diff options
Diffstat (limited to 'openpicc/os/boot/boot.s')
| -rw-r--r-- | openpicc/os/boot/boot.s | 150 |
1 files changed, 42 insertions, 108 deletions
diff --git a/openpicc/os/boot/boot.s b/openpicc/os/boot/boot.s index d9ac156..4fca262 100644 --- a/openpicc/os/boot/boot.s +++ b/openpicc/os/boot/boot.s @@ -4,9 +4,7 @@ .extern exit .extern AT91F_LowLevelInit .extern pio_irq_isr_value - .extern ssc_tx_pending - .extern ssc_tx_fiq_fdt_cdiv - .extern ssc_tx_fiq_fdt_ssc + .extern tc_sniffer_next_buffer_for_fiq .text .code 32 @@ -47,15 +45,14 @@ .equ AT91C_BASE_MC, (0xFFFFFF00) .equ AT91C_BASE_PIOA, 0xFFFFF400 .equ AT91C_BASE_TC0, 0xFFFA0000 +.equ AT91C_BASE_TC2, 0xFFFA0080 .equ AT91C_BASE_SSC, 0xFFFD4000 .equ SSC_CR, 0x0 .equ SSC_RCMR, 0x10 .equ SSC_CR_TXEN, 0x100 .equ AT91C_TC_SWTRG, ((1 << 2)|1) .equ AT91C_TC_CLKEN, (1 << 0) -.equ PIO_DATA, (1 << 27) -.equ PIO_FRAME, (1 << 20) -.equ PIO_SSC_TF, (1 << 15) +.equ PIO_DATA, (1 << 18) .equ PIOA_SODR, 0x30 .equ PIOA_CODR, 0x34 .equ PIOA_PDSR, 0x3c @@ -71,6 +68,8 @@ .equ PIO_SECONDARY_IRQ, 31 .equ PIO_SECONDARY_IRQ_BIT, (1 << PIO_SECONDARY_IRQ) +.equ BUFSIZE, 1024 + start: _start: _mainCRTStartup: @@ -90,7 +89,6 @@ _mainCRTStartup: ldr r10, =AT91C_BASE_PIOA ldr r12, =AT91C_BASE_TC0 ldr r8, =AT91C_BASE_AIC - mov r9, #AT91C_TC_SWTRG /*ldr r9, =AT91C_BASE_SSC*/ mov sp, r0 sub r0, r0, #FIQ_STACK_SIZE @@ -196,7 +194,7 @@ endless_loop: my_fiq_handler: /* code that uses pre-initialized FIQ reg */ /* r8 tmp - r9 AT91C_TC_SWTRG + r9 tmp r10 AT91C_BASE_PIOA r11 tmp r12 AT91C_BASE_TC0 @@ -215,111 +213,47 @@ my_fiq_handler: str r8, [r11] tst r8, #PIO_DATA /* check for PIO_DATA change */ - ldrne r11, [r10, #PIOA_PDSR] - tstne r11, #PIO_DATA /* check for PIO_DATA == 1 */ - /*strne r9, [r12, #TC_CCR] /* software trigger */ - - movne r11, #PIO_DATA - strne r11, [r10, #PIOA_IDR] /* disable further PIO_DATA FIQ */ - beq .no_pio_data -/* .loop_high: - ldr r11, [r10, #PIOA_PDSR] - tst r11, #PIO_DATA - bne .loop_high - str r9, [r12, #TC_CCR] /* software trigger */ - -.no_pio_data: - tst r8, #PIO_SSC_TF /* check for SSC Transmit Frame signal */ - ldrne r11, [r10, #PIOA_PDSR] - tstne r11, #PIO_SSC_TF /* check for SSC_TF == 1 */ - - movne r11, #PIO_SSC_TF - strne r11, [r10, #PIOA_IDR] /* disable further SSC_TF FIQ */ - - ldrne r11, =ssc_tx_pending - ldrne r8, [r11] - tstne r8, #0x01 /* Check whether a TX is pending */ - beq .no_ssc - b .no_ssc + beq .no_buffer - mov r8, #PIO_LED1 - str r8, [r10, #PIOA_SODR] /* disable LED */ + ldr r11, [r10, #PIOA_PDSR] + tst r11, #PIO_DATA /* check for PIO_DATA == 1 */ + beq .no_buffer + +/* mov r11, #PIO_LED2 + str