?? 今天折腾了一天的SPI设备的驱动加载，甚至动用了逻辑分析仪来查看spi总线的波形，主要包括两个SPI设备，at45db321d和mcp2515，一个是串行的dataflash，一个是can总线设备芯片。前者对于我们来说非常重要，我们可以借助该设备对uboot和kernel以及根文件系统进行更新。
??? 预备知识：设备和驱动是如何匹配的？系统的热插拔是如何实现的？
??? 首先一点，设备和驱动是严格区分的，设备是设备，驱动是驱动，设备通过struct device来定义，当然用户也可以将该结构体封装到自己定义的device结构体中，例如，struct platform_device，这是我们采用platform_bus_type总线的设备定义的结构体形式：
include/linux/platform_device.h文件中:
struct platform_device {
??? const char??? * name;
??? u32??????? id;
??? struct device??? dev;
??? u32??????? num_resources;
??? struct resource??? * resource;
};
只要是9260的外围模块，就像IIC硬件控制器,SPI硬件控制器，都被完全的定义成这种结构体的格式，这种结构体主要包含了硬件资源和名称，硬件资源分为寄存器和IRQ两种。platform_device通过向内核注册struct device dev这个结构体来告诉内核加载这个设备，
??? 方法就是? device_register(&platform_device->dev)??
内核不关心你使用的是platform_device还是spi_device，内核只关心你的struct device结构体，内核通过这个struct device结构体自然能够顺藤摸瓜找到你是platform_device还是spi_device，这就是linux最引以为傲的contian_of()大法。
驱动通过struct driver这个结构体来定义，与struct device一致，你也可以用自己的结构体去封装：例如，struct platform_driver。
include/linux/platform_device.h文件中:
struct platform_driver {
??? int (*probe)(struct platform_device *);
??? int (*remove)(struct platform_device *);
??? void (*shutdown)(struct platform_device *);
??? int (*suspend)(struct platform_device *,pm_message_t state);
??? int (*suspend_late)(struct platform_device *,pm_message_t state);
??? int (*resume_early)(struct platform_device *);
??? int (*resume)(struct platform_device *);
??? struct device_driver driver;
};
与device一致，应用程序通过driver_register(&platform_driver->driver)向内核中注册你当前的驱动，而内核不关心你封装成的结构，而内核搜索的方法还是同样的contain_of大法。
?
系统如何将这两者匹配上的？而不会将iic的设备加载到spi的驱动上面？不会将这个iic设备的驱动加载到那个iic设备上，设备和驱动之间是如何联系的？总线，这就是总线的作用！
include/linux/device.h文件中有总线类型的定义。
struct bus_type {
??? const char??????? * name;
??? struct subsystem??? subsys;
??? struct kset??????? drivers;
??? struct kset??????? devices;
??? struct klist??????? klist_devices;
??? struct klist??????? klist_drivers;
??? struct blocking_notifier_head bus_notifier;
??? struct bus_attribute??? * bus_attrs;
??? struct device_attribute??? * dev_attrs;
??? struct driver_attribute??? * drv_attrs;
??? int??????? (*match)(struct device * dev,struct device_driver * drv);
??? int??????? (*uevent)(struct device *dev,char **envp,
????????????????? int num_envp,char *buffer,int buffer_size);
??? int??????? (*probe)(struct device * dev);
??? int??????? (*remove)(struct device * dev);
??? void??????? (*shutdown)(struct device * dev);
??? int (*suspend)(struct device * dev,pm_message_t state);
??? int (*suspend_late)(struct device * dev,pm_message_t state);
??? int (*resume_early)(struct device * dev);
??? int (*resume)(struct device * dev);
};
这个总线设备中最重要的可能是match成员，由于我们一般很少去建立一个新的总线，所以我们很少涉及总线的编程，我们就只关注我们所关注的。
总线如何将两者关联起来，热插拔大家知道吧，当一个设备被通过device_register注册到内核中时，会导致一个热插拔事件产生，系统会遍历该总线上的所有驱动程序，调用bus的match算法，来寻找与该设备相匹配的驱动程序，当一个驱动注册到内核的时候，处理过程与此相似（这是我理解的阿，大家批评指正），而一般的macth算法都比较简单，例如platform_bus的匹配算法就很简单，就是比较platform_device和platform_driver的name成员，如果匹配成功，就加载相应的设备或者驱动！这就完成了一个连接的过程。。。
?
