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wolfBoot/hal/stm32c5.c

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/* stm32c5.c
*
* Copyright (C) 2026 wolfSSL Inc.
*
* This file is part of wolfBoot.
*
* wolfBoot is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* wolfBoot 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
*/
/* STM32C5 family (e.g. STM32C5A3ZGT6 on NUCLEO-C5A3ZG). Cortex-M33
* without TrustZone in this configuration. Dual-bank 1 MB flash on
* the -ZG variant (2 x 512 KB), 8 KB pages, 128-bit (quad-word) write
* quantum with per-quad-word ECC.
*
* Default sysclk after reset is HSIDIV3 = HSIS / 3 (RCC_CFGR1.SW=0).
* This port brings SYSCLK to 144 MHz via the PSIS clock chain (HSE
* 48 MHz reference) in clock_init(). When WOLFBOOT_RESTORE_CLOCK
* is defined (default in options.mk), hal_prepare_boot() switches
* SYSCLK back to HSIDIV3 before handoff but leaves PSIS, PSI and
* HSE running so the loaded firmware's own clock_psi_on() bumps
* SYSCLK back up to 144 MHz cleanly without re-stabilizing HSE.
* Pass WOLFBOOT_RESTORE_CLOCK=0 to skip the SYSCLK switch entirely
* and have the loaded firmware inherit PSIS @ 144 MHz directly.
*/
#include <stdint.h>
#include <string.h>
#include <image.h>
#include "hal/stm32c5.h"
#include "hal.h"
#include "printf.h"
static void RAMFUNCTION flash_set_waitstates(unsigned int waitstates)
{
uint32_t reg = FLASH_ACR;
if ((reg & FLASH_ACR_LATENCY_MASK) != waitstates) {
FLASH_ACR = (reg & ~FLASH_ACR_LATENCY_MASK) | waitstates;
while ((FLASH_ACR & FLASH_ACR_LATENCY_MASK) != waitstates)
;
}
}
static RAMFUNCTION void flash_wait_complete(void)
{
while ((FLASH_SR & (FLASH_SR_BSY | FLASH_SR_WBNE | FLASH_SR_DBNE)) != 0)
;
}
static void RAMFUNCTION flash_clear_errors(void)
{
/* On STM32C5, error flags are cleared via the dedicated FLASH_CCR
* register (write 1 to clear). Always clear all known flags so a
* stale error from a prior cycle does not block the next operation.
*/
FLASH_CCR = FLASH_CCR_CLR_EOP | FLASH_CCR_CLR_WRPERR |
FLASH_CCR_CLR_PGSERR | FLASH_CCR_CLR_STRBERR |
FLASH_CCR_CLR_INCERR | FLASH_CCR_CLR_OPTCHANGEERR;
}
/* Mask of FLASH_SR error flags worth aborting on. */
#define FLASH_SR_ERR_MASK (FLASH_SR_WRPERR | FLASH_SR_PGSERR | \
FLASH_SR_STRBERR | FLASH_SR_INCERR | \
FLASH_SR_OPTCHANGEERR)
/* C5 flash programming requires 128-bit (quad-word, 16-byte) writes
* to produce valid ECC. Partial writes leave the per-quad-word ECC
* undefined and reads come back with bit-flipped "corrected" data.
* For unaligned heads/tails we read the existing flash content and
* merge so that every written quad-word is a complete ECC block.
*/
int RAMFUNCTION hal_flash_write(uint32_t address, const uint8_t *data, int len)
{
int i = 0;
uint32_t qword[4];
uint8_t *qword_bytes = (uint8_t *)qword;
uint8_t *dst = (uint8_t *)address;
while (i < len) {
uint32_t cur_addr = (uint32_t)dst + i;
uint32_t *dst_aligned = (uint32_t *)(cur_addr & 0xFFFFFFF0U);
int byte_offset = (int)(cur_addr - (uint32_t)dst_aligned);
int write_len = 16 - byte_offset;
int j;
uint32_t sr;
if (write_len > len - i)
write_len = len - i;
/* Build the full 16-byte ECC block: start with the existing
* flash content for any head/tail bytes outside the requested
* range, then overlay the caller's bytes. memcpy keeps the
* source pointer alignment-agnostic.
