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正在研究mw8686 的Linux SDIO驱动，编译好后在s3c6410运行，发现未能出现网络接口设备。一查之下，它使用sdio总线进行操作驱动和设备，但是在 /sys/bus/sdio/devices 没有看到任何设备。因此推理是这个导致WiFi无法使用SDIO的原因。因为sdio驱动的初始化是放在probe当中，而probe是在sdio设备与sdio driver的match的过程中执行中。没有设备，意味着无法进行SDIO初始化。
我用的是Linux 2.6.28的版本，在网络上找到几个其它版本，主要Linux 2.6.21的，利用下午上课时间，进行一下课堂实验。发现这两个版本的实现差别很大，实际上两个分水岭。刚开始没明白这个道理，被两个版本的的源码搞得很混乱，因此为了解决问题，对这个两版本的SDIO实现进行分析
关于mw8686的模块分析，参见我的博文
首先根据档和源码来看三星发了几个关健的BSP，一个是针对linux 2.6.21.另外一个针对 linux 2.6.28的。这两个对SDIO的驱动采用不同的实际，有一篇官方文档可以看看，里面对Linux 2.6.21 SDIO实现分析得详细。
<<SMDK6400 6410 HS MMC porting Guide v1.0 >>,但是网上只能找到这一个
如果你对Linux 2.6的驱动模型相当了解，实际也能很快分析清楚。
SDIO总线
首先mw8686的if_sdio.c直接使用了sdio 总线。这个虚拟总线是由 driver/mmc/core/sdio_bus.c实现，在两个版本，这个基本是变化不大的地方。要注意，这里的SDIO和MMC是两个兼容的接口，因此在源码中两个术语经常互换.
sdio bus是一个标准的Linux 的总线，因此它需要有标准 bus device 和标准bus driver来注册到系统中。
这是 sdio_bus.c的总线定义
|
static struct bus_type sdio_bus_type = {
.name = "sdio",
.dev_attrs = sdio_dev_attrs,
.match = sdio_bus_match,
.uevent = sdio_bus_uevent,
.probe = sdio_bus_probe,
.remove = sdio_bus_remove,
};
int sdio_register_bus(void)
{
return bus_register(&sdio_bus_type);
}
void sdio_unregister_bus(void)
{
bus_unregister(&sdio_bus_type);
} |
而对应总线驱动struct device_driver 是 struct sdio_driver
|
/*
* SDIO function device driver
*/
struct sdio_driver {
char *name;
const struct sdio_device_id *id_table;
int (*probe)(struct sdio_func *, const struct sdio_device_id *);
void (*remove)(struct sdio_func *);
struct device_driver drv;
}; |
它使用 如下两个函数来注册和销毁sdio_driver.
extern int sdio_register_driver(struct sdio_driver *);
extern void sdio_unregister_driver(struct sdio_driver *);
而对应总线设备的就是 struct device 是 struct sdio_func,这个名字与device差别太大了，因此我一开没有太在意。
|
/*
* SDIO function devices
*/
struct sdio_func {
struct mmc_card *card; /* the card this device belongs to */
struct device dev; /* the device */
sdio_irq_handler_t *irq_handler; /* IRQ callback */
unsigned int num; /* function number */
unsigned char class; /* standard interface class */
unsigned short vendor; /* vendor id */
unsigned short device; /* device id */
unsigned max_blksize; /* maximum block size */
unsigned cur_blksize; /* current block size */
unsigned enable_timeout; /* max enable timeout in msec */
unsigned int state; /* function state */
#define SDIO_STATE_PRESENT (1<<0) /* present in sysfs */
u8 tmpbuf[4]; /* DMA:able scratch buffer */
unsigned num_info; /* number of info strings */
const char **info; /* info strings */
struct sdio_func_tuple *tuples;
}; |
对于sdio_func操作
int sdio_add_func(struct sdio_func *func);
void sdio_remove_func(struct sdio_func *func);
在drivers/net/wireless/libertas/if_sdio.c
它定义了如下的 sdio_driver
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static struct sdio_driver if_sdio_driver = {
.name = "libertas_sdio",
.id_table = if_sdio_ids,
