It is convenient to write a length value for preceding a block of data. Of course the length is not known or is hard to calculate a priori. So add a way to mark the start on a stack, so the length can be updated when known.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v1: None
include/acpi/acpigen.h | 3 ++ include/dm/acpi.h | 7 +++++ lib/acpi/acpigen.c | 32 +++++++++++++++++++++ test/dm/acpigen.c | 64 ++++++++++++++++++++++++++++++++++++++++-- 4 files changed, 104 insertions(+), 2 deletions(-)
diff --git a/include/acpi/acpigen.h b/include/acpi/acpigen.h index 7365cce738..31366f5e34 100644 --- a/include/acpi/acpigen.h +++ b/include/acpi/acpigen.h @@ -65,4 +65,7 @@ void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size); */ void acpigen_emit_string(struct acpi_ctx *ctx, const char *str);
+void acpigen_write_len_f(struct acpi_ctx *ctx); +void acpigen_pop_len(struct acpi_ctx *ctx); + #endif diff --git a/include/dm/acpi.h b/include/dm/acpi.h index 7563a4c60a..2bd03eaa0a 100644 --- a/include/dm/acpi.h +++ b/include/dm/acpi.h @@ -22,6 +22,9 @@ /* Length of an ACPI name string including nul terminator */ #define ACPI_NAME_MAX (ACPI_NAME_LEN + 1)
+/* Number of nested objects supported */ +#define ACPIGEN_LENSTACK_SIZE 10 + #if !defined(__ACPI__)
/** @@ -34,12 +37,16 @@ * adding a new table. The RSDP holds pointers to the RSDT and XSDT. * @rsdt: Pointer to the Root System Description Table * @xsdt: Pointer to the Extended System Description Table + * @len_stack: Stack of 'length' words to fix up later + * @ltop: Points to current top of stack (0 = empty) */ struct acpi_ctx { void *current; struct acpi_rsdp *rsdp; struct acpi_rsdt *rsdt; struct acpi_xsdt *xsdt; + char *len_stack[ACPIGEN_LENSTACK_SIZE]; + int ltop; };
/** diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c index 1223f0d1c4..8a1c3e8256 100644 --- a/lib/acpi/acpigen.c +++ b/lib/acpi/acpigen.c @@ -37,6 +37,38 @@ void acpigen_emit_dword(struct acpi_ctx *ctx, uint data) acpigen_emit_byte(ctx, (data >> 24) & 0xff); }
+/* + * Maximum length for an ACPI object generated by this code, + * + * If you need to change this, change acpigen_write_len_f(ctx) and + * acpigen_pop_len(ctx) + */ +#define ACPIGEN_MAXLEN 0xfffff + +void acpigen_write_len_f(struct acpi_ctx *ctx) +{ + assert(ctx->ltop < (ACPIGEN_LENSTACK_SIZE - 1)); + ctx->len_stack[ctx->ltop++] = ctx->current; + acpigen_emit_byte(ctx, 0); + acpigen_emit_byte(ctx, 0); + acpigen_emit_byte(ctx, 0); +} + +void acpigen_pop_len(struct acpi_ctx *ctx) +{ + int len; + char *p; + + assert(ctx->ltop > 0); + p = ctx->len_stack[--ctx->ltop]; + len = ctx->current - (void *)p; + assert(len <= ACPIGEN_MAXLEN); + /* generate store length for 0xfffff max */ + p[0] = (0x80 | (len & 0xf)); + p[1] = (len >> 4 & 0xff); + p[2] = (len >> 12 & 0xff); +} + void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size) { int i; diff --git a/test/dm/acpigen.c b/test/dm/acpigen.c index 3d580a23a5..f9c15b7503 100644 --- a/test/dm/acpigen.c +++ b/test/dm/acpigen.c @@ -22,7 +22,7 @@ #define TEST_STRING "frogmore" #define TEST_STREAM2 "\xfa\xde"
-static int alloc_context(struct acpi_ctx **ctxp) +static int alloc_context_size(struct acpi_ctx **ctxp, int size) { struct acpi_ctx *ctx;
@@ -30,7 +30,8 @@ static int alloc_context(struct acpi_ctx **ctxp) ctx = malloc(sizeof(*ctx)); if (!ctx) return -ENOMEM; - ctx->current = malloc(150); + ctx->current = malloc(size); + ctx->ltop = 0; if (!ctx->current) return -ENOMEM; *ctxp = ctx; @@ -38,6 +39,11 @@ static int alloc_context(struct acpi_ctx **ctxp) return 0; }
+static int alloc_context(struct acpi_ctx **ctxp) +{ + return alloc_context_size(ctxp, 150); +} + static void free_context(struct acpi_ctx **ctxp) { free(*ctxp); @@ -334,3 +340,57 @@ static int dm_test_acpi_spi(struct unit_test_state *uts) return 0; } DM_TEST(dm_test_acpi_spi, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT); + +/** + * get_length() - decode a three-byte length field + * + * @ptr: Length encoded as per ACPI + * @return decoded length, or -EINVAL on error + */ +static int get_length(u8 *ptr) +{ + if (!(*ptr & 0x80)) + return -EINVAL; + + return (*ptr & 0xf) | ptr[1] << 4 | ptr[2] << 12; +} + +/* Test emitting a length */ +static int dm_test_acpi_len(struct unit_test_state *uts) +{ + const int size = 0xc0000; + struct acpi_ctx *ctx; + u8 *ptr; + int i; + + ut_assertok(alloc_context_size(&ctx, size)); + + ptr = acpigen_get_current(ctx); + + /* Write a byte and a 3-byte length */ + acpigen_write_len_f(ctx); + acpigen_emit_byte(ctx, 0x23); + acpigen_pop_len(ctx); + ut_asserteq(1 + 3, get_length(ptr)); + + /* Write 200 bytes so we need two length bytes */ + ptr = ctx->current; + acpigen_write_len_f(ctx); + for (i = 0; i < 200; i++) + acpigen_emit_byte(ctx, 0x23); + acpigen_pop_len(ctx); + ut_asserteq(200 + 3, get_length(ptr)); + + /* Write 40KB so we need three length bytes */ + ptr = ctx->current; + acpigen_write_len_f(ctx); + for (i = 0; i < 40000; i++) + acpigen_emit_byte(ctx, 0x23); + acpigen_pop_len(ctx); + ut_asserteq(40000 + 3, get_length(ptr)); + + free_context(&ctx); + + return 0; +} +DM_TEST(dm_test_acpi_len, 0);