昨天其实还有一个问题可能大家没有注意到，没有解释清楚，其实是有问题的，我们的at91_add_device_spi函数如下：
static struct spi_board_info ek_spi_devices[] = {
#if !defined(CONFIG_MMC_AT91)
??? {??? /* DataFlash chip */
??????? .modalias??? = "mtd_dataflash",
??????? .chip_select??? = 1,
??????? .max_speed_hz??? = 15 * 1000 * 1000,
??????? .bus_num??? = 0,
??? },
#if defined(CONFIG_MTD_AT91_DATAFLASH_CARD)
??? {??? /* DataFlash card */
??????? .modalias??? = "mtd_dataflash",
??????? .chip_select??? = 0,
#endif
#endif
#if defined(CONFIG_SND_AT73C213) || defined(CONFIG_SND_AT73C213_MODULE)
??? {??? /* AT73C213 DAC */
??????? .modalias??? = "at73c213",
??????? .max_speed_hz??? = 10 * 1000 * 1000,
??????? .bus_num??? = 1,
#endif
/* spi can,add by mrz */
#if defined(CONFIG_CAN_MCP2515_MODULE) ||defined(CONFIG_CAN_MCP2515)
//defined(CONFIG_CAN_MCP2515)?
??? {
??????? .modalias = "mcp2515",
??????? .chip_select = 0,
//??????? .controller_data = AT91_PIN_PB3,
??????? .irq = AT91_PIN_PC6,//AT91SAM9260_ID_IRQ0,
??????? .platform_data = &mcp251x_data,
??????? .max_speed_hz = 10 * 1000 * 1000,
??????? .bus_num = 1,
??????? .mode = 0,
??? /*
??? {
??????? .modalias = "mcp2515",
??????? .chip_select = 1,
//??????? .controller_data = AT91_PIN_PC5,
??????? .irq = AT91_PIN_PC7,//AT91SAM9260_ID_IRQ1,
*/
#elif defined(CONFIG_CAN_MCP251X)
??? {
??????? .modalias = "mcp251x",
??? {
??????? .modalias = "mcp251x",
#endif
}
void __init at91_add_device_spi(struct spi_board_info *devices,int nr_devices)
{
??? int i;
??? unsigned long cs_pin;
??? short enable_spi0 = 0;
??? short enable_spi1 = 0;
??? /* Choose SPI chip-selects */
??? /*这里加载我们定义的spi_board_info结构体，也就是两个spi设备的信息，注意，他们这里没有使用spi_device结构体来做，而是使用一个板级信息体来完成。*/
??? for (i = 0; i < nr_devices; i++) {
??? /*该成员定义的就是cs引脚*/
??????? if (devices[i].controller_data)
??????????? cs_pin = (unsigned long) devices[i].controller_data;
??????? else if (devices[i].bus_num == 0)
??????????? cs_pin = spi0_standard_cs[devices[i].chip_select];
??????? else
??????????? cs_pin = spi1_standard_cs[devices[i].chip_select];
??? /*根据需要加载的设备，确定需要打开哪几个SPI控制器，我们系统中有两个控制器，所以我们在以模块的方式加载驱动的时候，我们的设备必须在刚开始就被初始化！*/
??????? if (devices[i].bus_num == 0)
??????????? enable_spi0 = 1;
??????? else
??????????? enable_spi1 = 1;
??????? /* enable chip-select pin */
????? /*将片选引脚设置为输出*/
??????? at91_set_gpio_output(cs_pin,1);
??????? /* pass chip-select pin to driver */
??????? devices[i].controller_data = (void *) cs_pin;
??? }
??? /*到此，循环执行完毕，向内核注册这些板级信息体*/
??? spi_register_board_info(devices,nr_devices);
??? /* Configure SPI bus(es) */
??? /*如果发现spi0上有设备注册，则打开spi0*/
??? if (enable_spi0) {
??????? at91_set_A_periph(AT91_PIN_PA0,0);??? /* SPI0_MISO */
??????? at91_set_A_periph(AT91_PIN_PA1,0);??? /* SPI0_MOSI */
??????? at91_set_A_periph(AT91_PIN_PA2,0);??? /* SPI1_SPCK */
