When there was no other way to match a I2C device to driver i2c_match_id()
was exclusively used.  However, now there are other types of tables which
are commonly supplied, matching on an i2c_device_id table is used less
frequently.  Instead of _always_ calling i2c_match_id() from within the
framework, we only need to do so from drivers which have no other way of
matching.  This patch makes i2c_match_id() available to the aforementioned
device drivers.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Tested-by: NKieran Bingham <kieran@bingham.xyz>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NKieran Bingham <kieran@bingham.xyz>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Currently the I2C framework insists on devices supplying an I2C ID
table.  Many of the devices which do so unnecessarily adding quite a
few wasted lines to kernel code.  This patch allows drivers a means
to 'not' supply the aforementioned table and match on DT match tables
instead.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Tested-by: NKieran Bingham <kieran@bingham.xyz>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NKieran Bingham <kieran@bingham.xyz>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

This function provides a single call for all I2C devices which need to
match firstly using traditional OF means i.e by of_node, then if that
fails we attempt to match using the supplied I2C client name with a
list of supplied compatible strings with the '<vendor>,' string
removed.  The latter is required due to the unruly naming conventions
used currently by I2C devices.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
[Kieran: Fix static inline usage on !CONFIG_OF]
Tested-by: NKieran Bingham <kieran@bingham.xyz>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NKieran Bingham <kieran@bingham.xyz>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

A great deal of I2C devices are currently matched via DT node name, and
as such the compatible naming convention of '<vendor>,<device>' has gone
somewhat awry - some nodes don't supply one, some supply an arbitrary
string and others the correct device name with an arbitrary vendor prefix.

In an effort to correct this problem we have to supply a mechanism to
match a device by compatible string AND by simple device name.  This
function strips off the '<vendor>,' part of a supplied compatible string
and attempts to match without it.

It is also used for sysfs, where a user can choose to instantiate a
device on an i2c bus using the sysfs interface by providing a string and
address to match and communicate with the device on the bus. Presently
this string is only matched against the old i2c device id style strings,
even in the presence of full device tree compatible strings with vendor
prefixes.

Providing a vendor-prefixed string to the sysfs interface will not match
against the device tree of_match_device() calls as there is no device
tree node to parse from the sysfs interface.

This function can match both vendor prefixed and stripped compatible
strings on the sysfs interface.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NKieran Bingham <kieran@bingham.xyz>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Here we're providing dereference protection for i2c_match_id(), which
saves us having to do it each time it's called.  We're also stripping
out the (now) needless checks in i2c_device_match().  This patch paves
the way for other, similar code trimming.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Tested-by: NKieran Bingham <kieran@bingham.xyz>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NKieran Bingham <kieran@bingham.xyz>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Support a dynamic clock by reading the frequency and setting the
divisor in the transfer function instead of during probe.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Use i2c_adapter->timeout for the completion timeout value. The core
default is 1 second.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Documentation/i2c/i2c-protocol states that Combined transactions should
separate messages with a Start bit and end the whole transaction with a
Stop bit. This patch adds support for issuing only a Start between
messages instead of a Stop followed by a Start.

This implementation differs from downstream i2c-bcm2708 in 2 respects:
- it uses an interrupt to detect that the transfer is active instead
  of using polling. There is no interrupt for Transfer Active, but by
  not prefilling the FIFO it's possible to use the TXW interrupt.
- when resetting/disabling the controller between transfers it writes
  CLEAR to the control register instead of just zero.
  Using just zero gave many errors. This might be the reason why
  downstream had to disable this feature and make it available with a
  module parameter.

I have run thousands of transfers to a DS1307 (rtc), MMA8451 (accel)
and AT24C32 (eeprom) in parallel without problems.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Acked-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The controller can't support this flag, so remove it.

Documentation/i2c/i2c-protocol states that all of the message is sent:

I2C_M_IGNORE_NAK:
    Normally message is interrupted immediately if there is [NA] from the
    client. Setting this flag treats any [NA] as [A], and all of
    message is sent.

