linux-toradex.git/drivers/bus/hisi_lpc.c, branch v6.3 Linux kernel for Apalis and Colibri modules bus: hisi_lpc: Use platform_device_register_full() 2022-09-08T02:27:29+00:00 John Garry john.garry@huawei.com 2022-09-05T08:23:06+00:00 4678a2d352e055a186dd02613d54e30785810fb0 The code to create the child platform device is essentially the same as what platform_device_register_full() does, so change over to use that same function to reduce duplication. Signed-off-by: John Garry <john.garry@huawei.com> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
The code to create the child platform device is essentially the same as
what platform_device_register_full() does, so change over to use
that same function to reduce duplication.

Signed-off-by: John Garry <john.garry@huawei.com>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Don't guard ACPI IDs with ACPI_PTR() 2022-09-08T02:27:29+00:00 Andy Shevchenko andriy.shevchenko@linux.intel.com 2022-09-05T08:23:05+00:00 e8cd65061fac64d6d0b5c3f5c3059c326b1492f0 The OF ID table is not guarded, and the ACPI table does not needs it either. The IDs do not depend on the configuration. Hence drop ACPI_PTR() from the code and move ID table closer to its user. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
The OF ID table is not guarded, and the ACPI table does not needs it either.
The IDs do not depend on the configuration. Hence drop ACPI_PTR() from the
code and move ID table closer to its user.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Correct error code for timeout 2022-09-08T02:27:29+00:00 Andy Shevchenko andriy.shevchenko@linux.intel.com 2022-09-05T08:23:04+00:00 5e3e70b8e1ae98358d1534e27b0a8259ce3efee8 The usual error code is -ETIMEDOUT, the currently used -ETIME is specific for timers. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
The usual error code is -ETIMEDOUT, the currently used -ETIME is specific
for timers.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Use devm_platform_ioremap_resource 2022-09-08T02:27:29+00:00 Andy Shevchenko andriy.shevchenko@linux.intel.com 2022-09-05T08:23:03+00:00 23bea44cd00c618dca7877366cf8a5340ac110e9 The struct resource is not used for anything else, so we can simplify the code a bit by using the helper function. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
The struct resource is not used for anything else, so we can simplify
the code a bit by using the helper function.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Don't dereference fwnode handle 2022-09-08T02:27:28+00:00 Andy Shevchenko andriy.shevchenko@linux.intel.com 2022-09-05T08:23:02+00:00 947f11d153f20f87828a15e829d69890db71bcf7 Use dev_fwnode() and acpi_fwnode_handle() instead of dereferencing an fwnode handle directly, which is a better coding practice. While at it, reuse fwnode instead of ACPI_COMPANION(). Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
Use dev_fwnode() and acpi_fwnode_handle() instead of dereferencing
an fwnode handle directly, which is a better coding practice.

While at it, reuse fwnode instead of ACPI_COMPANION().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
hisi_lpc: Use acpi_dev_for_each_child() 2022-07-01T19:19:29+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-06-30T18:13:52+00:00 d674553009afc9b24cab2bbec71628609edbbb27 Instead of walking the list of children of an ACPI device directly, use acpi_dev_for_each_child() to carry out an action for all of the given ACPI device's children. This will help to eliminate the children list head from struct acpi_device as it is redundant and it is used in questionable ways in some places (in particular, locking is needed for walking the list pointed to it safely, but it is often missing). While at it, simplify hisi_lpc_acpi_set_io_res() by making it accept a struct acpi_device pointer from the caller, instead of going to struct device and back to get the same result, and clean up confusion regarding hostdev and its ACPI companion in that function. Also remove a redundant check from it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: John Garry <john.garry@huawei.com> 
Instead of walking the list of children of an ACPI device directly,
use acpi_dev_for_each_child() to carry out an action for all of
the given ACPI device's children.

This will help to eliminate the children list head from struct
acpi_device as it is redundant and it is used in questionable ways
in some places (in particular, locking is needed for walking the
list pointed to it safely, but it is often missing).

While at it, simplify hisi_lpc_acpi_set_io_res() by making it accept
a struct acpi_device pointer from the caller, instead of going to
struct device and back to get the same result, and clean up confusion
regarding hostdev and its ACPI companion in that function.

