Merge tag 'ib-mfd-regulator-arm-v4.8' of...

!Edrivers/base/platform.c

!Edrivers/base/bus.c

     </sect1>

     <sect1><title>Device Drivers DMA Management</title>

     <sect1>

       <title>Buffer Sharing and Synchronization</title>

       <para>

         The dma-buf subsystem provides the framework for sharing buffers

         for hardware (DMA) access across multiple device drivers and

         subsystems, and for synchronizing asynchronous hardware access.

       </para>

       <para>

         This is used, for example, by drm "prime" multi-GPU support, but

         is of course not limited to GPU use cases.

       </para>

       <para>

         The three main components of this are: (1) dma-buf, representing

         a sg_table and exposed to userspace as a file descriptor to allow

         passing between devices, (2) fence, which provides a mechanism

         to signal when one device as finished access, and (3) reservation,

         which manages the shared or exclusive fence(s) associated with

         the buffer.

       </para>

       <sect2><title>dma-buf</title>

!Edrivers/dma-buf/dma-buf.c

!Iinclude/linux/dma-buf.h

       </sect2>

       <sect2><title>reservation</title>

!Pdrivers/dma-buf/reservation.c Reservation Object Overview

!Edrivers/dma-buf/reservation.c

!Iinclude/linux/reservation.h

       </sect2>

       <sect2><title>fence</title>

!Edrivers/dma-buf/fence.c

!Edrivers/dma-buf/seqno-fence.c

!Iinclude/linux/fence.h

!Edrivers/dma-buf/seqno-fence.c

!Iinclude/linux/seqno-fence.h

!Edrivers/dma-buf/reservation.c

!Iinclude/linux/reservation.h

!Edrivers/dma-buf/sync_file.c

!Iinclude/linux/sync_file.h

       </sect2>

     </sect1>

     <sect1><title>Device Drivers DMA Management</title>

!Edrivers/base/dma-coherent.c

!Edrivers/base/dma-mapping.c

     </sect1>

| ARM            | MMU-500         | #841119,#826419 | N/A                     |

|                |                 |                 |                         |

| Cavium         | ThunderX ITS    | #22375, #24313  | CAVIUM_ERRATUM_22375    |

| Cavium         | ThunderX ITS    | #23144          | CAVIUM_ERRATUM_23144    |

| Cavium         | ThunderX GICv3  | #23154          | CAVIUM_ERRATUM_23154    |

| Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456    |

| Cavium         | ThunderX SMMUv2 | #27704          | N/A		       |

   display-timings are used instead.

Optional properties (required if display-timings are used):

 - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing

 - display-timings : A node that describes the display timings as defined in

   Documentation/devicetree/bindings/display/display-timing.txt.

 - fsl,data-mapping : should be "spwg" or "jeida"

* Ricoh RN5T618 PMIC

* Ricoh RN5T567/RN5T618 PMIC

Ricoh RN5T618 is a power management IC which integrates 3 step-down

DCDC converters, 7 low-dropout regulators, a Li-ion battery charger,

fuel gauge, ADC, GPIOs and a watchdog timer. It can be controlled

through a I2C interface.

Ricoh RN5T567/RN5T618 is a power management IC family which integrates

3 to 4 step-down DCDC converters, 7 low-dropout regulators, GPIOs and

a watchdog timer. The RN5T618 provides additionally a Li-ion battery

charger, fuel gauge and an ADC. It can be controlled through an I2C

interface.

Required properties:

 - compatible: should be "ricoh,rn5t618"

 - compatible: must be one of

		"ricoh,rn5t567"

		"ricoh,rn5t618"

 - reg: the I2C slave address of the device

Sub-nodes:

 - regulators: the node is required if the regulator functionality is

   needed. The valid regulator names are: DCDC1, DCDC2, DCDC3, LDO1,

   LDO2, LDO3, LDO4, LDO5, LDORTC1 and LDORTC2.

   needed. The valid regulator names are: DCDC1, DCDC2, DCDC3, DCDC4

   (RN5T567), LDO1, LDO2, LDO3, LDO4, LDO5, LDORTC1 and LDORTC2.

   The common bindings for each individual regulator can be found in:

   Documentation/devicetree/bindings/regulator/regulator.txt

Each mount of the devpts filesystem is now distinct such that ptys

and their indicies allocated in one mount are independent from ptys

and their indicies in all other mounts.

To support containers, we now allow multiple instances of devpts filesystem,

such that indices of ptys allocated in one instance are independent of indices

allocated in other instances of devpts.

All mounts of the devpts filesystem now create a /dev/pts/ptmx node

with permissions 0000.

To preserve backward compatibility, this support for multiple instances is

enabled only if:

To retain backwards compatibility the a ptmx device node (aka any node

created with "mknod name c 5 2") when opened will look for an instance

of devpts under the name "pts" in the same directory as the ptmx device

node.

	- CONFIG_DEVPTS_MULTIPLE_INSTANCES=y, and

	- '-o newinstance' mount option is specified while mounting devpts

IOW, devpts now supports both single-instance and multi-instance semantics.

If CONFIG_DEVPTS_MULTIPLE_INSTANCES=n, there is no change in behavior and

this referred to as the "legacy" mode. In this mode, the new mount options

(-o newinstance and -o ptmxmode) will be ignored with a 'bogus option' message

on console.

