diff options
Diffstat (limited to 'drivers/acorn/block/mfm.S')
| -rw-r--r-- | drivers/acorn/block/mfm.S | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/acorn/block/mfm.S b/drivers/acorn/block/mfm.S new file mode 100644 index 00000000000..c90cbd41ce2 --- /dev/null +++ b/drivers/acorn/block/mfm.S @@ -0,0 +1,162 @@ +@ Read/Write DMA code for the ST506/MFM hard drive controllers on the A400 Acorn Archimedes +@ motherboard and on ST506 expansion podules. +@ (c) David Alan Gilbert (linux@treblig.org) 1996-1999 + +#include <asm/assembler.h> + +hdc63463_irqdata: +@ Controller base address + .global hdc63463_baseaddress +hdc63463_baseaddress: + .word 0 + + .global hdc63463_irqpolladdress +hdc63463_irqpolladdress: + .word 0 + + .global hdc63463_irqpollmask +hdc63463_irqpollmask: + .word 0 + +@ where to read/write data from the kernel data space + .global hdc63463_dataptr +hdc63463_dataptr: + .word 0 + +@ Number of bytes left to transfer + .global hdc63463_dataleft +hdc63463_dataleft: + .word 0 + +@ ------------------------------------------------------------------------- +@ hdc63463_writedma: DMA from host to controller +@ internal reg usage: r0=hdc base address, r1=irq poll address, r2=poll mask +@ r3=data ptr, r4=data left, r5,r6=temporary + .global hdc63463_writedma +hdc63463_writedma: + stmfd sp!,{r4-r7} + adr r5,hdc63463_irqdata + ldmia r5,{r0,r1,r2,r3,r4} + +writedma_again: + + @ test number of remaining bytes to transfer + cmp r4,#0 + beq writedma_end + bmi writedma_end + + @ Check the hdc is interrupting + ldrb r5,[r1,#0] + tst r5,r2 + beq writedma_end + + @ Transfer a block of upto 256 bytes + cmp r4,#256 + movlt r7,r4 + movge r7,#256 + + @ Check the hdc is still busy and command has not ended and no errors + ldr r5,[r0,#32] @ Status reg - 16 bit - its the top few bits which are status + @ think we should continue DMA until it drops busy - perhaps this was + @ the main problem with corrected errors causing a hang + @tst r5,#0x3c00 @ Test for things which should be off + @bne writedma_end + and r5,r5,#0x8000 @ This is test for things which should be on: Busy + cmp r5,#0x8000 + bne writedma_end + + @ Bytes remaining at end + sub r4,r4,r7 + + @ HDC Write register location + add r0,r0,#32+8 + +writedma_loop: + @ OK - pretty sure we should be doing this + + ldr r5,[r3],#4 @ Get a word to be written + @ get bottom half to be sent first + mov r6,r5,lsl#16 @ Separate the first 2 bytes + orr r2,r6,r6,lsr #16 @ Duplicate them in the bottom half of the word + @ now the top half + mov r6,r5,lsr#16 @ Get 2nd 2 bytes + orr r6,r6,r6,lsl#16 @ Duplicate + @str r6,[r0] @ to hdc + stmia r0,{r2,r6} + subs r7,r7,#4 @ Dec. number of bytes left + bne writedma_loop + + @ If we were too slow we had better go through again - DAG - took out with new interrupt routine + @ sub r0,r0,#32+8 + @ adr r2,hdc63463_irqdata + @ ldr r2,[r2,#8] + @ b writedma_again + +writedma_end: + adr r5,hdc63463_irqdata+12 + stmia r5,{r3,r4} + ldmfd sp!,{r4-r7} + RETINSTR(mov,pc,lr) + +@ ------------------------------------------------------------------------- +@ hdc63463_readdma: DMA from controller to host +@ internal reg usage: r0=hdc base address, r1=irq poll address, r2=poll mask +@ r3=data ptr, r4=data left, r5,r6=temporary + .global hdc63463_readdma +hdc63463_readdma: + stmfd sp!,{r4-r7} + adr r5,hdc63463_irqdata + ldmia r5,{r0,r1,r2,r3,r4} + +readdma_again: + @ test number of remaining bytes to transfer + cmp r4,#0 + beq readdma_end + bmi readdma_end + + @ Check the hdc is interrupting + ldrb r5,[r1,#0] + tst r5,r2 + beq readdma_end + + @ Check the hdc is still busy and command has not ended and no errors + ldr r5,[r0,#32] @ Status reg - 16 bit - its the top few bits which are status + @ think we should continue DMA until it drops busy - perhaps this was + @ the main problem with corrected errors causing a hang + @tst r5,#0x3c00 @ Test for things which should be off + @bne readdma_end + and r5,r5,#0x8000 @ This is test for things which should be on: Busy + cmp r5,#0x8000 + bne readdma_end + + @ Transfer a block of upto 256 bytes + cmp r4,#256 + movlt r7,r4 + movge r7,#256 + + @ Bytes remaining at end + sub r4,r4,r7 + + @ Set a pointer to the data register in the HDC + add r0,r0,#8 +readdma_loop: + @ OK - pretty sure we should be doing this + ldmia r0,{r5,r6} + mov r5,r5,lsl#16 + mov r6,r6,lsl#16 + orr r6,r6,r5,lsr #16 + str r6,[r3],#4 + subs r7,r7,#4 @ Decrement bytes to go + bne readdma_loop + + @ Try reading multiple blocks - if this was fast enough then I do not think + @ this should help - NO taken out DAG - new interrupt handler has + @ non-consecutive memory blocks + @ sub r0,r0,#8 + @ b readdma_again + +readdma_end: + adr r5,hdc63463_irqdata+12 + stmia r5,{r3,r4} + ldmfd sp!,{r4-r7} + RETINSTR(mov,pc,lr) |