ${CMAKE_CURRENT_BINARY_DIR}/${TARGET})
 endfunction()
diff --git a/src/rp2_common/pico_low_power/low_power.c b/src/rp2_common/pico_low_power/low_power.c
@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <string.h>
+
 #include "pico.h"
 
 #include "pico/low_power.h"
@@ -714,20 +716,44 @@ int low_power_pstate_until_gpio_pin_state(uint gpio_pin, bool edge, bool high, p
 }
 
 #if !PICO_RUNTIME_NO_INIT_LOW_POWER_REBOOT_CHECK
+
+static inline void reset_persistent_data(void) {
+    size_t persistent_data_size = (uint32_t)__persistent_data_end__ - (uint32_t)__persistent_data_start__;
+    __builtin_memset((void*)(uint32_t)__persistent_data_start__, 0, persistent_data_size);
+}
+
 void __weak runtime_init_low_power_reboot_check(void) {
     // check if we came from powman reboot
     if (powman_hw->chip_reset & POWMAN_CHIP_RESET_HAD_SWCORE_PD_BITS) {
-        // we came from powman reboot, so execute the resume function
+        pstate_bitset_t persistent_pstate = pstate_bitset_none();
+        low_power_persistent_pstate_get(&persistent_pstate);
+        pstate_bitset_t pstate = pstate_bitset_none();
+        pstate_bitset_from_powman_power_state(&pstate, powman_hw->scratch[6]);
+
+        // check if persistent data was turned off
+        if (!pstate_bitset_none_set(&persistent_pstate)) {
+            for (int i=0; i < POWMAN_POWER_DOMAIN_COUNT; i++) {
+                if (!pstate_bitset_is_set(&pstate, (powman_power_domain_t)i) && pstate_bitset_is_set(&persistent_pstate, (powman_power_domain_t)i)) {
+                    reset_persistent_data();
+                    break;
+                }
+            }
+        }
+
+        // execute the resume function, if present
         if (powman_hw->scratch[7]) {
-            pstate_bitset_t pstate = pstate_bitset_none();
-            pstate_bitset_from_powman_power_state(&pstate, powman_hw->scratch[6]);
             ((low_power_pstate_resume_func)powman_hw->scratch[7])(&pstate);
-            // clear the scratch registers
-            powman_hw->scratch[6] = 0;
-            powman_hw->scratch[7] = 0;
         }
+
+        // clear the scratch registers
+        powman_hw->scratch[6] = 0;
+        powman_hw->scratch[7] = 0;
+
         // Switch powman timer back to xosc
         powman_timer_set_1khz_tick_source_xosc();
+    } else {
+        // not a powman reboot, so clear persistent data
+        reset_persistent_data();
     }
 }
 #endif
diff --git a/src/rp2_common/pico_low_power/section_persistent_data.incl.template b/src/rp2_common/pico_low_power/section_persistent_data.incl.template
@@ -4,6 +4,6 @@ SECTIONS
         __persistent_data_start__ = .;
         *(.persistent_data*)
         . = ALIGN(4);
-    }
+    } > @PERSISTENT_DATA_SECTION@
     PROVIDE(__persistent_data_end__ = .);
 }
diff --git a/src/rp2_common/pico_standard_link/script_include/memmap_copy_to_ram.incl b/src/rp2_common/pico_standard_link/script_include/memmap_copy_to_ram.incl
@@ -3,6 +3,7 @@ INCLUDE "set_memory_locations.incl"
 
 /* Include memory regions used */
 INCLUDE "memory_flash.incl"
+INCLUDE "memory_xip_ram.incl"
 INCLUDE "memory_ram.incl"
 INCLUDE "memory_scratch.incl"
 INCLUDE "memory_generated.incl"
diff --git a/src/rp2_common/pico_standard_link/script_include/memmap_default.incl b/src/rp2_common/pico_standard_link/script_include/memmap_default.incl
@@ -3,6 +3,7 @@ INCLUDE "set_memory_locations.incl"
 
 /* Include memory regions used */
 INCLUDE "memory_flash.incl"
+INCLUDE "memory_xip_ram.incl"
 INCLUDE "memory_ram.incl"
 INCLUDE "memory_scratch.incl"
 INCLUDE "memory_generated.incl"
diff --git a/src/rp2_common/pico_standard_link/script_include/memmap_no_flash.incl b/src/rp2_common/pico_standard_link/script_include/memmap_no_flash.incl
@@ -2,6 +2,7 @@
 INCLUDE "set_memory_locations.incl"
 
 /* Include memory regions used */
+INCLUDE "memory_xip_ram.incl"
 INCLUDE "memory_ram.incl"
 INCLUDE "memory_scratch.incl"
 INCLUDE "memory_generated.incl"
diff --git a/src/rp2_common/pico_standard_link/script_include/memory_aliases_flash.incl b/src/rp2_common/pico_standard_link/script_include/memory_aliases_flash.incl
@@ -2,5 +2,6 @@
 
 REGION_ALIAS("TEXT_STORE", FLASH);
 REGION_ALIAS("RAM_STORE", FLASH);
+REGION_ALIAS("XIP_RAM_STORE", FLASH);
 REGION_ALIAS("SCRATCH_X_STORE", FLASH);
 REGION_ALIAS("SCRATCH_Y_STORE", FLASH);
diff --git a/src/rp2_common/pico_standard_link/script_include/memory_aliases_no_flash.incl b/src/rp2_common/pico_standard_link/script_include/memory_aliases_no_flash.incl
@@ -2,5 +2,6 @@
 
 REGION_ALIAS("TEXT_STORE", RAM);
 REGION_ALIAS("RAM_STORE", RAM);
+REGION_ALIAS("XIP_RAM_STORE", XIP_RAM);
 REGION_ALIAS("SCRATCH_X_STORE", SCRATCH_X);
 REGION_ALIAS("SCRATCH_Y_STORE", SCRATCH_Y);