.probe = if_sdio_probe,
.remove = if_sdio_remove,
};
static int __init if_sdio_init_module(void)
{
int ret = 0;
ret = sdio_register_driver(&if_sdio_driver);
return ret;
}
static void __exit if_sdio_exit_module(void)
{
sdio_unregister_driver(&if_sdio_driver);
}
|
SDIO采用的与MMC兼容的命令接口，因此对于mmc的操作，LINUX又封装一层，使用数据结构 mmc_host
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struct mmc_host {
struct device *parent;
struct device class_dev;
int index;
const struct mmc_host_ops *ops;
unsigned int f_min;
unsigned int f_max;
u32 ocr_avail;
unsigned long caps; /* Host capabilities */
/* host specific block data */
unsigned int max_seg_size; /* see blk_queue_max_segment_size */
unsigned short max_hw_segs; /* see blk_queue_max_hw_segments */
unsigned short max_phys_segs; /* see blk_queue_max_phys_segments */
unsigned short unused;
unsigned int max_req_size; /* maximum number of bytes in one req */
unsigned int max_blk_size; /* maximum size of one mmc block */
unsigned int max_blk_count; /* maximum number of blocks in one req */
/* private data */
spinlock_t lock; /* lock for claim and bus ops */
struct mmc_ios ios; /* current io bus settings */
u32 ocr; /* the current OCR setting */
/* group bitfields together to minimize padding */
unsigned int use_spi_crc:1;
unsigned int claimed:1; /* host exclusively claimed */
unsigned int bus_dead:1; /* bus has been released */
#ifdef CONFIG_MMC_DEBUG
unsigned int removed:1; /* host is being removed */
#endif
struct mmc_card *card; /* device attached to this host */
wait_queue_head_t wq;
struct delayed_work detect;
const struct mmc_bus_ops *bus_ops; /* current bus driver */
unsigned int bus_refs; /* reference counter */
unsigned int sdio_irqs;
struct task_struct *sdio_irq_thread;
atomic_t sdio_irq_thread_abort;
#ifdef CONFIG_LEDS_TRIGGERS
struct led_trigger *led; /* activity led */
#endif
struct dentry *debugfs_root;
unsigned long private[0] ____cacheline_aligned;
};
|
而mmc_host是一个特殊内核类 mmc_host,它会在 /sys/class/ 建立一个mmc_host类.
|
//drivers/mmc/core/host.c
static struct class mmc_host_class = {
.name = "mmc_host",
.dev_release = mmc_host_classdev_release,
};
int mmc_register_host_class(void)
{
return class_register(&mmc_host_class);
}
void mmc_unregister_host_class(void)
{
class_unregister(&mmc_host_class);
} |
mmc_host用于描述MMC接口 CPU一侧的设备,它可以看成是class device的特例，而插入的SDIO设备，如SD卡则封装成数据结构,如果mmc_host发送命令和数据是通过 struct mmc_host_ops 操作
struct mmc_host_ops {
void (*request)(struct mmc_host *host, struct mmc_request *req);
void (*set_ios)(struct mmc_host *host, struct mmc_ios *ios);
int (*get_ro)(struct mmc_host *host);
int (*get_cd)(struct mmc_host *host);
void (*enable_sdio_irq)(struct mmc_host *host, int enable);
}; |
如果SDIO设备操作，直接采用如下定义
static struct mmc_host_ops s3c_hsmmc_ops = {
.request = s3c_hsmmc_request,
.set_ios = s3c_hsmmc_set_ios,
}; |
mmc_card /mmc_bus
