diff --git a/components/bt/hli_vectors.S b/components/bt/hli_vectors.S index 3a6ab92af0..525cd1b53d 100644 --- a/components/bt/hli_vectors.S +++ b/components/bt/hli_vectors.S @@ -8,41 +8,124 @@ #include "sdkconfig.h" #include "soc/soc.h" +/* Interrupt stack size, for C code. + * TODO: reduce and make configurable. + */ #define L5_INTR_STACK_SIZE 4096 + +/* Save area for the CPU state: + * - 64 words for the general purpose registers + * - 7 words for some of the special registers: + * - WINDOWBASE, WINDOWSTART — only WINDOWSTART is truly needed + * - SAR, LBEG, LEND, LCOUNT — since the C code might use these + * - EPC1 — since the C code might cause window overflow exceptions + * This is not laid out a standard exception frame structure + * for simplicity of the save/restore code. + */ +#define REG_FILE_SIZE (64 * 4) +#define SPECREG_OFFSET REG_FILE_SIZE +#define SPECREG_SIZE (7 * 4) +#define REG_SAVE_AREA_SIZE (SPECREG_OFFSET * SPECREG_SIZE) + .data _l5_intr_stack: .space L5_INTR_STACK_SIZE +_l5_save_ctx: + .space REG_SAVE_AREA_SIZE + .section .iram1,"ax" .global xt_highint5 .type xt_highint5,@function .align 4 xt_highint5: - /* Allocate exception frame and save minimal context. */ - mov a0, sp - addi sp, sp, -XT_STK_FRMSZ - s32i a0, sp, XT_STK_A1 - #if XCHAL_HAVE_WINDOWED - s32e a0, sp, -12 /* for debug backtrace */ - #endif - rsr a0, EPS_5 /* save interruptee's PS */ - s32i a0, sp, XT_STK_PS - rsr a0, EPC_5 /* save interruptee's PC */ - s32i a0, sp, XT_STK_PC - #if XCHAL_HAVE_WINDOWED - s32e a0, sp, -16 /* for debug backtrace */ - #endif - s32i a12, sp, XT_STK_A12 /* _xt_context_save requires A12- */ - s32i a13, sp, XT_STK_A13 /* A13 to have already been saved */ - call0 _xt_context_save + /* disable exception mode, window overflow */ + movi a0, PS_INTLEVEL(5) | PS_EXCM /*TOCHECK*/ + wsr a0, PS + rsync -_highint5_stack_switch: - mov a7, sp + movi a0, _l4_save_ctx + /* save 4 lower registers */ + s32i a1, a0, 4 + s32i a2, a0, 8 + s32i a3, a0, 12 + rsr a2, EXCSAVE_5 /* holds the value of a0 */ + s32i a2, a0, 0 + + /* Save special registers */ + addi a0, a0, SPECREG_OFFSET + rsr a2, WINDOWBASE + s32i a2, a0, 0 + rsr a2, WINDOWSTART + s32i a2, a0, 4 + rsr a2, SAR + s32i a2, a0, 8 + rsr a2, LBEG + s32i a2, a0, 12 + rsr a2, LEND + s32i a2, a0, 16 + rsr a2, LCOUNT + s32i a2, a0, 20 + rsr a2, EPC1 + s32i a2, a0, 24 + + /* Save the remaining physical registers. + * 4 registers are already saved, which leaves 60 registers to save. + * (FIXME: consider the case when the CPU is configured with physical 32 registers) + * These 60 registers are saved in 5 iterations, 12 registers at a time. + */ + movi a1, 5 + movi a3, _l5_save_ctx + 4 * 4 + + /* This is repeated 5 times, each time the window is shifted by 12 registers. + * We come here with a1 = downcounter, a3 = save pointer, a2 and a0 unused. + */ +1: + s32i a4, a3, 0 + s32i a5, a3, 4 + s32i a6, a3, 8 + s32i a7, a3, 12 + s32i a8, a3, 16 + s32i a9, a3, 20 + s32i a10, a3, 24 + s32i a11, a3, 28 + s32i a12, a3, 32 + s32i a13, a3, 36 + s32i a14, a3, 40 + s32i a15, a3, 44 + + /* We are about to rotate the window, so that a12-a15 will become the new a0-a3. + * Copy a0-a3 to a12-15 to still have access to these values. + * At the same time we can decrement the counter and adjust the save area pointer + */ + + /* a0 is constant (_l5_save_ctx), no need to copy */ + addi a13, a1, -1 /* copy and decrement the downcounter */ + /* a2 is scratch so no need to copy */ + addi a15, a3, 48 /* copy and adjust the save area pointer */ + beqz a13, 