Also remove a redundant check from it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: John Garry <john.garry@huawei.com>
bus: hisi_lpc: fix missing platform_device_put() in hisi_lpc_acpi_probe() 2022-07-01T19:09:20+00:00 Yang Yingliang yangyingliang@huawei.com 2022-07-01T09:43:52+00:00 54872fea6a5ac967ec2272aea525d1438ac6735a In error case in hisi_lpc_acpi_probe() after calling platform_device_add(), hisi_lpc_acpi_remove() can't release the failed 'pdev', so it will be leak, call platform_device_put() to fix this problem. I'v constructed this error case and tested this patch on D05 board. Fixes: 99c0228d6ff1 ("HISI LPC: Re-Add ACPI child enumeration support") Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Acked-by: John Garry <john.garry@huawei.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
In error case in hisi_lpc_acpi_probe() after calling platform_device_add(),
hisi_lpc_acpi_remove() can't release the failed 'pdev', so it will be leak,
call platform_device_put() to fix this problem.
I'v constructed this error case and tested this patch on D05 board.

Fixes: 99c0228d6ff1 ("HISI LPC: Re-Add ACPI child enumeration support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
bus: hisi_lpc: Fixup IO ports addresses to avoid use-after-free in host removal 2020-02-28T09:30:49+00:00 John Garry john.garry@huawei.com 2020-01-16T18:48:34+00:00 a6dd255bdd7d00bbdbf78ba00bde9fc64f86c3a7 Some released ACPI FW for Huawei boards describes incorrect the port IO address range for child devices, in that it tells us the IO port max range is 0x3fff for each child device, which is not correct. The address range should be [e4:e8) or similar. With this incorrect upper range, the child device IO port resources overlap. As such, the kernel thinks that the LPC host serial device is a child of the IPMI device: root@(none)$ more /proc/ioports [...] 00ffc0e3-00ffffff : hisi-lpc-ipmi.0.auto 00ffc0e3-00ffc0e3 : ipmi_si 00ffc0e4-00ffc0e4 : ipmi_si 00ffc0e5-00ffc0e5 : ipmi_si 00ffc2f7-00ffffff : serial8250.1.auto 00ffc2f7-00ffc2fe : serial root@(none)$ They should both be siblings. Note that these are logical PIO addresses, which have a direct mapping from the FW IO port ranges. This shows up as a real issue when we enable CONFIG_KASAN and CONFIG_DEBUG_TEST_DRIVER_REMOVE - we see use-after-free warnings in the host removal path: ================================================================== BUG: KASAN: use-after-free in release_resource+0x38/0xc8 Read of size 8 at addr ffff0026accdbc38 by task swapper/0/1 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc6-00001-g68e186e77b5c-dirty #1593 Hardware name: Huawei Taishan 2180 /D03, BIOS Hisilicon D03 IT20 Nemo 2.0 RC0 03/30/2018 Call trace: dump_backtrace+0x0/0x290 show_stack+0x14/0x20 dump_stack+0xf0/0x14c print_address_description.isra.9+0x6c/0x3b8 __kasan_report+0x12c/0x23c kasan_report+0xc/0x18 __asan_load8+0x94/0xb8 release_resource+0x38/0xc8 platform_device_del.part.10+0x80/0xe0 platform_device_unregister+0x20/0x38 hisi_lpc_acpi_remove_subdev+0x10/0x20 device_for_each_child+0xc8/0x128 hisi_lpc_acpi_remove+0x4c/0xa8 hisi_lpc_remove+0xbc/0xc0 platform_drv_remove+0x3c/0x68 really_probe+0x174/0x548 driver_probe_device+0x7c/0x148 device_driver_attach+0x94/0xa0 __driver_attach+0xa4/0x110 bus_for_each_dev+0xe8/0x158 driver_attach+0x30/0x40 bus_add_driver+0x234/0x2f0 driver_register+0xbc/0x1d0 __platform_driver_register+0x7c/0x88 hisi_lpc_driver_init+0x18/0x20 do_one_initcall+0xb4/0x258 kernel_init_freeable+0x248/0x2c0 kernel_init+0x10/0x118 ret_from_fork+0x10/0x1c ... The issue here is that the kernel created an incorrect parent-child resource dependency between two devices, and references the false parent node when deleting the second child device, when it had been deleted already. Fix up the child device resources from FW to create proper IO port resource relationships for broken FW. With this, the IO port layout looks more healthy: root@(none)$ more /proc/ioports [...] 00ffc0e3-00ffc0e7 : hisi-lpc-ipmi.0.auto 00ffc0e3-00ffc0e3 : ipmi_si 00ffc0e4-00ffc0e4 : ipmi_si 00ffc0e5-00ffc0e5 : ipmi_si 00ffc2f7-00ffc2ff : serial8250.1.auto 00ffc2f7-00ffc2fe : serial Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
Some released ACPI FW for Huawei boards describes incorrect the port IO
address range for child devices, in that it tells us the IO port max range
is 0x3fff for each child device, which is not correct. The address range
should be [e4:e8) or similar. With this incorrect upper range, the child
device IO port resources overlap.

