1 ========================= 1 =========================
2 Mellanox watchdog drivers 2 Mellanox watchdog drivers
3 ========================= 3 =========================
4 4
5 for x86 based system switches 5 for x86 based system switches
6 ============================= 6 =============================
7 7
8 This driver provides watchdog functionality fo 8 This driver provides watchdog functionality for various Mellanox
9 Ethernet and Infiniband switch systems. 9 Ethernet and Infiniband switch systems.
10 10
11 Mellanox watchdog device is implemented in a p 11 Mellanox watchdog device is implemented in a programmable logic device.
12 12
13 There are 2 types of HW watchdog implementatio 13 There are 2 types of HW watchdog implementations.
14 14
15 Type 1: 15 Type 1:
16 Actual HW timeout can be defined as a power 16 Actual HW timeout can be defined as a power of 2 msec.
17 e.g. timeout 20 sec will be rounded up to 32 17 e.g. timeout 20 sec will be rounded up to 32768 msec.
18 The maximum timeout period is 32 sec (32768 18 The maximum timeout period is 32 sec (32768 msec.),
19 Get time-left isn't supported 19 Get time-left isn't supported
20 20
21 Type 2: 21 Type 2:
22 Actual HW timeout is defined in sec. and it' 22 Actual HW timeout is defined in sec. and it's the same as
23 a user-defined timeout. 23 a user-defined timeout.
24 Maximum timeout is 255 sec. 24 Maximum timeout is 255 sec.
25 Get time-left is supported. 25 Get time-left is supported.
26 26
27 Type 3: 27 Type 3:
28 Same as Type 2 with extended maximum timeout 28 Same as Type 2 with extended maximum timeout period.
29 Maximum timeout is 65535 sec. 29 Maximum timeout is 65535 sec.
30 30
31 Type 1 HW watchdog implementation exist in old 31 Type 1 HW watchdog implementation exist in old systems and
32 all new systems have type 2 HW watchdog. 32 all new systems have type 2 HW watchdog.
33 Two types of HW implementation have also diffe 33 Two types of HW implementation have also different register map.
34 34
35 Type 3 HW watchdog implementation can exist on 35 Type 3 HW watchdog implementation can exist on all Mellanox systems
36 with new programmer logic device. 36 with new programmer logic device.
37 It's differentiated by WD capability bit. 37 It's differentiated by WD capability bit.
38 Old systems still have only one main watchdog. 38 Old systems still have only one main watchdog.
39 39
40 Mellanox system can have 2 watchdogs: main and 40 Mellanox system can have 2 watchdogs: main and auxiliary.
41 Main and auxiliary watchdog devices can be ena 41 Main and auxiliary watchdog devices can be enabled together
42 on the same system. 42 on the same system.
43 There are several actions that can be defined 43 There are several actions that can be defined in the watchdog:
44 system reset, start fans on full speed and inc 44 system reset, start fans on full speed and increase register counter.
45 The last 2 actions are performed without a sys 45 The last 2 actions are performed without a system reset.
46 Actions without reset are provided for auxilia 46 Actions without reset are provided for auxiliary watchdog device,
47 which is optional. 47 which is optional.
48 Watchdog can be started during a probe, in thi 48 Watchdog can be started during a probe, in this case it will be
49 pinged by watchdog core before watchdog device 49 pinged by watchdog core before watchdog device will be opened by
50 user space application. 50 user space application.
51 Watchdog can be initialised in nowayout way, i 51 Watchdog can be initialised in nowayout way, i.e. oncse started
52 it can't be stopped. 52 it can't be stopped.
53 53
54 This mlx-wdt driver supports both HW watchdog 54 This mlx-wdt driver supports both HW watchdog implementations.
55 55
56 Watchdog driver is probed from the common mlx_ 56 Watchdog driver is probed from the common mlx_platform driver.
57 Mlx_platform driver provides an appropriate se 57 Mlx_platform driver provides an appropriate set of registers for
58 Mellanox watchdog device, identity name (mlx-w 58 Mellanox watchdog device, identity name (mlx-wdt-main or mlx-wdt-aux),
59 initial timeout, performed action in expiratio 59 initial timeout, performed action in expiration and configuration flags.
60 watchdog configuration flags: nowayout and sta 60 watchdog configuration flags: nowayout and start_at_boot, hw watchdog
61 version - type1 or type2. 61 version - type1 or type2.
62 The driver checks during initialization if the 62 The driver checks during initialization if the previous system reset
63 was done by the watchdog. If yes, it makes a n 63 was done by the watchdog. If yes, it makes a notification about this event.
64 64
65 Access to HW registers is performed through a 65 Access to HW registers is performed through a generic regmap interface.
66 Programmable logic device registers have littl 66 Programmable logic device registers have little-endian order.
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