mmc_remove_host() will cause the mmc core to switch off the bus power by
eventually calling pxamci_set_ios(). This function uses the regulator or
the GPIO which have been freed already.

This causes the following Oops on module unload.

[   49.519649] Unable to handle kernel paging request at virtual address 30303a70
[   49.526878] pgd = c7084000
[   49.529563] [30303a70] *pgd=00000000
[   49.533136] Internal error: Oops: 5 [#1]
[   49.537025] last sysfs file: /sys/devices/platform/pxa27x-ohci/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/scsi_level
[   49.547471] Modules linked in: pxamci(-) eeti_ts
[   49.552061] CPU: 0    Not tainted  (2.6.32-rc8 #322)
[   49.557001] PC is at regulator_is_enabled+0x3c/0xbc
[   49.561846] LR is at regulator_is_enabled+0x30/0xbc
[   49.566691] pc : [<c01a2448>]    lr : [<c01a243c>]    psr: 60000013
[   49.566702] sp : c7083e70  ip : 30303a30  fp : 00000000
[   49.578093] r10: c705e200  r9 : c7082000  r8 : c705e2e0
[   49.583280] r7 : c7061340  r6 : c7061340  r5 : c7083e70  r4 : 00000000
[   49.589759] r3 : c04dc434  r2 : c04dc434  r1 : c03eecea  r0 : 00000047
[   49.596241] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   49.603329] Control: 0000397f  Table: a7084018  DAC: 00000015
[   49.609031] Process rmmod (pid: 1101, stack limit = 0xc7082278)
[   49.614908] Stack: (0xc7083e70 to 0xc7084000)
[   49.619238] 3e60:                                     c7082000 c703c4f8 c705ea00 c04f4074
[   49.627366] 3e80: 00000000 c705e3a0 ffffffff c0247ddc c70361a0 00000000 c705e3a0 ffffffff
[   49.635499] 3ea0: c705e200 bf006400 c78c4f00 c705e200 c705e3a0 ffffffff c705e200 ffffffff
[   49.643633] 3ec0: c04d8ac8 c02476d0 ffffffff c0247c60 c705e200 c0248678 c705e200 c0249064
[   49.651765] 3ee0: ffffffff bf006204 c04d8ad0 c04d8ad0 c04d8ac8 bf007490 00000880 c00440c4
[   49.659898] 3f00: 0000b748 c01c5708 bf007490 c01c44c8 c04d8ac8 c04d8afc bf007490 c01c4570
[   49.668031] 3f20: bf007490 bf00750c c04f4258 c01c37a4 00000000 bf00750c c7083f44 c007b014
[   49.676162] 3f40: 4000d000 6d617870 08006963 00000001 00000000 c7085000 00000001 00000000
[   49.684287] 3f60: 4000d000 c7083f8c 00000001 bea01a54 00005401 c7ab1400 c00440c4 00082000
[   49.692420] 3f80: bf00750c 00000880 c7083f8c 00000000 4000cfa8 00000000 00000880 bea01cc8
[   49.700552] 3fa0: 00000081 c0043f40 00000000 00000880 bea01cc8 00000880 00000006 00000000
[   49.708677] 3fc0: 00000000 00000880 bea01cc8 00000081 00000097 0000cca4 0000b748 00000000
[   49.716802] 3fe0: 4001a4f0 bea01cc0 00018bf4 4001a4fc 20000010 bea01cc8 a063e021 a063e421
[   49.724958] [<c01a2448>] (regulator_is_enabled+0x3c/0xbc) from [<c0247ddc>] (mmc_regulator_set_ocr+0x14/0xd8)
[   49.734836] [<c0247ddc>] (mmc_regulator_set_ocr+0x14/0xd8) from [<bf006400>] (pxamci_set_ios+0xd8/0x17c [pxamci])
[   49.745044] [<bf006400>] (pxamci_set_ios+0xd8/0x17c [pxamci]) from [<c02476d0>] (mmc_power_off+0x50/0x58)
[   49.754555] [<c02476d0>] (mmc_power_off+0x50/0x58) from [<c0247c60>] (mmc_detach_bus+0x68/0xc4)
[   49.763207] [<c0247c60>] (mmc_detach_bus+0x68/0xc4) from [<c0248678>] (mmc_stop_host+0xd4/0x1bc)
[   49.771944] [<c0248678>] (mmc_stop_host+0xd4/0x1bc) from [<c0249064>] (mmc_remove_host+0xc/0x20)
[   49.780681] [<c0249064>] (mmc_remove_host+0xc/0x20) from [<bf006204>] (pxamci_remove+0xc8/0x174 [pxamci])
[   49.790211] [<bf006204>] (pxamci_remove+0xc8/0x174 [pxamci]) from [<c01c5708>] (platform_drv_remove+0x1c/0x24)
[   49.800164] [<c01c5708>] (platform_drv_remove+0x1c/0x24) from [<c01c44c8>] (__device_release_driver+0x7c/0xc4)
[   49.810110] [<c01c44c8>] (__device_release_driver+0x7c/0xc4) from [<c01c4570>] (driver_detach+0x60/0x8c)
[   49.819535] [<c01c4570>] (driver_detach+0x60/0x8c) from [<c01c37a4>] (bus_remove_driver+0x90/0xcc)
[   49.828452] [<c01c37a4>] (bus_remove_driver+0x90/0xcc) from [<c007b014>] (sys_delete_module+0x1d8/0x254)
[   49.837891] [<c007b014>] (sys_delete_module+0x1d8/0x254) from [<c0043f40>] (ret_fast_syscall+0x0/0x28)
[   49.847145] Code: eb06c53a e596c030 e1a0500d e59f106c (e59c0040)
[   49.853566] ---[ end trace b5fa66a00cea142f ]---
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Reported-by: Sven Neumann <s.neumann@raumfeld.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: linux-mmc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@kernel.org
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>