Antwort: [PATCH v2 13/35] acpigen: Support writing a length
Hi Simon,
-"Simon Glass" schrieb: -
> Betreff: [PATCH v2 13/35] acpigen: Support writing a length
>
> 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
> ---
>
> Changes in v2: None
> Changes in v1: None
>
> include/acpi/acpigen.h | 3 ++
> include/dm/acpi.h | 7 +
> lib/acpi/acpigen.c | 33 ++
> test/dm/acpigen.c | 64 --
> 4 files changed, 105 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..bd1fa24fb6 100644
> --- a/lib/acpi/acpigen.c
> +++ b/lib/acpi/acpigen.c
> @@ -10,6 +10,7 @@
>
> #include
> #include
> +#include
> #include
> #include
>
> @@ -37,6 +38,38 @@ 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 0xf
> +
> +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 0xf max */
> + p[0] = (0x80 | (len & 0xf));
Nit: Without context this code is hard to understand.
I would propose adding a comment pointing to "ACPI 6.3 20.2.4 Package Length
Encoding" and using a define for 0x80 (something like ACPI_PKG_LEN_3_BYTES ...).
> + 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
[PATCH v2 13/35] acpigen: Support writing a length
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
---
Changes in v2: None
Changes in v1: None
include/acpi/acpigen.h | 3 ++
include/dm/acpi.h | 7 +
lib/acpi/acpigen.c | 33 ++
test/dm/acpigen.c | 64 --
4 files changed, 105 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..bd1fa24fb6 100644
--- a/lib/acpi/acpigen.c
+++ b/lib/acpi/acpigen.c
@@ -10,6 +10,7 @@
#include
#include
+#include
#include
#include
@@ -37,6 +38,38 @@ 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 0xf
+
+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 0xf 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 = 0xc;
+ struct acpi_ctx *ctx;
+ u8 *ptr;
+ int i;
+
+ ut_assertok(alloc_context_size(, size));
+
+ ptr = acpigen_get_current(ctx);
+
+ /* Write a byte and a 3-byte length */
+