>From the BCM2835 ARM Peripherals datasheet:

    The ERR field is set when the slave fails to acknowledge either
    its address or a data byte written to it.

So when the controller doesn't receive an ack, it sets ERR and raises
an interrupt. In other words, the whole message is not sent.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Writing to an AT24C32 generates on average 2x i2c transfer errors per
32-byte page write. Which amounts to a lot for a 4k write. This is due
to the fact that the chip doesn't respond during it's internal write
cycle when the at24 driver tries and retries the next write.
Only a handful drivers use dev_err() on transfer error, so switch to
dev_dbg() instead.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

If an unexpected TXW or RXR interrupt occurs (msg_buf_remaining == 0),
the driver has no way to fill/drain the FIFO to stop the interrupts.
In this case the controller has to be disabled and the transfer
completed to avoid hang.

(CLKT | ERR) and DONE interrupts are completed in their own paths, and
the controller is disabled in the transfer function after completion.
Unite the code paths and do disabling inside the interrupt routine.

Clear interrupt status bits in the united completion path instead of
trying to do it on every interrupt which isn't necessary.
Only CLKT, ERR and DONE can be cleared that way.

Add the status value to the error value in case of TXW/RXR errors to
distinguish them from the other S_LEN error.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Writing messages larger than the FIFO size results in a hang, rendering
the machine unusable. This is because the RXD status flag is set on the
first interrupt which results in bcm2835_drain_rxfifo() stealing bytes
from the buffer. The controller continues to trigger interrupts waiting
for the missing bytes, but bcm2835_fill_txfifo() has none to give.
In this situation wait_for_completion_timeout() apparently is unable to
stop the madness.

The BCM2835 ARM Peripherals datasheet has this to say about the flags:
  TXD: is set when the FIFO has space for at least one byte of data.
  RXD: is set when the FIFO contains at least one byte of data.
  TXW: is set during a write transfer and the FIFO is less than full.
  RXR: is set during a read transfer and the FIFO is or more full.

Implementing the logic from the downstream i2c-bcm2708 driver solved
the hang problem.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NEric Anholt <eric@anholt.net>
Reviewed-by: NMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Pull i2c fix from Wolfram Sang:
 "A bugfix for the I2C core fixing a (rare) race condition"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: core: fix NULL pointer dereference under race condition

Merge branches 'sched-urgent-for-linus' and 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull stack vmap fixups from Thomas Gleixner:
 "Two small patches related to sched_show_task():

   - make sure to hold a reference on the task stack while accessing it

   - remove the thread_saved_pc printout

  .. and add a sanity check into release_task_stack() to catch problems
  with task stack references"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Remove pointless printout in sched_show_task()
  sched/core: Fix oops in sched_show_task()

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  fork: Add task stack refcounting sanity check and prevent premature task stack freeing

Pull MD fixes from Shaohua Li:
 "There are several bug fixes queued:

   - fix raid5-cache recovery bugs

   - fix discard IO error handling for raid1/10

   - fix array sync writes bogus position to superblock

   - fix IO error handling for raid array with external metadata"

* tag 'md/4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
  md: be careful not lot leak internal curr_resync value into metadata. -- (all)
  raid1: handle read error also in readonly mode
  raid5-cache: correct condition for empty metadata write
  md: report 'write_pending' state when array in sync
  md/raid5: write an empty meta-block when creating log super-block
  md/raid5: initialize next_checkpoint field before use
  RAID10: ignore discard error
  RAID1: ignore discard error

Pull SCSI fixes from James Bottomley:
 "Two more important data integrity fixes related to RAID device drivers
  which wrongly throw away the SYNCHRONIZE CACHE command in the non-RAID
  path and a memory leak in the scsi_debug driver"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: arcmsr: Send SYNCHRONIZE_CACHE command to firmware
  scsi: scsi_debug: Fix memory leak if LBP enabled and module is unloaded
  scsi: megaraid_sas: Fix data integrity failure for JBOD (passthrough) devices

Pull input subsystem updates from Dmitry Torokhov.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: psmouse - cleanup Focaltech code
  Input: i8042 - add XMG C504 to keyboard reset table

Pull FireWire (IEEE 1394) fixes from Stefan Richter:

 - add missing input validation to the firewire-net driver. Invalid
   IP-over-1394 encapsulation headers could trigger buffer overflows
   (CVE 2016-8633).

