SATA Introduction

Outline
 Communication Layer
 A Command Example
 SATA Physical Layer
 SATA Link Layer
 SATA Transport Layer
 SATA FIS Type
 SATA Command Layer Protocol
(Command sequence)

SATA Communication Layers
Application Layer
Transport Layer
Link Layer
Physical Layer
8b/10b stream
Status
FIS
8b/10b stream
FIS
Command
Application Layer
Transport Layer
Link Layer
Physical Layer
8b/10b stream
Status
FIS
8b/10b stream
FIS
Command

Command & FIS
#2
#1
#3
READ DMA Command Input Command OuputDATA
＊其實這張圖並不是很正確,因為Data Payload的5dwords是指FIS的大小，並不是
Command Input/Output的大小，但是Command看到的欄位(Input/Output)的確
是填在FIS中的。

Command Inputs
 Main Field：

Command Outputs
Reserved for Normal Output
 Main Field：
 Normal Output
 Error Output
Status=0x51
Error=
0x04CMD Abort
(Command is invalid)
0x10ID Not Found
(Command parameter is
invalid , eg. invalid LBA)
0x40Uncorrectable
data error
(ECC Error)
0x80ICRC Error
(Data transmitted/
received has CRC error)
 Reissue the command.

SATA Status
 1 : the device is busy .
 1 : device is ready to accept all commands.
 0 : device only accepts a few commands.
(DEVICE RESET, EXEUTE DEVICE DIAGNOSTIC, IDENTIFY PACKET DEVICE, PACKET).
 1 : device had a data fatal hard error . Prevents writing data.
 1 : device is ready for data transfer.
 1 : an error occurred during execution command.
 1 : device has prepared this command for service.(DMA Queued)
Status = 50  (DRDY=1,BSY=0,DRQ=0,ERR=0)
Status = 58  (DRDY=1,BSY=0,DRQ=1.ERR=0)
Status = D0  (DRDY=1,BSY=1,DRQ=0,ERR=0)

Physical Layer
 How to Power-On?
Host sends COMREST signal to device.
 OOB(Out-of-band) : COMREST(H2D)、COMINIT(D2H)、COMWAKE。
Power-On Sequence Timing Diagram

Link Layer
 Resolves arbitration conflicts if both host and device request transmission.
 Inserts frame envelope around Transport layer data (i.e. SOF, EOF, HOLD, etc.).
 Receives data in the form of DWORDs from the Transport layer.
 Calculates CRC on Transport layer data to do error checking .
 8b/10b encoding/decoding  Byte + Control .
Primitive Description
SOF Start of frame
EOF End of frame
HOLD Hold data
transmission
HOLDA Send ack.
while HOLD is
received
CONT Continue
repeating
previous
primitive.
SOF FIS1 HOLD
FIS1
(cont.)
CRC EOFLink Layer 
FIS1 FIS2 FIS3
Transport Layer 
Dword DwordDwordDwordsDwordDwordsSIZE 
FIS(Frame Information Structure)

Transmission example
FIS1
FIS1
(Cont.)
1. Transmitter has data ready ,and
send (X_RDY) two times .
2. Receiver send (R_RDY) when ready
to receive data.
3. Transmitter start a data transfer
when (R_RDY) is received .
4. Receiver send (R_IP) to transmitter
that receiver is still receiving data
now.
5. When transmitter not have next
data ready , (HOLD) is sent to
receiver.
6. (HOLDA) will be sent by receiver as
long as (HOLD) is received.
7. (EOF) is sent when a data transfer is
finished.
8. After (EOF) is sent , the transmitter
will send (WTRM) while waiting for
reception status from receiver.
9. If receiver detected this received
data no error , (R_OK) is sent ,
otherwise (R_ERR) is sent.

