Question

我正在使用一个使用512M启动时间分配内存的特定编码器。我应该通过dts文件配置分配内存。物理内存在dts文件中分为低位和高位：

    /* 256MB at 0x0 */
    memory@0 {
            device_type = "memory";
            reg =  <0x0 0x00000000 0x0 0x10000000>;
    };

    /* 2GB at 0x8010000000 */
    memory@8000000000 {
            device_type = "memory";
            reg =  <0x80 0x10000000 0x0 0x80000000>;
    };

现在我想从高内存中分配开机时间。我可以考虑创建一个dts条目，如下所示

encoder: encoder@0xxxxxxxxx {
    compatible = "xyz, abc";
    reg=    <0x0 0x80000000 0x0 0x20000000>;
}

这里编码器@ xxxx是实际的器件入口，它已经有一组寄存器区域如下：

    encoder: encoder@0xxxxxxxxx{
        compatible = "xyz, abc";
        #address-cells = <1>;
        #size-cells = <1>;
        reg = <0x0 0xxxxxxxxxx 0x0 0x1234>;
        status = "disabled";
    };

因此，在添加雕刻后的内存后，条目将如下所示：

    encoder: encoder@0xxxxxxxxx{
        compatible = "xyz, abc";
        #address-cells = <1>;
        #size-cells = <1>;
        reg = <0x0 0xxxxxxxxxx 0x0 0x1234>;
        reg=  <0x0 0x80000000 0x0 0x20000000>;
        status = "disabled";
    };

这会有用吗？我不确定驱动程序代码如何知道已雕刻的内存的起始地址和大小？有人可以帮忙吗？谢谢。

Answer 1

我通过从我的设备的高内存下部创建内存来实现这一点。为此，我修改了我的dtsi文件，以反映下面的mew内存映射：

/* 256MB at 0x0 - this is the low memory region*/
        memory@0 {
                device_type = "memory";
                reg =  <0x0 0x00000000 0x0 0x10000000>;
        };

        /* 1GB at 0x8010000000 - high memory region, this used to be 2GB earlier. I curved out to 1GB and allocated 1GB to my device*/
        memory@8000000000 {
                device_type = "memory";
                reg =  <0x80 0x10000000 0x0 0x40000000>;
        };



/* 1GB carved out for my device.*/
        my_device: mydevice@8050000000 {
                compatible = "xxx,xxx-yyy";
                reg = <0x00 0x20810000 0x0 0x010000>,
                      **<0x80 0x50000000 0x0 0x40000000>;**
                interrupts = <GIC_SHARED xx IRQ_TYPE_LEVEL_HIGH>;
                status = "disabled";
        };

1GB的分配有点太多了，我已经修改为256MB，但这在这里并不重要。

然后在驱动程序中我重试了内存细节如下：

struct resource *res;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0); /*this is to get hold of the the registers of my device*/

res = platform_get_resource(pdev, IORESOURCE_MEM, 1); /* this is the device memory for my device which had been set aside in the dtsi file above.*/

For using the memories retrieve as above use the below:

res->start /* start address of the memory region */
res->end - res->start + 1 /* this is to calculate the size of the memory*/
devm_ioremap_resource(&pdev->dev, res); /* this will give the mapped kernel virtual address for the memory bank*/

使用dts配置分配启动时内存

1 个答案: