spi驅(qū)動(dòng)模型和i2c的類(lèi)似，都按照主機(jī)外設(shè)分離來(lái)設(shè)計(jì)的。但我覺(jué)得比i2c的要簡(jiǎn)明好多。
上文配置的spi驅(qū)動(dòng)最外層是platform總線然后是spi總線然后是字符設(shè)備。
spi驅(qū)動(dòng)模型分為
spi主控制器驅(qū)動(dòng)，對(duì)應(yīng)結(jié)構(gòu)體spi_master-spi_s3c24xx.c。控制怎么發(fā)。
spi外設(shè)驅(qū)動(dòng)，對(duì)應(yīng)結(jié)構(gòu)體spi_driver-----spidev.c。實(shí)現(xiàn)與用戶(hù)的接口。
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對(duì)于te6410,linux2.6.36.2 ?2012-6-10?
在板子文件mach-smdk6410.c中注冊(cè)平臺(tái)設(shè)備，
在spi_s3c64xx.c中使用platform_driver_probe(platform_driver_register)注冊(cè)平臺(tái)驅(qū)動(dòng)，
在平臺(tái)驅(qū)動(dòng)的probe函數(shù)中，注冊(cè)使用spi_register_master注冊(cè)spi主機(jī)控制器驅(qū)動(dòng)，實(shí)現(xiàn)操作spi寄存器。
在spidev.c中使用spi_register_driver注冊(cè)spi外設(shè)驅(qū)動(dòng)。并注冊(cè)字符設(shè)備實(shí)現(xiàn)與用戶(hù)空間的接口。或者不使用字符設(shè)備也行，比如mcp2515沒(méi)有使用字符設(shè)備，而是按照net_device的思路來(lái)實(shí)現(xiàn)用戶(hù)接口的。

由于平臺(tái)設(shè)備寫(xiě)進(jìn)了板子文件，所以在系統(tǒng)啟動(dòng)時(shí)會(huì)自動(dòng)注冊(cè)這個(gè)平臺(tái)設(shè)備及將其掛在平臺(tái)總線。由于平臺(tái)驅(qū)動(dòng)也編譯進(jìn)了內(nèi)核，所以也會(huì)自動(dòng)注冊(cè)即也掛在了平臺(tái)總線。平臺(tái)核心會(huì)匹配兩者，
成功后，調(diào)用平臺(tái)驅(qū)動(dòng)的probe函數(shù)來(lái)注冊(cè)spi主機(jī)控制器驅(qū)動(dòng)此時(shí)會(huì)將主機(jī)控制器驅(qū)動(dòng)掛在spi總線。在spi外設(shè)驅(qū)動(dòng)insmod進(jìn)內(nèi)核時(shí)即也掛上了spi總線，spi核心會(huì)匹配兩者，
成功后，調(diào)用spi外設(shè)驅(qū)動(dòng)的probe函數(shù)實(shí)現(xiàn)真正的用戶(hù)接口比如cdev，net_device。

而在spi外設(shè)驅(qū)動(dòng)實(shí)現(xiàn)的read,write等函數(shù)，最終調(diào)用的是匹配的spi主機(jī)控制器驅(qū)動(dòng)的transfer()

***************************************************************************************
關(guān)于spi_driver和spi_device的匹配：
spi_driver中name字段
static struct spi_driver spidev_spi_driver = {
?? ?.driver = {
?? ??? ?.name =?? ??? ?"spidev",
?? ??? ?.owner =?? ?THIS_MODULE,
?? ?},
...
}
和mach-smdk6410.c中的modalias字段
static struct spi_board_info s3c2410_spi0_board[] = { ?
??????? [0] = { ?
???????????????? .modalias = "spidev",?
??????????????? .bus_num??????? = 0,????
??????????????? .chip_select??????? = 0,?
??????????????? .max_speed_hz???????? = 500*1000, ?
??????? }, ?
};?
要一致才行。
如果使用id_table來(lái)匹配則id_table中的項(xiàng)目要與spi_board_info中的modalias 匹配( 假如.modalias = "mcp2515", )，則在mcp251x.c中

static const struct spi_device_id mcp251x_id_table[] = {
?? ?{ "mcp2510",?? ?CAN_MCP251X_MCP2510 },
?? ?{ "mcp2515",?? ?CAN_MCP251X_MCP2515 },//必須的
?? ?{ },
};