Transport Layer
1. Constructs Frame Information Structures (FISes) for
transmission
2. Decomposes received Frame Information Structures

SATA FIS types
 Different FISes are used for different types of commands.
FIS Type Size FIS name Direction Used for
27h 20 Command FIS
(Register FIS ,C=1)
Host to Device Non-Data, PIO, DMA,
FPDMA
27h 20 Control FIS
(Register FIS , C=0)
Host to Device Non-Data, PIO, DMA,
FPDMA
34h 20 Response FIS
(Register FIS -D2H)
Device to Host Non-Data, PIO, DMA,
FPDMA
39h 4 DMA Activate FIS Device to Host DMA , DMAQ ,FPDMA
41h 28 FPDMA Setup FIS Bi-directional FPDMA
46h 4~8196 Data FIS Bi-directional PIO, DMA, FPDMA
58h 12 BIST Active FIS Bi-directional BIST
5Fh 20 PIO Setup FIS Device to Host PIO, ATAPI
A1h 8 Set Device Bits FIS Bi-directional DMAQ , FPDMA

Register FIS – Host to Device (27h)
 C bit set to 1.
 Used for ?
Host sends "Command" to
device.
 N,H bit is not supported for
SATA.
 C bit cleared to 0.
 S bit–SRST (Soft Reset). If set
to one, the bit indicates that
a Soft Reset operation has
been requested by the host.

Response FIS (34h) (Register FIS - D2H)
 When sent ?
 Power-On
 Command completion
& return device status
 I : Interrupt pending Bit.
 reflects the Interrupt
Pending state of the
device.
 If the received BSY and
DRQ are both cleared host
adapter shall discard the
contents of the received
FIS.

PIO Setup FIS (5Fh) (D2H)
 When sent ?
 Sent to host before sending a Data FIS containing PIO read.
 Sent to host to request a Data FIS containing PIO write data.
 Ending status (E_Status) :
 Contains the new value of the Status register at the conclusion of the
subsequent Data FIS.
 E_Status is returned before the PIO Read data transfer.
 D bit indicates whether host
memory is being written or read
by device .
1=write (D2H)
0=read (H2D)
starting status
ending status

Data FIS (46h) (bidirectional)
 Contains read (device-to-host) or write (host-to-device) data
 Minimum: 1 Dword + 4 bytes
 Maximum: 8192 bytes (2048Dwords) + 4 bytes
 The high order word (word 1) of the last Dword is padded with
zeros when only a partial Dword (odd number of words) is to be
transmitted.

DMA Activate FIS (39h) (D2H)
 When sent ?
 When device is ready to start receive DMA write data.
 Must be received prior to each write Data FIS from device .
 Not used on DMA reads .

Set Device Bits(A1h) (D2H)
 Sends updated Error and Status bits to the host
 Does not alter BSY (bit 7) or DRQ (bit 3) of the Status register
 Used for DMA Queuing
 To set the SERV bit in the Status register for queued commands.
 Used for FPDMA native queuing
 SActive bits indicate which commands are queued and which are completed.
 32 tags supported .
SERV

FPDMA Setup FIS(41h) (bidirectional)
 When sent?
Used for selecting the
memory buffer for
data transfer .
 A (auto-activate) bit
 Device will not send
a DMA Activate FIS to
throttle write data;
host can send Data FIS
immediately
 D (direction) bit
 1=write , 0=read
 DMA Buffer Identifier fields (Buffer ID=Tag)  共32個Buffer,與NCQ Tag對應。
 Bottom 5 bits of Low field carry the Tag (Identify the DMA buffer region in host memory )
 All other bits are zero
 DMA Buffer Offset
 Random access .
 DMA Transfer Count
 Number of bytes to be read or written.
0
0
Tag

Serial Transport Device Command Layer
Protocol State Machines
1. Power-on and COMRESET protocol
2. Device Idle protocol
3. Software reset protocol
4. EXECUTE DEVICE DIAGNOSTIC command protocol
5. DEVICE RESET command protocol
6. Non-data command protocol
7. PIO data-in (Read) command protocol
8. PIO data-out (Write) command protocol
9. DMA data-in (Read) command protocol
10. DMA data-out (Write) command protocol
11. READ DMA QUEUED command protocol (TCQ)
12. WRITE DMA QUEUED command protocol (TCQ)
13. FPDMA QUEUED command protocol (NCQ)(SATA II)
14. PACKET protocol

Power-on and COMRESET protocol
 After completing a phy reset sequence, device runs diagnostics and
transmits a FIS with the results.
COMREST
Begin phy reset sequence Execute diagnostics
Response FIS (I=0)
Detect phy reset sequence
completion
1. Update shadow register
(BSY=0)
2.Interrupt host
3.Host reads Status register
Update task file register
Detect phy reset
sequence completion
ISR . IS_PHY_RDY