??????? at91_clock_associate("spi0_clk",&at91sam9260_spi0_device.dev,"spi_clk");
??????? platform_device_register(&at91sam9260_spi0_device);
??? }
??? /*spi0设备也是如此*/
??? if (enable_spi1) {
??????? at91_set_A_periph(AT91_PIN_PB0,0);??? /* SPI1_MISO */
??????? at91_set_A_periph(AT91_PIN_PB1,0);??? /* SPI1_MOSI */
??????? at91_set_A_periph(AT91_PIN_PB2,0);??? /* SPI1_SPCK */
??????? at91_clock_associate("spi1_clk",&at91sam9260_spi1_device.dev,"spi_clk");
??????? platform_device_register(&at91sam9260_spi1_device);
??? }
}
从上面这个函数我们可以看出，这个函数就完成了两个功能：
1、向内核完成spi板级信息结构体的注册
2、注册了两个platform_device：spi0与spi1，这两个设备是spi总线控制器！
那么我们客户端spi_device设备的注册是如何完成的？不知道，呵呵
我今天仔细的看代码才发现玄机所在。
内核的注释很清晰的告诉我们，我们的spi设备是不允许热插拔！！这是由于spi设备驱动的框架不允许，我们的spi_device设备注册不是在板级初始化的时候完成的。
在spi控制器的驱动加载的时候，也就是platform_driver：atmel_spi驱动加载的时候，
driver/spi/atmel_spi.c文件中：
static int __init atmel_spi_probe(struct platform_device *pdev)
{
??? struct resource??????? *regs;
??? int??????????? irq;
??? struct clk??????? *clk;
??? int??????????? ret;
??? struct spi_master??? *master;
??? struct atmel_spi??? *as;
??? regs = platform_get_resource(pdev,IORESOURCE_MEM,0);
??? if (!regs)
??????? return -ENXIO;
??? irq = platform_get_irq(pdev,0);
??? if (irq < 0)
??????? return irq;
??? clk = clk_get(&pdev->dev,"spi_clk");
??? if (IS_ERR(clk))
??????? return PTR_ERR(clk);
?
/* setup spi core then atmel-specific driver state */
??? ret = -ENOMEM;
??? master = spi_alloc_master(&pdev->dev,sizeof *as);
??? if (!master)
??????? goto out_free;
??? master->bus_num = pdev->id;
??? master->num_chipselect = 4;
??? master->setup = atmel_spi_setup;
??? master->transfer = atmel_spi_transfer;
??? master->cleanup = atmel_spi_cleanup;
??? platform_set_drvdata(pdev,master);
??? as = spi_master_get_devdata(master);
??? as->buffer = dma_alloc_coherent(&pdev->dev,BUFFER_SIZE,
??????????????????? &as->buffer_dma,GFP_KERNEL);
??? if (!as->buffer)
??????? goto out_free;
??? spin_lock_init(&as->lock);
??? INIT_LIST_HEAD(&as->queue);
??? as->pdev = pdev;
??? as->regs = ioremap(regs->start,(regs->end - regs->start) + 1);
??? if (!as->regs)
??????? goto out_free_buffer;
??? as->irq = irq;
??? as->clk = clk;
#ifdef CONFIG_ARCH_AT91
??? if (!cpu_is_at91rm9200())
??????? as->new_1 = 1;
#endif
??? ret = request_irq(irq,atmel_spi_interrupt,
??????????? pdev->dev.bus_id,master);
??? if (ret)
??????? goto out_unmap_regs;
??? /* Initialize the hardware */
??? clk_enable(clk);
??? spi_writel(as,CR,SPI_BIT(SWRST));
??? spi_writel(as,MR,SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
??? spi_writel(as,PTCR,SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
??? spi_writel(as,SPI_BIT(SPIEN));
??? /* go! */
??? dev_info(&pdev->dev,"Atmel SPI Controller at 0x%08lx (irq %d)/n",