MODULE_DEVICE_TABLE(spi, mcp251x_id_table);

static struct spi_driver mcp251x_can_driver = {
?? ?.driver = {
?? ??? ?.name = "mcp2515",//無(wú)關(guān),可以不是mcp2515
?? ??? ?.bus = &spi_bus_type,
?? ??? ?.owner = THIS_MODULE,
?? ?},

?? ?.id_table = mcp251x_id_table,
}

匹配原理
spi_master注冊(cè)過(guò)程中會(huì)掃描arch/.../mach-*/board-*.c 中調(diào)用spi_register_board_info注冊(cè)的信息，為每一個(gè)與本總線編號(hào)相同的信息建立一個(gè)spi_device。
根據(jù)Linux內(nèi)核的驅(qū)動(dòng)模型，注冊(cè)在同一總線下的驅(qū)動(dòng)和設(shè)備會(huì)進(jìn)行匹配。spi_bus_type總線匹配的依據(jù)是名字。這樣當(dāng)自己編寫(xiě)的spi_driver和spi_device同名的時(shí)候，
spi_driver的probe方法就會(huì)被調(diào)用。spi_driver就能看到與自己匹配的spi_device了。
http://blog.csdn.net/yuanlulu/article/details/6318165

如果有idtable的話，就匹配idtable里各個(gè)項(xiàng)目的name,這樣就可以支持多個(gè)name了,如源碼
spi.c
static int spi_match_device(struct device *dev, struct device_driver *drv) {const struct spi_device *spi = to_spi_device(dev);const struct spi_driver *sdrv = to_spi_driver(drv);/* Attempt an OF style match */if (of_driver_match_device(dev, drv))return 1;if (sdrv->id_table)return !!spi_match_id(sdrv->id_table, spi);return strcmp(spi->modalias, drv->name) == 0; }static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,const struct spi_device *sdev) {while (id->name[0]) {if (!strcmp(sdev->modalias, id->name))return id;id++;}return NULL; }

