Printing register base addresses & register contents

Srini,

In u-boot, you can use md and mw commands to read and write the device registers. Example:

u-boot#md
md - memory display

Usage:
md [.b, .w, .l] address [# of objects]
u-boot#mw
mw - memory write (fill)

Usage:
mw [.b, .w, .l] address value [count]

u-boot#md 0x4818155C 1
4818155c: 00030100    ....
u-boot#mw 0x4818155C 0x2
u-boot#md 0x4818155C 1
4818155c: 00000002    ....

You can also read/write register inside the u-boot (not after loading it) using the  __raw_readl() and __raw_writel() functions. Examples:

__raw_readl(CONTROL_STATUS)

__raw_writel(reload, base + 0x2C);

You can print the I2C0 I2C_BUF register like below:

printf("I2C0.I2C_BUF = %x\n",__raw_readl(0x48028094)); //I2C0 base addr is 0x48028000, I2C_BUF offset is 0x94

BR
Pavel

BR
Pavel

In linux kernel, you should use the printk function, instead of printf.

Also, you should translate the physical address to virtual, then you can read/write:

static void __iomem *base;
    
base = ioremap(0x48028000, SZ_4K);
    
printk("I2C0.I2C_BUF = %x\n",__raw_readl(base+0x94));

In user space (after linux kernel boot up), you can use the devmem2 tool:

evm:~# devmem2

Usage:    devmem2 { address } [ type [ data ] ]
    address : memory address to act upon
    type    : access operation type : [b]yte, [h]alfword, [w]ord
    data    : data to be written

BR
Pavel