[PATCH 0/3] aspeed:lpc: Fix lpc-snoop probe exception

From: Igor Kononenko
Date: Sun Aug 21 2022 - 12:07:04 EST

The bmc might be rebooted while the host is still reachable and the host
might send requests through configured lpc-kcs channels in same time.
That leads to raise lpc-snoop/lpc-kcs interrupts that haven't adjusted IRQ
handlers yet on next early kernel boot, because on the aspeed-chip reboot
might keep lpc-registers on a unclean state that is configured on the last
boot.

The described way might raise the next exception:
```
[ 1.360110] irq 35: nobody cared (try booting with the "irqpoll" option)
[ 1.360145] CPU: 0 PID: 1 Comm: swapper Not tainted 5.4.43-c109de3-24cc5b6 #1
[ 1.360158] Hardware name: Generic DT based system
[ 1.360168] Backtrace:
[ 1.360228] [<80107f5c>] (dump_backtrace) from [<80108184>] (show_stack+0x20/0x24)
[ 1.360250] r7:00000023 r6:00000000 r5:00000000 r4:9d12d560
[ 1.360283] [<80108164>] (show_stack) from [<8084ae54>] (dump_stack+0x20/0x28)
[ 1.360316] [<8084ae34>] (dump_stack) from [<80156790>] (__report_bad_irq+0x40/0xc0)
[ 1.360344] [<80156750>] (__report_bad_irq) from [<801566c0>] (note_interrupt+0x238/0x290)
[ 1.360366] r9:9d0ae000 r8:9d00c600 r7:00000023 r6:00000000 r5:00000000 r4:9d12d560
[ 1.360408] [<80156488>] (note_interrupt) from [<80153594>] (handle_irq_event+0xb4/0xc4)
[ 1.360429] r10:00000000 r9:9d0ae000 r8:9d00c600 r7:00000001 r6:00000000 r5:00000000
[ 1.360440] r4:9d12d560 r3:00000000
[ 1.360466] [<801534e0>] (handle_irq_event) from [<8015788c>] (handle_level_irq+0xac/0x180)
[ 1.360480] r5:80c7d35c r4:9d12d560
[ 1.360503] [<801577e0>] (handle_level_irq) from [<80152a5c>] (__handle_domain_irq+0x6c/0xc8)
[ 1.360519] r5:80c7d35c r4:9d12d560
[ 1.360545] [<801529f0>] (__handle_domain_irq) from [<801021cc>] (avic_handle_irq+0x68/0x70)
[ 1.360568] r9:9d0ae000 r8:9d12d608 r7:9d0afc84 r6:ffffffff r5:9d0afc50 r4:9d002380
[ 1.360587] [<80102164>] (avic_handle_irq) from [<80101a6c>] (__irq_svc+0x6c/0x90)
[ 1.360603] Exception stack(0x9d0afc50 to 0x9d0afc98)
[ 1.360620] fc40: 00000000 00000100 00000000 00000000
[ 1.360640] fc60: 9d12d560 98bbd0c0 00000000 00000023 9d12d608 60000053 00000000 9d0afcd4
[ 1.360657] fc80: 9d0afc80 9d0afca0 801570ec 80154cdc 40000053 ffffffff
[ 1.360670] r5:40000053 r4:80154cdc
[ 1.360693] [<801549e0>] (__setup_irq) from [<801555e4>] (request_threaded_irq+0xdc/0x15c)
[ 1.360715] r9:98bbb340 r8:00000023 r7:9d12d570 r6:9d12d560 r5:00000000 r4:98bbd0c0
[ 1.360741] [<80155508>] (request_threaded_irq) from [<801589d8>] (devm_request_threaded_irq+0x70/0xc4)
[ 1.360762] r10:80a7353c r9:00000000 r8:98bbb340 r7:9d130e10 r6:00000023 r5:804f4a70
[ 1.360774] r4:98bbd020 r3:00000080
[ 1.360800] [<80158968>] (devm_request_threaded_irq) from [<804f4ebc>] (aspeed_lpc_snoop_probe+0x100/0x2ac)
[ 1.360821] r10:00000000 r9:9d130e10 r8:98bbd040 r7:00000000 r6:9d130e00 r5:98bbb340
[ 1.360830] r4:00000000
[ 1.360851] [<804f4dbc>] (aspeed_lpc_snoop_probe) from [<8056a5c4>] (platform_drv_probe+0x44/0x80)
[ 1.360873] r9:80c5ef90 r8:00000000 r7:80cc2938 r6:00000000 r5:80c5ef90 r4:9d130e10
[ 1.360910] [<8056a580>] (platform_drv_probe) from [<80568420>] (really_probe+0x26c/0x498)
[ 1.360924] r5:80cc282c r4:9d130e10
[ 1.360949] [<805681b4>] (really_probe) from [<80568c28>] (driver_probe_device+0x138/0x184)
[ 1.360970] r10:80b0050c r9:80adadb0 r8:00000007 r7:80c5ef90 r6:9d130e10 r5:00000000
[ 1.360981] r4:80c5ef90
[ 1.361004] [<80568af0>] (driver_probe_device) from [<80568fe4>] (device_driver_attach+0xb8/0xc0)
[ 1.361020] r7:80c5ef90 r6:9d130e54 r5:00000000 r4:9d130e10
[ 1.361046] [<80568f2c>] (device_driver_attach) from [<80569070>] (__driver_attach+0x84/0x16c)
[ 1.361063] r7:80c61128 r6:9d130e10 r5:00000001 r4:80c5ef90
[ 1.361088] [<80568fec>] (__driver_attach) from [<80566068>] (bus_for_each_dev+0x84/0xcc)
[ 1.361106] r7:80c61128 r6:80568fec r5:80c5ef90 r4:00000000
[ 1.361130] [<80565fe4>] (bus_for_each_dev) from [<80569180>] (driver_attach+0x28/0x30)
[ 1.361147] r6:00000000 r5:9d1a3d40 r4:80c5ef90
[ 1.361169] [<80569158>] (driver_attach) from [<80566a08>] (bus_add_driver+0x114/0x200)
[ 1.361195] [<805668f4>] (bus_add_driver) from [<80569814>] (driver_register+0x98/0x128)
[ 1.361214] r7:00000000 r6:80ca0ca0 r5:00000000 r4:80c5ef90
[ 1.361241] [<8056977c>] (driver_register) from [<8056b528>] (__platform_driver_register+0x40/0x54)
[ 1.361256] r5:000000b8 r4:80b2575c
[ 1.361294] [<8056b4e8>] (__platform_driver_register) from [<80b2577c>] (aspeed_lpc_snoop_driver_init+0x20/0x28)
[ 1.361331] [<80b2575c>] (aspeed_lpc_snoop_driver_init) from [<80b01318>] (do_one_initcall+0x84/0x184)
[ 1.361356] [<80b01294>] (do_one_initcall) from [<80b01540>] (kernel_init_freeable+0x128/0x1ec)
[ 1.361375] r7:80b3f858 r6:80ca0ca0 r5:000000b8 r4:80b61914
[ 1.361412] [<80b01418>] (kernel_init_freeable) from [<80864060>] (kernel_init+0x18/0x11c)
[ 1.361435] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80864048
[ 1.361444] r4:00000000
[ 1.361470] [<80864048>] (kernel_init) from [<801010e8>] (ret_from_fork+0x14/0x2c)
[ 1.361483] Exception stack(0x9d0affb0 to 0x9d0afff8)
[ 1.361500] ffa0: 00000000 00000000 00000000 00000000
[ 1.361518] ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 1.361535] ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 1.361547] r5:80864048 r4:00000000
[ 1.361555] handlers:
[ 1.361592] [<(ptrval)>] aspeed_lpc_snoop_irq
[ 1.361609] Disabling IRQ #35

