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-rw-r--r--Documentation/spi/spi-summary25
1 files changed, 17 insertions, 8 deletions
diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary
index 76ea6c8..8861e47 100644
--- a/Documentation/spi/spi-summary
+++ b/Documentation/spi/spi-summary
@@ -156,21 +156,29 @@ using the driver model to connect controller and protocol drivers using
device tables provided by board specific initialization code. SPI
shows up in sysfs in several locations:
+ /sys/devices/.../CTLR ... physical node for a given SPI controller
+
/sys/devices/.../CTLR/spiB.C ... spi_device on bus "B",
chipselect C, accessed through CTLR.
+ /sys/bus/spi/devices/spiB.C ... symlink to that physical
+ .../CTLR/spiB.C device
+
/sys/devices/.../CTLR/spiB.C/modalias ... identifies the driver
that should be used with this device (for hotplug/coldplug)
- /sys/bus/spi/devices/spiB.C ... symlink to the physical
- spiB.C device
-
/sys/bus/spi/drivers/D ... driver for one or more spi*.* devices
- /sys/class/spi_master/spiB ... class device for the controller
- managing bus "B". All the spiB.* devices share the same
+ /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
physical SPI bus segment, with SCLK, MOSI, and MISO.
+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
+those /sys/class entries are only useful to quickly identify busses.
+
How does board-specific init code declare SPI devices?
------------------------------------------------------
@@ -337,7 +345,8 @@ SPI protocol drivers somewhat resemble platform device drivers:
The driver core will autmatically attempt to bind this driver to any SPI
device whose board_info gave a modalias of "CHIP". Your probe() code
-might look like this unless you're creating a class_device:
+might look like this unless you're creating a device which is managing
+a bus (appearing under /sys/class/spi_master).
static int __devinit CHIP_probe(struct spi_device *spi)
{
@@ -442,7 +451,7 @@ An SPI controller will probably be registered on the platform_bus; write
a driver to bind to the device, whichever bus is involved.
The main task of this type of driver is to provide an "spi_master".
-Use spi_alloc_master() to allocate the master, and class_get_devdata()
+Use spi_alloc_master() to allocate the master, and spi_master_get_devdata()
to get the driver-private data allocated for that device.
struct spi_master *master;
@@ -452,7 +461,7 @@ to get the driver-private data allocated for that device.
if (!master)
return -ENODEV;
- c = class_get_devdata(&master->cdev);
+ c = spi_master_get_devdata(master);
The driver will initialize the fields of that spi_master, including the
bus number (maybe the same as the platform device ID) and three methods

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