r11, [r10, #PIOA_CODR] /* enable LED */ + + /* Load the TC2.CV into r9 */ + ldr r9, [r12, #TC2_CV] - mov r8, #0x00 - str r8, [r11] /* Set ssc_tx_pending to 0 */ + ldr r11, =tc_sniffer_next_buffer_for_fiq + ldr r11, [r11] + /* r11 now contains the value of tc_sniffer_next_buffer_for_fiq, e.q. the address + * of the next buffer */ - ldr r11, =ssc_tx_fiq_fdt_cdiv - ldr r11, [r11] /* r11 == ssc_tx_fiq_fdt_cdiv */ - -/* Problem: LDR from the timer and loop still take too long and cause us to miss the exact time. - * (One load-from-timer,compare,jump-back-if-less cycle are 7 CPU cycles, which are 2 carrier cycles.) - * Strategy: Spin on TC2 till 3 or 4 carrier cycles before the actual time. Then go into an unrolled - * 'loop' for the remaining time. (load-from-timer,compare,jump-forward-if-greater-or-equal are 5 CPU - * cycles if the condition is not reached.) - * - * At 47.923200 MHz 7 processor cycles are 2 carrier cycles of the 13.56MHz carrier - */ - .equ SUB_TIME, 4 /* subtract 4 carrier cycles == 14 processor cycles */ - - mov r8, #SUB_TIME - sub r11, r11, r8 /* r11 == fdt_cdiv-SUB_TIME */ - -.wait_for_fdt_cdiv: - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - blt .wait_for_fdt_cdiv /* spin while TC2.CV is less fdt_cdiv-SUB_TIME */ - - mov r8, #SUB_TIME - add r11, r11, r8 /* r11 == fdt_cdiv */ - -/* Seven copies of the loop contents, covering for 35 CPU cycles, or 10 carrier cycles */ - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired /* jump forward if TC2.CV is greater than or equal fdt_cdiv */ - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bge .fdt_expired - -.fdt_expired: - str r9, [r12, #TC_CCR] /* SWTRG on TC0 */ - - ldr r11, =ssc_tx_fiq_fdt_ssc - ldr r11, [r11] /* r11 == ssc_tx_fiq_fdt_ssc */ - -.wait_for_fdt_ssc: - ldr r8, [r12, #TC2_CV] - cmp r8, r11 - bmi .wait_for_fdt_ssc /* spin while TC2.CV is less fdt_ssc */ + /* Jump to .no_buffer if the pointer is 0, indicating that no buffer is set */ + cmp r11, #0 + beq .no_buffer - mov r11, #PIO_LED1 - str r11, [r10, #PIOA_CODR] /* enable LED */ + /* Increment the value at the location the pointer points to */ + ldr r8, [r11] + add r8, r8, #1 + str r8, [r11] + + /* At this point: + r8 = count + r9 = TC2.CV + r11 = pointer to buffer + */ + + cmp r8, #BUFSIZE + bge .no_buffer + + str r9, [r11, r8, LSL #2] + +.no_buffer: +/* mov r11, #PIO_LED2 + str r11, [r10, #PIOA_SODR] /* disable LED */ - ldr r11, =AT91C_BASE_SSC - mov r8, #SSC_CR_TXEN - str r8, [r11, #SSC_CR] /* Write TXEN to SSC_CR, enables tx */ - -.no_ssc: /* Trigger PIO_SECONDARY_IRQ */ mov r11, #PIO_SECONDARY_IRQ_BIT ldr r8, =AT91C_BASE_AIC |