Socket CAN 对CAN protocol做了封装，对CAN设备的读写变成了类似tcp/ip的读写网络（socket操作）。
目标环境：linux2.6.37， i.mx27开发板带mcp2515
首先注册spi device和mcp2515 device：
代码
1 static const int plat27_pins[] __initconst= {
2 ...
3
4 #if (defined CONFIG_SPI_IMX || defined CONFIG_SPI_IMX_MODULE )
5 //PD27_PF_CSPI1_SS1, //use mxc_gpio_mode instead mxc_gpio_setup_multiple_pins otherwise spi-imx.c can't request it
6 //PD28_PF_CSPI1_SS0,
7 PD25_PF_CSPI1_RDY,
8 PD29_PF_CSPI1_SCLK,
9 PD30_PF_CSPI1_MISO,
10 PD31_PF_CSPI1_MOSI,
11 #endif
12 }
13
14 #if (defined CONFIG_SPI_IMX || defined CONFIG_SPI_IMX_MODULE )
15 static int cspi1_ss[] = {GPIO_PORTD + 28}; //CSPI1 ss0=PD28, ss1=PD27
16 static const struct spi_imx_master cspi_pdata __initconst = {
17 .chipselect = cspi1_ss,
18 .num_chipselect = ARRAY_SIZE(cspi1_ss),
19 };
20
21 #if (defined CONFIG_CAN_MCP251X || defined CONFIG_CAN_MCP251X_MODULE )
22 static struct mcp251x_platform_data mcp251x_info = {
23 .oscillator_frequency = 16*1000*1000,
24 };
25
26 static struct spi_board_info plat27_spi_board_info[] __initdata = {
27 {
28 .modalias = "mcp2515", //must match with device driver id_table name
29 .bus_num = 0, //0 for CSPI1, 1 for CSPI2, ...
30 .chip_select = 0, //0 for SS0 ,1 for SS1, ....
31 .max_speed_hz = 2*1000*1000, //maxium is 10MHz, but will lost data in my experience
32 .irq = IRQ_GPIOC(15),
33 .platform_data = &mcp251x_info,
34 .mode = SPI_MODE_0, //not required exactly since mcp251x driver will set it to SPI_MODE_0
35 },
36 };
37 #endif
38 #endif
39
40 static void __init XXX_init(void)
41 {
42 ...
43
44 #if (defined CONFIG_SPI_IMX || defined CONFIG_SPI_IMX_MODULE )
45 mxc_gpio_mode(GPIO_PORTD | 28 | GPIO_GPIO | GPIO_OUT);
46 imx27_add_spi_imx0(&cspi_pdata);
47
48 #if (defined CONFIG_CAN_MCP251X || defined CONFIG_CAN_MCP251X_MODULE )
49 spi_register_board_info(plat27_spi_board_info, ARRAY_SIZE(plat27_spi_board_info));
50 #endif
51 #endif
52
53 }
make menuconfig中加入:
代码
1 [*]Networking support->
2 <M>CAN bus subsystem support->
3 <M>Raw CAN Protocal
4 <M>Broadcast Manage CAN Protocal
5 CAN Device Drivers->
6 <M>Platform CAN driver with Netlink support
7 [*]CAN bit-timing calculation
8 <M>Microchip MCP251x SPI CAN controllers
9
10 Device drivers->
11 [*]SPI support ->
12 <*>Freescale i.MX spi controllers
13
14
编译安装mod：
insmod can.ko
insmod can-raw.ko
insmod can-bcm.ko
insmod can-dev.ko
insmod mcp251x.ko
最新版busybox的ip还是不支持socketcan，所以要自己编译一个。
上http://corp-dev.linuxfoundation.org/collaborate/workgroups/networking/iproute2下载iproute2，目前版本是2.6.35。
编译iproute2的时候有很多问题，安装了bison，flex，libdb4.7-dev还是死在tc目录，后来想想只要用它的ip，于是最终修改Makefile如下：
CC = /opt/arm-2010q1/bin/arm-none-linux-gnueabi-gcc
SUBDIRS=lib ip
make通过，把ip目录中的ip（elf文件）拷到目标板中运行：
chmod 777 ip
./ip link set can0 up type can bitrate 250000
./ip -details link show can0
can0设置好后可以用以下命令修改bitrate
ifconfig can0 down
echo 125000 > /sys/class/net/can0/can_bitrate
ifconfig can0 up
到这一步socketcan就算配置完成了，不过还是可以给它添加一些工具。
1.用socketcan里的can-utils：
sudo apt-get install subversion
svn checkout svn://svn.berlios.de/socketcan/trunk socketcan
cp -r socketcan ../Workspaces
修改socketcan/can-utils/Makefile
PREFIX=./bin
KERNELDIR = http://www.cnblogs.com/linux-2.6.37
CC=/opt/arm-2010q1/bin/arm-none-linux-gnueabi-gcc （新增）
socketcan和linux2.6.37带的socketcan版本不同，导致有些不能编译成功，不过大部分工具都有了，剩下的如果要的话可以考虑merge linux内核----还不如自己写工具呢
2.在http://www.pengutronix.de/software/socket-can下载can-utils 4.0.6，里面有5个工具，不过搞不定它的configure，手工编译之吧：
先在include下建一个can_config.h，里面就一句话#define VERSION 20090105 （随便怎么写吧，我是看到can.ko的版本是20090105）
然后进到src目录
/opt/arm-2010q1/bin/arm-none-linux-gnueabi-gcc -o xxx xxx.c -I$PWD/../include -I$PWD/***/linux-2.6.37/include （faint，http://www.cnblogs.com/被转成www.cnblogs.com）
除了canconfig.c通不过（需要libsocketcan.h，好在已经有iproute2了）其他的都成功。 感觉这个cansend比socketcan里的cansend好用。