 - IP-over-1394 link fragmentation headers were read and written
   incorrectly, breaking fragmented RX/TX with other OS's stacks.

* tag 'firewire-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: net: fix fragmented datagram_size off-by-one
  firewire: net: guard against rx buffer overflows

Pull media fixes from Mauro Carvalho Chehab:
 "A series of fixup patches meant to fix the usage of DMA on stack, plus
  one warning fixup"

* tag 'media/v4.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (32 commits)
  [media] radio-bcm2048: don't ignore errors
  [media] pctv452e: fix semicolon.cocci warnings
  [media] flexcop-usb: don't use stack for DMA
  [media] stk-webcam: don't use stack for DMA
  [media] s2255drv: don't use stack for DMA
  [media] cpia2_usb: don't use stack for DMA
  [media] digitv: handle error code on RC query
  [media] dw2102: return error if su3000_power_ctrl() fails
  [media] nova-t-usb2: handle error code on RC query
  [media] technisat-usb2: use DMA buffers for I2C transfers
  [media] pctv452e: don't call BUG_ON() on non-fatal error
  [media] pctv452e: don't do DMA on stack
  [media] nova-t-usb2: don't do DMA on stack
  [media] gp8psk: don't go past the buffer size
  [media] gp8psk: don't do DMA on stack
  [media] dtv5100: don't do DMA on stack
  [media] dtt200u: handle USB control message errors
  [media] dtt200u: don't do DMA on stack
  [media] dtt200u-fe: handle errors on USB control messages
  [media] dtt200u-fe: don't do DMA on stack
  ...

Pull PCI fixes from Bjorn Helgaas:

 - fix for a Qualcomm driver issue that causes a use-before-set crash

 - fix for DesignWare iATU unroll support that causes external aborts
   when enabling the host bridge

* tag 'pci-v4.9-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: designware: Check for iATU unroll support after initializing host
  PCI: qcom: Fix pp->dev usage before assignment

Pull MTD fixes from Brian Norris:

 - MAINTAINERS updates to reflect some new maintainers/submaintainers.

   We have some great volunteers who've been developing and reviewing
   already. We're going to try a group maintainership model, so
   eventually you'll probably see pull requests from people besides me.

 - NAND fixes from Boris:
    "Three simple fixes:

      - fix a non-critical bug in the gpmi driver
      - fix a bug in the 'automatic NAND timings selection' feature
        introduced in 4.9-rc1
      - fix a false positive uninitialized-var warning"

* tag 'for-linus-20161104' of git://git.infradead.org/linux-mtd:
  mtd: mtk: avoid warning in mtk_ecc_encode
  mtd: nand: Fix data interface configuration logic
  mtd: nand: gpmi: disable the clocks on errors
  MAINTAINERS: add more people to the MTD maintainer team
  MAINTAINERS: add a maintainer for the SPI NOR subsystem

Pull MMC fixes from Ulf Hansson:
 "MMC host:

   - sdhci-msm: Fix error path in probe
   - dw_mmc-pltfm: Avoid NULL pointer dereference"

* tag 'mmc-v4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci-msm: Fix error return code in sdhci_msm_probe()
  mmc: dw_mmc-pltfm: fix the potential NULL pointer dereference

Pull GPIO fixes from Linus Walleij:
 "Some GPIO fixes for the v4.9 series:

   - Fix a nasty file descriptor leak when getting line handles.

   - A fix for a cleanup that seemed innocent but created a problem for
     drivers instantiating several gpiochips for one single OF node.

