Embedded Linux Device Drivers training course

Developing for embedded Linux

• Getting and configuring a cross toolchain
• Linux bootloaders: U-Boot

The Linux kernel

• Where to get the kernel source
• Board support packages
• Kernel configuration options
• Building and loading a kernel

Kernel modules

• Writing a module and compiling "out of tree"
• Loading and testing on the target
• Passing parameters
• Modules and the GPL license

Device driver basics

• Types of device driver
• Different ways for applications to interact with the driver
• Character drivers
• Building and testing a simple “misc” character device driver

Kernel debugging

• Review of printk and the magic sysrq key
• Interactive debugging using kgdb
• What to do when the board won't boot

Sysfs and proc

• Classes of driver: /sys/class
• Driver attributes
• Extending the proc file system

Wait queues and completions

• Waiting for things to happen: wait queues
• One-shot events: completions

Kernel locking

• Mutual exclusion using kernel mutexes
• Spinlocks
• Atomic operations

Advanced character driver functions

• Notifying events: poll and fasync
• Driver specific interfaces: ioctl

Time and timers

• Getting the system time: high resolution timers
• Delays and sleeps
• Kernel timers

Interrupts

• Installing an interrupt handler
• Synchronising using using spin_lock_irq
• Deferred processing using tasklets and work queues

Accessing hardware

• Memory regions
• Allocating and freeing memory
• Overview of device tree and how to extract information from a device tree
• Mapping in device memory: ioremap
• DMA buffers: coherent and stream mappings
• Memory barriers

Sharing memory

• mmap: sharing device registers
• mmap: sharing DMA buffers
• get_user_pages: how to access user memory