OpenWrt – Rev 4
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#include "AT91RM9200_inc.h"
#define ARM_MODE_USER 0x10
#define ARM_MODE_FIQ 0x11
#define ARM_MODE_IRQ 0x12
#define ARM_MODE_SVC 0x13
#define ARM_MODE_ABORT 0x17
#define ARM_MODE_UNDEF 0x1B
#define ARM_MODE_SYS 0x1F
#define I_BIT 0x80
#define F_BIT 0x40
#define T_BIT 0x20
/* -----------------------------------------------------------------------------
AT91F_ASM_SPI_Handler
---------------------
Handler called by the AIC
Save context
Call C handler
Restore context
----------------------------------------------------------------------------- */
.global AT91F_ST_ASM_HANDLER
AT91F_ST_ASM_HANDLER:
/* Adjust and save LR_irq in IRQ stack */
sub r14, r14, #4
stmfd sp!, {r14}
/* Write in the IVR to support Protect Mode
No effect in Normal Mode
De-assert the NIRQ and clear the source in Protect Mode */
ldr r14, =AT91C_BASE_AIC
str r14, [r14, #AIC_IVR]
/* Save SPSR and r0 in IRQ stack */
mrs r14, SPSR
stmfd sp!, {r0, r14}
/* Enable Interrupt and Switch in SYS Mode */
mrs r0, CPSR
bic r0, r0, #I_BIT
orr r0, r0, #ARM_MODE_SYS
msr CPSR_c, r0
/* Save scratch/used registers and LR in User Stack */
stmfd sp!, { r1-r3, r12, r14}
ldr r1, =AT91F_ST_HANDLER
mov r14, pc
bx r1
/* Restore scratch/used registers and LR from User Stack */
ldmia sp!, { r1-r3, r12, r14}
/* Disable Interrupt and switch back in IRQ mode */
mrs r0, CPSR
bic r0, r0, #ARM_MODE_SYS
orr r0, r0, #I_BIT | ARM_MODE_IRQ
msr CPSR_c, r0
/* Mark the End of Interrupt on the AIC */
ldr r0, =AT91C_BASE_AIC
str r0, [r0, #AIC_EOICR]
/* Restore SPSR_irq and r0 from IRQ stack */
ldmia sp!, {r0, r14}
msr SPSR_cxsf, r14
/* Restore adjusted LR_irq from IRQ stack directly in the PC */
ldmia sp!, {pc}^