   - Fix a unpredictable problem using irq_domain_simple() in the mvebu
     driver by converting it to a lineas irqdomain"

* tag 'gpio-v4.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio/mvebu: Use irq_domain_add_linear
  gpio: of: fix GPIO drivers with multiple gpio_chip for a single node
  gpio: GPIO_GET_LINE{HANDLE,EVENT}_IOCTL: Fix file descriptor leak

Pull nfsd bugfixes from Bruce Fields:
 "Fixes for some recent regressions including fallout from the vmalloc'd
  stack change (after which we can no longer encrypt stuff on the
  stack)"

* tag 'nfsd-4.9-1' of git://linux-nfs.org/~bfields/linux:
  nfsd: Fix general protection fault in release_lock_stateid()
  svcrdma: backchannel cannot share a page for send and rcv buffers
  sunrpc: fix some missing rq_rbuffer assignments
  sunrpc: don't pass on-stack memory to sg_set_buf
  nfsd: move blocked lock handling under a dedicated spinlock

Pull btrfs fixes from Chris Mason:
 "Some fixes that Dave Sterba collected.  We held off on these last week
  because I was focused on the memory corruption testing"

* 'for-4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix WARNING in btrfs_select_ref_head()
  Btrfs: remove some no-op casts
  btrfs: pass correct args to btrfs_async_run_delayed_refs()
  btrfs: make file clone aware of fatal signals
  btrfs: qgroup: Prevent qgroup->reserved from going subzero
  Btrfs: kill BUG_ON in do_relocation

Pull overlayfs fixes from Miklos Szeredi:
 "Fix two more POSIX ACL bugs introduced in 4.8 and add a missing fsync
  during copy up to prevent possible data loss"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fsync after copy-up
  ovl: fix get_acl() on tmpfs
  ovl: update S_ISGID when setting posix ACLs

Pull drm fixes from Dave Airlie:
 "Fixes for amdgpu, radeon, intel, imx and virtio-gpu.

  This is a bit larger than I'd like, but I had some stuff I meant to
  send for -rc3 but was waiting for the PAT regression fix to land. So
  this is really fixes for rc3 and rc4 in one go.

  There are a set of fixes for an oops we've been seeing around MST
  display unplug, along with more suspend/resume and shutdown fixes for
  amdgpu, one power management follow on fix for nouveau, and set of imx
  fixes, and a single virtio-gpu regression fix"

* tag 'drm-fixes-for-v4.9-rc4' of git://people.freedesktop.org/~airlied/linux: (54 commits)
  virtio-gpu: fix vblank events
  drm/nouveau/acpi: fix check for power resources support
  drm/i915: Fix SKL+ 90/270 degree rotated plane coordinate computation
  drm/i915: Remove two invalid warns
  drm/i915: Rotated view does not need a fence
  drm/i915/fbc: fix CFB size calculation for gen8+
  drm: i915: Wait for fences on new fb, not old
  drm/i915: Clean up DDI DDC/AUX CH sanitation
  drm/i915: Respect alternate_aux_channel for all DDI ports
  drm/i915/gen9: fix watermarks when using the pipe scaler
  drm/i915: Fix mismatched INIT power domain disabling during suspend
  drm/i915: fix a read size argument
  drm/i915: Use fence_write() from rpm resume
  drm/i915/gen9: fix DDB partitioning for multi-screen cases
  drm/i915: workaround sparse warning on variable length arrays
  drm/i915: keep declarations in i915_drv.h
  drm/amd/powerplay: fix bug get wrong evv voltage of Polaris.
  drm/amdgpu/si_dpm: workaround for SI kickers
  drm/radeon/si_dpm: workaround for SI kickers
  drm/amdgpu: fix s3 resume back, uvd dpm randomly can't disable.
  ...

dw_pcie_iatu_unroll_enabled() reads a dbi_base register.  Reading any
dbi_base register before pp->ops->host_init has been called causes
"imprecise external abort" on platforms like ARTPEC-6, where the PCIe
module is disabled at boot and first enabled in pp->ops->host_init.  Move
dw_pcie_iatu_unroll_enabled() to dw_pcie_setup_rc(), since it is after
pp->ops->host_init, but before pp->iatu_unroll_enabled is actually used.