??????????? (unsigned long)regs->start,irq);
??? /*spi注册这个主控制器*/
??? ret = spi_register_master(master);
??? if (ret)
??????? goto out_reset_hw;
??? return 0;
out_reset_hw:
??? spi_writel(as,SPI_BIT(SWRST));
??? clk_disable(clk);
??? free_irq(irq,master);
out_unmap_regs:
??? iounmap(as->regs);
out_free_buffer:
??? dma_free_coherent(&pdev->dev,as->buffer,
??????????? as->buffer_dma);
out_free:
??? clk_put(clk);
??? spi_master_put(master);
??? return ret;
}
而这个spi_register_master位于driver/spi/spi.c文件中，该函数调用了scan_boardinfo(master)，扫描该spi master下面设备。该函数就存在于该文件下：该函数调用了spi_new_device(master,chip)，这个chip就是一个spi_board_info结构体，这就是at91_add_device_spi第一个作用的用处：向内核的链表注册spi_board_info结构体的用处所在。我们来看函数的调用过程：
atmel_spi_probe----->spi_register_master----->scan_boardinfo
---->spi_new_device
我们来看这个spi_new_device函数：
struct spi_device *spi_new_device(struct spi_master *master,
????????????????? struct spi_board_info *chip)
{
??? struct spi_device??? *proxy;
??? struct device??????? *dev = master->cdev.dev;
??? int??????????? status;
??? /* NOTE:? caller did any chip->bus_num checks necessary */
??? if (!spi_master_get(master))
??????? return NULL;
??? /*靠，终于找到你了，先暴打一顿，舒服了。。这里就分配了我们重要的spi_device结构体*/
??? proxy = kzalloc(sizeof *proxy,GFP_KERNEL);
??? if (!proxy) {
??????? dev_err(dev,"can't alloc dev for cs%d/n",
??????????? chip->chip_select);
??????? goto fail;
??? }
/*这就是将我们的信息体中的数据转化为spi_device识别的数据*/
??? proxy->master = master;
??? proxy->chip_select = chip->chip_select;
??? proxy->max_speed_hz = chip->max_speed_hz;
??? proxy->mode = chip->mode;
??? proxy->irq = chip->irq;
??? proxy->modalias = chip->modalias;
??? snprintf(proxy->dev.bus_id,sizeof proxy->dev.bus_id,
??????????? "%s.%u",master->cdev.class_id,
??????????? chip->chip_select);
??? proxy->dev.parent = dev;
??? proxy->dev.bus = &spi_bus_type;
??? /*这里很重要，如果你的spi设备是dataflash的话，保存的就是你的分区表！！！所以我们要返回去修改我们的spi_boardinfo结构体*/
??? proxy->dev.platform_data = (void *) chip->platform_data;
??? /*片选信号*/
??? proxy->controller_data = chip->controller_data;
??? proxy->controller_state = NULL;
??? proxy->dev.release = spidev_release;
??? /* drivers may modify this default i/o setup */
??? status = master->setup(proxy);
??? if (status < 0) {
??????? dev_dbg(dev,"can't %s %s,status %d/n",
??????????????? "setup",proxy->dev.bus_id,status);
??????? goto fail;
??? }
??? /* driver core catches callers that misbehave by defining
???? * devices that already exist.
???? */
??? /*看到这句话，大家放心了吧，大家也就知道怎么找到spi_driver驱动的。。。*/
??? status = device_register(&proxy->dev);
??? if (status < 0) {
??????? dev_dbg(dev,
??????????????? "add",status);
??????? goto fail;
??? }
??? dev_dbg(dev,"registered child %s/n",proxy->dev.bus_id);
??? return proxy;
fail:
??? spi_master_put(master);
??? kfree(proxy);
??? return NULL;
}
?
下面我们要解决最后的一个问题，dataflash的分区的问题，看了这么多，大家应该知道怎么解决了吧！
我们看mtd_dataflash.c文件中驱动加载函数调用了下面这个函数来添加flash设备。。
static int __devinit
add_dataflash(struct spi_device *spi,char *name,
??????? int nr_pages,int pagesize,int pageoffset)
{
??? struct dataflash??????? *priv;
??? struct mtd_info??????????? *device;
??? /*这里就告诉我们要在spi_boardinfo结构体的platform_data成员指向一个我们需要的flash_platform_data数据！*/
??? struct flash_platform_data??? *pdata = spi->dev.platform_data;
??? priv = kzalloc(sizeof *priv,GFP_KERNEL);
??? if (!priv)
??????? return -ENOMEM;
??? init_MUTEX(&priv->lock);
??? priv->spi = spi;
??? priv->page_size = pagesize;
??? priv->page_offset = pageoffset;
??? /* name must be usable with cmdlinepart */
??? sprintf(priv->name,"spi%d.%d-%s",
??????????? spi->master->bus_num,spi->chip_select,
??????????? name);
??? device = &priv->mtd;
??? device->name = (pdata && pdata->name) ? pdata->name : priv->name;
??? device->size = nr_pages * pagesize;
??? device->erasesize = pagesize;
??? device->writesize = pagesize;
??? device->owner = THIS_MODULE;
??? device->type = MTD_DATAFLASH;
??? device->flags = MTD_WRITEABLE;
??? device->erase = dataflash_erase;
??? device->read = dataflash_read;
??? device->write = dataflash_write;
??? device->priv = priv;
??? dev_info(&spi->dev,"%s (%d KBytes)/n",name,device->size/1024);
??? dev_set_drvdata(&spi->dev,priv);
??? if (mtd_has_partitions()) {
??????? struct mtd_partition??? *parts;
??????? int??????????? nr_parts = 0;
??? /*我们这里没有定义该宏，所以不会在命令行传递分区表*/
#ifdef CONFIG_MTD_CMDLINE_PARTS
??????? static const char *part_probes[] = { "cmdlinepart",NULL,};
??????? nr_parts = parse_mtd_partitions(device,part_probes,&parts,0);
#endif
??????? if (nr_parts <= 0 && pdata && pdata->parts) {
??????????? parts = pdata->parts;
??????????? nr_parts = pdata->nr_parts;
??????? }
??????? if (nr_parts > 0) {
??????????? priv->partitioned = 1;
??????????? return add_mtd_partitions(device,parts,nr_parts);
??????? }
??? } else if (pdata && pdata->nr_parts)
??????? dev_warn(&spi->dev,"ignoring %d default partitions on %s/n",
??????????????? pdata->nr_parts,device->name);
??? return add_mtd_device(device) == 1 ? -ENODEV : 0;
}
?
所以我们需要修改这个文件：
arch/arm/mach-at91/board-sam9260ek.c文件：
添加如下：
#if? !defined(CONFIG_MMC_AT91)
#define??? SIZE_1PAGE??? 528
#define??? SIZE_1M (unsigned long)(1024*1024)
static struct mtd_partition ek_dataflash_partition[] = {
??? {
??????? .name??? = "U-boot ENV",
??????? .offset??? = 0,
??????? .size??? = 64*SIZE_1PAGE,
??? {
??????? .name??? = "U-BOOT",
??????? .offset??? = 64*SIZE_1PAGE,
??????? .size??? = 400*SIZE_1PAGE,
??? {
??????? .name ="Kernel",
??????? .offset=464*SIZE_1PAGE,
??????? .size??? = 4000*SIZE_1PAGE,
??? {
??????? .name ="Root fs",
??????? .offset=4464*SIZE_1PAGE,
??????? .size??? = (8192-4464)*SIZE_1PAGE,
};
struct flash_platform_data dataflash_atmel={
??? .name="AT45DB321",
??? .parts=ek_dataflash_partition,
??? .nr_parts=ARRAY_SIZE(ek_dataflash_partition),
};
#endif
修改spi_boardinfo结构体：
static struct spi_board_info ek_spi_devices[] = {
#if !defined(CONFIG_MMC_AT91)
??? {??? /* DataFlash chip */
??????? .modalias??? = "mtd_dataflash",
??????? .platform_data=&dataflash_atmel,
添加platform_data结构成员。
这里我们建立mtd_partition结构体要注意，由于dataflash是以528字节每页的，其实，at45db321x芯片可以设置为512字节每页，这个操作是不可以逆转的，那个位是一个otp位，用过的人就应该知道，但是出厂的时候默认的528字节每页。
如果我们不是以528个字节为单位的话，内核将出警告，强制将分区加载为readonly格式。
到此，分区加载成功，dmesg输出如下信息：
<6>mtd_dataflash spi0.1: AT45DB321x (4224 KBytes)
<5>Creating 4 MTD partitions on "AT45DB321":
<5>0x00000000-0x00008400 : "U-boot ENV"
<5>0x00008400-0x0003bd00 : "U-BOOT"
<5>0x0003bd00-0x0023f700 : "Kernel"
<5>0x0023f700-0x00420000 : "Root fs"
linux简直太伟大了，使用得越多，就越能体会到其思想的伟大！灵活！
?
