[acpi] Add support for ACPI power off

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 274 insertions, 0 deletions

diff --git a/src/core/acpi.c b/src/core/acpi.c
index b0ccfa78..955637e0 100644
--- a/src/core/acpi.c
+++ b/src/core/acpi.c
@@ -24,6 +24,8 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <errno.h>
+#include <byteswap.h>
+#include <ipxe/uaccess.h>
 #include <ipxe/acpi.h>
 #include <ipxe/interface.h>
 
@@ -41,6 +43,22 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  */
 
 /**
+ * Transcribe ACPI table signature (for debugging)
+ *
+ * @v signature		ACPI table signature
+ * @ret name		ACPI table signature name
+ */
+static const char * acpi_name ( uint32_t signature ) {
+	static union {
+		uint32_t signature;
+		char name[5];
+	} u;
+
+	u.signature = cpu_to_le32 ( signature );
+	return u.name;
+}
+
+/**
  * Fix up ACPI table checksum
  *
  * @v acpi		ACPI table header
@@ -55,6 +73,262 @@ void acpi_fix_checksum ( struct acpi_description_header *acpi ) {
 	acpi->checksum -= sum;
 }
 
+/**
+ * Locate ACPI root system description table within a memory range
+ *
+ * @v start		Start address to search
+ * @v len		Length to search
+ * @ret rsdt		ACPI root system description table, or UNULL
+ */
+static userptr_t acpi_find_rsdt_range ( userptr_t start, size_t len ) {
+	static const char signature[8] = RSDP_SIGNATURE;
+	struct acpi_rsdp rsdp;
+	userptr_t rsdt;
+	size_t offset;
+	uint8_t sum;
+	unsigned int i;
+
+	/* Search for RSDP */
+	for ( offset = 0 ; ( ( offset + sizeof ( rsdp ) ) < len ) ;
+	      offset += RSDP_STRIDE ) {
+
+		/* Check signature and checksum */
+		copy_from_user ( &rsdp, start, offset, sizeof ( rsdp ) );
+		if ( memcmp ( rsdp.signature, signature,
+			      sizeof ( signature ) ) != 0 )
+			continue;
+		for ( sum = 0, i = 0 ; i < sizeof ( rsdp ) ; i++ )
+			sum += *( ( ( uint8_t * ) &rsdp ) + i );
+		if ( sum != 0 )
+			continue;
+
+		/* Extract RSDT */
+		rsdt = phys_to_user ( le32_to_cpu ( rsdp.rsdt ) );
+		DBGC ( rsdt, "RSDT %#08lx found via RSDP %#08lx\n",
+		       user_to_phys ( rsdt, 0 ),
+		       user_to_phys ( start, offset ) );
+		return rsdt;
+	}
+
+	return UNULL;
+}
+
+/**
+ * Locate ACPI root system description table
+ *
+ * @v ebda		Extended BIOS data area, or UNULL
+ * @ret rsdt		ACPI root system description table, or UNULL
+ */
+userptr_t acpi_find_rsdt ( userptr_t ebda ) {
+	userptr_t rsdt;
+
+	/* Search EBDA, if applicable */
+	if ( ebda ) {
+		rsdt = acpi_find_rsdt_range ( ebda, RSDP_EBDA_LEN );
+		if ( rsdt )
+			return rsdt;
+	}
+
+	/* Search fixed BIOS area */
+	rsdt = acpi_find_rsdt_range ( phys_to_user ( RSDP_BIOS_START ),
+				      RSDP_BIOS_LEN );
+	if ( rsdt )
+		return rsdt;
+
+	return UNULL;
+}
+
+/**
+ * Locate ACPI table
+ *
+ * @v rsdt		ACPI root system description table
+ * @v signature		Requested table signature
+ * @v index		Requested index of table with this signature
+ * @ret table		Table, or UNULL if not found
+ */
+userptr_t acpi_find ( userptr_t rsdt, uint32_t signature, unsigned int index ) {
+	struct acpi_description_header acpi;
+	struct acpi_rsdt *rsdtab;
+	typeof ( rsdtab->entry[0] ) entry;
+	userptr_t table;
+	size_t len;
+	unsigned int count;
+	unsigned int i;
+
+	/* Read RSDT header */
+	copy_from_user ( &acpi, rsdt, 0, sizeof ( acpi ) );
+	if ( acpi.signature != cpu_to_le32 ( RSDT_SIGNATURE ) ) {
+		DBGC ( rsdt, "RSDT %#08lx has invalid signature:\n",
+		       user_to_phys ( rsdt, 0 ) );
+		DBGC_HDA ( rsdt, user_to_phys ( rsdt, 0 ), &acpi,
+			   sizeof ( acpi ) );
+		return UNULL;
+	}
+	len = le32_to_cpu ( acpi.length );
+	if ( len < sizeof ( rsdtab->acpi ) ) {
+		DBGC ( rsdt, "RSDT %#08lx has invalid length:\n",
+		       user_to_phys ( rsdt, 0 ) );
+		DBGC_HDA ( rsdt, user_to_phys ( rsdt, 0 ), &acpi,
+			   sizeof ( acpi ) );
+		return UNULL;
+	}
+
+	/* Calculate number of entries */
+	count = ( ( len - sizeof ( rsdtab->acpi ) ) / sizeof ( entry ) );
+
+	/* Search through entries */
+	for ( i = 0 ; i < count ; i++ ) {
+
+		/* Get table address */
+		copy_from_user ( &entry, rsdt,
+				 offsetof ( typeof ( *rsdtab ), entry[i] ),
+				 sizeof ( entry ) );
+
+		/* Read table header */
+		table = phys_to_user ( entry );
+		copy_from_user ( &acpi.signature, table, 0,
