diff options
Diffstat (limited to 'meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0085-spi-Document-SPI-slave-controller-support.patch')
| -rw-r--r-- | meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0085-spi-Document-SPI-slave-controller-support.patch | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0085-spi-Document-SPI-slave-controller-support.patch b/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0085-spi-Document-SPI-slave-controller-support.patch new file mode 100644 index 0000000..57436d2 --- /dev/null +++ b/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0085-spi-Document-SPI-slave-controller-support.patch @@ -0,0 +1,66 @@ +From 0be2c71f293e8c8423e5378cc73f71e10205ad54 Mon Sep 17 00:00:00 2001 +From: Geert Uytterhoeven <geert+renesas@glider.be> +Date: Thu, 8 Sep 2016 15:01:48 +0200 +Subject: [PATCH 3/7] spi: Document SPI slave controller support + +Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> +--- + Documentation/spi/spi-summary | 27 ++++++++++++++++++++------- + 1 file changed, 20 insertions(+), 7 deletions(-) + +diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary +index d1824b3..1721c1b 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 +-- +1.7.10.4 |