?
?
那么这两种设备驱动中最重要的类型在linux中如何表现出来，那我们就有必要介绍一下从2.6开始实现的sys文件系统了，
/sys/bus $ cat /etc/fstab
proc??????????? /proc?? proc??? defaults??? 0?? 0
devpts?? /dev/pts?? devpts? defaults?? 0 0
tmpfs?????????? /dev/shm???????? tmpfs? defaults??????? 0?????? 0
sysfs?????????? /sys???????????? sysfs????????? defaults??????? 0?????? 0
/dev/mtdblock2? /mnt/flash2???? yaffs?? defaults??????? 0?????? 0
加载这个文件系统对于我们分析设备模型是非常有好处的。
sys文件夹下一般有如下的目录：
/sys $ ls -al
drwxr-xr-x?? 10 root???? root??????????? 0 Jan? 1? 1970 .
drwxrwxrwx?? 11 1000???? tao????????? 4096 May 22 06:56 ..
drwxr-xr-x??? 7 root???? root??????????? 0 Oct 27 14:09 block
drwxr-xr-x??? 8 root???? root??????????? 0 Jan? 1? 1970 bus
drwxr-xr-x?? 21 root???? root??????????? 0 Jan? 1? 1970 class
drwxr-xr-x??? 4 root???? root??????????? 0 Jan? 1? 1970 devices
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 firmware
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 fs
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 kernel
drwxr-xr-x?? 22 root???? root??????????? 0 Oct 27 14:10 module
block是由于历史原因形成的block设备的文件夹。我们关心的是bus文件夹。
我们以spi设备为例：spi部分要包括两种设备，一种是platform_device，一种是spi_device。
在arch/arm/mach-at91/at91sam9260_device.c文件中，定义的SPI硬件控制模块设备，这我们不需要关心。
还有一种是spi_device，定义在arch/arm/mach-at91/board-sam9260ek.c文件中，这就是我们的dataflash和mcp2515设备，
所以如何设备加载成功的话，在bus下面的每个目录里面，都存在devices和drivers两个文件夹，分别对应设备和文件。
/sys/bus/platform/devices $ ls -al
drwxr-xr-x??? 2 root???? root??????????? 0 Oct 27 16:01 .
drwxr-xr-x??? 4 root???? root??????????? 0 Jan? 1? 1970 ..
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 at91_i2c -> ../../../devices/platform/at91_i2c
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 at91_nand -> ../../../devices/platform/at91_nand
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 at91_ohci -> ../../../devices/platform/at91_ohci
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 atmel_spi.0 -> ../../../devices/platform/atmel_spi.0
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 atmel_spi.1 -> ../../../devices/platform/atmel_spi.1
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 atmel_usart.0 -> ../../../devices/platform/atmel_usart.0
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 atmel_usart.1 -> ../../../devices/platform/atmel_usart.1
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 atmel_usart.2 -> ../../../devices/platform/atmel_usart.2
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:01 macb -> ../../../devices/platform/macb
驱动
/sys/bus/platform/drivers/atmel_spi $ ls -al
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 .
drwxr-xr-x??? 8 root???? root??????????? 0 Jan? 1? 1970 ..
