1What:		/sys/class/ata_...
2Date:		August 2008
3Contact:	Gwendal Grignou<gwendal@google.com>
4Description:
5
6Provide a place in sysfs for storing the ATA topology of the system.  This allows
7retrieving various information about ATA objects.
8
9Files under /sys/class/ata_port
10-------------------------------
11
12	For each port, a directory ataX is created where X is the ata_port_id of
13	the port. The device parent is the ata host device.
14
15idle_irq (read)
16
17	Number of IRQ received by the port while idle [some ata HBA only].
18
19nr_pmp_links (read)
20
21	If a SATA Port Multiplier (PM) is connected, number of link behind it.
22
23Files under /sys/class/ata_link
24-------------------------------
25
26	Behind each port, there is a ata_link. If there is a SATA PM in the
27	topology, 15 ata_link objects are created.
28
29	If a link is behind a port, the directory name is linkX, where X is
30	ata_port_id of the port.
31	If a link is behind a PM, its name is linkX.Y where X is ata_port_id
32	of the parent port and Y the PM port.
33
34hw_sata_spd_limit
35
36	Maximum speed supported by the connected SATA device.
37
38sata_spd_limit
39
40	Maximum speed imposed by libata.
41
42sata_spd
43
44	Current speed of the link [1.5, 3Gps,...].
45
46Files under /sys/class/ata_device
47---------------------------------
48
49	Behind each link, up to two ata device are created.
50	The name of the directory is devX[.Y].Z where:
51	- X is ata_port_id of the port where the device is connected,
52	- Y the port of the PM if any, and
53	- Z the device id: for PATA, there is usually 2 devices [0,1],
54	only 1 for SATA.
55
56class
57	Device class. Can be "ata" for disk, "atapi" for packet device,
58	"pmp" for PM, or "none" if no device was found behind the link.
59
60dma_mode
61
62	Transfer modes supported by the device when in DMA mode.
63	Mostly used by PATA device.
64
65pio_mode
66
67	Transfer modes supported by the device when in PIO mode.
68	Mostly used by PATA device.
69
70xfer_mode
71
72	Current transfer mode.
73
74id
75
76	Cached result of IDENTIFY command, as described in ATA8 7.16 and 7.17.
77	Only valid if the device is not a PM.
78
79gscr
80
81	Cached result of the dump of PM GSCR register.
82	Valid registers are:
83	0: 	SATA_PMP_GSCR_PROD_ID,
84	1: 	SATA_PMP_GSCR_REV,
85	2: 	SATA_PMP_GSCR_PORT_INFO,
86	32:	SATA_PMP_GSCR_ERROR,
87	33:	SATA_PMP_GSCR_ERROR_EN,
88	64:	SATA_PMP_GSCR_FEAT,
89	96:	SATA_PMP_GSCR_FEAT_EN,
90	130:	SATA_PMP_GSCR_SII_GPIO
91	Only valid if the device is a PM.
92
93trim
94
95	Shows the DSM TRIM mode currently used by the device. Valid
96	values are:
97	unsupported:		Drive does not support DSM TRIM
98	unqueued:		Drive supports unqueued DSM TRIM only
99	queued:			Drive supports queued DSM TRIM
100	forced_unqueued:	Drive's queued DSM support is known to be
101				buggy and only unqueued TRIM commands
102				are sent
103
104spdn_cnt
105
106	Number of time libata decided to lower the speed of link due to errors.
107
108ering
109
110	Formatted output of the error ring of the device.
111