*/
memcpy(qword_bytes, (const uint8_t *)dst_aligned, 16);
memcpy(qword_bytes + byte_offset, data + i, write_len);
flash_wait_complete();
flash_clear_errors();
FLASH_CR |= FLASH_CR_PG;
for (j = 0; j < 4; j++) {
dst_aligned[j] = qword[j];
ISB();
}
flash_wait_complete();
sr = FLASH_SR;
if ((sr & FLASH_SR_EOP) != 0)
FLASH_CCR = FLASH_CCR_CLR_EOP;
if ((sr & FLASH_SR_ERR_MASK) != 0) {
flash_clear_errors();
FLASH_CR &= ~FLASH_CR_PG;
hal_cache_invalidate();
return -1;
}
FLASH_CR &= ~FLASH_CR_PG;
i += write_len;
DSB();
}
hal_cache_invalidate();
return 0;
}
void RAMFUNCTION hal_flash_unlock(void)
{
flash_wait_complete();
if ((FLASH_CR & FLASH_CR_LOCK) != 0) {
FLASH_KEYR = FLASH_KEY1;
DMB();
FLASH_KEYR = FLASH_KEY2;
DMB();
while ((FLASH_CR & FLASH_CR_LOCK) != 0)
;
}
}
void RAMFUNCTION hal_flash_lock(void)
{
flash_wait_complete();
if ((FLASH_CR & FLASH_CR_LOCK) == 0)
FLASH_CR |= FLASH_CR_LOCK;
}
void RAMFUNCTION hal_flash_opt_unlock(void)
{
flash_wait_complete();
if ((FLASH_OPTCR & FLASH_OPTCR_OPTLOCK) != 0) {
FLASH_OPTKEYR = FLASH_OPTKEY1;
DMB();
FLASH_OPTKEYR = FLASH_OPTKEY2;
DMB();
while ((FLASH_OPTCR & FLASH_OPTCR_OPTLOCK) != 0)
;
}
}
/* Re-lock the option control register only. Callers that actually
* want to commit modified option bytes must set OPTSTRT themselves
* (and wait for completion) before calling this; setting OPTSTRT here
* unconditionally would trigger an option-byte program/reload on
* every lock and is a foot-gun.
*/
void RAMFUNCTION hal_flash_opt_lock(void)
{
flash_wait_complete();
if ((FLASH_OPTCR & FLASH_OPTCR_OPTLOCK) == 0)
FLASH_OPTCR |= FLASH_OPTCR_OPTLOCK;
}
/* Page erase. PNB[5:0] selects the page within the bank; BKSEL (bit 31)
* selects bank 2 when the address falls into the upper half of flash.
*/
int RAMFUNCTION hal_flash_erase(uint32_t address, int len)
{
uint32_t end;
uint32_t p;
uint32_t sr;
flash_clear_errors();
if (len <= 0)
return -1;
if (address < ARCH_FLASH_OFFSET)
return -1;
/* Reject ranges that extend past the last valid flash byte
* up-front rather than partially erasing and returning success.
*/
if ((uint64_t)address + (uint64_t)len > (uint64_t)FLASH_TOP + 1U)
return -1;
/* End-exclusive bound so a single-page erase (e.g. len ==
* FLASH_PAGE_SIZE, or smaller len that still resolves to one
* page) actually runs the loop body.
*/
end = address + (uint32_t)len;
for (p = address; p < end; p += FLASH_PAGE_SIZE) {
uint32_t reg;
uint32_t bksel = 0;
uint32_t base;
if (p >= FLASH_BANK2_BASE) {
bksel = FLASH_CR_BKSEL;
base = FLASH_BANK2_BASE;
} else {
base = FLASHMEM_ADDRESS_SPACE;
}
reg = FLASH_CR & ~((uint32_t)(FLASH_CR_PNB_MASK << FLASH_CR_PNB_SHIFT) |
FLASH_CR_BKSEL);
reg |= (((p - base) / FLASH_PAGE_SIZE) << FLASH_CR_PNB_SHIFT) |
FLASH_CR_PER | bksel;
FLASH_CR = reg;
DMB();
FLASH_CR |= FLASH_CR_STRT;
flash_wait_complete();
sr = FLASH_SR;
if ((sr & FLASH_SR_ERR_MASK) != 0) {
flash_clear_errors();
FLASH_CR &= ~FLASH_CR_PER;
hal_cache_invalidate();
return -1;
}
}
FLASH_CR &= ~FLASH_CR_PER;
hal_cache_invalidate();
return 0;
}
#if defined(DUALBANK_SWAP) && defined(__WOLFBOOT)
/* RAMFUNCTION reset helper for hal_flash_dualbank_swap(). Mirrors the
* test app's system_reset(): preserves AIRCR.PRIGROUP, DSB before/after.
*/
static void RAMFUNCTION stm32c5_reboot(void)
{
uint32_t prigroup = AIRCR & 0x0700U;
DSB();
AIRCR = AIRCR_VKEY | prigroup | AIRCR_SYSRESETREQ;
DSB();
while (1)
;
}
/* Toggle FLASH_OPTCR.SWAP_BANK via the OPTSR_CUR / OPTSR_PRG / OPTSTRT
* sequence and reboot. The new bank mapping takes effect on reset (no
* separate OBL_LAUNCH register on C5). Modeled on hal/stm32h5.c.
*/
void RAMFUNCTION hal_flash_dualbank_swap(void)
{
uint32_t cur;
cur = FLASH_OPTSR_CUR & FLASH_OPTSR_SWAP_BANK;
flash_clear_errors();
hal_flash_unlock();
hal_flash_opt_unlock();
if (cur != 0)
FLASH_OPTSR_PRG &= ~FLASH_OPTSR_SWAP_BANK;
else
FLASH_OPTSR_PRG |= FLASH_OPTSR_SWAP_BANK;
FLASH_OPTCR |= FLASH_OPTCR_OPTSTRT;
DMB();
hal_flash_opt_lock();
hal_flash_lock();
stm32c5_reboot();
}
/* Mirror the wolfBoot image into bank 2 so 0x08000000 boots correctly
* regardless of which physical bank SWAP_BANK currently maps there.
* Only runs when bank 2 doesn't already match. Stages 4 KB at a time
* via a static RAM buffer to keep stack pressure bounded.
*/
#define BOOTLOADER_COPY_MEM_SIZE (0x1000)
static uint8_t bootloader_copy_mem[BOOTLOADER_COPY_MEM_SIZE];
static void fork_bootloader(void)
{
uint32_t src = FLASHMEM_ADDRESS_SPACE;
uint32_t dst = FLASH_BANK2_BASE;
int i;
if (memcmp((const void *)src, (const void *)dst, BOOTLOADER_SIZE) == 0)
return;
hal_flash_unlock();
hal_flash_erase(dst, BOOTLOADER_SIZE);
for (i = 0; i < (int)BOOTLOADER_SIZE; i += BOOTLOADER_COPY_MEM_SIZE) {
memcpy(bootloader_copy_mem, (const void *)(src + i),
BOOTLOADER_COPY_MEM_SIZE);
hal_flash_write(dst + i, bootloader_copy_mem,
BOOTLOADER_COPY_MEM_SIZE);
}
hal_flash_lock();
}
#endif /* DUALBANK_SWAP && __WOLFBOOT */
/* --- UART: USART2 on PA2 (TX) / PA3 (RX), AF7 (NUCLEO-C5A3ZG VCP).
* Register/peripheral macros live in stm32c5.h; the values below are
* board/clock specific and stay here.
*/
#define UART_TX_PIN (2)
#define UART_RX_PIN (3)
#define UART_PIN_AF (7)
/* PCLK1 == SYSCLK after clock_init (PPRE1 = /1). */
#define USART2_PCLK (144000000U)
#if defined(DEBUG_UART) || !defined(__WOLFBOOT)
static void uart2_pins_setup(void)
{
uint32_t reg;
RCC_AHB2ENR |= RCC_AHB2ENR_GPIOAEN;
reg = RCC_AHB2ENR;
(void)reg;
reg = GPIOA_MODER & ~(0x3u << (UART_TX_PIN * 2));
GPIOA_MODER = reg | (0x2u << (UART_TX_PIN * 2));
reg = GPIOA_MODER & ~(0x3u << (UART_RX_PIN * 2));
GPIOA_MODER = reg | (0x2u << (UART_RX_PIN * 2));
reg = GPIOA_AFRL & ~(0xFu << (UART_TX_PIN * 4));
GPIOA_AFRL = reg | (UART_PIN_AF << (UART_TX_PIN * 4));
reg = GPIOA_AFRL & ~(0xFu << (UART_RX_PIN * 4));
GPIOA_AFRL = reg | (UART_PIN_AF << (UART_RX_PIN * 4));
GPIOA_PUPDR &= ~(0x3u << (UART_TX_PIN * 2));
GPIOA_PUPDR &= ~(0x3u << (UART_RX_PIN * 2));
}
void uart_init(void)
{
uint32_t reg;
uart2_pins_setup();
RCC_APB1LENR |= RCC_APB1LENR_USART2EN;
reg = RCC_APB1LENR;
(void)reg;
USART2_CR1 &= ~UART_CR1_UE;
USART2_BRR = USART2_PCLK / 115200;
USART2_CR1 |= UART_CR1_TE | UART_CR1_RE | UART_CR1_UE;
}
void uart_write(const char *buf, unsigned int sz)
{
while (sz-- > 0) {
while ((USART2_ISR & UART_ISR_TXE) == 0)
;
USART2_TDR = *buf++;
}
}
#endif /* DEBUG_UART || !__WOLFBOOT */
/* Generous polling budgets. HSE on a 48 MHz crystal typically takes
* a few ms to stabilize; the SYSCLK/PSIS switches complete in a few
* cycles. These are spin loops, not wall-clock counters, so the
* actual wait scales with whatever clock is currently driving the
* core (HSIDIV3 at boot -> very slow -> larger budget needed).
