解密设备树 [英] Deciphering Device Tree

问题描述

这是我从嵌入式Linux内核上的设备树中摘录的摘录. 这就是我现在的理解:

Here is an excerpt I pulled from a device tree on my embedded Linux Kernel. This is how I understand it now:

1)aemif接口位于物理地址0x30000000

1) The aemif interface is located at physical address 0x30000000

2)aemif驱动程序位于名为davinci_aemif.c的文件中，它使用名为aemif

2) The aemif driver is located in a file called davinci_aemif.c and it uses a clock called aemif

3)aemif上有2个设备，一个是cs2，另一个是nand(我认为这个假设是正确的)

3) The aemif has 2 devices on it, one being cs2 and the other being nand (I don't think this assumption is correct)

现在要提问的问题

1)reg = <0x21000a00 0x100>;行在做什么? 0x30000000上的aemif如何在0x21000a00上具有地址空间?

1) What is the line reg = <0x21000a00 0x100>; doing? How can the aemif which is located at 0x30000000 have address space at 0x21000a00?

2)为什么cs2定义为cs2@30000000，而不是cs2@1,0

2) Why is cs2 defined cs2@30000000 and not cs2@1,0

3)reg = <0x2 0x0 0x8000000 0x6 0x0 0x100>;行在做什么?

4)关于信号线(ta，rhold，rstrobe等)的设置的任何解释都将有所帮助.

4) Any explanation of how the signal lines (ta, rhold, rstrobe, etc.) are set up would be helpful.

aemif@30000000 {
        compatible = "ti,davinci-aemif";
        #address-cells = <0x2>;
        #size-cells = <0x1>;
        reg = <0x21000a00 0x100>;
        ranges = <0x2 0x0 0x30000000 0x8000000 0x3 0x0 0x34000000 0x4000000 0x4 0x0 0x38000000 0x4000000 0x5 0x0 0x3c000000 0x4000000 0x6 0x0 0x21000a00 0x100>;
        clocks = <0x11>;
        clock-names = "aemif";

        cs2@30000000 {
            compatible = "ti,davinci-cs";
            #address-cells = <0x1>;
            #size-cells = <0x1>;
            ti,davinci-cs-ta = <0xc>;
            ti,davinci-cs-rhold = <0x6>;
            ti,davinci-cs-rstrobe = <0x17>;
            ti,davinci-cs-rsetup = <0x9>;
            ti,davinci-cs-whold = <0x8>;
            ti,davinci-cs-wstrobe = <0x17>;
            ti,davinci-cs-wsetup = <0x8>;
        };

        nand@2,0 {
            compatible = "ti,davinci-nand";
            reg = <0x2 0x0 0x8000000 0x6 0x0 0x100>;
            #address-cells = <0x1>;
            #size-cells = <0x1>;
            ti,davinci-chipselect = <0x0>;
            ti,davinci-mask-ale = <0x2000>;
            ti,davinci-mask-cle = <0x4000>;
            ti,davinci-mask-chipsel = <0x0>;
            ti,davinci-ecc-mode = "hw";
            ti,davinci-ecc-bits = <0x4>;
            ti,davinci-nand-use-bbt;
            ti,davinci-no-subpage-write;
            clocks = <0x11>;
            clock-names = "aemif";

            partition@0 {
                label = "u-boot";
                reg = <0x0 0x100000>;
                read-only;
            };

            partition@100000 {
                label = "params";
                reg = <0x100000 0x80000>;
                read-only;
            };

            partition@180000 {
                label = "ubifs";
                reg = <0x180000 0x1fe80000>;
            };
        };
    };

推荐答案

您的设备树显然是错误的.

Your device tree is obviously wrong.

1/reg = <0x21000a00 0x100>;通知aemif实际上位于0x21000a00且具有32个寄存器(0x100/4)，因此单元地址必须为0x21000a00:aemif@21000a00

1/ reg = <0x21000a00 0x100>; is informing that aemif is actually located at 0x21000a00 and has 32 registers (0x100/4) so the unit-address must be 0x21000a00: aemif@21000a00

2/再次，单位地址必须与reg属性匹配，cs2中没有reg属性.

2/ again, the unit-address must match the reg property, you have no reg property in cs2..

3/reg = <0x2 0x0 0x8000000 0x6 0x0 0x100>; reg指节点父级的ranges属性.在这里，它可以解释为: -从范围0x2开始，偏移量为0x0(即0x30000000)，大小为0x8000000 -范围为0x6，偏移量为0x0，大小为0x100

3/ reg = <0x2 0x0 0x8000000 0x6 0x0 0x100>; reg refers to the ranges property of the node parent. Here, it can be interpreted as: - from range 0x2, at offset 0x0 (that would be 0x30000000), size 0x8000000 - from range 0x6, offset 0x0, size 0x100

4//您将不得不寻找一个具有"ti，davinci-cs"兼容字符串的驱动程序，但由于它没有成为主流，所以我无能为力.

4/ you'll have to look a the driver having the "ti,davinci-cs" compatible string, I can't help as it is not mainlined.

这篇关于解密设备树的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！