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hardware_flash: preserve QSPI pad state over flash access calls.

Browse source 
Add new function, flash_start_xip(), which explicitly performs a
first-time XIP setup (including initialising pads). This is mostly
useful for PICO_NO_FLASH=1 binaries where there is actually an attached
external flash.

Fixes #2333
This commit is contained in:
Luke Wren 2025-07-16 15:58:13 +01:00
parent c7f37fc211
commit ba2a205908
2 changed files with 105 additions and 25 deletions
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112
src/rp2_common/hardware_flash/flash.c
View file

@ -14,6 +14,7 @@
#include "hardware/structs/qmi.h"
#include "hardware/regs/otp_data.h"
#endif
#include "hardware/structs/pads_qspi.h"
#include "hardware/xip_cache.h"
#define FLASH_BLOCK_ERASE_CMD 0xd8
@ -71,6 +72,22 @@ static void __no_inline_not_in_flash_func(flash_enable_xip_via_boot2)(void) {
#endif
//-----------------------------------------------------------------------------
// State save/restore
// Most functions save and restore the QSPI pad state over the call. (The main
// exception is flash_start_xip() which is explicitly intended to initialise
// them). The expectation is that by the time you do any flash operations,
// you have either gone through a normal flash boot process or (in the case
// of PICO_NO_FLASH=1) you have called flash_start_xip(). Any further
// modifications to the pad state are therefore deliberate changes that we
// should preserve.
//
// Additionally, on RP2350, we save and restore the window 1 QMI configuration
// if the user has not opted into bootrom CS1 support via FLASH_DEVINFO OTP
// flags. This avoids clobbering CS1 setup (e.g. PSRAM) performed by the
// application.
#if PICO_RP2350
// This is specifically for saving/restoring the registers modified by RP2350
// flash_exit_xip() ROM func, not the entirety of the QMI window state.
@ -108,9 +125,69 @@ static void __no_inline_not_in_flash_func(flash_rp2350_restore_qmi_cs1)(const fl
}
#endif
typedef struct flash_hardware_save_state {
#if PICO_RP2350
flash_rp2350_qmi_save_state_t qmi_save;
#endif
uint32_t qspi_pads[count_of(pads_qspi_hw->io)];
} flash_hardware_save_state_t;
static void __no_inline_not_in_flash_func(flash_save_hardware_state)(flash_hardware_save_state_t *state) {
// Commit any pending writes to external RAM, to avoid losing them in a subsequent flush:
xip_cache_clean_all();
for (size_t i = 0; i < count_of(pads_qspi_hw->io); ++i) {
state->qspi_pads[i] = pads_qspi_hw->io[i];
}
#if PICO_RP2350
flash_rp2350_save_qmi_cs1(&state->qmi_save);
#endif
}
static void __no_inline_not_in_flash_func(flash_restore_hardware_state)(flash_hardware_save_state_t *state) {
for (size_t i = 0; i < count_of(pads_qspi_hw->io); ++i) {
pads_qspi_hw->io[i] = state->qspi_pads[i];
}
#if PICO_RP2350
// Tail call!
flash_rp2350_restore_qmi_cs1(&state->qmi_save);
#endif
}
//-----------------------------------------------------------------------------
// Actual flash programming shims (work whether or not PICO_NO_FLASH==1)
void __no_inline_not_in_flash_func(flash_start_xip)(void) {
rom_connect_internal_flash_fn connect_internal_flash_func = (rom_connect_internal_flash_fn)rom_func_lookup_inline(ROM_FUNC_CONNECT_INTERNAL_FLASH);
rom_flash_exit_xip_fn flash_exit_xip_func = (rom_flash_exit_xip_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_EXIT_XIP);
rom_flash_flush_cache_fn flash_flush_cache_func = (rom_flash_flush_cache_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_FLUSH_CACHE);
rom_flash_enter_cmd_xip_fn flash_enter_cmd_xip_func = (rom_flash_enter_cmd_xip_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_ENTER_CMD_XIP);
assert(connect_internal_flash_func && flash_exit_xip_func && flash_flush_cache_func && flash_enter_cmd_xip_func);
// Commit any pending writes to external RAM, to avoid losing them in the subsequent flush:
xip_cache_clean_all();
#if PICO_RP2350
flash_rp2350_qmi_save_state_t qmi_save;
flash_rp2350_save_qmi_cs1(&qmi_save);
#endif
// Use ROM calls to get from ~any state to a state where low-speed flash access works:
connect_internal_flash_func();
flash_exit_xip_func();
flash_flush_cache_func();
flash_enter_cmd_xip_func();
// If a boot2 is available then call it now. Slight limitation here is that if this is a
// NO_FLASH binary which was loaded via bootrom LOAD_MAP, we should actually have a better
// flash setup than this available via xip setup func stub left in boot RAM, but we can't