Software reset protocol
 Causes diagnostics to be run, returning the appropriate signature.
Control FIS
Host writes Control register with
SRST=1
Start reset
Response FIS (I=0)
Host writes Control register with
SRST=0
1. Update shadow registers
(BSY=0)
2. Interrupt host
3. Host reads task file registers
Execute diagnostics
Update task file
registers with signature
Good: Error = 01h
Bad: Error = not 01h
Control FIS ISR . IS_SW_RST

Device Idle
protocol
Power-On 
Command FIS
1
Receive FIS
& Check FIS
2
3
ISR . NON_DATA
ISR . READ_CMD
ISR . WRITE_CMD
4

EXECUTE DEVICE DIAGNOSTIC command protocol
EXECUTE
DEVICE
DIAGNOSTIC
(0x90)
1
 Send Response FIS (D2H) with good statusA
 Send Response FIS (D2H) with bad statusB

Response FIS for EXECUTE DIAGNOSTIC
I = 0  for SW_RST or HW_RST (Power-On)
Error = 1  Deivce 0 passed,Device 1 passed or not present
Count = 1 , LBA = 1 General
Send status
ATA ATAPI

Non-data command protocol
 DEVICE RESET and EXECUTE DEVICE DIAGNOSTIC commands use same sequence.
Command FIS
1. Host initializes shadow task
file registers (BSY=1)
Parse command
Response FIS
2. Write Command register
(BSY=0)
2. Interrupt host
3. Host reads Status register
Process command
Send status

Non-data command protocol
Non-data command 
1
ISR . IS_NON_DATA_CMD
2
 Response FIS (D2H)3
CFA ERASE SECTORS
CFA REQUEST EXTENDED ERROR CODE
CHECK POWER MODE
FLUSH CACHE
FLUSH CACHE EXT
GET MEDIA STATUS
IDLE
IDLE IMMEDIATE
INITIALIZE DEVICE PARAMETERS
MEDIA EJECT
MEDIA LOCK
MEDIA UNLOCK
NOP
READ NATIVE MAX ADDRESS
READ NATIVE MAX ADDRESS EXT
READ VERIFY SECTOR(S)
READ VERIFY SECTOR(S) EXT
SECURITY ERASE PREPARE
SECURITY FREEZE LOCK
SEEK
SET FEATURES
SET MAX ADDRESS
SET MAX ADDRESS EXT
SET MULTIPLE MODE
SLEEP
SMART DISABLE OPERATION
SMART ENABLE/DISABLE AUTOSAVE
SMART ENABLE OPERATION
SMART EXECUTE OFFLINE IMMEDIATE
SMART RETURN STATUS
STANDBY
STANDBY IMMEDIATE
*DEVICE RESET
*EXECUTE DEVICE DIAGNOSTIC

DEVICE RESET command protocol
DEVICE RESET 
(0x08)
1
I = 1
Error = 1  Deivce 0 passed,Device 1 passed or not present
Count = 1 , LBA = EB1401 General
 Response FIS (D2H)2

Task file
 The task file is in the ATA device
 In parallel ATA, accesses to these registers result in parallel ATA traffic
 In serial ATA, a Shadow Task file register bank is also managed by the host
to mirror the ATA device’s task file
Serial ATA
Host
adapter
Shadow
Task file
Device
Task file
PCI Bus
Parallel ATA
Host
adapter
PASS
Device
Task file
PCI Bus
Task file
Command Register
Data Register
Device Register
Device Control
Register
Status Register /
Feature Register
Sector Count Register
LBA Register
SStatus,SError,SContr
ol,SActive register

