linux中probe函数传递参数的寻找（下）

最新推荐文章于 2024-07-26 16:18:35 发布

xiafeng1113

最新推荐文章于 2024-07-26 16:18:35 发布

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分类专栏： spi驱动 linux内核设备驱动开发文章标签： linux spi 设备注册

本文链接：https://blog.youkuaiyun.com/xiafeng1113/article/details/8474612

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本文深入解析了Linux系统中SPI设备的配置过程，包括设备信息如何与spi_bus_type关联，涉及的关键函数及其作用，如spi_register_board_info、spi_new_device等。

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linux中probe函数传递参数的寻找（下）

通过追寻driver的脚步，我们有了努力的方向：只有找到spi_bus_type的填充device即可，下面该从device去打通，当两个连通之日，也是任督二脉打通之时。先从设备定义去查看，在mach-smdk6410.c中定义了硬件设备信息，从这作为突破口。

/* for mx25lx*/

static void cs_set_level(unsigned line_id, int lvl) {

gpio_direction_output(line_id, lvl);

};

static struct s3c64xx_spi_csinfos3c64xx_spi1_csinfo = {

.fb_delay=0x3,

.line=S3C64XX_GPC(7),

.set_level=cs_set_level,

};

static int mx25lx_ioSetup(struct spi_device*spi)

{

printk(KERN_INFO"mx25lx: setup gpio pins CS and External Int\n");

s3c_gpio_setpull(S3C64XX_GPL(8),S3C_GPIO_PULL_UP); //External interrupt from CAN controller

s3c_gpio_cfgpin(S3C64XX_GPL(8),S3C_GPIO_SFN(3)); //External interrupt from CAN controller (hopefully external interrupt)

//s3c_gpio_cfgpin(S3C64XX_GPL(8),S3C_GPIO_INPUT); //External interrupt from CAN controller

s3c_gpio_setpull(S3C64XX_GPC(7),S3C_GPIO_PULL_NONE); // Manual chipselect pin as used in 6410_set_cs

s3c_gpio_cfgpin(S3C64XX_GPC(7),S3C_GPIO_OUTPUT); // Manualchip select pin as used in 6410_set_cs

return0;

}

static struct mx25lx_platform_datamx25lx_info =

{

.oscillator_frequency= 8000000,

.board_specific_setup= mx25lx_ioSetup,

.transceiver_enable= NULL,

.power_enable= NULL,

};

static struct spi_board_info __initdataforlinx6410_mc251x_info[] =

{

.modalias= "mcp2515",

.platform_data = &mx25lx_info,

.irq= IRQ_EINT(16),

.max_speed_hz= 10*1000*1000,

.bus_num= 1,

.chip_select= 0,

.mode= SPI_MODE_0,

.controller_data=&s3c64xx_spi1_csinfo,

};

struct platform_device s3c64xx_device_spi0= {

.name = "s3c64xx-spi",

.id = 0,

.num_resources =ARRAY_SIZE(s3c64xx_spi0_resource),

.resource =s3c64xx_spi0_resource,

.dev= {

.dma_mask = &spi_dmamask,

.coherent_dma_mask = DMA_BIT_MASK(32),

.platform_data= &s3c64xx_spi0_pdata,

};

static struct platform_device*smdk6410_devices[] __initdata =

{

……

/*addby fatfish*/

&s3c64xx_device_spi0,

&s3c64xx_device_spi1,

};

其中platform_device定义为：

struct platform_device {

constchar * name;

int id;

structdevice dev;

u32 num_resources;

structresource * resource;

conststruct platform_device_id *id_entry;

/*MFD cell pointer */

structmfd_cell *mfd_cell;

/*arch specific additions */

structpdev_archdata archdata;

};

初始化函数如下：

static void __initsmdk6410_machine_init(void)

{

……

s3c64xx_spi_set_info(0,0,1);

s3c64xx_spi_set_info(1,0,1);

spi_register_board_info(forlinx6410_mc251x_info,ARRAY_SIZE(forlinx6410_mc251x_info));

……

}

其中的注册板信息的函数如下，后项参数为1，其中board_list为spi.c中定义的全局变量，即：static LIST_HEAD(board_list);。

int __init

spi_register_board_info(structspi_board_info const *info, unsigned n)

{

structboardinfo *bi;

inti;

bi= kzalloc(n * sizeof(*bi), GFP_KERNEL);

if(!bi)

return-ENOMEM;

for(i = 0; i < n; i++, bi++, info++) {

structspi_master *master;

memcpy(&bi->board_info,info, sizeof(*info));

mutex_lock(&board_lock);

list_add_tail(&bi->list,&board_list);

list_for_each_entry(master,&spi_master_list, list)

spi_match_master_to_boardinfo(master,&bi->board_info);

mutex_unlock(&board_lock);

}

return0;

}

其中结果成员如下：

先加锁，然后将board_list加入链接中，在遍历设备，最关键的函数是：

static voidspi_match_master_to_boardinfo(struct spi_master *master,

structspi_board_info *bi)

{

structspi_device *dev;

if(master->bus_num != bi->bus_num)

return;

dev= spi_new_device(master, bi);

if(!dev)

dev_err(master->dev.parent,"can't create new device for %s\n",

bi->modalias);

}

spi_new_device作用是实例化一个新设备，定义如下：

struct spi_device *spi_new_device(structspi_master *master,

struct spi_board_info *chip)

{

structspi_device *proxy;

int status;

proxy= spi_alloc_device(master);

if(!proxy)

returnNULL;

……

strlcpy(proxy->modalias,chip->modalias, sizeof(proxy->modalias));

proxy->dev.platform_data = (void *)chip->platform_data;

proxy->controller_data= chip->controller_data;

proxy->controller_state= NULL;

status= spi_add_device(proxy);

if(status < 0) {

spi_dev_put(proxy);

returnNULL;

}

returnproxy;

}

拷贝了platform_data，即mx25lx_info。其中的spi_alloc_device函数定义如下：

struct spi_device *spi_alloc_device(structspi_master *master)

{

structspi_device *spi;

structdevice *dev =master->dev.parent;

if(!spi_master_get(master))

returnNULL;

spi= kzalloc(sizeof *spi, GFP_KERNEL);

if(!spi) {

dev_err(dev,"cannot alloc spi_device\n");

spi_master_put(master);

returnNULL;

}

spi->master= master;

spi->dev.parent= dev;

spi->dev.bus= &spi_bus_type;

spi->dev.release= spidev_release;

device_initialize(&spi->dev);

returnspi;

}

在这个定义中将spi_bus_type和dev联系起来，不过此时还没有我们定义的设备信息，设备信息在接下来的赋值中完成。

最后是spi_add_device，将设备信息提交。

int spi_add_device(struct spi_device *spi)

{

staticDEFINE_MUTEX(spi_add_lock);

structdevice *dev = spi->master->dev.parent;

structdevice *d;

intstatus;

……

mutex_lock(&spi_add_lock);

d= bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));

……

status= spi_setup(spi);

if(status < 0) {

dev_err(dev,"can't setup %s, status %d\n",

dev_name(&spi->dev),status);

gotodone;

}

……

done:

mutex_unlock(&spi_add_lock);

returnstatus;

}

最终完成将spi_bus_type与定义的device信息联系起来。由于本人才疏学浅，不正确的地方，恳求大牛指正，在此表示感谢！