Fixes: a0601a47 ("PCI: designware: Add iATU Unroll feature")
Tested-by: NJames Le Cuirot <chewi@gentoo.org>
Signed-off-by: NNiklas Cassel <niklas.cassel@axis.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NJoao Pinto <jpinto@synopsys.com>
Acked-by: NOlof Johansson <olof@lixom.net>

Pull KVM updates from Paolo Bonzini:
 "One NULL pointer dereference, and two fixes for regressions introduced
  during the merge window.

  The rest are fixes for MIPS, s390 and nested VMX"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: x86: Check memopp before dereference (CVE-2016-8630)
  kvm: nVMX: VMCLEAR an active shadow VMCS after last use
  KVM: x86: drop TSC offsetting kvm_x86_ops to fix KVM_GET/SET_CLOCK
  KVM: x86: fix wbinvd_dirty_mask use-after-free
  kvm/x86: Show WRMSR data is in hex
  kvm: nVMX: Fix kernel panics induced by illegal INVEPT/INVVPID types
  KVM: document lock orders
  KVM: fix OOPS on flush_work
  KVM: s390: Fix STHYI buffer alignment for diag224
  KVM: MIPS: Precalculate MMIO load resume PC
  KVM: MIPS: Make ERET handle ERL before EXL
  KVM: MIPS: Fix lazy user ASID regenerate for SMP

Pull MIPS fixes from Ralf Baechle:
 "A set of MIPS fixes for 4.9:

   - lots of fixes for printk continuations
   - six fixes for FP related code.
   - fix max_low_pfn with disabled highmem
   - fix KASLR handling of NULL FDT and KASLR for generic kernels
   - fix build of compressed image
   - provide default mips_cpc_default_phys_base to ignore CPC
   - fix reboot on Malta"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: Fix max_low_pfn with disabled highmem
  MIPS: Correct MIPS I FP sigcontext layout
  MIPS: Fix ISA I/II FP signal context offsets
  MIPS: Remove FIR from ISA I FP signal context
  MIPS: Fix ISA I FP sigcontext access violation handling
  MIPS: Fix FCSR Cause bit handling for correct SIGFPE issue
  MIPS: ptrace: Also initialize the FP context on individual FCSR writes
  MIPS: dump_tlb: Fix printk continuations
  MIPS: Fix __show_regs() output
  MIPS: traps: Fix output of show_code
  MIPS: traps: Fix output of show_stacktrace
  MIPS: traps: Fix output of show_backtrace
  MIPS: Fix build of compressed image
  MIPS: generic: Fix KASLR for generic kernel.
  MIPS: KASLR: Fix handling of NULL FDT
  MIPS: Malta: Fixup reboot
  MIPS: CPC: Provide default mips_cpc_default_phys_base to ignore CPC

Pull parisc updates from Helge Deller:
 "The first three patches are trivial and add some required KERN_CONT,
  ignore the new pkey syscalls on parisc and use the LINUX_GATEWAY_ADDR
  define instead of hardcoded values.

  The two patches from Dave Anglin are important.

  The first one avoids trashing the sr2 and sr3 space registers in the
  Light-weight syscall path. Especially the usage of sr3 is critical
  since it may get trashed by the interrupt handler.

  The second patch is even more important and tagged for stable series.
  It protects one critical section in the syscall entry path by
  disabling local interrupts. Without disabling interrupts, the sr7
  space register may not be in sync with the current stack setup and
  thus an incoming hardware interrupt may destroy memory in random
  userspace areas"

* 'parisc-4.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Ignore the pkey system calls for now
  parisc: Use LINUX_GATEWAY_ADDR define instead of hardcoded value
  parisc: Ensure consistent state when switching to kernel stack at syscall entry
  parisc: Avoid trashing sr2 and sr3 in LWS code
  parisc: use KERN_CONT when printing device inventory

Race condition between registering an I2C device driver and
deregistering an I2C adapter device which is assumed to manage that
I2C device may lead to a NULL pointer dereference due to the
uninitialized list head of driver clients.

