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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 10:32:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 10:32:00 -0700
commit5f0e685f316a1de6d3af8b23eaf46651faca32ab (patch)
treeaf1ed231b7fcfc65b146be59a0aee699aa9f6353 /Documentation
parentf8974cb71310a05632aada76be6a27576d61e609 (diff)
parent87bf5ab82884c829366914aaa813cc8b07b9fe58 (diff)
downloadlinux-5f0e685f316a1de6d3af8b23eaf46651faca32ab.tar.bz2
Merge tag 'spi-for-linus' of git://git.secretlab.ca/git/linux-2.6
Pull SPI changes for v3.4 from Grant Likely: "Mostly a bunch of new drivers and driver bug fixes; but this also includes a few patches that create a core message queue infrastructure for the spi subsystem instead of making each driver open code it." * tag 'spi-for-linus' of git://git.secretlab.ca/git/linux-2.6: (34 commits) spi/fsl-espi: Make sure pm is within 2..32 spi/fsl-espi: make the clock computation easier to read spi: sh-hspi: modify write/read method spi: sh-hspi: control spi clock more correctly spi: sh-hspi: convert to using core message queue spi: s3c64xx: Fix build spi: s3c64xx: remove unnecessary callback msg->complete spi: remove redundant variable assignment spi: release lock on error path in spi_pump_messages() spi: Compatibility with direction which is used in samsung DMA operation spi-topcliff-pch: add recovery processing in case wait-event timeout spi-topcliff-pch: supports a spi mode setup and bit order setup by IO control spi-topcliff-pch: Fix issue for transmitting over 4KByte spi-topcliff-pch: Modify pci-bus number dynamically to get DMA device info spi/imx: simplify error handling to free gpios spi: Convert to DEFINE_PCI_DEVICE_TABLE spi: add Broadcom BCM63xx SPI controller driver SPI: add CSR SiRFprimaII SPI controller driver spi-topcliff-pch: fix -Wuninitialized warning spi: Mark spi_register_board_info() __devinit ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/spi/omap-spi.txt20
-rw-r--r--Documentation/spi/spi-summary58
2 files changed, 66 insertions, 12 deletions
diff --git a/Documentation/devicetree/bindings/spi/omap-spi.txt b/Documentation/devicetree/bindings/spi/omap-spi.txt
new file mode 100644
index 000000000000..81df374adbb9
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/omap-spi.txt
@@ -0,0 +1,20 @@
+OMAP2+ McSPI device
+
+Required properties:
+- compatible :
+ - "ti,omap2-spi" for OMAP2 & OMAP3.
+ - "ti,omap4-spi" for OMAP4+.
+- ti,spi-num-cs : Number of chipselect supported by the instance.
+- ti,hwmods: Name of the hwmod associated to the McSPI
+
+
+Example:
+
+mcspi1: mcspi@1 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ compatible = "ti,omap4-mcspi";
+ ti,hwmods = "mcspi1";
+ ti,spi-num-cs = <4>;
+};
+
diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary
index 4884cb33845d..7312ec14dd89 100644
--- a/Documentation/spi/spi-summary
+++ b/Documentation/spi/spi-summary
@@ -1,7 +1,7 @@
Overview of Linux kernel SPI support
====================================
-21-May-2007
+02-Feb-2012
What is SPI?
------------
@@ -483,9 +483,9 @@ also initialize its own internal state. (See below about bus numbering
and those methods.)
After you initialize the spi_master, then use spi_register_master() to
-publish it to the rest of the system. At that time, device nodes for
-the controller and any predeclared spi devices will be made available,
-and the driver model core will take care of binding them to drivers.
+publish it to the rest of the system. At that time, device nodes for the
+controller and any predeclared spi devices will be made available, and
+the driver model core will take care of binding them to drivers.
If you need to remove your SPI controller driver, spi_unregister_master()
will reverse the effect of spi_register_master().
@@ -521,21 +521,53 @@ SPI MASTER METHODS
** When you code setup(), ASSUME that the controller
** is actively processing transfers for another device.
- master->transfer(struct spi_device *spi, struct spi_message *message)
- This must not sleep. Its responsibility is arrange that the
- transfer happens and its complete() callback is issued. The two
- will normally happen later, after other transfers complete, and
- if the controller is idle it will need to be kickstarted.
-
master->cleanup(struct spi_device *spi)
Your controller driver may use spi_device.controller_state to hold
state it dynamically associates with that device. If you do that,
be sure to provide the cleanup() method to free that state.
+ master->prepare_transfer_hardware(struct spi_master *master)
+ This will be called by the queue mechanism to signal to the driver
+ that a message is coming in soon, so the subsystem requests the
+ driver to prepare the transfer hardware by issuing this call.
+ This may sleep.
+
+ master->unprepare_transfer_hardware(struct spi_master *master)
+ This will be called by the queue mechanism to signal to the driver
+ that there are no more messages pending in the queue and it may
+ relax the hardware (e.g. by power management calls). This may sleep.
+
+ master->transfer_one_message(struct spi_master *master,
+ struct spi_message *mesg)
+ The subsystem calls the driver to transfer a single message while
+ queuing transfers that arrive in the meantime. When the driver is
+ finished with this message, it must call
+ spi_finalize_current_message() so the subsystem can issue the next
+ transfer. This may sleep.
+
+ DEPRECATED METHODS
+
+ master->transfer(struct spi_device *spi, struct spi_message *message)
+ This must not sleep. Its responsibility is arrange that the
+ transfer happens and its complete() callback is issued. The two
+ will normally happen later, after other transfers complete, and
+ if the controller is idle it will need to be kickstarted. This
+ method is not used on queued controllers and must be NULL if
+ transfer_one_message() and (un)prepare_transfer_hardware() are
+ implemented.
+
SPI MESSAGE QUEUE
-The bulk of the driver will be managing the I/O queue fed by transfer().
+If you are happy with the standard queueing mechanism provided by the
+SPI subsystem, just implement the queued methods specified above. Using
+the message queue has the upside of centralizing a lot of code and
+providing pure process-context execution of methods. The message queue
+can also be elevated to realtime priority on high-priority SPI traffic.
+
+Unless the queueing mechanism in the SPI subsystem is selected, the bulk
+of the driver will be managing the I/O queue fed by the now deprecated
+function transfer().
That queue could be purely conceptual. For example, a driver used only
for low-frequency sensor access might be fine using synchronous PIO.
@@ -561,4 +593,6 @@ Stephen Street
Mark Underwood
Andrew Victor
Vitaly Wool
-
+Grant Likely
+Mark Brown
+Linus Walleij