+				 sizeof ( acpi.signature ) );
+
+		/* Check table signature */
+		if ( acpi.signature != cpu_to_le32 ( signature ) )
+			continue;
+
+		/* Check index */
+		if ( index-- )
+			continue;
+
+		DBGC ( rsdt, "RSDT %#08lx found %s at %08lx\n",
+		       user_to_phys ( rsdt, 0 ), acpi_name ( signature ),
+		       user_to_phys ( table, 0 ) );
+		return table;
+	}
+
+	DBGC ( rsdt, "RSDT %#08lx could not find %s\n",
+	       user_to_phys ( rsdt, 0 ), acpi_name ( signature ) );
+	return UNULL;
+}
+
+/**
+ * Extract \_Sx value from DSDT/SSDT
+ *
+ * @v zsdt		DSDT or SSDT
+ * @v signature		Signature (e.g. "_S5_")
+ * @ret sx		\_Sx value, or negative error
+ *
+ * In theory, extracting the \_Sx value from the DSDT/SSDT requires a
+ * full ACPI parser plus some heuristics to work around the various
+ * broken encodings encountered in real ACPI implementations.
+ *
+ * In practice, we can get the same result by scanning through the
+ * DSDT/SSDT for the signature (e.g. "_S5_"), extracting the first
+ * four bytes, removing any bytes with bit 3 set, and treating
+ * whatever is left as a little-endian value.  This is one of the
+ * uglier hacks I have ever implemented, but it's still prettier than
+ * the ACPI specification itself.
+ */
+static int acpi_sx_zsdt ( userptr_t zsdt, uint32_t signature ) {
+	struct acpi_description_header acpi;
+	union {
+		uint32_t dword;
+		uint8_t byte[4];
+	} buf;
+	size_t offset;
+	size_t len;
+	unsigned int sx;
+	uint8_t *byte;
+
+	/* Read table header */
+	copy_from_user ( &acpi, zsdt, 0, sizeof ( acpi ) );
+	len = le32_to_cpu ( acpi.length );
+
+	/* Locate signature */
+	for ( offset = sizeof ( acpi ) ;
+	      ( ( offset + sizeof ( buf ) /* signature */ + 3 /* pkg header */
+		  + sizeof ( buf ) /* value */ ) < len ) ;
+	      offset++ ) {
+
+		/* Check signature */
+		copy_from_user ( &buf, zsdt, offset, sizeof ( buf ) );
+		if ( buf.dword != cpu_to_le32 ( signature ) )
+			continue;
+		DBGC ( zsdt, "DSDT/SSDT %#08lx found %s at offset %#zx\n",
+		       user_to_phys ( zsdt, 0 ), acpi_name ( signature ),
+		       offset );
+		offset += sizeof ( buf );
+
+		/* Read first four bytes of value */
+		copy_from_user ( &buf, zsdt, ( offset + 3 /* pkg header */ ),
+				 sizeof ( buf ) );
+		DBGC ( zsdt, "DSDT/SSDT %#08lx found %s containing "
+		       "%02x:%02x:%02x:%02x\n", user_to_phys ( zsdt, 0 ),
+		       acpi_name ( signature ), buf.byte[0], buf.byte[1],
+		       buf.byte[2], buf.byte[3] );
+
+		/* Extract \Sx value.  There are three potential
+		 * encodings that we might encounter:
+		 *
+		 * - SLP_TYPa, SLP_TYPb, rsvd, rsvd
+		 *
+		 * - <byteprefix>, SLP_TYPa, <byteprefix>, SLP_TYPb, ...
+		 *
+		 * - <dwordprefix>, SLP_TYPa, SLP_TYPb, 0, 0
+		 *
+		 * Since <byteprefix> and <dwordprefix> both have bit
+		 * 3 set, and valid SLP_TYPx must have bit 3 clear
+		 * (since SLP_TYPx is a 3-bit field), we can just skip
+		 * any bytes with bit 3 set.
+		 */
+		byte = &buf.byte[0];
+		if ( *byte & 0x08 )
+			byte++;
+		sx = *(byte++);
+		if ( *byte & 0x08 )
+			byte++;
+		sx |= ( *byte << 8 );
+		return sx;
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * Extract \_Sx value from DSDT/SSDT
+ *
+ * @v rsdt		ACPI root system description table
+ * @v signature		Signature (e.g. "_S5_")
+ * @ret sx		\_Sx value, or negative error
+ */
+int acpi_sx ( userptr_t rsdt, uint32_t signature ) {
+	struct acpi_fadt fadtab;
+	userptr_t fadt;
+	userptr_t dsdt;
+	userptr_t ssdt;
+	unsigned int i;
+	int sx;
+
+	/* Try DSDT first */
+	fadt = acpi_find ( rsdt, FADT_SIGNATURE, 0 );
+	if ( fadt ) {
+		copy_from_user ( &fadtab, fadt, 0, sizeof ( fadtab ) );
+		dsdt = phys_to_user ( fadtab.dsdt );
+		if ( ( sx = acpi_sx_zsdt ( dsdt, signature ) ) >= 0 )
+			return sx;
+	}
+
+	/* Try all SSDTs */
+	for ( i = 0 ; ; i++ ) {
+		ssdt = acpi_find ( rsdt, SSDT_SIGNATURE, i );
+		if ( ! ssdt )
+			break;
+		if ( ( sx = acpi_sx_zsdt ( ssdt, signature ) ) >= 0 )
+			return sx;
+	}
+
+	DBGC ( rsdt, "RSDT %#08lx could not find \\_Sx \"%s\"\n",
+	       user_to_phys ( rsdt, 0 ), acpi_name ( signature ) );
+	return -ENOENT;
+}
+
 /******************************************************************************
  *
  * Interface methods