PIO Read command protocol
Command FIS
PIO Setup FIS ( I=1 ,D=1 , Status=58, E_status=D0 )
Data FIS
(BSY=0,DRQ=1) (BSY=1,DRQ=0)
PIO Setup FIS ( I=1 ,D=1 , Status=58, E_status=50 )
Update task file registers
(BSY=0,DRQ=0)
Data FIS (Final)
(BSY=0,DRQ=1)
(BSY=1,DRQ=0)
(BSY=0,DRQ=1)
(BSY=0,DRQ=0)
1. Update shadow registers with PIO Setup
“starting” contents 
2. Interrupt host 3. Host reads Status register
4. Host reads Data register n times
“ending” contents 
>8K
4. Host reads Data register last times
Preparing a DRQ data block
Transmit data
If error has occurred ,
Send Response FIS
Response FIS ( I=1,Status=51)
Interrupt host (BSY=0)
Preparing a DRQ data block

PIO Write command protocol
Response FIS ( I=1 , Status=50?)
Data FIS
Device-to-host register FIS
2. Interrupt host (BSY=0)
Command FIS
3.Wait Device return FIS
(BSY=0,DRQ=0)
(BSY=0,DRQ=1)
(BSY=1,DRQ=0)
(BSY=0,DRQ=1)
(BSY=1,DRQ=0)
2. Host reads Status register
3. Host Write Data register first times
>8K
4. Host Write Data register n times
1st Data FIS
Prepare to receive DRQ data block
Receive data
Send status
Device processing data

DMA Read command protocol
Command FIS (READ DMA)
Data FIS
DMA controller receives data
Response FIS (I=1)
2. Interrupt host
(DRQ=0, BSY=0)
>8K
Send status
(BSY=0,DRQ=0)
Send data
Prepare data

DMA Write command protocol
Command FIS (WRITE DMA)
DMA Activate FIS
1. Activate DMA controller
2. DMA controller transfers
write data
Response FIS ( I=1)
2. Interrupt host
(DRQ=0, BSY=0)
Data FIS
>8K
Send status
Receive data
Prepare to receive
Ready to receive data

Read DMA Queued command protocol
Response FIS (Status=50)
Interrupt host (BSY=0,DRQ=0)
1. Host initializes DMA controller
(BSY=1)
 ( BSY=01 ,REL= Count[2]=1,
I/O = Count[1] = 0 , Count[0]=1 ,
I=1 if release interrupt enabled )
2. Send READ DMA QUEUED Command
Count[7:3] = TAG
Response FIS ( Status=58, Count[7:3]=TAG )
(BSY=0,DRQ=1)
(BSY=0,DRQ=0)
(BSY=1)
1. Interrupt host
2. Host deactivates 3rd DMA controller
3. Host issue SERVICE command
>8K
Read TAG & backup DMA controller context
Queue command
Command FIS (READ DMA QUEUED)
Set Device Bits FIS ( SERV=1 , I=1 )Device is ready to transfer data
& Service request
Command FIS (SERVICE)
Host release bus / command
(BSY=0,DRQ=1)
(BSY=0)
more commads
Data FIS Send data
 ( REL= Count[2]=0,
I/O = Count[1] = 1 ,
Count[0]=0)
I/O = Count[1] = 1 ,
Count[0]=1)
Response with command that
ready to execute
Wait for the CPU to respond to the interrupt  Deactivate the 3rd party DMA engine
Send status
last command queued in(BSY=1)
more queued commands not complete

Write DMA Queued command protocol
1. Host initializes DMA controller
(BSY=1)
 ( BSY=01 ,REL= Count[2]=1,
I/O = Count[1] = 0 , Count[0]=1 ,
I=1 if release interrupt enabled )
2. Send READ DMA QUEUED Command
Count[7:3] = TAG
Response FIS ( Status=58, Count[7:3]=TAG )
(BSY=0,DRQ=1)
(BSY=0,DRQ=0)
(BSY=1)
1. Interrupt host
2. Host deactivates DMA
controller
3. Host issue SERVICE command
>8K
Read TAG & restore DMA controller context
Queue command
Command FIS (WRITE DMA QUEUED)
Set Device Bits FIS ( SERV=1 , I=1 ) Device is ready to transfer data
& Service request
Command FIS (SERVICE)
Host release bus / command
(BSY=0,DRQ=1)
(BSY=0)
more commads
DMA Activate FIS
Receive data
DMA controller sends data
I/O = Count[1] = 1 ,
Count[0]=0)
I/O = Count[1] = 1 ,
Count[0]=1)
Response with command that
ready to execute
Send status
last command queued in(BSY=1)