The root cause of the issue is that the I2C bus may know about the
registered device driver and thus it is matched by bus_for_each_drv(),
but the list of clients is not initialized and commonly it is NULL,
because I2C device drivers define struct i2c_driver as static and
clients field is expected to be initialized by I2C core:

  i2c_register_driver()             i2c_del_adapter()
    driver_register()                 ...
      bus_add_driver()                ...
        ...                           bus_for_each_drv(..., __process_removed_adapter)
      ...                               i2c_do_del_adapter()
    ...                                   list_for_each_entry_safe(..., &driver->clients, ...)
    INIT_LIST_HEAD(&driver->clients);

To solve the problem it is sufficient to do clients list head
initialization before calling driver_register().

The problem was found while using an I2C device driver with a sluggish
registration routine on a bus provided by a physically detachable I2C
master controller, but practically the oops may be reproduced under
the race between arbitraty I2C device driver registration and managing
I2C bus device removal e.g. by unbinding the latter over sysfs:

% echo 21a4000.i2c > /sys/bus/platform/drivers/imx-i2c/unbind
  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  Internal error: Oops: 17 [#1] SMP ARM
  CPU: 2 PID: 533 Comm: sh Not tainted 4.9.0-rc3+ #61
  Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
  task: e5ada400 task.stack: e4936000
  PC is at i2c_do_del_adapter+0x20/0xcc
  LR is at __process_removed_adapter+0x14/0x1c
  Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
  Control: 10c5387d  Table: 35bd004a  DAC: 00000051
  Process sh (pid: 533, stack limit = 0xe4936210)
  Stack: (0xe4937d28 to 0xe4938000)
  Backtrace:
  [<c0667be0>] (i2c_do_del_adapter) from [<c0667cc0>] (__process_removed_adapter+0x14/0x1c)
  [<c0667cac>] (__process_removed_adapter) from [<c0516998>] (bus_for_each_drv+0x6c/0xa0)
  [<c051692c>] (bus_for_each_drv) from [<c06685ec>] (i2c_del_adapter+0xbc/0x284)
  [<c0668530>] (i2c_del_adapter) from [<bf0110ec>] (i2c_imx_remove+0x44/0x164 [i2c_imx])
  [<bf0110a8>] (i2c_imx_remove [i2c_imx]) from [<c051a838>] (platform_drv_remove+0x2c/0x44)
  [<c051a80c>] (platform_drv_remove) from [<c05183d8>] (__device_release_driver+0x90/0x12c)
  [<c0518348>] (__device_release_driver) from [<c051849c>] (device_release_driver+0x28/0x34)
  [<c0518474>] (device_release_driver) from [<c0517150>] (unbind_store+0x80/0x104)
  [<c05170d0>] (unbind_store) from [<c0516520>] (drv_attr_store+0x28/0x34)
  [<c05164f8>] (drv_attr_store) from [<c0298acc>] (sysfs_kf_write+0x50/0x54)
  [<c0298a7c>] (sysfs_kf_write) from [<c029801c>] (kernfs_fop_write+0x100/0x214)
  [<c0297f1c>] (kernfs_fop_write) from [<c0220130>] (__vfs_write+0x34/0x120)
  [<c02200fc>] (__vfs_write) from [<c0221088>] (vfs_write+0xa8/0x170)
  [<c0220fe0>] (vfs_write) from [<c0221e74>] (SyS_write+0x4c/0xa8)
  [<c0221e28>] (SyS_write) from [<c0108a20>] (ret_fast_syscall+0x0/0x1c)
Signed-off-by: NVladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

When low memory doesn't reach HIGHMEM_START (e.g. up to 256MB at PA=0 is
common) and highmem is present above HIGHMEM_START (e.g. on Malta the
RAM overlayed by the IO region is aliased at PA=0x90000000), max_low_pfn
will be initially calculated very large and then clipped down to
HIGHMEM_START.

