--- /dev/null
+#ifndef _IPXE_ATA_H
+#define _IPXE_ATA_H
+
+#include <stdint.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/interface.h>
+
+/** @file
+ *
+ * ATA devices
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/**
+ * An ATA Logical Block Address
+ *
+ * ATA controllers have three byte-wide registers for specifying the
+ * block address: LBA Low, LBA Mid and LBA High. This allows for a
+ * 24-bit address. Some devices support the "48-bit address feature
+ * set" (LBA48), in which case each of these byte-wide registers is
+ * actually a two-entry FIFO, and the "previous" byte pushed into the
+ * FIFO is used as the corresponding high-order byte. So, to set up
+ * the 48-bit address 0x123456abcdef, you would issue
+ *
+ * 0x56 -> LBA Low register
+ * 0xef -> LBA Low register
+ * 0x34 -> LBA Mid register
+ * 0xcd -> LBA Mid register
+ * 0x12 -> LBA High register
+ * 0xab -> LBA High register
+ *
+ * This structure encapsulates this information by providing a single
+ * 64-bit integer in native byte order, unioned with bytes named so
+ * that the sequence becomes
+ *
+ * low_prev -> LBA Low register
+ * low_cur -> LBA Low register
+ * mid_prev -> LBA Mid register
+ * mid_cur -> LBA Mid register
+ * high_prev -> LBA High register
+ * high_cur -> LBA High register
+ *
+ * Just to complicate matters further, in non-LBA48 mode it is
+ * possible to have a 28-bit address, in which case bits 27:24 must be
+ * written into the low four bits of the Device register.
+ */
+union ata_lba {
+ /** LBA as a 64-bit integer in native-endian order */
+ uint64_t native;
+ /** ATA registers */
+ struct {
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+ uint8_t low_cur;
+ uint8_t mid_cur;
+ uint8_t high_cur;
+ uint8_t low_prev;
+ uint8_t mid_prev;
+ uint8_t high_prev;
+ uint16_t pad;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+ uint16_t pad;
+ uint8_t high_prev;
+ uint8_t mid_prev;
+ uint8_t low_prev;
+ uint8_t high_cur;
+ uint8_t mid_cur;
+ uint8_t low_cur;
+#else
+#error "I need a byte order"
+#endif
+ } bytes;
+};
+
+/** An ATA 2-byte FIFO register */
+union ata_fifo {
+ /** Value in native-endian order */
+ uint16_t native;
+ /** ATA registers */
+ struct {
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+ uint8_t cur;
+ uint8_t prev;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+ uint8_t prev;
+ uint8_t cur;
+#else
+#error "I need a byte order"
+#endif
+ } bytes;
+};
+
+/** ATA command block */
+struct ata_cb {
+ /** Logical block address */
+ union ata_lba lba;
+ /** Sector count */
+ union ata_fifo count;
+ /** Error/feature register */
+ union ata_fifo err_feat;
+ /** Device register */
+ uint8_t device;
+ /** Command/status register */
+ uint8_t cmd_stat;
+ /** Use LBA48 extended addressing */
+ int lba48;
+};
+
+/** Obsolete bits in the ATA device register */
+#define ATA_DEV_OBSOLETE 0xa0
+
+/** LBA flag in the ATA device register */
+#define ATA_DEV_LBA 0x40
+
+/** Slave ("device 1") flag in the ATA device register */
+#define ATA_DEV_SLAVE 0x10
+
+/** Master ("device 0") flag in the ATA device register */
+#define ATA_DEV_MASTER 0x00
+
+/** Mask of non-LBA portion of device register */
+#define ATA_DEV_MASK 0xf0
+
+/** "Read sectors" command */
+#define ATA_CMD_READ 0x20
+
+/** "Read sectors (ext)" command */
+#define ATA_CMD_READ_EXT 0x24
+
+/** "Write sectors" command */
+#define ATA_CMD_WRITE 0x30
+
+/** "Write sectors (ext)" command */
+#define ATA_CMD_WRITE_EXT 0x34
+
+/** "Identify" command */
+#define ATA_CMD_IDENTIFY 0xec
+
+/** Command completed in error */
+#define ATA_STAT_ERR 0x01
+
+/**
+ * Structure returned by ATA IDENTIFY command
+ *
+ * This is a huge structure with many fields that we don't care about,
+ * so we implement only a few fields.
+ */
+struct ata_identity {
+ uint16_t ignore_a[27]; /* words 0-26 */
+ uint16_t model[20]; /* words 27-46 */
+ uint16_t ignore_b[13]; /* words 47-59 */
+ uint32_t lba_sectors; /* words 60-61 */
+ uint16_t ignore_c[21]; /* words 62-82 */
+ uint16_t supports_lba48; /* word 83 */
+ uint16_t ignore_d[16]; /* words 84-99 */
+ uint64_t lba48_sectors; /* words 100-103 */
+ uint16_t ignore_e[152]; /* words 104-255 */
+};
+
+/** Supports LBA48 flag */
+#define ATA_SUPPORTS_LBA48 ( 1 << 10 )
+
+/** ATA sector size */
+#define ATA_SECTOR_SIZE 512
+
+/** An ATA command information unit */
+struct ata_cmd {
+ /** ATA command block */
+ struct ata_cb cb;
+ /** Data-out buffer (may be NULL)
+ *
+ * If non-NULL, this buffer must be ata_command::cb::count
+ * sectors in size.
+ */
+ userptr_t data_out;
+ /** Data-out buffer length
+ *
+ * Must be zero if @c data_out is NULL
+ */
+ size_t data_out_len;
+ /** Data-in buffer (may be NULL)
+ *
+ * If non-NULL, this buffer must be ata_command::cb::count
+ * sectors in size.
+ */
+ userptr_t data_in;
+ /** Data-in buffer length
+ *
+ * Must be zero if @c data_in is NULL
+ */
+ size_t data_in_len;
+};
+
+extern int ata_command ( struct interface *control, struct interface *data,
+ struct ata_cmd *command );
+#define ata_command_TYPE( object_type ) \
+ typeof ( int ( object_type, struct interface *data, \
+ struct ata_cmd *command ) )
+
+extern int ata_open ( struct interface *block, struct interface *ata,
+ unsigned int device, unsigned int max_count );
+
+#endif /* _IPXE_ATA_H */
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