// easily detect this case to take advantage of this.
flash_init_boot2_copyout();
flash_enable_xip_via_boot2();
#if PICO_RP2350
flash_rp2350_restore_qmi_cs1(&qmi_save);
#endif
}
void __no_inline_not_in_flash_func(flash_range_erase)(uint32_t flash_offs, size_t count) {
#ifdef PICO_FLASH_SIZE_BYTES
hard_assert(flash_offs + count <= PICO_FLASH_SIZE_BYTES);
@ -123,12 +200,8 @@ void __no_inline_not_in_flash_func(flash_range_erase)(uint32_t flash_offs, size_
rom_flash_flush_cache_fn flash_flush_cache_func = (rom_flash_flush_cache_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_FLUSH_CACHE);
assert(connect_internal_flash_func && flash_exit_xip_func && flash_range_erase_func && flash_flush_cache_func);
flash_init_boot2_copyout();
// Commit any pending writes to external RAM, to avoid losing them in the subsequent flush:
xip_cache_clean_all();
#if PICO_RP2350
flash_rp2350_qmi_save_state_t qmi_save;
flash_rp2350_save_qmi_cs1(&qmi_save);
#endif
flash_hardware_save_state_t state;
flash_save_hardware_state(&state);
// No flash accesses after this point
__compiler_memory_barrier();
@ -138,9 +211,7 @@ void __no_inline_not_in_flash_func(flash_range_erase)(uint32_t flash_offs, size_
flash_range_erase_func(flash_offs, count, FLASH_BLOCK_SIZE, FLASH_BLOCK_ERASE_CMD);
flash_flush_cache_func(); // Note this is needed to remove CSn IO force as well as cache flushing
flash_enable_xip_via_boot2();
#if PICO_RP2350
flash_rp2350_restore_qmi_cs1(&qmi_save);
#endif
flash_restore_hardware_state(&state);
}
void __no_inline_not_in_flash_func(flash_flush_cache)(void) {
@ -160,11 +231,8 @@ void __no_inline_not_in_flash_func(flash_range_program)(uint32_t flash_offs, con
rom_flash_flush_cache_fn flash_flush_cache_func = (rom_flash_flush_cache_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_FLUSH_CACHE);
assert(connect_internal_flash_func && flash_exit_xip_func && flash_range_program_func && flash_flush_cache_func);
flash_init_boot2_copyout();
xip_cache_clean_all();
#if PICO_RP2350
flash_rp2350_qmi_save_state_t qmi_save;
flash_rp2350_save_qmi_cs1(&qmi_save);
#endif
flash_hardware_save_state_t state;
flash_save_hardware_state(&state);
__compiler_memory_barrier();
@ -173,9 +241,8 @@ void __no_inline_not_in_flash_func(flash_range_program)(uint32_t flash_offs, con
flash_range_program_func(flash_offs, data, count);
flash_flush_cache_func(); // Note this is needed to remove CSn IO force as well as cache flushing
flash_enable_xip_via_boot2();
#if PICO_RP2350
flash_rp2350_restore_qmi_cs1(&qmi_save);
#endif
flash_restore_hardware_state(&state);
}
//-----------------------------------------------------------------------------
@ -208,11 +275,8 @@ void __no_inline_not_in_flash_func(flash_do_cmd)(const uint8_t *txbuf, uint8_t *
rom_flash_flush_cache_fn flash_flush_cache_func = (rom_flash_flush_cache_fn)rom_func_lookup_inline(ROM_FUNC_FLASH_FLUSH_CACHE);
assert(connect_internal_flash_func && flash_exit_xip_func && flash_flush_cache_func);
flash_init_boot2_copyout();
xip_cache_clean_all();
#if PICO_RP2350
flash_rp2350_qmi_save_state_t qmi_save;
flash_rp2350_save_qmi_cs1(&qmi_save);
#endif
flash_hardware_save_state_t state;
flash_save_hardware_state(&state);
__compiler_memory_barrier();
connect_internal_flash_func();
@ -260,9 +324,7 @@ void __no_inline_not_in_flash_func(flash_do_cmd)(const uint8_t *txbuf, uint8_t *
flash_flush_cache_func();
flash_enable_xip_via_boot2();
#if PICO_RP2350
flash_rp2350_restore_qmi_cs1(&qmi_save);
#endif
flash_restore_hardware_state(&state);
}
#endif

18
src/rp2_common/hardware_flash/include/hardware/flash.h
View file

@ -56,6 +56,24 @@
extern "C" {
#endif
/*! \brief Initialise QSPI interface and external QSPI devices for execute-in-place
* \ingroup hardware_flash
*
* This function performs the same first-time flash setup that would normally occur during startup
* of a flash binary.
*
* This is mostly useful for initialising flash on a PICO_NO_FLASH=1 binary. In spite of the name,
* this binary type really means "preloaded to RAM" and there may still be a flash device.
*
* This function does not preserve the QSPI interface state or pad state. However, on RP2350 it does
* preserve the QMI window 1 configuration if you have not opted into bootrom CS1 support via
* FLASH_DEVINFO. This is in contrast to most other functions in this library, which preserve at
* least the QSPI pad state.
*
*/
void flash_start_xip(void);
/*! \brief Erase areas of flash
* \ingroup hardware_flash
*