As such, the kernel thinks that the LPC host serial device is a child of
the IPMI device:

root@(none)$ more /proc/ioports
[...]
00ffc0e3-00ffffff : hisi-lpc-ipmi.0.auto
  00ffc0e3-00ffc0e3 : ipmi_si
  00ffc0e4-00ffc0e4 : ipmi_si
  00ffc0e5-00ffc0e5 : ipmi_si
  00ffc2f7-00ffffff : serial8250.1.auto
    00ffc2f7-00ffc2fe : serial
root@(none)$

They should both be siblings. Note that these are logical PIO addresses,
which have a direct mapping from the FW IO port ranges.

This shows up as a real issue when we enable CONFIG_KASAN and
CONFIG_DEBUG_TEST_DRIVER_REMOVE - we see use-after-free warnings in the
host removal path:

==================================================================
BUG: KASAN: use-after-free in release_resource+0x38/0xc8
Read of size 8 at addr ffff0026accdbc38 by task swapper/0/1

CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc6-00001-g68e186e77b5c-dirty #1593
Hardware name: Huawei Taishan 2180 /D03, BIOS Hisilicon D03 IT20 Nemo 2.0 RC0 03/30/2018
Call trace:
dump_backtrace+0x0/0x290
show_stack+0x14/0x20
dump_stack+0xf0/0x14c
print_address_description.isra.9+0x6c/0x3b8
__kasan_report+0x12c/0x23c
kasan_report+0xc/0x18
__asan_load8+0x94/0xb8
release_resource+0x38/0xc8
platform_device_del.part.10+0x80/0xe0
platform_device_unregister+0x20/0x38
hisi_lpc_acpi_remove_subdev+0x10/0x20
device_for_each_child+0xc8/0x128
hisi_lpc_acpi_remove+0x4c/0xa8
hisi_lpc_remove+0xbc/0xc0
platform_drv_remove+0x3c/0x68
really_probe+0x174/0x548
driver_probe_device+0x7c/0x148
device_driver_attach+0x94/0xa0
__driver_attach+0xa4/0x110
bus_for_each_dev+0xe8/0x158
driver_attach+0x30/0x40
bus_add_driver+0x234/0x2f0
driver_register+0xbc/0x1d0
__platform_driver_register+0x7c/0x88
hisi_lpc_driver_init+0x18/0x20
do_one_initcall+0xb4/0x258
kernel_init_freeable+0x248/0x2c0
kernel_init+0x10/0x118
ret_from_fork+0x10/0x1c

...

The issue here is that the kernel created an incorrect parent-child
resource dependency between two devices, and references the false parent
node when deleting the second child device, when it had been deleted
already.

Fix up the child device resources from FW to create proper IO port
resource relationships for broken FW.

With this, the IO port layout looks more healthy:

root@(none)$ more /proc/ioports
[...]
00ffc0e3-00ffc0e7 : hisi-lpc-ipmi.0.auto
  00ffc0e3-00ffc0e3 : ipmi_si
  00ffc0e4-00ffc0e4 : ipmi_si
  00ffc0e5-00ffc0e5 : ipmi_si
00ffc2f7-00ffc2ff : serial8250.1.auto
  00ffc2f7-00ffc2fe : serial

