Mastering Embedded Linux Programming - Second Edition

The platform data

In the absence of device tree support, there is a fallback method of describing hardware using C structures, known as the platform data.

Each piece of hardware is described by struct platform_device, which has a name and a pointer to an array of resources. The type of the resource is determined by flags, which include the following:

• IORESOURCE_MEM: This is the physical address of a region of memory
• IORESOURCE_IO: This is the physical address or port number of IO registers
• IORESOURCE_IRQ: This is the interrupt number

Here is an example of the platform data for an Ethernet controller taken from arch/arm/mach-versatile/core.c, which has been edited for clarity:

#define VERSATILE_ETH_BASE     0x10010000 #define IRQ_ETH                25 static ...