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Console: Use callee-saved registers 

This allows the console drivers to be implemented in C

Change-Id: Ibac859c4bcef0e92a0dcacc6b58ac19bc69b8342
Signed-off-by: Sathees Balya <sathees.balya@arm.com>
This commit is contained in:
Sathees Balya 2018-07-31 15:11:11 +01:00
parent 8ae41aec32
commit d35cc347db
1 changed files with 84 additions and 67 deletions
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151
drivers/console/aarch64/multi_console.S
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@ -39,10 +39,11 @@
* persistent memory (e.g. the data section). * persistent memory (e.g. the data section).
* In : x0 - address of console_t structure * In : x0 - address of console_t structure
* Out: x0 - Always 1 (for easier tail calling) * Out: x0 - Always 1 (for easier tail calling)
* Clobber list: x0, x1, x14, x15 * Clobber list: x0, x1
* ----------------------------------------------- * -----------------------------------------------
*/ */
func console_register func console_register
stp x21, x30, [sp, #-16]!
#if ENABLE_ASSERTIONS #if ENABLE_ASSERTIONS
/* Assert that x0 isn't a NULL pointer */ /* Assert that x0 isn't a NULL pointer */
cmp x0, #0 cmp x0, #0
@ -59,18 +60,17 @@ func console_register
not_on_stack: not_on_stack:
/* Assert that this struct isn't in the list */ /* Assert that this struct isn't in the list */
mov x1, x0 /* Preserve x0 and x30 */ mov x1, x0 /* Preserve x0 and x30 */
mov x15, x30
bl console_is_registered bl console_is_registered
cmp x0, #0 cmp x0, #0
ASM_ASSERT(eq) ASM_ASSERT(eq)
mov x30, x15
mov x0, x1 mov x0, x1
#endif /* ENABLE_ASSERTIONS */ #endif /* ENABLE_ASSERTIONS */
adrp x14, console_list adrp x21, console_list
ldr x1, [x14, :lo12:console_list] /* X1 = first struct in list */ ldr x1, [x21, :lo12:console_list] /* X1 = first struct in list */
str x0, [x14, :lo12:console_list] /* list head = new console */ str x0, [x21, :lo12:console_list] /* list head = new console */
str x1, [x0, #CONSOLE_T_NEXT] /* new console next ptr = X1 */ str x1, [x0, #CONSOLE_T_NEXT] /* new console next ptr = X1 */
mov x0, #1 mov x0, #1
ldp x21, x30, [sp], #16
ret ret
endfunc console_register endfunc console_register
@ -80,7 +80,7 @@ endfunc console_register
* of currently active consoles and remove it. * of currently active consoles and remove it.
* In: x0 - address of console_t struct to remove * In: x0 - address of console_t struct to remove
* Out: x0 - removed address, or NULL if not found * Out: x0 - removed address, or NULL if not found
* Clobber list: x0, x1, x14 * Clobber list: x0, x1
* ----------------------------------------------- * -----------------------------------------------
*/ */
func console_unregister func console_unregister
@ -89,25 +89,28 @@ func console_unregister
cmp x0, #0 cmp x0, #0
ASM_ASSERT(ne) ASM_ASSERT(ne)
#endif /* ENABLE_ASSERTIONS */ #endif /* ENABLE_ASSERTIONS */
adrp x14, console_list stp x21, xzr, [sp, #-16]!
add x14, x14, :lo12:console_list /* X14 = ptr to first struct */ adrp x21, console_list
ldr x1, [x14] /* X1 = first struct */ add x21, x21, :lo12:console_list /* X21 = ptr to first struct */
ldr x1, [x21] /* X1 = first struct */
unregister_loop: unregister_loop:
cbz x1, unregister_not_found cbz x1, unregister_not_found
cmp x0, x1 cmp x0, x1
b.eq unregister_found b.eq unregister_found
ldr x14, [x14] /* X14 = next ptr of struct */ ldr x21, [x21] /* X21 = next ptr of struct */
ldr x1, [x14] /* X1 = next struct */ ldr x1, [x21] /* X1 = next struct */
b unregister_loop b unregister_loop
unregister_found: unregister_found:
ldr x1, [x1] /* X1 = next struct */ ldr x1, [x1] /* X1 = next struct */
str x1, [x14] /* prev->next = cur->next */ str x1, [x21] /* prev->next = cur->next */
ldp x21, xzr, [sp], #16
ret ret
unregister_not_found: unregister_not_found:
mov x0, #0 /* return NULL if not found */ mov x0, #0 /* return NULL if not found */
ldp x21, xzr, [sp], #16
ret ret
endfunc console_unregister endfunc console_unregister
@ -117,7 +120,7 @@ endfunc console_unregister
* registered or not. * registered or not.
* In: x0 - address of console_t struct to remove * In: x0 - address of console_t struct to remove
* Out: x0 - 1 if it is registered, 0 if not. * Out: x0 - 1 if it is registered, 0 if not.
