Merge tag 'v4.13-rc1' into patchwork

Linux v4.13-rc1

* tag 'v4.13-rc1': (11136 commits)
  Linux v4.13-rc1
  random: reorder READ_ONCE() in get_random_uXX
  random: suppress spammy warnings about unseeded randomness
  replace incorrect strscpy use in FORTIFY_SOURCE
  kmod: throttle kmod thread limit
  kmod: add test driver to stress test the module loader
  MAINTAINERS: give kmod some maintainer love
  xtensa: use generic fb.h
  fault-inject: add /proc/<pid>/fail-nth
  fault-inject: simplify access check for fail-nth
  fault-inject: make fail-nth read/write interface symmetric
  fault-inject: parse as natural 1-based value for fail-nth write interface
  fault-inject: automatically detect the number base for fail-nth write interface
  kernel/watchdog.c: use better pr_fmt prefix
  MAINTAINERS: move the befs tree to kernel.org
  lib/atomic64_test.c: add a test that atomic64_inc_not_zero() returns an int
  mm: fix overflow check in expand_upwards()
  ubifs: Set double hash cookie also for RENAME_EXCHANGE
  ubifs: Massage assert in ubifs_xattr_set() wrt. init_xattrs
  ubifs: Don't leak kernel memory to the MTD
  ...

1 files changed, 20 insertions, 7 deletions

diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary
index d1824b399b2d..1721c1b570c3 100644
--- a/Documentation/spi/spi-summary
+++ b/Documentation/spi/spi-summary
@@ -62,8 +62,8 @@ chips described as using "three wire" signaling: SCK, data, nCSx.
 (That data line is sometimes called MOMI or SISO.)
 
 Microcontrollers often support both master and slave sides of the SPI
-protocol.  This document (and Linux) currently only supports the master
-side of SPI interactions.
+protocol.  This document (and Linux) supports both the master and slave
+sides of SPI interactions.
 
 
 Who uses it?  On what kinds of systems?
@@ -154,9 +154,8 @@ control audio interfaces, present touchscreen sensors as input interfaces,
 or monitor temperature and voltage levels during industrial processing.
 And those might all be sharing the same controller driver.
 
-A "struct spi_device" encapsulates the master-side interface between
-those two types of driver.  At this writing, Linux has no slave side
-programming interface.
+A "struct spi_device" encapsulates the controller-side interface between
+those two types of drivers.
 
 There is a minimal core of SPI programming interfaces, focussing on
 using the driver model to connect controller and protocol drivers using
@@ -177,10 +176,24 @@ shows up in sysfs in several locations:
    /sys/bus/spi/drivers/D ... driver for one or more spi*.* devices
 
    /sys/class/spi_master/spiB ... symlink (or actual device node) to
-	a logical node which could hold class related state for the
-	controller managing bus "B".  All spiB.* devices share one
+	a logical node which could hold class related state for the SPI
+	master controller managing bus "B".  All spiB.* devices share one
 	physical SPI bus segment, with SCLK, MOSI, and MISO.
 
+   /sys/devices/.../CTLR/slave ... virtual file for (un)registering the
+	slave device for an SPI slave controller.
+	Writing the driver name of an SPI slave handler to this file
+	registers the slave device; writing "(null)" unregisters the slave
+	device.
+	Reading from this file shows the name of the slave device ("(null)"
+	if not registered).
+
+   /sys/class/spi_slave/spiB ... symlink (or actual device node) to
+	a logical node which could hold class related state for the SPI
+	slave controller on bus "B".  When registered, a single spiB.*
+	device is present here, possible sharing the physical SPI bus
+	segment with other SPI slave devices.
+
 Note that the actual location of the controller's class state depends
 on whether you enabled CONFIG_SYSFS_DEPRECATED or not.  At this time,
 the only class-specific state is the bus number ("B" in "spiB"), so