If CONFIG_DEVPTS_MULTIPLE_INSTANCES=y and devpts is mounted without the

'newinstance' option (as in current start-up scripts) the new mount binds

to the initial kernel mount of devpts. This mode is referred to as the

'single-instance' mode and the current, single-instance semantics are

preserved, i.e PTYs are common across the system.

The only difference between this single-instance mode and the legacy mode

is the presence of new, '/dev/pts/ptmx' node with permissions 0000, which

can safely be ignored.

If CONFIG_DEVPTS_MULTIPLE_INSTANCES=y and 'newinstance' option is specified,

the mount is considered to be in the multi-instance mode and a new instance

of the devpts fs is created. Any ptys created in this instance are independent

of ptys in other instances of devpts. Like in the single-instance mode, the

/dev/pts/ptmx node is present. To effectively use the multi-instance mode,

open of /dev/ptmx must be a redirected to '/dev/pts/ptmx' using a symlink or

bind-mount.

Eg: A container startup script could do the following:

	$ chmod 0666 /dev/pts/ptmx

	$ rm /dev/ptmx

	$ ln -s pts/ptmx /dev/ptmx

	$ ns_exec -cm /bin/bash

	# We are now in new container

	$ umount /dev/pts

	$ mount -t devpts -o newinstance lxcpts /dev/pts

	$ sshd -p 1234

where 'ns_exec -cm /bin/bash' calls clone() with CLONE_NEWNS flag and execs

/bin/bash in the child process.  A pty created by the sshd is not visible in

the original mount of /dev/pts.

As an option instead of placing a /dev/ptmx device node at /dev/ptmx

it is possible to place a symlink to /dev/pts/ptmx at /dev/ptmx or

to bind mount /dev/ptx/ptmx to /dev/ptmx.  If you opt for using

the devpts filesystem in this manner devpts should be mounted with

the ptmxmode=0666, or chmod 0666 /dev/pts/ptmx should be called.

Total count of pty pairs in all instances is limited by sysctls:

kernel.pty.max = 4096		- global limit

kernel.pty.reserve = 1024	- reserve for initial instance

kernel.pty.reserve = 1024	- reserved for filesystems mounted from the initial mount namespace

kernel.pty.nr			- current count of ptys

Per-instance limit could be set by adding mount option "max=<count>".

This feature was added in kernel 3.4 together with sysctl kernel.pty.reserve.

In kernels older than 3.4 sysctl kernel.pty.max works as per-instance limit.

User-space changes

------------------

In multi-instance mode (i.e '-o newinstance' mount option is specified at least

once), following user-space issues should be noted.

1. If -o newinstance mount option is never used, /dev/pts/ptmx can be ignored

   and no change is needed to system-startup scripts.

2. To effectively use multi-instance mode (i.e -o newinstance is specified)

   administrators or startup scripts should "redirect" open of /dev/ptmx to

   /dev/pts/ptmx using either a bind mount or symlink.

	$ mount -t devpts -o newinstance devpts /dev/pts

   followed by either

	$ rm /dev/ptmx

	$ ln -s pts/ptmx /dev/ptmx

	$ chmod 666 /dev/pts/ptmx

   or

	$ mount -o bind /dev/pts/ptmx /dev/ptmx

3. The '/dev/ptmx -> pts/ptmx' symlink is the preferred method since it

   enables better error-reporting and treats both single-instance and

   multi-instance mounts similarly.

   But this method requires that system-startup scripts set the mode of

   /dev/pts/ptmx correctly (default mode is 0000). The scripts can set the

   mode by, either

   	- adding ptmxmode mount option to devpts entry in /etc/fstab, or

	- using 'chmod 0666 /dev/pts/ptmx'

4. If multi-instance mode mount is needed for containers, but the system

   startup scripts have not yet been updated, container-startup scripts

   should bind mount /dev/ptmx to /dev/pts/ptmx to avoid breaking single-

   instance mounts.

   Or, in general, container-startup scripts should use:

	mount -t devpts -o newinstance -o ptmxmode=0666 devpts /dev/pts

	if [ ! -L /dev/ptmx ]; then

		mount -o bind /dev/pts/ptmx /dev/ptmx

	fi

   When all devpts mounts are multi-instance, /dev/ptmx can permanently be

   a symlink to pts/ptmx and the bind mount can be ignored.

5. A multi-instance mount that is not accompanied by the /dev/ptmx to

   /dev/pts/ptmx redirection would result in an unusable/unreachable pty.

	mount -t devpts -o newinstance lxcpts /dev/pts

   immediately followed by:

	open("/dev/ptmx")

    would create a pty, say /dev/pts/7, in the initial kernel mount.

    But /dev/pts/7 would be invisible in the new mount.

6. The permissions for /dev/pts/ptmx node should be specified when mounting

   /dev/pts, using the '-o ptmxmode=%o' mount option (default is 0000).

	mount -t devpts -o newinstance -o ptmxmode=0644 devpts /dev/pts

   The permissions can be later be changed as usual with 'chmod'.

	chmod 666 /dev/pts/ptmx

7. A mount of devpts without the 'newinstance' option results in binding to

   initial kernel mount.  This behavior while preserving legacy semantics,

   does not provide strict isolation in a container environment. i.e by

   mounting devpts without the 'newinstance' option, a container could

   get visibility into the 'host' or root container's devpts.

   To workaround this and have strict isolation, all mounts of devpts,

   including the mount in the root container, should use the newinstance

   option.