如果SD卡的之存储设备进行块设备操作,则需要另一个额外的mmc bus总线，并且需要定义mmc_card结构，对应(device).并且进行存储的块设备操作定义在mmc_driver类。
如果SDIO设备本身不需要这个总线
在mmc又单独定义一个 mmc总线,
|
static struct bus_type mmc_bus_type = {
.name = "mmc",
.dev_attrs = mmc_dev_attrs,
.match = mmc_bus_match,
.uevent = mmc_bus_uevent,
.probe = mmc_bus_probe,
.remove = mmc_bus_remove,
.suspend = mmc_bus_suspend,
.resume = mmc_bus_resume,
};
int mmc_register_bus(void)
{
return bus_register(&mmc_bus_type);
}
void mmc_unregister_bus(void)
{
bus_unregister(&mmc_bus_type);
} |
mmc_card.它可以看一个bus device 设备
|
// include/linux/mmc/card.h
/*
* MMC device
*/
struct mmc_card {
struct mmc_host *host; /* the host this device belongs to */
struct device dev; /* the device */
unsigned int rca; /* relative card address of device */
unsigned int type; /* card type */
#define MMC_TYPE_MMC 0 /* MMC card */
#define MMC_TYPE_SD 1 /* SD card */
#define MMC_TYPE_SDIO 2 /* SDIO card */
unsigned int state; /* (our) card state */
#define MMC_STATE_PRESENT (1<<0) /* present in sysfs */
#define MMC_STATE_READONLY (1<<1) /* card is read-only */
#define MMC_STATE_HIGHSPEED (1<<2) /* card is in high speed mode */
#define MMC_STATE_BLOCKADDR (1<<3) /* card uses block-addressing */
u32 raw_cid[4]; /* raw card CID */
u32 raw_csd[4]; /* raw card CSD */
u32 raw_scr[2]; /* raw card SCR */
struct mmc_cid cid; /* card identification */
struct mmc_csd csd; /* card specific */
struct mmc_ext_csd ext_csd; /* mmc v4 extended card specific */
struct sd_scr scr; /* extra SD information */
struct sd_switch_caps sw_caps; /* switch (CMD6) caps */
unsigned int sdio_funcs; /* number of SDIO functions */
struct sdio_cccr cccr; /* common card info */
struct sdio_cis cis; /* common tuple info */
struct sdio_func *sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */
unsigned num_info; /* number of info strings */
const char **info; /* info strings */
struct sdio_func_tuple *tuples; /* unknown common tuples */
struct dentry *debugfs_root;
}; |
mmc_card 与 sdio 总线的device (sdio_func)的交互的关系体现在 mmc_card中sdio_func定义
而mmc_card与mmc_host关系体现在定义 mmc_card的host定义中
而mmc_bus中，其驱动就是mmc_driver
|
/*
* MMC device driver (e.g., Flash card, I/O card...)
*/
struct mmc_driver {
struct device_driver drv;
int (*probe)(struct mmc_card *);
void (*remove)(struct mmc_card *);
int (*suspend)(struct mmc_card *, pm_message_t);
int (*resume)(struct mmc_card *);
};
extern int mmc_register_driver(struct mmc_driver *);
extern void mmc_unregister_driver(struct mmc_driver *) |
而使用了mmc_driver 好象只有处理SD卡块设备
|
//driver/mmc/core/block.c
static struct mmc_driver mmc_driver = {
.drv = {
.name = "mmcblk",
},
.probe = mmc_blk_probe,
.remove = mmc_blk_remove,
.suspend = mmc_blk_suspend,
.resume = mmc_blk_resume,
}; |
它大体有如下关系，这里出问题就是BSP这一侧 sdio channel1的驱动
Linux 2.6.21的SDIO的实现
在Linu 2.6.21的SDIO驱动，它是除了是mmc_host的驱动外，还是一个Platform驱动.身兼两职.
