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authorVijay Kumar Banerjee <vijaykumar9597@gmail.com>2019-07-18 19:54:30 +0530
committerChris Johns <chrisj@rtems.org>2019-07-20 11:13:15 +1000
commitd8d58768c35ae03e55c078acb0186cd5d368271a (patch)
tree135f8bcaf61714977c705e4a7beae28f2f962646
parent248c7089b9787a6bf89205e58e618eaa4417eb42 (diff)
downloadrtems-docs-d8d58768c35ae03e55c078acb0186cd5d368271a.tar.bz2
user/bsps : Add documentation for Beagle
-rw-r--r--user/bsps/arm/beagle.rst91
1 files changed, 89 insertions, 2 deletions
diff --git a/user/bsps/arm/beagle.rst b/user/bsps/arm/beagle.rst
index a36efde..84bfe2d 100644
--- a/user/bsps/arm/beagle.rst
+++ b/user/bsps/arm/beagle.rst
@@ -1,8 +1,95 @@
.. SPDX-License-Identifier: CC-BY-SA-4.0
-.. Copyright (C) 2019 TBD
+.. Copyright (C) 2019 Vijay Kumar Banerjee
beagle
======
-TODO.
+This BSP supports four variants, `beagleboardorig`, `beagleboardxm`, `beaglebonewhite`
+and `beagleboneblack`. The basic hardware initialization is not performed by
+the BSP. A boot loader with device tree support must be used to start the BSP,
+e.g. U-Boot.
+
+TODO(These drivers are present but not documented yet):
+
+ * Clock driver.
+ * Network Interface Driver.
+ * SDcard driver.
+ * GPIO Driver.
+ * Console driver.
+ * PWM Driver.
+ * RTC driver.
+
+Boot via U-Boot
+---------------
+To boot via uboot, the ELF must be converted to a U-Boot image like below:
+
+.. code-block:: none
+
+ arm-rtems5-objcopy hello.exe -O app.bin
+ gzip 9 app.bin
+ mkimage -A arm -O linux -T kernel -a 0x80000000 -e 0x80000000 -n RTEMS -d app.bin.gz rtems-app.img
+
+Getting the Device Tree Blob
+----------------------------
+
+The Device Tree Blob(dtb) is needed to load the device tree while starting up
+the kernel. We build the dtb from the FreeBSD source matching the commit hash
+from the libbsd HEAD of freebsd-org. For example if the HEAD is at
+"19a6ceb89dbacf74697d493e48c388767126d418"
+Then the right dts file is:
+https://github.com/freebsd/freebsd/blob/19a6ceb89dbacf74697d493e48c388767126d418/sys/gnu/dts/arm/am335x-boneblack.dts
+
+.. code-block:: none
+
+ #building the dtb
+ #We will use the script from https://github.com/freebsd/freebsd/blob/19a6ceb89dbacf74697d493e48c388767126d418/sys/tools/fdt/make_dtb.sh
+
+ export MACHINE='arm' #The make_dtb.sh script uses environment variable MACHINE
+ SCRIPT_DIR=$HOME/freebsd/sys/tools/fdt
+ #The arguments to the script are
+ # $1 -> Build Tree
+ # $2 -> DTS source file
+ # $3 -> output path of the DTB file
+ ${SCRIPT_DIR}/make_dtb.sh ${SCRIPT_DIR}/../../ \
+ ${SCRIPT_DIR}/../../gnu/dts/arm/am335x-boneblack.dts \
+ $(pwd)
+Writing the uEnv.txt file
+-------------------------
+
+The uEnv.txt file is needed to set any environment variable before the kernel is
+loaded. Each line is a u-boot command that the uboot will execute during
+starting up.
+
+Add the following to a file named uEnv.txt:
+
+.. code-block:: none
+
+ setenv bootdelay 5
+ uenvcmd=run boot
+ boot=fatload mmc 0 0x80800000 rtems-app.img ; fatload mmc 0 0x88000000 am335x-boneblack.dtb ; bootm 0x80800000 - 0x88000000
+
+I2C Driver
+----------
+
+This BSP uses the I2C framework and is registered using
+``am335x_i2c_bus_register()`` the function prototype is given below:
+
+.. code-block:: C
+
+ int am335x_i2c_bus_register(
+ const char *bus_path,
+ uintptr_t register_base,
+ uint32_t input_clock,
+ rtems_vector_number irq
+ );
+
+This function is needed only while registering with custom path with custom
+values. For registering the `/dev/i2c-0` device, a wrapper function is provided,
+``bbb_register_i2c_0()`` similarly ``bbb_register_i2c_1()`` and
+``bbb_register_i2c_2()`` are respectively used to register `i2c-1` and `i2c-2`.
+
+SPI Driver
+----------
+
+The SPI device `/dev/spi-0` can be registered with ``bbb_register_spi_0()```