如何从嵌入式 Linux (ARM) 中通过 SPI 连接的闪存 read/write？

Question

我正在使用 Yocto 和 meta-atmel 构建嵌入式 Linux(4.4.19)。我的板上有一个通过 SPI 连接的闪存。我尝试了几种写在上面的方法。但他们都失败了。怎么把read/write数据放进去呢？

一些信息：

闪存类型 4Mbit：
s25fl164k (http://www.farnell.com/datasheets/1756778.pdf)

通过设备树包含：

    spi1: spi@f8008000 {
        cs-gpios = <&pioC 25 GPIO_ACTIVE_HIGH>;
        status = "okay";

        m25p80@0 {
            compatible = "spansion,s25fl164k";
            spi-max-frequency = <50000000>;
            reg = <0>;
        };
    };

内核配置：

MTD 设备已激活
SPI 激活
SPI 设备驱动程序已激活

dmesg 启动时打印：

[    2.630000] Creating 8 MTD partitions on "atmel_nand":
[    2.640000] 0x000000000000-0x000000040000 : "bootstrap"
[    2.640000] 0x000000040000-0x0000000c0000 : "uboot"
[    2.650000] 0x0000000c0000-0x000000100000 : "env"
[    2.660000] 0x000000100000-0x000000140000 : "env_redundant"
[    2.660000] 0x000000140000-0x000000180000 : "spare"
[    2.670000] 0x000000180000-0x000000200000 : "dtb"
[    2.670000] 0x000000200000-0x000000800000 : "kernel"
[    2.680000] 0x000000800000-0x000010000000 : "rootfs"
[    2.690000] atmel_spi f0004000.spi: version: 0x213
[    2.690000] atmel_spi f0004000.spi: DMA TX channel not available, SPI unable to use DMA
[    2.700000] atmel_spi f0004000.spi: Atmel SPI Controller using PIO only
[    2.700000] atmel_spi f0004000.spi: Atmel SPI Controller at 0xf0004000 (irq 25)
[    2.710000] m25p80 spi32766.0: at25df321a (4096 Kbytes)

fdisk打印（看mtdblock8）：

root@sama5d3xek:~# fdisk -l
Disk /dev/ram0: 8 MiB, 8388608 bytes, 16384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/ram1: 8 MiB, 8388608 bytes, 16384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/ram2: 8 MiB, 8388608 bytes, 16384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/ram3: 8 MiB, 8388608 bytes, 16384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/mtdblock0: 256 KiB, 262144 bytes, 512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock1: 512 KiB, 524288 bytes, 1024 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock2: 256 KiB, 262144 bytes, 512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock3: 256 KiB, 262144 bytes, 512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock4: 256 KiB, 262144 bytes, 512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock5: 512 KiB, 524288 bytes, 1024 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock6: 6 MiB, 6291456 bytes, 12288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock7: 248 MiB, 260046848 bytes, 507904 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mtdblock8: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mmcblk0: 7.4 GiB, 7985954816 bytes, 15597568 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device         Boot Start      End  Sectors  Size Id Type
/dev/mmcblk0p1       8192 15597567 15589376  7.4G  b W95 FAT32

Reading/writing 测试：

cat /dev/mtdblock8
echo "hello" > /dev/mtdblock8
cat /dev/mtdblock8

我没有得到任何 results/errors。

正在安装：

mkdir /tmp/abc
mount -t jffs2 /dev/mtdblock8 /tmp/abc
mount: /dev/mtdblock8: can't read superblock

有什么想法吗？

我喜欢做演示。假设在 SPI 闪存的位置 12345 上写入 "hello Linux"。

Answer 1

您可以使用内存技术设备 (MTD) 子系统对闪存分区进行 erase/write/read 操作。 SPI 闪存在您的 case.Use 中安装到 mtdblock8，使用以下命令查看所有现有分区

cat /proc/mtd

要写入mtd 设备，请使用nandwrite 命令。它适用于 busybox。

安装尝试

mount -t jffs2 /dev/block/mtdblock8 /tmp/abc

MTD 详情： http://free-electrons.com/blog/managing-flash-storage-with-linux/

mtd 实用程序的详细信息： http://processors.wiki.ti.com/index.php/Mtdutils

Answer 2

所以，让我们一步步来吧。您的 SPI NOR 闪存在设备树中有描述，看来您已经成功地正确配置了您的内核（即添加了相关的驱动程序）。您的日志证实了这一点：

[    2.710000] m25p80 spi32766.0: at25df321a (4096 Kbytes)

/dev/mtd8 似乎也是与该设备关联的 MTD 设备（根据您的尺寸分析）。您应该能够通过检查 /sys/class/mtd.

来确认它

现在，为了对设备进行编程，您需要 1) 擦除要写入的扇区，2) 写入这些扇区，最后回读并确认。要写入，您可以使用 write() 系统调用（即 cat somefile > /dev/mtd8）。要擦除，您需要一个 ioctl 系统调用，即 flash_erase 命令。

MTD网站有一些相关资料：

http://www.linux-mtd.infradead.org/index.html

hashdefine回复中提到的自由电子post也可以。

Answer 3

您可以尝试降低时钟频率，这解决了我使用 SPI FLASH 的问题：

spi-max-frequency = <10000000>

Answer 4

您可以使用 mtd_debug 命令工具。使用此工具可以测试 read/write 一个字节。这很方便定位问题。

Answer 5

可能设备被U-Boot锁定了，你内核的m25p80驱动没有实现ioctl UNLOCK。以前看过，参考erasing-flash-nor-ioctlmemunlock-return-status。

Answer 6

我的设备树 table 文件中有错误。 spi1、图像传感器接口（isi1）和 i2c（i2c1）使用相同的引脚。编译内核+dts 时没有显示错误。通常，fdisk + mtd_debug 的组合对于检查低级别的驱动程序和硬件非常有用。在我的例子中 SAMA5D35 + 自己的主板 @ dts:

ahb {
    apb {
        spi1: spi@f8008000 {
            cs-gpios = <&pioC 25 GPIO_ACTIVE_LOW>;
            status = "okay";
            m25p80@0 {
                compatible = "spansion,s25fl132k", "jedec,spi-nor";
                spi-max-frequency = <108000000>;
                reg = <0>;
                m25p,fast-read;
            };
        };

        // conflicts with spi1 
        i2c1: i2c@f0018000 {
            status = "disabled";
        };
        // confilcts with spi1 (pin PC27 periph B TWCK1 pin, conflicts with SPI1_NPCS2, ISI_D10)
        isi: isi@f0034000 {
            status = "disabled";
        };
};

现在可以正常使用了

如何从嵌入式 Linux (ARM) 中通过 SPI 连接的闪存 read/write？

How to read/write from an Flash connected through SPI in an embedded Linux (ARM)?

linux

linux-kernel

embedded-linux

kernel-module

flash-memory