*/
#define HSE_TIMEOUT 0x100000u
#define PSI_TIMEOUT 0x10000u
#define SW_TIMEOUT 0x10000u
/* Bring SYSCLK to 144 MHz via the PSIS clock chain. Mirrors the
* sequence emitted by STM32CubeMX's mx_rcc_init() for this target:
* HSE -> PSI (ref 48 MHz, out 144 MHz) -> PSIS -> SYSCLK, all bus
* prescalers /1, flash 4 WS + WRHIGHFREQ delay 2. On any timeout
* we leave the chip on its reset clock so boot still proceeds.
*/
static void clock_psi_on(void)
{
uint32_t reg;
volatile uint32_t timeout;
/* 1. Enable HSE (48 MHz on NUCLEO-C5A3ZG). */
if ((RCC_CR1 & RCC_CR1_HSEON) == 0)
RCC_CR1 |= RCC_CR1_HSEON;
timeout = HSE_TIMEOUT;
while (((RCC_CR1 & RCC_CR1_HSERDY) == 0) && (--timeout != 0))
;
if (timeout == 0)
return;
/* 2. Configure PSI: ref source = HSE, ref freq = 48 MHz,
* output = 144 MHz. PSIS/PSIDIV3/PSIK are all off at reset
* so a plain field write is safe on first boot.
*/
reg = RCC_CR2 & ~RCC_CR2_PSI_FIELDS_MASK;
reg |= RCC_CR2_PSIREFSRC_HSE | RCC_CR2_PSIREF_48MHZ |
RCC_CR2_PSIFREQ_144MHZ;
RCC_CR2 = reg;
/* 3. Enable PSIS, wait for ready. */
RCC_CR1 |= RCC_CR1_PSISON;
timeout = PSI_TIMEOUT;
while (((RCC_CR1 & RCC_CR1_PSISRDY) == 0) && (--timeout != 0))
;
if (timeout == 0)
return;
/* 4. All bus prescalers /1. Reset value is already 0; explicit
* write keeps the intent visible.
*/
RCC_CFGR2 = 0;
/* 5. Flash 4 WS + prefetch BEFORE switching SYSCLK to 144 MHz. */
flash_set_waitstates(FLASH_ACR_LATENCY_4WS);
FLASH_ACR |= FLASH_ACR_PRFTEN;
/* 6. Switch SYSCLK to PSIS. */
reg = RCC_CFGR1 & ~RCC_CFGR1_SW_MASK;
RCC_CFGR1 = reg | RCC_CFGR1_SW_PSIS;
timeout = SW_TIMEOUT;
while (((RCC_CFGR1 & RCC_CFGR1_SWS_MASK) != RCC_CFGR1_SWS_PSIS) &&
(--timeout != 0))
;
if (timeout == 0)
return; /* SYSCLK is still HSIDIV3; skip 144-MHz-only setup. */
/* 7. Programming delay 2 (required at HCLK >= 136 MHz). */
reg = FLASH_ACR & ~FLASH_ACR_WRHIGHFREQ_MASK;
FLASH_ACR = reg | FLASH_ACR_WRHIGHFREQ_DELAY2;
}
#ifdef WOLFBOOT_RESTORE_CLOCK
/* Lightweight system-clock restore: switch SYSCLK back to HSIDIV3.
* PSIS, PSI, HSE, and FLASH_ACR are deliberately left at their
* PSIS-runtime values (4 WS / WRHIGHFREQ delay 2 are over-provisioned
* for HSIDIV3 16 MHz but harmless). Mirrors ST's
* HAL_RCC_ResetSystemClock() rather than the full HAL_RCC_Reset().