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Clean some types 2019-11-05T00:47:21+00:00 John Garry john.garry@huawei.com 2019-11-04T17:22:17+00:00 663accf1872b22c5eff05235d4750f3a253f5158 Sparse complains of these: drivers/bus/hisi_lpc.c:82:38: warning: incorrect type in argument 1 (different address spaces) drivers/bus/hisi_lpc.c:82:38: expected void const volatile [noderef] <asn:2>*addr drivers/bus/hisi_lpc.c:82:38: got unsigned char * drivers/bus/hisi_lpc.c:131:35: warning: incorrect type in argument 1 (different address spaces) drivers/bus/hisi_lpc.c:131:35: expected unsigned char *mbase drivers/bus/hisi_lpc.c:131:35: got void [noderef] <asn:2>*membase drivers/bus/hisi_lpc.c:186:35: warning: incorrect type in argument 1 (different address spaces) drivers/bus/hisi_lpc.c:186:35: expected unsigned char *mbase drivers/bus/hisi_lpc.c:186:35: got void [noderef] <asn:2>*membase drivers/bus/hisi_lpc.c:228:16: warning: cast to restricted __le32 drivers/bus/hisi_lpc.c:251:13: warning: incorrect type in assignment (different base types) drivers/bus/hisi_lpc.c:251:13: expected unsigned int [unsigned] [usertype] val drivers/bus/hisi_lpc.c:251:13: got restricted __le32 [usertype] <noident> Clean them up. Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
Sparse complains of these:
drivers/bus/hisi_lpc.c:82:38: warning: incorrect type in argument 1 (different address spaces)
drivers/bus/hisi_lpc.c:82:38:    expected void const volatile [noderef] <asn:2>*addr
drivers/bus/hisi_lpc.c:82:38:    got unsigned char *
drivers/bus/hisi_lpc.c:131:35: warning: incorrect type in argument 1 (different address spaces)
drivers/bus/hisi_lpc.c:131:35:    expected unsigned char *mbase
drivers/bus/hisi_lpc.c:131:35:    got void [noderef] <asn:2>*membase
drivers/bus/hisi_lpc.c:186:35: warning: incorrect type in argument 1 (different address spaces)
drivers/bus/hisi_lpc.c:186:35:    expected unsigned char *mbase
drivers/bus/hisi_lpc.c:186:35:    got void [noderef] <asn:2>*membase
drivers/bus/hisi_lpc.c:228:16: warning: cast to restricted __le32
drivers/bus/hisi_lpc.c:251:13: warning: incorrect type in assignment (different base types)
drivers/bus/hisi_lpc.c:251:13:    expected unsigned int [unsigned] [usertype] val
drivers/bus/hisi_lpc.c:251:13:    got restricted __le32 [usertype] <noident>

Clean them up.

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
bus: hisi_lpc: Add .remove method to avoid driver unbind crash 2019-08-13T06:54:34+00:00 John Garry john.garry@huawei.com 2019-07-30T13:29:56+00:00 10e62b47973b0b0ceda076255bcb147b83e20517 The original driver author seemed to be under the impression that a driver cannot be removed if it does not have a .remove method. Or maybe if it is a built-in platform driver. This is not true. This crash can be created: root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# echo HISI0191\:00 > unbind root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# ipmitool raw 6 1 Unable to handle kernel paging request at virtual address ffff000010035010 Mem abort info: ESR = 0x96000047 Exception class = DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000047 CM = 0, WnR = 1 swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000000118b000 [ffff000010035010] pgd=0000041ffbfff003, pud=0000041ffbffe003, pmd=0000041ffbffd003, pte=0000000000000000 Internal error: Oops: 96000047 [#1] PREEMPT SMP Modules linked in: CPU: 17 PID: 1473 Comm: ipmitool Not tainted 5.2.0-rc5-00003-gf68c53b414a3-dirty #198 Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon D05 IT21 Nemo 2.0 RC0 04/18/2018 pstate: 20000085 (nzCv daIf -PAN -UAO) pc : hisi_lpc_target_in+0x7c/0x120 lr : hisi_lpc_target_in+0x70/0x120 sp : ffff00001efe3930 x29: ffff00001efe3930 x28: ffff841f9f599200 x27: 0000000000000002 x26: 0000000000000000 x25: 0000000000000080 x24: 00000000000000e4 x23: 0000000000000000 x22: 0000000000000064 x21: ffff801fb667d280 x20: 0000000000000001 x19: ffff00001efe39ac x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff841febe60340 x7 : ffff801fb55c52e8 x6 : 0000000000000000 x5 : 0000000000ffc0e3 x4 : 0000000000000001 x3 : ffff801fb667d280 x2 : 0000000000000001 x1 : ffff000010035010 x0 : ffff000010035000 Call trace: hisi_lpc_target_in+0x7c/0x120 hisi_lpc_comm_in+0x88/0x98 logic_inb+0x5c/0xb8 port_inb+0x18/0x20 bt_event+0x38/0x808 smi_event_handler+0x4c/0x5a0 check_start_timer_thread.part.4+0x40/0x58 sender+0x78/0x88 smi_send.isra.6+0x94/0x108 i_ipmi_request+0x2c4/0x8f8 ipmi_request_settime+0x124/0x160 handle_send_req+0x19c/0x208 ipmi_ioctl+0x2c0/0x990 do_vfs_ioctl+0xb8/0x8f8 ksys_ioctl+0x80/0xb8 __arm64_sys_ioctl+0x1c/0x28 el0_svc_common.constprop.0+0x64/0x160 el0_svc_handler+0x28/0x78 el0_svc+0x8/0xc Code: 941d1511 aa0003f9 f94006a0 91004001 (b9000034) ---[ end trace aa842b86af7069e4 ]--- The problem here is that the host goes away but the associated logical PIO region remains registered, as do the children devices. Fix by adding a .remove method to tidy-up by removing the child devices and unregistering the logical PIO region. Cc: stable@vger.kernel.org Fixes: adf38bb0b595 ("HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings") Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Wei Xu <xuwei5@hisilicon.com> 
The original driver author seemed to be under the impression that a driver
cannot be removed if it does not have a .remove method. Or maybe if it is
a built-in platform driver.

