233 lines
4.5 KiB
C
233 lines
4.5 KiB
C
#include <AT91SAM7S64.h>
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#include <stdint.h>
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#define USED __attribute__((used))
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#define USED_NAKED __attribute__((used,naked))
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#define USED_INT(type) __attribute__((used,interrupt(#type)))
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#if MCK > 30000000
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#define FLASH_CYCLES AT91C_MC_FWS_1FWS
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#else
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#define FLASH_CYCLES AT91C_MC_FWS_0FWS
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#endif
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#ifndef MAIN_OSC_FREQ
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#define MAIN_OSC_FREQ 18432000
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#endif
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#if MAIN_OSC_FREQ != 18432000
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#error Unsupported main oscilator frequency
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#endif
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#if MCK == 23961600
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#define PLL_DIV 5
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#define PLL_MUL 26
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#define PLL_USBDIV_EXP 1
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#define MCK_DIV_EXP 2
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#elif MCK == 47923200
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#define PLL_DIV 5
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#define PLL_MUL 26
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#define PLL_USBDIV_EXP 1
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#define MCK_DIV_EXP 1
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#else
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#error "Unsupported main clock frequency"
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#endif
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#define PLL_FREQ ((MAIN_OSC_FREQ * PLL_MUL) / PLL_DIV)
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#if PLL_FREQ > 180000000
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#error "PLL frequency too high"
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#elif PLL_FREQ < 80000000
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#error "PLL frequency too low"
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#endif
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#if PLL_FREQ > 155000000
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#define PLL_RANGE AT91C_CKGR_OUT_2
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#else
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#define PLL_RANGE AT91C_CKGR_OUT_0
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#endif
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#if PLL_USBDIV > 2
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#error "PLL frequency too high for USB"
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#endif
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#define USB_FREQ (PLL_FREQ / (1<<PLL_USBDIV_EXP))
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#if USB_FREQ > 48120000 || USB_FREQ < 47880000
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#warning "USB frequency outside limits"
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#endif
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#if MCK * (1<<MCK_DIV_EXP) != PLL_FREQ
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#error PLL frequency is not a the correct multiple of the main clock
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#endif
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/* CPU modes */
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#define Mode_USR 0x10
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#define Mode_FIQ 0x11
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#define Mode_IRQ 0x12
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#define Mode_SVC 0x13
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#define Mode_ABT 0x17
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#define Mode_UND 0x1B
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#define Mode_SYS 0x1F
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/* IRQ disable bit */
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#define I_Bit 0x80
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/* FIQ disable bit */
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#define F_Bit 0x40
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#define SET_MODE_STACK(mode, stack_end) \
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asm("msr CPSR_c, %0\nldr sp, =" #stack_end "\n" ::"i" ((mode)|I_Bit|F_Bit))
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#define ENABLE_INTS() \
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asm("mrs r0, cpsr\nand r0, %0\nmsr cpsr_c, r0\n"::"i" (~(I_Bit|F_Bit)):"r0")
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extern void *USR_Stack_End;
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extern void *UND_Stack_End;
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extern void *ABT_Stack_End;
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extern void *FIQ_Stack_End;
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extern void *IRQ_Stack_End;
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extern void *SVC_Stack_End;
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extern uint8_t _data[];
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extern uint8_t _etext[];
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extern uint8_t _edata[];
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extern uint8_t __bss_start[];
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extern uint8_t __bss_end[];
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extern int
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main(int argc, char *argv[]);
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static void
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copy_initialized(void)
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{
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uint8_t *ram = _data;
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uint8_t *rom = _etext;
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while(ram < _edata) {
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*ram++ = *rom++;
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}
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}
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static void
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clear_bss(void)
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{
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uint8_t *m = __bss_start;
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while(m < __bss_end) {
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*m++ = 0;
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}
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}
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static void
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Reset_handler(void) USED_NAKED;
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static void
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SPU_handler(void) __attribute__((interrupt("IRQ")));
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static void
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Reset_handler(void)
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{
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/* Setup flash timing */
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*AT91C_MC_FMR = FLASH_CYCLES | (MCK / 666666 + 1);
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/* Disable watchdog */
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*AT91C_WDTC_WDMR = AT91C_WDTC_WDDIS;
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/* Setup reset controller */
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*AT91C_RSTC_RMR = (0xa5<<24) | AT91C_RSTC_URSTS;
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/* Start main oscilator */
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*AT91C_CKGR_MOR = AT91C_CKGR_MOSCEN | (6<<8);
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/* Wait for oscillator to start */
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while(!(*AT91C_PMC_SR & AT91C_PMC_MOSCS));
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/* Setup PLL */
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*AT91C_CKGR_PLLR = ((PLL_USBDIV_EXP << 28) | ((PLL_MUL-1)<<16) | PLL_RANGE
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| (28<<8) | PLL_DIV);
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/* Wait for PLL to lock */
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while(!(*AT91C_PMC_SR & AT91C_PMC_LOCK));
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*AT91C_PMC_MCKR = (MCK_DIV_EXP << 2);
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while(!(*AT91C_PMC_SR & AT91C_PMC_MCKRDY));
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*AT91C_PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK;
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while(!(*AT91C_PMC_SR & AT91C_PMC_MCKRDY));
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SET_MODE_STACK(Mode_UND, UND_Stack_End);
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SET_MODE_STACK(Mode_ABT, ABT_Stack_End);
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SET_MODE_STACK(Mode_FIQ, FIQ_Stack_End);
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SET_MODE_STACK(Mode_IRQ, IRQ_Stack_End);
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SET_MODE_STACK(Mode_SVC, SVC_Stack_End);
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#ifdef RUN_AS_SYSTEM
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SET_MODE_STACK(Mode_SYS, USR_Stack_End);
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#else
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SET_MODE_STACK(Mode_USR, USR_Stack_End);
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#endif
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copy_initialized();
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clear_bss();
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*AT91C_AIC_SPU = (uint32_t)SPU_handler;
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ENABLE_INTS();
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main(0,0);
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while(1);
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}
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static void
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Undef_handler(void) USED_INT(UNDEF);
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static void
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Undef_handler(void)
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{
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}
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static void
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SWI_handler(void) USED_INT(SWI);
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static void
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SWI_handler(void)
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{
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}
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static void
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PAbt_handler(void) USED_INT(ABORT);
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static void
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PAbt_handler(void)
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{
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}
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static void
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DAbt_handler(void) USED_INT(ABORT);
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static void
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DAbt_handler(void)
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{
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}
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static void
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SPU_handler(void)
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{
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*AT91C_AIC_EOICR = 0;
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}
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static void
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Vectors(void) __attribute__ ((naked, section(".vectrom")));
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static void
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Vectors(void)
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{
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asm("ldr pc, =Reset_handler\n");
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asm("ldr pc, =Undef_handler\n");
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asm("ldr pc, =SWI_handler\n");
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asm("ldr pc, =PAbt_handler\n");
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asm("ldr pc, =DAbt_handler\n");
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asm("nop\n");
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asm("ldr pc,[pc,#-0xf20]\n"); /* Vector From AIC_IVR */
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asm("ldr pc,[pc,#-0xf20]\n"); /* Vector From AIC_FVR */
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}
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void foo_dummy()
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{
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Vectors();
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}
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