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diff --git a/sys/doc/ata/ata-10 b/sys/doc/ata/ata-10 new file mode 100644 index 000000000000..f4c0336944d4 --- /dev/null +++ b/sys/doc/ata/ata-10 @@ -0,0 +1,213 @@ +10. Protocol Overview + +Commands can be grouped into different classes according to the protocols +followed for command execution. The command classes with their associated +protocols are defined below. + +For all commands, the host first checks if BSY=1, and should proceed no +further unless and until BSY=0. For most commands, the host will also wait for +DRDY=1 before proceeding. Those commands shown with DRDY=x can be executed +when DRDY=0. + +Data transfers may be accomplished in more ways than are described below, but +these sequences should work with all known implementations of ATA drives. + +10.1 PIO Data In Commands + +This class includes: + + - Identify Drive + - Read Buffer + - Read Long + - Read Sector(s) + +Execution includes the transfer of one or more 512 byte (>512 bytes on Read +Long) sectors of data from the drive to the host. + + a) The host writes any required parameters to the Features, Sector Count, + Sector Number, Cylinder and Drive/Head registers. + b) The host writes the command code to the Command Register. + c) The drive sets BSY and prepares for data transfer. + d) When a sector of data is available, the drive sets DRQ and clears BSY + prior to asserting INTRQ. + e) After detecting INTRQ, the host reads the Status Register, then reads one + sector of data via the Data Register. In response to the Status Register + being read, the drive negates INTRQ. + f) The drive clears DRQ. If transfer of another sector is required, the drive + also sets BSY and the above sequence is repeated from d). + +10.1.1 PIO Read Command + + +- a) -+-- b) -+ +- e) -+--------+ +- e) -+--------+ + |Setup | Issue | | Read |Transfer| | Read |Transfer| + | |Command| |Status| Data |:::::::|Status| Data | + +------+-------+ +------+--------+ +------+--------+ + |BSY=0 | |BSY=1 |BSY=0 | |BSY=1 |BSY=0 | |BSY=1 + |DRDY=1 | | | | | | + |DRQ=1 | |DRQ=0 |DRQ=1 | |DRQ=0 + |Assert|Negate | |Assert|Negate + INTRQ INTRQ INTRQ INTRQ + +If Error Status is presented, the drive is prepared to transfer data, and it +is at the host's discretion that the data is transferred. + +10.1.2 PIO Read Aborted Command + + +- a) -+-- b) -+ +- e) -+ + |Setup | Issue | | Read | + | |Command| |Status| + +------+-------+ +------+ + |BSY=0 | |BSY=1 |BSY=0 | + |DRDY=1 | | + |DRQ=1 |DRQ=0 + |Assert|Negate + INTRQ INTRQ + +Although DRQ=1, there is no data to be transferred under this condition. + +10.2 PIO Data Out Commands + +This class includes: + + - Format + - Write Buffer + - Write Long + - Write Sector(s) + +Execution includes the transfer of one or more 512 byte (>512 bytes on Write +Long) sectors of data from the drive to the host. + + a) The host writes any required parameters to the Features, Sector Count, + Sector Number, Cylinder and Drive/Head registers. + b) The host writes the command code to the Command Register. + c) The drive sets DRQ when it is ready to accept the first sector of data. + d) The host writes one sector of data via the Data Register. + e) The drive clears DRQ and sets BSY. + f) When the drive has completed processing of the sector, it clears BSY and + asserts INTRQ. If transfer of another sector is required, the drive also + sets DRQ. + g) After detecting INTRQ, the host reads the Status Register. + h) The drive clears the interrupt. + i) If transfer of another sector is required, the above sequence is repeated + from d). + +10.2.1 PIO Write Command + + +- a) -+-- b) -+ +--------+ +- e) -+--------+ +- e) -+ + |Setup | Issue | |Transfer| | Read |Transfer| | Read | + | |Command| | Data | |Status| Data |:::::::|Status| + +------+-------+ +--------+ +------+--------+ +------+ + |BSY=0 | |BSY=1 |BSY=0 |BSY=1 |BSY=0 | |BSY=1 |BSY=0 | + |DRDY=1 | | | | | | | + |DRQ=1 |DRQ=0 |DRQ=1 | |DRQ=0 | | + | | |Assert|Negate | |Assert|Negate + INTRQ INTRQ INTRQ INTRQ + +10.2.2 PIO Write Aborted Command + + +- a) -+-- b) -+ +- e) -+ + |Setup | Issue | | Read | + | |Command| |Status| + +------+-------+ +------+ + |BSY=0 | |BSY=1 |BSY=0 | + |DRDY=1 | | + | |Assert|Negate + INTRQ INTRQ + +10.3 Non-Data Commands + +This class includes: + + - Execute Drive Diagnostic (DRDY=x) + - Idle + - Initialize Drive Parameters (DRDY=x) + - Read Power Mode + - Read Verify Sector(s) + - Recalibrate + - Seek + - Set Features + - Set Multiple Mode + - Standby + +Execution of these commands involves no data transfer. + + a) The host writes any required parameters to the Features, Sector Count, + Sector Number, Cylinder and Drive/Head registers. + b) The host writes the command code to the Command Register. + c) The drive sets BSY. + d) When the drive has completed processing, it clears BSY and asserts INTRQ. + g) The host reads the Status Register. + h) The drive negates INTRQ. + +10.4 Miscellaneous Commands + +This class includes: + + - Read Multiple + - Sleep + - Write Multiple + - Write Same + +The protocol for these commands is contained in the individual command +descriptions. + +10.5 DMA Data Transfer Commands (Optional) + +This class comprises: + + - Read DMA + - Write DMA + +Data transfers using DMA commands differ in two ways from PIO transfers: + + - data transfers are performed using the slave-DMA channel + - no intermediate sector interrupts are issued on multi-sector commands + +Initiation of the DMA transfer commands is identical to the Read Sector or +Write Sector commands except that the host initializes the slave-DMA channel +prior to issuing the command. + +The interrupt handler for DMA transfers is different in that: + + - no intermediate sector interrupts are issued on multi-sector commands + - the host resets the DMA channel prior to reading status from the drive. + +The DMA protocol allows high performance multi-tasking operating systems to +eliminate processor overhead associated with PIO transfers. + + a) Command Phase + 1) Host initializes the slave-DMA channel + 2) Host updates the Command Block Registers + 3) Host writes command code to the Command Register + b) Data Phase - the register contents are not valid during a DMA Data Phase. + 1) The slave-DMA channel qualifies data transfers to and from the drive + with DMARQ + c) Status Phase + 1) Drive generates the interrupt to the host + 2) Host resets the slave-DMA channel + 3) Host reads the Status Register and Error Register + +10.5.1 Normal DMA Transfer + + +--------------+-------+ +---------------------+ +---------+------+ + |Initialize DMA|Command| | DMA Data Transfer | |Reset DMA|Status| + +--------------+-------+ +---------------------+ +---------+------+ + |BSY=0 |BSY=1 |BSY=x |BSY=1 |BSY=0 + |DRQ=x |nIEN=0 + +10.5.2 Aborted DMA Transfer + + +--------------+-------+ +-------------+ +---------+------+ + |Initialize DMA|Command| | DMA Data | |Reset DMA|Status| + +--------------+-------+ +-------------+ +---------+------+ + |BSY=0 |BSY=1 |BSY=x |BSY=1 |BSY=0 + |DRQ=1 |nIEN=0 + +10.5.3 Aborted DMA Command + + +--------------+-------+ +---------+------+ + |Initialize DMA|Command| |Reset DMA|Status| + +--------------+-------+ +---------+------+ + |BSY=0 |BSY=1 |BSY=1 |BSY=0 + |nIEN=0 + |