* Clobber list: x0, x14 * Clobber list: x0
* ----------------------------------------------- * -----------------------------------------------
*/ */
func console_is_registered func console_is_registered
@ -126,19 +129,22 @@ func console_is_registered
cmp x0, #0 cmp x0, #0
ASM_ASSERT(ne) ASM_ASSERT(ne)
#endif /* ENABLE_ASSERTIONS */ #endif /* ENABLE_ASSERTIONS */
adrp x14, console_list stp x21, xzr, [sp, #-16]!
ldr x14, [x14, :lo12:console_list] /* X14 = first console struct */ adrp x21, console_list
ldr x21, [x21, :lo12:console_list] /* X21 = first console struct */
check_registered_loop: check_registered_loop:
cbz x14, console_not_registered /* Check if end of list */ cbz x21, console_not_registered /* Check if end of list */
cmp x0, x14 /* Check if the pointers are different */ cmp x0, x21 /* Check if the pointers are different */
b.eq console_registered b.eq console_registered
ldr x14, [x14, #CONSOLE_T_NEXT] /* Get pointer to next struct */ ldr x21, [x21, #CONSOLE_T_NEXT] /* Get pointer to next struct */
b check_registered_loop b check_registered_loop
console_not_registered: console_not_registered:
mov x0, #0 mov x0, #0
ldp x21, xzr, [sp], #16
ret ret
console_registered: console_registered:
mov x0, #1 mov x0, #1
ldp x21, xzr, [sp], #16
ret ret
endfunc console_is_registered endfunc console_is_registered
@ -186,38 +192,41 @@ endfunc console_set_scope
* In : x0 - character to be printed * In : x0 - character to be printed
* Out: x0 - printed character on success, or < 0 * Out: x0 - printed character on success, or < 0
if at least one console had an error if at least one console had an error
* Clobber list : x0, x1, x2, x12, x13, x14, x15 * Clobber list : x0, x1, x2
* --------------------------------------------- * ---------------------------------------------
*/ */
func console_putc func console_putc
mov x15, x30 stp x21, x30, [sp, #-16]!
mov w13, #ERROR_NO_VALID_CONSOLE /* W13 = current return value */ stp x19, x20, [sp, #-16]!
mov w12, w0 /* W12 = character to print */ mov w20, #ERROR_NO_VALID_CONSOLE /* W20 = current return value */
adrp x14, console_list mov w19, w0 /* W19 = character to print */
ldr x14, [x14, :lo12:console_list] /* X14 = first console struct */ adrp x21, console_list
ldr x21, [x21, :lo12:console_list] /* X21 = first console struct */
putc_loop: putc_loop:
cbz x14, putc_done cbz x21, putc_done
adrp x1, console_state adrp x1, console_state
ldrb w1, [x1, :lo12:console_state] ldrb w1, [x1, :lo12:console_state]
ldr w2, [x14, #CONSOLE_T_FLAGS] ldr w2, [x21, #CONSOLE_T_FLAGS]
tst w1, w2 tst w1, w2
b.eq putc_continue b.eq putc_continue
ldr x2, [x14, #CONSOLE_T_PUTC] ldr x2, [x21, #CONSOLE_T_PUTC]
cbz x2, putc_continue cbz x2, putc_continue
mov w0, w12 mov w0, w19
mov x1, x14 mov x1, x21
blr x2 blr x2
cmp w13, #ERROR_NO_VALID_CONSOLE /* update W13 if it's NOVALID */ cmp w20, #ERROR_NO_VALID_CONSOLE /* update W20 if it's NOVALID */
ccmp w0, #0, #0x8, ne /* else update it if W0 < 0 */ ccmp w0, #0, #0x8, ne /* else update it if W0 < 0 */
csel w13, w0, w13, lt csel w20, w0, w20, lt
putc_continue: putc_continue:
ldr x14, [x14] /* X14 = next struct */ ldr x21, [x21] /* X21 = next struct */
b putc_loop b putc_loop
putc_done: putc_done:
mov w0, w13 mov w0, w20
ret x15 ldp x19, x20, [sp], #16
ldp x21, x30, [sp], #16
ret
endfunc console_putc endfunc console_putc
/* --------------------------------------------- /* ---------------------------------------------
@ -230,42 +239,47 @@ endfunc console_putc
* if all active consoles report real errors * if all active consoles report real errors
* (other than just not having a char available). * (other than just not having a char available).
