49 lines
1.3 KiB
Rust
49 lines
1.3 KiB
Rust
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use cortex_m_rt::{pre_init};
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const DFU_TRIG_MSG: u32 = 0xDECAFBAD;
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extern "C" {
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// This symbol comes from memory.x
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static mut _dfu_msg: u32;
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}
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pub unsafe fn set_dfu_trigger() {
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_dfu_msg = DFU_TRIG_MSG;
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}
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/// Called by reset handler in lib.rs immediately after reset.
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/// This function should not be called outside of reset handler as
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/// bootloader expects MCU to be in reset state when called.
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#[pre_init]
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unsafe fn __pre_init() {
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if _dfu_msg == DFU_TRIG_MSG {
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_dfu_msg = 0x00000000;
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// Enable system config controller clock
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const RCC_APB2ENR: *mut u32 = 0xE000_ED88 as *mut u32;
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const RCC_APB2ENR_ENABLE_SYSCFG_CLOCK: u32 = 0x00004000;
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core::ptr::write_volatile(
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RCC_APB2ENR,
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*RCC_APB2ENR | RCC_APB2ENR_ENABLE_SYSCFG_CLOCK,
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);
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// Bypass BOOT pins and remap bootloader to 0x00000000
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const SYSCFG_MEMRMP: *mut u32 = 0x40013800 as *mut u32;
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const SYSCFG_MEMRMP_MAP_ROM: u32 = 0x00000001;
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core::ptr::write_volatile(
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SYSCFG_MEMRMP,
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*SYSCFG_MEMRMP | SYSCFG_MEMRMP_MAP_ROM,
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);
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asm!(
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// Set stack pointer to bootloader location
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"LDR R0, =0x1FFF0000",
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"LDR SP,[R0, #0]",
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// Jump to bootloader
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"LDR R0,[R0, #4]",
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"BX R0",
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);
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}
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}
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