NCQ ; TCQ
 Use“READ FPDMA QUEUED” , “WRITE FPDMA QUEUED” Command.
 The SATA host bus adapter(HBA) integrated its own first party DMA engine.
 Device issues“FPDMA Setup FIS”to HBA to select memory buffer directly without third-
party DMA engine and tells the HBA which command it wants to execute.
 Device issues“Send Device Bits FIS”to return status of multiple commands completed.
Drastically reduces the number of required CPU interrupts.
 For NCQ to be enabled, it must be supported and enabled in the SATA host bus adapter.
 Windows Vista/7 natively supports NCQ , not Windows XP .
 Use“READ DMA QUEUED” , “WRITE DMA QUEUED” Command.
 Available in both Parallel and Serial ATA
 Use ATA host bus adapter's third party DMA engine.
 It caused high CPU utilization without improving performance enough to make this
worthwhile , because service command and responding to interrupts uses CPU
time , CPU utilization rose quickly .
 Improve the overall performance of a hard drive device.
 Device can make its own decisions about how to order the requests.
 Up to queue 32 commands by using tag. ( IDENTIFY DEVICE word 75)

FPDMA Read command protocol
(BSY=0)
 ( BSY=0 ,DRQ= 0 , I=0 )
Send READ FPDMA QUEUED Command
Count[7:3] = NCQ TAG (BSY=1)
(BSY=0)
Select the DMA engine context by TAG
(DMA Buffer ID)
Host loads PRD pointer into DMA engine
Command FIS (READ FPDMA QUEUED)
Host sets SActive Register
(BSY=0)
more commads
Data FIS
Send data
DMA Setup FIS
Set Device Bits FIS (BSY=0 , I=1 , SActive )
(DMA Buffer ID= TAG , D=1 , I=0,
Transfer count )
this command not complete
Transfer count not exhausted
bit n in SActive field set to one
where n = TAG for each command
TAG value that has completed
Queue command
& store NCQ TAG in SActive
Send status
Multiple commands can be indicated as complete at a time
Update Host copy SActive Register

FPDMA Write command protocol
(BSY=0)
 ( BSY=0 ,DRQ= 0 , I=0 )
Send WRITE FPDMA QUEUED Command
Count[7:3] = NCQ TAG (BSY=1)
(BSY=0)
Select the DMA engine context by TAG
(DMA Buffer ID)
Host loads PRD pointer into DMA engine
DMA controller sends data
Command FIS (WRITE FPDMA QUEUED)
(BSY=0)
more commads
DMA Activate FIS
Receive data
DMA Setup FIS
Set Device Bits FIS (BSY=0 , I=1 ,SActive)
(DMA Buffer ID= TAG , D=0 , I=0,
Auto-Activate=1 ,Transfer count )
this command not complete
Transfer count not exhausted
bit n in SActive field set to one
where n = TAG for each command
TAG value that has completed
Queue command
& store NCQ TAG in SActive
Data FIS
if Auto-Activate==0
Send status
Multiple commands can be indicated as complete at a time
Host sets SActive Register
Update Host copy SActive Register

PIO Read command protocol
PIO READ
Command
1
Prepare Data
Block
2
Send PIO Setup FIS
to HOST3
Status = 0x58 
(DRDY=1,BSY=0,
DRQ=1.ERR=0) ,
More Data to transmitA
All Data transmit
completed
5
If error has occurred ,
Send Response FIS (status=0x51)B
4 Send Data FIS to HOST

PIO Write command protocol
PIO Write Command 
1
Prepare Data
block (Buffer)
2
Send PIO Setup FIS
to HOST3
4 Receive Data FIS from HOST
Send Response FIS (status=50 or 51)5

Read DMA Queued command protocol

Write DMA Queued command protocol

Power-on and COMRESET protocol
POWER-ON 
COMRESET 
1
Initialize HW
Execute diagnostics
3
 Send Response FIS (D2H)4
 ISR . IS_PHY_RDY2

Software reset protocol
ISR . IS_SW_RST3
Control FIS 
(SRST=1)
1
Control FIS
(SRST=0)
2
Initialize HW
Execute
diagnostics
4
 Send Response FIS
(D2H)
5

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Editor's Notes