* Out : x0 - read character, or < 0 on error * Out : x0 - read character, or < 0 on error
* Clobber list : x0, x1, x13, x14, x15 * Clobber list : x0, x1
* --------------------------------------------- * ---------------------------------------------
*/ */
func console_getc func console_getc
mov x15, x30 stp x30, xzr, [sp, #-16]!
stp x20, x21, [sp, #-16]!
getc_try_again: getc_try_again:
mov w13, #ERROR_NO_VALID_CONSOLE /* W13 = current return value */ mov w20, #ERROR_NO_VALID_CONSOLE /* W20 = current return value */
adrp x14, console_list adrp x21, console_list
ldr x14, [x14, :lo12:console_list] /* X14 = first console struct */ ldr x21, [x21, :lo12:console_list] /* X21 = first console struct */
cbnz x14, getc_loop cbnz x21, getc_loop
mov w0, w13 /* If no consoles registered */ mov w0, w20 /* If no consoles registered */
ret x15 /* return immediately. */ ldp x20, x21, [sp], #16
ldp x30, xzr, [sp], #16
ret /* return immediately. */
getc_loop: getc_loop:
adrp x0, console_state adrp x0, console_state
ldrb w0, [x0, :lo12:console_state] ldrb w0, [x0, :lo12:console_state]
ldr w1, [x14, #CONSOLE_T_FLAGS] ldr w1, [x21, #CONSOLE_T_FLAGS]
tst w0, w1 tst w0, w1
b.eq getc_continue b.eq getc_continue
ldr x1, [x14, #CONSOLE_T_GETC] ldr x1, [x21, #CONSOLE_T_GETC]
cbz x1, getc_continue cbz x1, getc_continue
mov x0, x14 mov x0, x21
blr x1 blr x1
cmp w0, #0 /* if X0 >= 0: return */ cmp w0, #0 /* if X0 >= 0: return */
b.ge getc_found b.ge getc_found
cmp w13, #ERROR_NO_PENDING_CHAR /* may update W13 (NOCHAR has */ cmp w20, #ERROR_NO_PENDING_CHAR /* may update W20 (NOCHAR has */
csel w13, w13, w0, eq /* precedence vs real errors) */ csel w20, w20, w0, eq /* precedence vs real errors) */
getc_continue: getc_continue:
ldr x14, [x14] /* X14 = next struct */ ldr x21, [x21] /* X21 = next struct */
cbnz x14, getc_loop cbnz x21, getc_loop
cmp w13, #ERROR_NO_PENDING_CHAR /* Keep scanning if at least */ cmp w20, #ERROR_NO_PENDING_CHAR /* Keep scanning if at least */
b.eq getc_try_again /* one console returns NOCHAR */ b.eq getc_try_again /* one console returns NOCHAR */
mov w0, w13 mov w0, w20
getc_found: getc_found:
ret x15 ldp x20, x21, [sp], #16
ldp x30, xzr, [sp], #16
ret
endfunc console_getc endfunc console_getc
/* --------------------------------------------- /* ---------------------------------------------
@ -274,34 +288,37 @@ endfunc console_getc
* data that hasn't been output. Calls all * data that hasn't been output. Calls all
* console's flush() handlers in succession. * console's flush() handlers in succession.
* Out: x0 - 0 on success, < 0 if at least one error * Out: x0 - 0 on success, < 0 if at least one error
* Clobber list : x0, x1, x2, x3, x4, x5, x13, x14, x15 * Clobber list : x0, x1, x2
* --------------------------------------------- * ---------------------------------------------
*/ */
func console_flush func console_flush
mov x15, x30 stp x30, xzr, [sp, #-16]!
mov w13, #ERROR_NO_VALID_CONSOLE /* W13 = current return value */ stp x20, x21, [sp, #-16]!
adrp x14, console_list mov w20, #ERROR_NO_VALID_CONSOLE /* W20 = current return value */
ldr x14, [x14, :lo12:console_list] /* X14 = first console struct */ adrp x21, console_list
ldr x21, [x21, :lo12:console_list] /* X21 = first console struct */
flush_loop: flush_loop:
cbz x14, flush_done cbz x21, flush_done
adrp x1, console_state adrp x1, console_state
ldrb w1, [x1, :lo12:console_state] ldrb w1, [x1, :lo12:console_state]
ldr w2, [x14, #CONSOLE_T_FLAGS] ldr w2, [x21, #CONSOLE_T_FLAGS]
tst w1, w2 tst w1, w2
b.eq flush_continue b.eq flush_continue
ldr x1, [x14, #CONSOLE_T_FLUSH] ldr x1, [x21, #CONSOLE_T_FLUSH]
cbz x1, flush_continue cbz x1, flush_continue
mov x0, x14 mov x0, x21
blr x1 blr x1
cmp w13, #ERROR_NO_VALID_CONSOLE /* update W13 if it's NOVALID */ cmp w20, #ERROR_NO_VALID_CONSOLE /* update W20 if it's NOVALID */
ccmp w0, #0, #0x8, ne /* else update it if W0 < 0 */ ccmp w0, #0, #0x8, ne /* else update it if W0 < 0 */
csel w13, w0, w13, lt csel w20, w0, w20, lt
flush_continue: flush_continue:
ldr x14, [x14] /* X14 = next struct */ ldr x21, [x21] /* X21 = next struct */
b flush_loop b flush_loop
flush_done: flush_done:
mov w0, w13 mov w0, w20
ret x15 ldp x20, x21, [sp], #16
ldp x30, xzr, [sp], #16
ret
endfunc console_flush endfunc console_flush