linux.git/drivers/i2c, branch v4.9-rc5

i2c: core: fix NULL pointer dereference under race condition

2016-11-04T19:36:58+00:00

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:
  [] (i2c_do_del_adapter) from [] (__process_removed_adapter+0x14/0x1c)
  [] (__process_removed_adapter) from [] (bus_for_each_drv+0x6c/0xa0)
  [] (bus_for_each_drv) from [] (i2c_del_adapter+0xbc/0x284)
  [] (i2c_del_adapter) from [] (i2c_imx_remove+0x44/0x164 [i2c_imx])
  [] (i2c_imx_remove [i2c_imx]) from [] (platform_drv_remove+0x2c/0x44)
  [] (platform_drv_remove) from [] (__device_release_driver+0x90/0x12c)
  [] (__device_release_driver) from [] (device_release_driver+0x28/0x34)
  [] (device_release_driver) from [] (unbind_store+0x80/0x104)
  [] (unbind_store) from [] (drv_attr_store+0x28/0x34)
  [] (drv_attr_store) from [] (sysfs_kf_write+0x50/0x54)
  [] (sysfs_kf_write) from [] (kernfs_fop_write+0x100/0x214)
  [] (kernfs_fop_write) from [] (__vfs_write+0x34/0x120)
  [] (__vfs_write) from [] (vfs_write+0xa8/0x170)
  [] (vfs_write) from [] (SyS_write+0x4c/0xa8)
  [] (SyS_write) from [] (ret_fast_syscall+0x0/0x1c)

Signed-off-by: Vladimir Zapolskiy 
Signed-off-by: Wolfram Sang 
Cc: stable@kernel.org

i2c: imx: defer probe if bus recovery GPIOs are not ready

2016-10-25T10:15:00+00:00

Some SoC might load the GPIO driver after the I2C driver and
using the I2C bus recovery mechanism via GPIOs. In this case
it is crucial to defer probing if the GPIO request functions
do so, otherwise the I2C driver gets loaded without recovery
mechanisms enabled.

Signed-off-by: Stefan Agner 
Acked-by: Uwe Kleine-König 
Acked-by: Li Yang 
Signed-off-by: Wolfram Sang 
Cc: stable@kernel.org

i2c: designware: Avoid aborted transfers with fast reacting I2C slaves

2016-10-25T10:09:09+00:00

I2C DesignWare may abort transfer with arbitration lost if I2C slave pulls
SDA down quickly after falling edge of SCL. Reason for this is unknown but
after trial and error it was found this can be avoided by enabling non-zero
SDA RX hold time for the receiver.

By the specification SDA RX hold time extends incoming SDA low to high
transition by n * ic_clk cycles but only when SCL is high. However it
seems to help avoid above faulty arbitration lost error.

Bits 23:16 in IC_SDA_HOLD register define the SDA RX hold time for the
receiver. Be conservative and enable 1 ic_clk cycle long hold time in
case boot firmware hasn't set it up.

Reported-by: Jukka Laitinen 
Signed-off-by: Jarkko Nikula 
Tested-by: Jukka Laitinen 
Signed-off-by: Wolfram Sang

i2c: i801: Fix I2C Block Read on 8-Series/C220 and later

2016-10-25T10:00:01+00:00

Starting with the 8-Series/C220 PCH (Lynx Point), the SMBus
controller includes a SPD EEPROM protection mechanism. Once the SPD
Write Disable bit is set, only reads are allowed to slave addresses
0x50-0x57.

However the legacy implementation of I2C Block Read since the ICH5
looks like a write, and is therefore blocked by the SPD protection
mechanism. This causes the eeprom and at24 drivers to fail.

So assume that I2C Block Read is implemented as an actual read on
these chipsets. I tested it on my Q87 chipset and it seems to work
just fine.

Signed-off-by: Jean Delvare 
Tested-by: Jarkko Nikula 
[wsa: rebased to v4.9-rc2]
Signed-off-by: Wolfram Sang

i2c: xgene: Avoid dma_buffer overrun

2016-10-25T09:50:52+00:00

SMBus block command uses the first byte of buffer for the data length.
The dma_buffer should be increased by 1 to avoid the overrun issue.

Reported-by: Phil Endecott 
Signed-off-by: Hoan Tran 
Signed-off-by: Wolfram Sang 
Cc: stable@kernel.org

i2c: digicolor: Fix module autoload

2016-10-25T09:49:01+00:00

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Signed-off-by: Javier Martinez Canillas 
Acked-by: Baruch Siach 
Signed-off-by: Wolfram Sang

i2c: xlr: Fix module autoload for OF registration

2016-10-25T09:49:00+00:00

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Signed-off-by: Javier Martinez Canillas 
Signed-off-by: Wolfram Sang

i2c: xlp9xx: Fix module autoload

2016-10-25T09:48:59+00:00

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Signed-off-by: Javier Martinez Canillas 
Signed-off-by: Wolfram Sang

i2c: jz4780: Fix module autoload

2016-10-25T09:48:58+00:00

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Signed-off-by: Javier Martinez Canillas 
Signed-off-by: Wolfram Sang

i2c: allow configuration of imx driver for ColdFire architecture

2016-10-25T09:48:57+00:00

The i2c controller used by Freescales iMX processors is the same
hardware module used on Freescales ColdFire family of processors.

We can use the existing i2c-imx driver on ColdFire family members.
Modify the configuration to allow it to be selected when compiling
for ColdFire targets.

Signed-off-by: Greg Ungerer 
Signed-off-by: Wolfram Sang