在这个版本中，首先是定义三个platform_deivce 以注册到系统当中。但是它定义在
arch/arm/plat-s3c24xx/devs.c (这会让人感当相当迷惑),它创建是 s3c-hsmmc设备
struct platform_device s3c_device_hsmmc0 = {
.name = "s3c-hsmmc",
.id = 0,
.num_resources = ARRAY_SIZE(s3c_hsmmc0_resource),
.resource = s3c_hsmmc0_resource,
.dev = {
.platform_data = &s3c_hsmmc0_platform,
}
};
struct platform_device s3c_device_hsmmc1 = {
.name = "s3c-hsmmc",
.id = 1,
.num_resources = ARRAY_SIZE(s3c_hsmmc1_resource),
.resource = s3c_hsmmc1_resource,
.dev = {
.platform_data = &s3c_hsmmc1_platform,
}
};
|
其platform_driver 定义在drivers/mmc/s3c-hsmmc.c
static struct platform_driver s3c_hsmmc_driver =
{
.probe = s3c_hsmmc_probe,
.remove = s3c_hsmmc_remove,
.suspend = s3c_hsmmc_suspend,
.resume = s3c_hsmmc_resume,
.driver = {
.name = "s3c-hsmmc",
.owner = THIS_MODULE,
},
};
static int __init s3c_hsmmc_drv_init(void)
{
return platform_driver_register(&s3c_hsmmc_driver);
}
static void __exit s3c_hsmmc_drv_exit(void)
{
platform_driver_unregister(&s3c_hsmmc_driver);
}
|
在s3c_hsmmc_probe函数中，会进行一系列的初始化操作.
Linux 2.6.28的SDIO的实现
Linux 2.6.28又做了进一步调整，原来的s3c-hsmmc的设备和驱动已经放弃，原来在s3c-hsmmc.c 已经成为残余代码，虽然在内核中，但是不会加入Makefile编译。
其新的platform_device 定义分布定义在 dev-hsmmc.c /dev-hsmmc1.c / dev-hsmmc2.c,可以看到设备名字已经变成了 s3c-sdhci
|
struct s3c_sdhci_platdata s3c_hsmmc0_def_platdata = {
.max_width = 4,
.host_caps = (MMC_CAP_4_BIT_DATA | MMC_CAP_MMC_HIGHSPEED |
MMC_CAP_SD_HIGHSPEED),
.cfg_ext_cd = setup_sdhci0_irq_cd,
.detect_ext_cd = detect_sdhci0_irq_cd,
.ext_cd = S3C_EINT(13),
};
struct platform_device s3c_device_hsmmc0 = {
.name = "s3c-sdhci",
.id = 0,
.num_resources = ARRAY_SIZE(s3c_hsmmc_resource),
.resource = s3c_hsmmc_resource,
.dev = {
.dma_mask = &s3c_device_hsmmc_dmamask,
.coherent_dma_mask = 0xffffffffUL,
.platform_data = &s3c_hsmmc0_def_platdata,
},
}; |
它会在系统初始化注册deivce.
而platform_driver定义在drivers/mmc/host/sdhci-s3c.c
|
//drivers/mmc/host/sdhci-s3c.c
static struct platform_driver sdhci_s3c_driver = {
.probe = sdhci_s3c_probe,
.remove = __devexit_p(sdhci_s3c_remove),
.suspend = sdhci_s3c_suspend,
.resume = sdhci_s3c_resume,
.driver = {
.owner = THIS_MODULE,
.name = "s3c-sdhci",
},
}; |
在测试WIFI模块时，在 /sys/bus/platform/devices中已经看到了 这两个device,但是在/sys/bus/sdio/deivces仍然没见到相应设备
[root@urbetter bin]# ls /sys/bus/platform/devices
dm9000_con201.0 s3c-keypad s3c-tvscaler s3c6400-uart.1
onenand s3c-lcd s3c-usbgadget s3c6400-uart.2
regulatory.0 s3c-mfc s3c-vpp s3c6400-uart.3
s3c-fimc.0 s3c-rotator s3c2410-ohci s3c6410-nand
s3c-fimc.1 s3c-sdhci.0 s3c2410-rtc s3c_otghcd
s3c-g2d s3c-sdhci.1 s3c2410-wdt sam-spi.0
s3c-g3d s3c-ts s3c2440-i2c sam-spi.1
s3c-jpeg s3c-tvenc s3c6400-uart.0 soc-audio |
