Difference between revisions of "Linux drivers development"
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Our custom drivers build is integrated to the Linux build system (kbuild). | Our custom drivers build is integrated to the Linux build system (kbuild). | ||
| − | You can select, in the linux "menuconfig | + | You can select, in the linux "menuconfig / xconfig" tool, which Armadeus drivers you want to add on your target. |
| − | drivers you want to add on your target. | + | <pre class="host"> |
| − | + | $ make linux-menuconfig | |
| + | </pre> | ||
| + | |||
| + | <pre class="config"> | ||
| + | Device Drivers ---> | ||
| + | Armadeus specific drivers ---> | ||
| + | </pre> | ||
Here is the way to add custom drivers: | Here is the way to add custom drivers: | ||
| − | * | + | * change current dir to your armadeus view |
| − | * put reference to this directory in the | + | * in ''target/linux/modules/'', add a directory for your driver (ex ''toto/'') |
| − | * in toto/ put your driver source code and create 2 files, Kconfig and Makefile. (Use | + | * put reference to this directory in the ''target/linux/modules/Makefile'' and ''target/linux/modules/Kconfig'' files |
| + | * in ''toto/'' put your driver source code and create 2 files, ''Kconfig'' and ''Makefile''. (Use ''target/linux/modules/gpio/Makefile'' & ''Kconfig'' as examples.) | ||
| − | To compile the modules, either launch: | + | To compile all the custom modules, either launch: |
| − | + | <pre class="host"> | |
| + | $ make -C target/linux/modules/ | ||
| + | </pre> | ||
or | or | ||
| − | + | <pre class="host"> | |
| + | $ make linux | ||
| + | </pre> | ||
| − | + | Only ''make linux'' will install the modules in the target rootfs image | |
== i.MX register access from driver == | == i.MX register access from driver == | ||
| − | To access i.MX registers from your driver, please use the | + | To access i.MX registers from your driver, please use the ''readw/readl/writew/writel'' helper functions. |
| − | + | Take a look at at ''arch/arm/mach-mx2/apf27.c'' or ''arch/arm/mach-imx/apf9328.c'' to have examples. | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
==Debug== | ==Debug== | ||
| − | Activate debug messages (from pr_debug() function) on console: | + | * Activate debug messages (from pr_debug() function) on console: |
| + | <pre class="apf"> | ||
# echo 8 > /proc/sys/kernel/printk | # echo 8 > /proc/sys/kernel/printk | ||
| + | </pre> | ||
== Useful Links == | == Useful Links == | ||
* http://old.kernelnewbies.org/documents/kdoc/kernel-api/linuxkernelapi.html | * http://old.kernelnewbies.org/documents/kdoc/kernel-api/linuxkernelapi.html | ||
* http://lwn.net/Articles/driver-porting/ | * http://lwn.net/Articles/driver-porting/ | ||
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Latest revision as of 17:55, 4 September 2013
This page summarizes all you need to know before starting to develop Linux drivers for your Armadeus board
Contents
Recommended reading before starting
We advise you to read (not necessarly understand ;-) ):
- Linux Device Drivers (3rd edition) book: http://lwn.net/Kernel/LDD3/
Adding your own drivers
Our custom drivers build is integrated to the Linux build system (kbuild). You can select, in the linux "menuconfig / xconfig" tool, which Armadeus drivers you want to add on your target.
$ make linux-menuconfig
Device Drivers --->
Armadeus specific drivers --->
Here is the way to add custom drivers:
- change current dir to your armadeus view
- in target/linux/modules/, add a directory for your driver (ex toto/)
- put reference to this directory in the target/linux/modules/Makefile and target/linux/modules/Kconfig files
- in toto/ put your driver source code and create 2 files, Kconfig and Makefile. (Use target/linux/modules/gpio/Makefile & Kconfig as examples.)
To compile all the custom modules, either launch:
$ make -C target/linux/modules/
or
$ make linux
Only make linux will install the modules in the target rootfs image
i.MX register access from driver
To access i.MX registers from your driver, please use the readw/readl/writew/writel helper functions. Take a look at at arch/arm/mach-mx2/apf27.c or arch/arm/mach-imx/apf9328.c to have examples.
Debug
- Activate debug messages (from pr_debug() function) on console:
# echo 8 > /proc/sys/kernel/printk
