Hi Nikos,
On Fri, May 06, 2022 at 09:55:45PM +0100, Nikos Nikoleris wrote:
> XSDT provides pointers to other ACPI tables much like RSDT. However,
> contrary to RSDT that provides 32-bit addresses, XSDT provides 64-bit
> pointers. ACPI requires that if XSDT is valid then it takes precedence
> over RSDT.
>
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@xxxxxxx>
> ---
> lib/acpi.h | 6 ++++
> lib/acpi.c | 103 ++++++++++++++++++++++++++++++++---------------------
> 2 files changed, 68 insertions(+), 41 deletions(-)
>
> diff --git a/lib/acpi.h b/lib/acpi.h
> index 42a2c16..d80b983 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -13,6 +13,7 @@
>
> #define RSDP_SIGNATURE ACPI_SIGNATURE('R','S','D','P')
> #define RSDT_SIGNATURE ACPI_SIGNATURE('R','S','D','T')
> +#define XSDT_SIGNATURE ACPI_SIGNATURE('X','S','D','T')
> #define FACP_SIGNATURE ACPI_SIGNATURE('F','A','C','P')
> #define FACS_SIGNATURE ACPI_SIGNATURE('F','A','C','S')
>
> @@ -56,6 +57,11 @@ struct rsdt_descriptor_rev1 {
> u32 table_offset_entry[0];
> } __attribute__ ((packed));
>
> +struct acpi_table_xsdt {
> + ACPI_TABLE_HEADER_DEF
> + u64 table_offset_entry[1];
nit: This should be "[0]" to match the usage above (in rsdt).
I was about to suggest using an unspecified size "[]", but after reading
what the C standard says about it (below), now I'm not sure. was the
"[1]" needed for something that I'm missing?
106) The length is unspecified to allow for the fact that
implementations may give array members different
alignments according to their lengths.
> +} __attribute__ ((packed));
> +
> struct fadt_descriptor_rev1
> {
> ACPI_TABLE_HEADER_DEF /* ACPI common table header */
> diff --git a/lib/acpi.c b/lib/acpi.c
> index de275ca..9b8700c 100644
> --- a/lib/acpi.c
> +++ b/lib/acpi.c
> @@ -38,45 +38,66 @@ static struct rsdp_descriptor *get_rsdp(void)
>
> void* find_acpi_table_addr(u32 sig)
nit: This one could also be fixed as well: "void *".
> {
> - struct rsdp_descriptor *rsdp;
> - struct rsdt_descriptor_rev1 *rsdt;
> - void *end;
> - int i;
> -
> - /* FACS is special... */
> - if (sig == FACS_SIGNATURE) {
> - struct fadt_descriptor_rev1 *fadt;
> - fadt = find_acpi_table_addr(FACP_SIGNATURE);
> - if (!fadt) {
> - return NULL;
> - }
> - return (void*)(ulong)fadt->firmware_ctrl;
> - }
> -
> - rsdp = get_rsdp();
> - if (rsdp == NULL) {
> - printf("Can't find RSDP\n");
> - return 0;
> - }
> -
> - if (sig == RSDP_SIGNATURE) {
> - return rsdp;
> - }
> -
> - rsdt = (void*)(ulong)rsdp->rsdt_physical_address;
> - if (!rsdt || rsdt->signature != RSDT_SIGNATURE)
> - return 0;
> -
> - if (sig == RSDT_SIGNATURE) {
> - return rsdt;
> - }
> -
> - end = (void*)rsdt + rsdt->length;
> - for (i=0; (void*)&rsdt->table_offset_entry[i] < end; i++) {
> - struct acpi_table *t = (void*)(ulong)rsdt->table_offset_entry[i];
> - if (t && t->signature == sig) {
> - return t;
> - }
> - }
> - return NULL;
> + struct rsdp_descriptor *rsdp;
> + struct rsdt_descriptor_rev1 *rsdt;
> + struct acpi_table_xsdt *xsdt = NULL;
> + void *end;
> + int i;
> +
> + /* FACS is special... */
> + if (sig == FACS_SIGNATURE) {
> + struct fadt_descriptor_rev1 *fadt;
> +
> + fadt = find_acpi_table_addr(FACP_SIGNATURE);
> + if (!fadt)
> + return NULL;
> +
> + return (void*)(ulong)fadt->firmware_ctrl;
> + }
> +
> + rsdp = get_rsdp();
> + if (rsdp == NULL) {
> + printf("Can't find RSDP\n");
> + return 0;
> + }
> +
> + if (sig == RSDP_SIGNATURE)
> + return rsdp;
> +
> + rsdt = (void *)(ulong)rsdp->rsdt_physical_address;
> + if (!rsdt || rsdt->signature != RSDT_SIGNATURE)
> + rsdt = NULL;
> +
> + if (sig == RSDT_SIGNATURE)
> + return rsdt;
> +
> + if (rsdp->revision > 1)
> + xsdt = (void *)(ulong)rsdp->xsdt_physical_address;
> + if (!xsdt || xsdt->signature != XSDT_SIGNATURE)
> + xsdt = NULL;
> +
To simplify this function a bit, finding the xsdt could be moved to some
kind of init function.
> + if (sig == XSDT_SIGNATURE)
> + return xsdt;
> +
> + // APCI requires that we first try to use XSDT if it's valid,
> + // we use to find other tables, otherwise we use RSDT.
> + if (xsdt) {
> + end = (void *)(ulong)xsdt + xsdt->length;
> + for (i = 0; (void *)&xsdt->table_offset_entry[i] < end; i++) {
> + struct acpi_table *t =
> + (void *)xsdt->table_offset_entry[i];
> + if (t && t->signature == sig)
> + return t;
> + }
> + } else if (rsdt) {
> + end = (void *)rsdt + rsdt->length;
> + for (i = 0; (void *)&rsdt->table_offset_entry[i] < end; i++) {
> + struct acpi_table *t =
> + (void *)(ulong)rsdt->table_offset_entry[i];
> + if (t && t->signature == sig)
> + return t;
> + }
> + }
The two for-loops could be moved into some common function, or maybe a
macro to deal with the fact that it deals with two different structures
(the rsdt and the xsdt). This is my attempt at making it a function:
void *scan_system_descriptor_table(void *dt)
{
int i;
void *end;
/* XXX: Not sure if this is the nicest thing to do, but the rsdt
* and the xsdt have "length" and "table_offset_entry" at the
* same offsets. */
struct acpi_table_xsdt *xsdt = dt;
end = (void *)(ulong)xsdt + xsdt->length;
for (i = 0; &xsdt->table_offset_entry[i] < end; i++) {
struct acpi_table *t = (void *)xsdt->table_offset_entry[i];
if (t && t->signature == sig)
return t;
}
Thanks,
Ricardo
> +
> + return NULL;
> }
> --
> 2.25.1
>
