[linux kernel]内核移植过程记录

系统版本：Ubuntu18.04-64

编译器版本：gcc version 7.4.0 (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1)

uboot版本：2018.07 -linux4sam_6.0

板子型号：at91sama5d3x-xplained

MCU型号：sama5d36

内核移植主要是裁剪一些不需要的功能，使用对应的交叉工具链把内核重新编译，设备树文件按照硬件去配置。

一、配置文件路径

arch/arm/configs/sama5_defconfig

//配置文件路径
arch/arm/configs/sama5_defconfig

//声明环境变量，指定交叉编译器
$ export CROSS_COMPILE=arm-linux-gnueabi-

//先按照默认配置编译内核文件，看是否会报错，编译出来的文件先进行烧录，是否能正确引导文件系统；
$ make ARCH=arm sama5_defconfig
$ make ARCH=arm

//图形化配置窗口调出
$ make ARCH=arm menuconfig

//单独编译设备树文件，生成dtb文件
$ make ARCH=arm dt

二、把编译的zImage和dtb文件烧录板子，根据打印信息，分析出硬件驱动的情况。

1、内核接收uboot传递过来的分区信息，要和设备树中的分区一致，后面再细讲；

Kernel command line: console=ttyS0,115200 earlyprintk mtdparts=atmel_nand:256k(bootstrap)ro,768k(uboot)ro,256K(env_redundant),256k(env),512k(dtb),6M(kernel)ro,-(rootfs) rootfstype=ubifs ubi.mtd=6 root=ubi0:rootfs

2、GPIO控制器驱动OK

AT91: PM: standby: standby, suspend: ulp0
gpio-at91 fffff200.gpio: at address (ptrval)
gpio-at91 fffff400.gpio: at address (ptrval)
gpio-at91 fffff600.gpio: at address (ptrval)
gpio-at91 fffff800.gpio: at address (ptrval)
gpio-at91 fffffa00.gpio: at address (ptrval)
pinctrl-at91 ahb:apb:pinctrl@fffff200: initialized AT91 pinctrl driver

3、DMA通道生效

at_hdmac ffffe600.dma-controller: Atmel AHB DMA Controller ( cpy set slave ), 8 channels
at_hdmac ffffe800.dma-controller: Atmel AHB DMA Controller ( cpy set slave ), 8 channels

4、USB控制器驱动注册成功

usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb

5、i2C总线驱动模型注册成功

at91_i2c f0014000.i2c: using dma0chan0 (tx) and dma0chan1 (rx) for DMA transfers
at91_i2c f0014000.i2c: AT91 i2c bus driver (hw version: 0x402).
at91_i2c f0018000.i2c: using dma0chan2 (tx) and dma0chan3 (rx) for DMA transfers
at91_i2c f0018000.i2c: AT91 i2c bus driver (hw version: 0x402).

6、蓝牙驱动注册成功

Bluetooth: Core ver 2.22
NET: Registered protocol family 31
Bluetooth: HCI device and connection manager initialized
Bluetooth: HCI socket layer initialized
Bluetooth: L2CAP socket layer initialized
Bluetooth: SCO socket layer initialized

7、串口、SPI、CAN驱动注册

ssc f0008000.ssc: Atmel SSC device at 0x(ptrval) (irq 20)
atmel_usart_serial.0.auto: ttyS2 at MMIO 0xf0020000 (irq = 24, base_baud = 4125000) is a ATMEL_SERIAL
atmel_usart_serial.1.auto: ttyS0 at MMIO 0xffffee00 (irq = 34, base_baud = 8250000) is a ATMEL_SERIAL
console [ttyS0] enabled
atmel_spi f0004000.spi: DMA TX channel not available, SPI unable to use DMA
atmel_spi f0004000.spi: Atmel SPI Controller using PIO only
m25p80 spi0.0: unrecognized JEDEC id bytes: 00, 00, 00
atmel_spi f0004000.spi: Atmel SPI Controller version 0x213 at 0xf0004000 (irq 19)
libphy: Fixed MDIO Bus: probed
CAN device driver interface
at91_can f000c000.can: device registered (reg_base=(ptrval), irq=42)

