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?
[device_register]
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()。
[driver_register]
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。
[总线]
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。。。
[sys文件系统]
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!
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,
- .max_speed_hz = 15 * 1000 * 1000,
- .bus_num = 0,
- },
- #endif
- #endif
- #if defined(CONFIG_SND_AT73C213) || defined(CONFIG_SND_AT73C213_MODULE)
- { /* AT73C213 DAC */
- .modalias = "at73c213",
- .chip_select = 0,
- .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,
- .platform_data = &mcp251x_data,
- .max_speed_hz = 10 * 1000 * 1000,
- .bus_num = 1,
- .mode = 0,
- },
- */
- #elif defined(CONFIG_CAN_MCP251X)
- {
- .modalias = "mcp251x",
- .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 = "mcp251x",
- .chip_select = 1,
- // .controller_data = AT91_PIN_PC5,
- .irq = AT91_PIN_PC7, //AT91SAM9260_ID_IRQ1,
- .platform_data = &mcp251x_data,
- .max_speed_hz = 10 * 1000 * 1000,
- .bus_num = 1,
- .mode = 0,
- },
- #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, 0,
- 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, CR, 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, CR, SPI_BIT(SWRST));
- clk_disable(clk);
- free_irq(irq, master);
- out_unmap_regs:
- iounmap(as->regs);
- out_free_buffer:
- dma_free_coherent(&pdev->dev, BUFFER_SIZE, 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, "can't %s %s, status %d\n",
- "add", proxy->dev.bus_id, 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",
- .chip_select = 1,
- .max_speed_hz = 15 * 1000 * 1000,
- .bus_num = 0,
- .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!
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