Linux Readl () and Writel () functions---for read-write registers

Writel () writes data to the memory-mapped I/O space,   writing 32-bit data (4 bytes) on the Wirtel () I/O. Prototypes: #include <asm/io.h> void Writel (unsigned char data, unsigned short addr) Readl () read data from memory-mapped I/O space, readl from I/O Reads 32-bit data (4 bytes). Prototypes: #include <asm/io.h> unsigned char readl (unsigned int addr) Note: variable    addr  is an I/O address. Return value: The value read from the I/O space.

Linux Readl () and Writel () functions---for read-write registers