This causes crashes when reading /sys/kernel/mm/page_idle/bitmap
(i.e. CONFIG_IDLE_PAGE_TRACKING=y) when highmem is disabled. pfn_valid()
will compare against max_mapnr which is derived from max_low_pfn when
there is no highend_pfn set up, and will return true for PFNs right up
to HIGHMEM_START, even though they are beyond the end of low memory and
no page structs will actually exist for these PFNs.

This is fixed by skipping high memory regions when initially calculating
max_low_pfn if highmem is disabled, so it doesn't get clipped too high.
We also clip regions which overlap the highmem boundary when highmem is
disabled, so that max_pfn doesn't extend into highmem either.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14490/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Complement commit 80cbfad7 ("MIPS: Correct MIPS I FP context
layout") and correct the way Floating Point General registers are stored
in a signal context with MIPS I hardware.

Use the S.D and L.D assembly macros to have pairs of SWC1 instructions
and pairs of LWC1 instructions produced, respectively, in an arrangement
which makes the memory representation of floating-point data passed
compatible with that used by hardware SDC1 and LDC1 instructions, where
available, regardless of the hardware endianness used.  This matches the
layout used by r4k_fpu.S, ensuring run-time compatibility for MIPS I
software across all o32 hardware platforms.

Define an EX2 macro to handle exceptions from both hardware instructions
implicitly produced from S.D and L.D assembly macros.
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14477/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Fix a regression introduced with commit 2db9ca0a ("MIPS: Use struct
mips_abi offsets to save FP context") for MIPS I/I FP signal contexts,
by converting save/restore code to the updated internal API.  Start FGR
offsets from 0 rather than SC_FPREGS from $a0 and use $a1 rather than
the offset of SC_FPC_CSR from $a0 for the Floating Point Control/Status
Register (FCSR).

Document the new internal API and adjust assembly code formatting for
consistency.
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14476/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Complement commit e50c0a8f ("Support the MIPS32 / MIPS64 DSP ASE.")
and remove the Floating Point Implementation Register (FIR) from the FP
register set recorded in a signal context with MIPS I processors too, in
line with the change applied to r4k_fpu.S.

The `sc_fpc_eir' slot is unused according to our current ABI and the FIR
register is read-only and always directly accessible from user software.

[ralf@linux-mips.org: This is also required because the next commit depends
on it.]
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14475/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Complement commit 0ae8dceaebe3 ("Merge with 2.3.10.") and use the local
`fault' handler to recover from FP sigcontext access violation faults,
like corresponding code does in r4k_fpu.S.  The `bad_stack' handler is
in syscall.c and is not suitable here as we want to propagate the error
condition up through the caller rather than killing the thread outright.
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14474/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Sanitize FCSR Cause bit handling, following a trail of past attempts:

* commit 42495484 ("MIPS: ptrace: Fix FP context restoration FCSR
regression"),

* commit 443c4403 ("MIPS: Always clear FCSR cause bits after
emulation"),

* commit 64bedffe ("MIPS: Clear [MSA]FPE CSR.Cause after
notify_die()"),

* commit b1442d39 ("MIPS: Prevent user from setting FCSR cause
bits"),

* commit b54d2901517d ("Properly handle branch delay slots in connection
with signals.").

Specifically do not mask these bits out in ptrace(2) processing and send
a SIGFPE signal instead whenever a matching pair of an FCSR Cause and
Enable bit is seen as execution of an affected context is about to
resume.  Only then clear Cause bits, and even then do not clear any bits
that are set but masked with the respective Enable bits.  Adjust Cause
bit clearing throughout code likewise, except within the FPU emulator
proper where they are set according to IEEE 754 exceptions raised as the
operation emulated executed.  Do so so that any IEEE 754 exceptions
subject to their default handling are recorded like with operations
executed by FPU hardware.
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14460/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Complement commit ac9ad83b ("MIPS: prevent FP context set via ptrace
being discarded") and also initialize the FP context whenever FCSR alone
is written with a PTRACE_POKEUSR request addressing FPC_CSR, rather than
along with the full FPU register set in the case of the PTRACE_SETFPREGS
request.
Signed-off-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14459/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>