2f /* have saved all registers ? */ + rotw 3 /* rotate the window and go back */ + j 1b + + /* the loop is complete */ +2: + rotw 4 /* this brings us back to the original window */ + /* a0 still points to _l5_save_ctx */ + + /* Can clear WINDOWSTART now, all registers are saved */ + rsr a2, WINDOWBASE + /* WINDOWSTART = (1 << WINDOWBASE) */ + movi a3, 1 + ssl a2 + sll a3, a3 + wsr a3, WINDOWSTART + +_highint4_stack_switch: + movi a0, 0 movi sp, _l5_intr_stack + L5_INTR_STACK_SIZE - 16 - s32e a7, sp, -12 - movi a0, _Level5Vector+6 /* For GDB: pretend we came from the interrupt vector */ - s32e a0, sp, -16 + s32e a0, sp, -12 /* For GDB: set null SP */ + s32e a0, sp, -16 /* For GDB: set null PC */ movi a0, _highint5_stack_switch /* For GDB: cosmetics, for the frame where stack switch happened */ /* Set up PS for C, disable all interrupts except NMI and debug, and clear EXCM. */ @@ -56,17 +139,84 @@ _highint5_stack_switch: l32e sp, sp, -12 /* switch back to the original stack */ - call0 _xt_context_restore - l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */ - wsr a0, EPS_5 - l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */ - wsr a0, EPC_5 - l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */ - l32i sp, sp, XT_STK_A1 /* remove exception frame */ - rsync /* ensure PS and EPC written */ + /* Done with C handler; re-enable exception mode, disabling window overflow */ + movi a2, PS_INTLEVEL(5) | PS_EXCM /* TOCHECK */ + wsr a2, PS + rsync - rsr a0, EXCSAVE_5 /* restore a0 */ - rfi 5 + /* Restore the special registers. + * WINDOWSTART will be restored near the end. + */ + movi a0, _l5_save_ctx + SPECREG_OFFSET + l32i a2, a0, 8 + wsr a2, SAR + l32i a2, a0, 12 + wsr a2, LBEG + l32i a2, a0, 16 + wsr a2, LEND + l32i a2, a0, 20 + wsr a2, LCOUNT + l32i a2, a0, 24 + wsr a2, EPC1 + + /* Restoring the physical registers. + * This is the reverse to the saving process above. + */ + + /* Rotate back to the final window, then start loading 12 registers at a time, + * in 5 iterations. + * Again, a1 is the downcounter and a3 is the save area pointer. + * After each rotation, a1 and a3 are copied from a13 and a15. + * To simplify the loop, we put the initial values into a13 and a15. + */ + rotw -4 + movi a15, _l5_save_ctx + 64 * 4 /* point to the end of the save area */ + movi a13, 5 + +1: + /* Copy a1 and a3 from their previous location, + * at the same time decrementing and adjusting the save area pointer. + */ + addi a1, a13, -1 + addi a3, a15, -48 + + /* Load 12 registers */ + l32i a4, a3, 0 + l32i a5, a3, 4 + l32i a6, a3, 8 + l32i a7, a3, 12 + l32i a8, a3, 16 + l32i a9, a3, 20 + l32i a10, a3, 24 + l32i a11, a3, 28 /* ensure PS and EPC written */ + l32i a12, a3, 32 + l32i a13, a3, 36 + l32i a14, a3, 40 + l32i a15, a3, 44 + + /* Done with the loop? */ + beqz a1, 2f + /* If no, rotate the window and repeat */ + rotw -3 + j 1b + +2: + /* Done with the loop. Only 4 registers (a0-a3 in the original window) remain + * to be restored. Also need to restore WINDOWSTART, since all the general + * registers are now in place. + */ + movi a0, _l5_save_ctx + + l32i a2, a0, SPECREG_OFFSET + 4 + wsr a2, WINDOWSTART + + l32i a1, a0, 4 + l32i a2, a0, 8 + l32i a3, a0, 12 + rsr a0, EXCSAVE_4 /* holds the value of a0 before the interrupt handler */ + + /* Return from the interrupt, restoring PS from EPS_5 */ + rfi 4 /* The linker has no reason to link in this file; all symbols it exports are already defined (weakly!) in the default int handler. Define a symbol here so we can use it to have the