```

Main caught of that state is the lpc-snoop driver found on the same
1e789080 address and have same IRQ#35 as for lpc-kcs, and lpc-snoop
registering earlier than lpc-kcs. So, on the lpc-snoop initialization
the lpc-snoop IRQ will be registried for IRQ#35, but it will
passthrough it for the LPC KCS handlers that is not registried yet.

Summary we got the `nobody cared` warning about more 100.000 unhandled
IRQ#35

Steps to reproduce:
* Turn-on BMC
* Turn-on HOST
* Run `watch 'ipmitool sensor'` on the host that is configured to pass
requests via kcs-channel(3,4)
* Reboot BMC.
* On the next BMC boot kernel(BMC) dmesg have exception mentioned above.

The following patchset aims to fixup described issue.

Igor Kononenko (3):
ipmi:kcs_bmc: Add cleanup regmap(interrupt-regs) on a shutdown.
drivers/misc: (aspeed-lpc-snoop): Add regmap cleanup on a shutdown.
drivers/misc: (aspeed-lpc-snoop): Fix platform_get_irq() error
checking

drivers/char/ipmi/kcs_bmc_aspeed.c | 8 +++++
drivers/soc/aspeed/aspeed-lpc-snoop.c | 46 ++++++++++++++++++++++++++-
2 files changed, 53 insertions(+), 1 deletion(-)

--
2.25.1