*
* Why not also disable HSE / tear down PSIS? Rapid HSE disable
* followed by re-enable in the loaded firmware's own clock_psi_on()
* is not reliable on this part - the oscillator does not always
* stabilize fast enough on a back-to-back cycle, the wait for
* HSERDY times out, and the chip stays at HSIDIV3 with the loaded
* firmware's UART baud divisor wrong by 9x. Leaving HSE on means
* clock_psi_on() in the loaded firmware skips the re-enable wait
* entirely (HSEON / HSERDY already set), which both fixes the boot
* hang and makes the loaded firmware's startup faster. Loaded
* firmware that needs the chip in a fully reset oscillator state
* can clear RCC itself.
*/
static void clock_psi_off(void)
{
volatile uint32_t timeout;
/* 1. Make sure HSIDIV3 is on (the post-reset source). */
if ((RCC_CR1 & RCC_CR1_HSIDIV3ON) == 0)
RCC_CR1 |= RCC_CR1_HSIDIV3ON;
timeout = PSI_TIMEOUT;
while (((RCC_CR1 & RCC_CR1_HSIDIV3RDY) == 0) && (--timeout != 0))
;
/* 2. Switch SYSCLK back to HSIDIV3. */
RCC_CFGR1 = (RCC_CFGR1 & ~RCC_CFGR1_SW_MASK) | RCC_CFGR1_SW_HSIDIV3;
timeout = SW_TIMEOUT;
while (((RCC_CFGR1 & RCC_CFGR1_SWS_MASK) != RCC_CFGR1_SWS_HSIDIV3) &&
(--timeout != 0))
;
/* FLASH_ACR and RCC_CFGR2 are deliberately left at their PSIS
* runtime values; over-provisioned for HSIDIV3 16 MHz but
* harmless. HSE / PSI tear-down is also deliberately not done
* here - the crystal does not reliably restart in the window
* between clock_psi_off() and the loaded firmware's own
* clock_psi_on() during a swap-then-jump (no reset between).
*/
}
#endif /* WOLFBOOT_RESTORE_CLOCK */
void hal_init(void)
{
clock_psi_on();
hal_cache_enable(1);
#if defined(DEBUG_UART) && defined(__WOLFBOOT)
uart_init();
uart_write("wolfBoot HAL Init\n", sizeof("wolfBoot HAL Init\n") - 1);
#endif
#if defined(DUALBANK_SWAP) && defined(__WOLFBOOT)
/* Make sure both bank starts hold an identical wolfBoot image so
* that 0x08000000 boots correctly after a SWAP_BANK toggle.
*/
fork_bootloader();
#endif
}
void hal_prepare_boot(void)
{
#if defined(DEBUG_UART) && defined(__WOLFBOOT)
/* Drain UART TX shift register before any SYSCLK change - otherwise
* the trailing byte (still being shifted out at PSIS / 144 MHz BRR)
* gets corrupted when SYSCLK switches and the next byte from the
* loaded firmware is preceded by garbage on the wire.
*/
while ((USART2_ISR & UART_ISR_TC) == 0)
;
#endif
#ifdef WOLFBOOT_RESTORE_CLOCK
clock_psi_off();
#endif
}
void RAMFUNCTION hal_cache_enable(int way)
{
uint32_t reg;
/* Mask WAYSEL before OR-in so passing way=0 after a prior
* way=1 call actually switches back to 1-way (1WAY == 0).
*/
reg = ICACHE_CR & ~ICACHE_CR_WAYSEL;
ICACHE_CR = reg | (way ? ICACHE_CR_2WAYS : ICACHE_CR_1WAY);
ICACHE_CR |= ICACHE_CR_CEN;
}
void RAMFUNCTION hal_cache_disable(void)
{
ICACHE_CR &= ~ICACHE_CR_CEN;
}
void RAMFUNCTION hal_cache_invalidate(void)
{
if ((ICACHE_CR & ICACHE_CR_CEN) == 0)
return;
if ((ICACHE_SR & ICACHE_SR_BUSYF) == 0)
ICACHE_CR |= ICACHE_CR_CACHEINV;
while ((ICACHE_SR & ICACHE_SR_BSYENDF) == 0)
;
/* ICACHE_SR is write-1-to-clear; use a plain store so we ack
* only BSYENDF and don't accidentally clear other latched
* flags such as ERRF.
*/
ICACHE_SR = ICACHE_SR_BSYENDF;
}
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