8、GMAC控制器上面的网络芯片没有驱动成功，因为id读取为全0xFF；

libphy: MACB_mii_bus: probed
Generic PHY f0028000.ethernet-ffffffff:01: attached PHY driver [Generic PHY] (mii_bus:phy_addr=f0028000.ethernet-ffffffff:01, irq=POLL)
macb f0028000.ethernet eth0: Cadence GEM rev 0x00020119 at 0xf0028000 irq 43 (eec1:d2:e6:c6)
macb f802c000.ethernet: invalid hw address, using random

9、ksz8081 芯片的id号能够读取到，但是驱动没有匹配成功；

libphy: MACB_mii_bus: probed
Micrel KSZ8081 or KSZ8091 f802c000.ethernet-ffffffff:01: attached PHY driver [Micrel KSZ8081 or KSZ8091] (mii_bus:phy_addr=f802c000.ethernet-ffffffff:01, irq=49)
macb f802c000.ethernet eth1: Cadence MACB rev 0x0001010c at 0xf802c000 irq 44 (36:d7:c3:e6:2a:c7)
已经打印出"Micrel KSZ8081 or KSZ8091",可能是时序的问题；

10、系统时钟的rtc，从打印信息可以看出，是使用cpu内部的rtc寄存器，而非外部的RX8025芯片，作为rtc0供系统读取调用；原因稍后分析。

qt1070 1-001b: ID 206 not supported
at91_rtc fffffeb0.rtc: registered as rtc0
at91_rtc fffffeb0.rtc: AT91 Real Time Clock driver.
i2c /dev entries driver

11、EMMC控制器信息，mmc0上面挂载了一片32GByte的EMMC芯片；

sdhci: Secure Digital Host Controller Interface driver
sdhci: Copyright© Pierre Ossman
atmel_mci f0000000.mmc: version: 0x505
atmel_mci f0000000.mmc: using dma0chan4 for DMA transfers
atmel_mci f0000000.mmc: Atmel MCI controller at 0xf0000000 irq 18, 1 slots
atmel_mci f8000000.mmc: version: 0x505
atmel_mci f8000000.mmc: using dma1chan0 for DMA transfers
atmel_mci f8000000.mmc: Atmel MCI controller at 0xf8000000 irq 25, 1 slots
sdhci-pltfm: SDHCI platform and OF driver helper

12、NAND Flash参数，及分区信息

nand: device found, Manufacturer ID: 0x01, Chip ID: 0xda
nand: AMD/Spansion S34ML02G2
nand: 256 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 128
Bad block table found at page 131008, version 0x01
Bad block table found at page 130944, version 0x01
7 cmdlinepart partitions found on MTD device atmel_nand
Creating 7 MTD partitions on “atmel_nand”:
0x000000000000-0x000000040000 : “bootstrap”
0x000000040000-0x000000100000 : “uboot”
0x000000100000-0x000000140000 : “env_redundant”
0x000000140000-0x000000180000 : “env”
0x000000180000-0x000000200000 : “dtb”
0x000000200000-0x000000800000 : “kernel”
0x000000800000-0x000010000000 : “rootfs”
分区信息，前面为地址，后面为分区大小。

NandFlash的参数信息，如果不清楚，也可以再uboot里面使用命令查看；

使用uboot查看nand info参数

=> nand info

Device 0: nand0, sector size 128 KiB

Page size 2048 b

OOB size 128 b

Erase size 131072 b

subpagesize 2048 b

options 0x40004200

bbt options 0x00008000

这个参数也同样重要，做文件系统ubi的时候会使用到具体的参数值；

二、编译出镜像文件路径为

//设备树文件
arch/arm/boot/dts/at91-sama5d3_xplaint.dts

//编译出的设备树镜像文件
arch/arm/boot/dts/at91-sama5d3_xplaint.dtb

//编译出的内核镜像文件
arch/arm/boot/zImage

最后根据配置生成的配置文件，在内核根目录下，默认为.config文件；

Tips：在做完修改之后，最好把.config文件备份一个，比如：cp .config Jackatmelconfig;以后不小心重新配置了，还可以返回以前的配置；

更多linux知识点推荐：

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[linux 底层]u-boot图形化裁剪配置

[Linux 底层]U-boot ksz9031网络驱动调试

[Linux 底层]U-boot调试命令使用技巧

[Linux 底层]U-boot编译移植

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[Linux 底层] 平台软件分层介绍

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