This is not true. This crash can be created:

root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# echo HISI0191\:00 > unbind
root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# ipmitool raw 6 1
 Unable to handle kernel paging request at virtual address ffff000010035010
 Mem abort info:
   ESR = 0x96000047
   Exception class = DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
 Data abort info:
   ISV = 0, ISS = 0x00000047
   CM = 0, WnR = 1
 swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000000118b000
 [ffff000010035010] pgd=0000041ffbfff003, pud=0000041ffbffe003, pmd=0000041ffbffd003, pte=0000000000000000
 Internal error: Oops: 96000047 [#1] PREEMPT SMP
 Modules linked in:
 CPU: 17 PID: 1473 Comm: ipmitool Not tainted 5.2.0-rc5-00003-gf68c53b414a3-dirty #198
 Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon D05 IT21 Nemo 2.0 RC0 04/18/2018
 pstate: 20000085 (nzCv daIf -PAN -UAO)
 pc : hisi_lpc_target_in+0x7c/0x120
 lr : hisi_lpc_target_in+0x70/0x120
 sp : ffff00001efe3930
 x29: ffff00001efe3930 x28: ffff841f9f599200
 x27: 0000000000000002 x26: 0000000000000000
 x25: 0000000000000080 x24: 00000000000000e4
 x23: 0000000000000000 x22: 0000000000000064
 x21: ffff801fb667d280 x20: 0000000000000001
 x19: ffff00001efe39ac x18: 0000000000000000
 x17: 0000000000000000 x16: 0000000000000000
 x15: 0000000000000000 x14: 0000000000000000
 x13: 0000000000000000 x12: 0000000000000000
 x11: 0000000000000000 x10: 0000000000000000
 x9 : 0000000000000000 x8 : ffff841febe60340
 x7 : ffff801fb55c52e8 x6 : 0000000000000000
 x5 : 0000000000ffc0e3 x4 : 0000000000000001
 x3 : ffff801fb667d280 x2 : 0000000000000001
 x1 : ffff000010035010 x0 : ffff000010035000
 Call trace:
  hisi_lpc_target_in+0x7c/0x120
  hisi_lpc_comm_in+0x88/0x98
  logic_inb+0x5c/0xb8
  port_inb+0x18/0x20
  bt_event+0x38/0x808
  smi_event_handler+0x4c/0x5a0
  check_start_timer_thread.part.4+0x40/0x58
  sender+0x78/0x88
  smi_send.isra.6+0x94/0x108
  i_ipmi_request+0x2c4/0x8f8
  ipmi_request_settime+0x124/0x160
  handle_send_req+0x19c/0x208
  ipmi_ioctl+0x2c0/0x990
  do_vfs_ioctl+0xb8/0x8f8
  ksys_ioctl+0x80/0xb8
  __arm64_sys_ioctl+0x1c/0x28
  el0_svc_common.constprop.0+0x64/0x160
  el0_svc_handler+0x28/0x78
  el0_svc+0x8/0xc
 Code: 941d1511 aa0003f9 f94006a0 91004001 (b9000034)
 ---[ end trace aa842b86af7069e4 ]---

The problem here is that the host goes away but the associated logical PIO
region remains registered, as do the children devices.

Fix by adding a .remove method to tidy-up by removing the child devices
and unregistering the logical PIO region.

Cc: stable@vger.kernel.org
Fixes: adf38bb0b595 ("HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings")
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>