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:10 atmel_spi.0 -> ../../../../devices/platform/atmel_spi.0
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 16:10 atmel_spi.1 -> ../../../../devices/platform/atmel_spi.1
--w-------??? 1 root???? root???????? 4096 Oct 27 16:10 bind
--w-------??? 1 root???? root???????? 4096 Oct 27 16:10 unbind
如果出现上面的这个情况，说明你的设备（两路spi总线）和驱动都加载成功了，如果你的devices下面没有spi.0设备和spi.1设备的话，说明
board-sam9260ek.c文件中的这个函数出错：
static void __init ek_board_init(void)
{
??? /* Serial */
??? at91_add_device_serial();
??? /* USB Host */
??? at91_add_device_usbh(&ek_usbh_data);
??? /* USB Device */
??? at91_add_device_udc(&ek_udc_data);
??? /* SPI */
??? at91_add_device_spi(ek_spi_devices,ARRAY_SIZE(ek_spi_devices));
??? /* NAND */
??? at91_add_device_nand(&ek_nand_data);
??? /* Ethernet */
??? at91_add_device_eth(&ek_macb_data);
??? /* MMC */
??? at91_add_device_mmc(0,&ek_mmc_data);
??? /* I2C */
??? at91_add_device_i2c();
}
这里是设备注册的地方，我们还应该在下面这个目录下看到这两个文件。
/sys/bus/spi/devices $ ls -al
drwxr-xr-x??? 2 root???? root??????????? 0 Oct 27 14:09 .
drwxr-xr-x??? 4 root???? root??????????? 0 Jan? 1? 1970 ..
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 14:09 spi0.1 -> ../../../devices/platform/atmel_spi.0/spi0.1
lrwxrwxrwx??? 1 root???? root??????????? 0 Oct 27 14:09 spi1.0 -> ../../../devices/platform/atmel_spi.1/spi1.0
这两个链接说明我们的两个spi设备注册都被接受了，剩下来就是驱动的问题。有人看不懂这个sys文件系统的层次关系，其实这里比较好说明，就是spi0.1是atmel_spi.0设备的子设备嘛，很好理解的。
驱动：
platform_driver驱动：
/sys/bus/platform/drivers $ ls -al
drwxr-xr-x??? 8 root???? root??????????? 0 Jan? 1? 1970 .
drwxr-xr-x??? 4 root???? root??????????? 0 Jan? 1? 1970 ..
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 at91_i2c
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 at91_nand
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 at91_ohci
drwxr-xr-x??? 2 root???? root??????????? 0 Oct 27 16:10 atmel_spi
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 atmel_usart
drwxr-xr-x??? 2 root???? root??????????? 0 Jan? 1? 1970 macb
我们可以看到这个驱动只有一个atmel_spi，这个驱动是在哪加载的？
driver/spi/atmel_spi.c文件加载的。
spi_driver驱动：
/sys/bus/spi/drivers $ ls -al
drwxr-xr-x??? 4 root???? root??????????? 0 Oct 27 14:10 .
drwxr-xr-x??? 4 root???? root??????????? 0 Jan? 1? 1970 ..
drwxr-xr-x??? 2 root???? root??????????? 0 Oct 27 14:10 mcp2515
drwxr-xr-x??? 2 root???? root??????????? 0 Oct 27 14:09 mtd_dataflash
这是我们加载的两个驱动，说明驱动也加载正常了。
下面我们来说说我们遇到的问题吧。 在设备和驱动都加载正常之后，出现与dataflash设备通信不上的情况，驱动加载的时候，读取芯片的状态字读出是0xff，说明工作不正常，动用逻辑分析仪监控spi总线的通信，意外的发现，sck信号和cs信号正常，但是mosi无信号输出，开始觉得可能是spi总线适配器有问题，后来仔细观察原理图之后，发现dataflash和mmc／sd是使用同样的io口的，即pa0,pa1,pa2，而我的内核配置中打开了对mmc的支持，所以导致mosi不正常，所以可能9260的mmc与dataflash不能同时使用，但9263的可以。 解决办法：make menuconfig Device Drivers--->MMC/SD card support，取消其支持，问题解决！