***************************************************************************************
在spidev.c實(shí)現(xiàn)了spi的字符設(shè)備驅(qū)動(dòng)
static struct spi_driver spidev_spi_driver = {.driver = {.name = "spidev",.owner = THIS_MODULE,},.probe = spidev_probe,.remove = __devexit_p(spidev_remove),/* NOTE: suspend/resume methods are not necessary here.* We don't do anything except pass the requests to/from* the underlying controller. The refrigerator handles* most issues; the controller driver handles the rest.*/ }; static int __init spidev_init(void) {int status;/* Claim our 256 reserved device numbers. Then register a class* that will key udev/mdev to add/remove /dev nodes. Last, register* the driver which manages those device numbers.*/BUILD_BUG_ON(N_SPI_MINORS > 256);status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);//注冊(cè)字符設(shè)備，這個(gè)才是真的用戶(hù)接口if (status < 0)return status;spidev_class = class_create(THIS_MODULE, "spidev");if (IS_ERR(spidev_class)) {unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);return PTR_ERR(spidev_class);}status = spi_register_driver(&spidev_spi_driver);//注冊(cè)spi_driverif (status < 0) {class_destroy(spidev_class);unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);}return status; }static const struct file_operations spidev_fops = {.owner = THIS_MODULE,/* REVISIT switch to aio primitives, so that userspace* gets more complete API coverage. It'll simplify things* too, except for the locking.*/.write = spidev_write,.read = spidev_read,.unlocked_ioctl = spidev_ioctl,.open = spidev_open,.release = spidev_release, }; static int __devinit spidev_probe(struct spi_device *spi) {struct spidev_data *spidev;int status;unsigned long minor;/* Allocate driver data */spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);if (!spidev)return -ENOMEM;/* Initialize the driver data */spidev->spi = spi;spin_lock_init(&spidev->spi_lock);mutex_init(&spidev->buf_lock);INIT_LIST_HEAD(&spidev->device_entry);/* If we can allocate a minor number, hook up this device.* Reusing minors is fine so long as udev or mdev is working.*/mutex_lock(&device_list_lock);minor = find_first_zero_bit(minors, N_SPI_MINORS);if (minor < N_SPI_MINORS) {struct device *dev;spidev->devt = MKDEV(SPIDEV_MAJOR, minor);dev = device_create(spidev_class, &spi->dev, spidev->devt,spidev, "spidev%d.%d",spi->master->bus_num, spi->chip_select);//創(chuàng)建設(shè)備文件status = IS_ERR(dev) ? PTR_ERR(dev) : 0;} else {dev_dbg(&spi->dev, "no minor number available!\n");status = -ENODEV;}if (status == 0) {set_bit(minor, minors);list_add(&spidev->device_entry, &device_list);}mutex_unlock(&device_list_lock);if (status == 0)spi_set_drvdata(spi, spidev);elsekfree(spidev);return status; }//spi讀，調(diào)用spidev_sync_read--spidev_sync--spi_async,最后這個(gè)函數(shù)是spi核心提供的，這個(gè)函數(shù)最終會(huì)調(diào)用master的transfer函數(shù)直接操作硬件來(lái)傳輸數(shù)據(jù)。 /* Read-only message with current device setup */ static ssize_t spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) {struct spidev_data *spidev;ssize_t status = 0;/* chipselect only toggles at start or end of operation */if (count > bufsiz)return -EMSGSIZE;spidev = filp->private_data;mutex_lock(&spidev->buf_lock);status = spidev_sync_read(spidev, count);if (status > 0) {unsigned long missing;missing = copy_to_user(buf, spidev->buffer, status);if (missing == status)status = -EFAULT;elsestatus = status - missing;}mutex_unlock(&spidev->buf_lock);return status; }static inline ssize_t spidev_sync_read(struct spidev_data *spidev, size_t len) {struct spi_transfer t = {.rx_buf = spidev->buffer,.len = len,};struct spi_message m;spi_message_init(&m);//初始化spi_message，spi_message_add_tail(&t, &m);return spidev_sync(spidev, &m); }static ssize_t spidev_sync(struct spidev_data *spidev, struct spi_message *message) {DECLARE_COMPLETION_ONSTACK(done);int status;message->complete = spidev_complete;message->context = &done;spin_lock_irq(&spidev->spi_lock);if (spidev->spi == NULL)status = -ESHUTDOWN;elsestatus = spi_async(spidev->spi, message);//異步傳輸，如果是同步傳輸，則會(huì)阻塞一直到這個(gè)消息被處理完。spin_unlock_irq(&spidev->spi_lock);if (status == 0) {wait_for_completion(&done);status = message->status;if (status == 0)status = message->actual_length;}return status; }//spi寫(xiě)，調(diào)用spidev_sync_write--spidev_sync--spi_async,最后這個(gè)函數(shù)是spi核心提供的，這個(gè)函數(shù)最終會(huì)調(diào)用master的transfer函數(shù)直接操作硬件來(lái)傳輸數(shù)據(jù)。 /* Write-only message with current device setup */ static ssize_t spidev_write(struct file *filp, const char __user *buf,size_t count, loff_t *f_pos) {struct spidev_data *spidev;ssize_t status = 0;unsigned long missing;/* chipselect only toggles at start or end of operation */if (count > bufsiz)return -EMSGSIZE;spidev = filp->private_data;mutex_lock(&spidev->buf_lock);missing = copy_from_user(spidev->buffer, buf, count);if (missing == 0) {status = spidev_sync_write(spidev, count);} elsestatus = -EFAULT;mutex_unlock(&spidev->buf_lock);return status; }
http://blog.csdn.net/songqqnew/article/details/7037583

轉(zhuǎn)載于:https://www.cnblogs.com/-song/archive/2011/12/03/3331907.html

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