///////////////////////////////////////////////////postcore_initcall优先级比module_init高postcore_initcall(i2c_init);static int __init i2c_init(void){ retval = bus_register(&i2c_bus_type); retval = class_register(&i2c_adapter_class); retval = i2c_add_driver(&dummy_driver);}/////////////////////////////////////////////////static struct i2c_driver dummy_driver = { .driver.name = "dummy", .probe = dummy_probe, .remove = dummy_remove, .id_table = dummy_id,};/////////////////////////////////////////////////static struct device_attribute i2c_adapter_attrs[] = { __ATTR(name, S_IRUGO, show_adapter_name, NULL), { },};static struct class i2c_adapter_class = { .owner = THIS_MODULE, .name = "i2c-adapter", .dev_attrs = i2c_adapter_attrs,};/////////////////////////////////////////////////struct bus_type i2c_bus_type = { .name = "i2c", .dev_attrs = i2c_dev_attrs, .match = i2c_device_match, .uevent = i2c_device_uevent, .probe = i2c_device_probe, .remove = i2c_device_remove, .shutdown = i2c_device_shutdown, .suspend = i2c_device_suspend, .resume = i2c_device_resume,};总线提供了match和probe方法：match方法的用来进行client device（ 是i2c_client 吧）和client driver的配对。在向总线i2c_bus_type注册设备或者驱动时 （i2c_add_driver函数或（i2c_register_driver）函数）会调用此方法/////////////////////////////////////////////////static int i2c_device_match(struct device *dev, struct device_driver *drv){//可以看出匹配的对象是struct i2c_client和 struct i2c_driver实例//也就是struct i2c_client被看成device了？ struct i2c_client *client = to_i2c_client(dev); struct i2c_driver *driver = to_i2c_driver(drv); /* make legacy i2c drivers bypass driver model probing entirely; * such drivers scan each i2c adapter/bus themselves. */ if (!is_newstyle_driver(driver)) return 0; /* match on an id table if there is one *///匹配//可知//static struct i2c_driver at24_driver// .id_table = at24_ids,这个ID表是用来匹配的，和i2c client的名字进行匹配 if (driver->id_table) return i2c_match_id(driver->id_table, client) != NULL; return 0;}/////////////////////////////////////////////////i2c_bus_type的probe方法是通过传递进来的drv找到包含此drv的i2c_driver驱动，然后再去调用i2c_driver的probe方法，此处就是at24_probe。为什么要这样呢？因为driver_register后，注册的是i2c_driver->drv，而drv中的probe未初始化，我们需要调用的是i2c-driver的probe方法。static int i2c_device_probe(struct device *dev){ struct i2c_client *client = to_i2c_client(dev); struct i2c_driver *driver = to_i2c_driver(dev->driver); int status; if (!driver->probe || !driver->id_table) return -ENODEV; client->driver = driver; if (!device_can_wakeup(&client->dev)) device_init_wakeup(&client->dev, client->flags & I2C_CLIENT_WAKE); dev_dbg(dev, "probe\n"); status = driver->probe(client, i2c_match_id(driver->id_table, client)); if (status) client->driver = NULL; return status;}//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////** * i2c_add_numbered_adapter - declare i2c adapter, use static bus number * @adap: the adapter to register (with adap->nr initialized) * Context: can sleep * * This routine is used to declare an I2C adapter when its bus number * matters. For example, use it for I2C adapters from system-on-chip CPUs, * or otherwise built in to the system's mainboard, and where i2c_board_info * is used to properly configure I2C devices. * * If no devices have pre-been declared for this bus, then be sure to * register the adapter before any dynamically allocated ones. Otherwise * the required bus ID may not be available. * * When this returns zero, the specified adapter became available for * clients using the bus number provided in adap->nr. Also, the table * of I2C devices pre-declared using i2c_register_board_info() is scanned, * and the appropriate driver model device nodes are created. Otherwise, a * negative errno value is returned. *///这个函数在i2c核心层//在匹配完成后调用s3c24xx_i2c_probe函数调用i2c_add_numbered_adapter//执行完i2c_add_numbered_adapter函数后，内核的i2c总线上已有adapter device和client device//只和client匹配，不和adapter匹配，adapter和client已经关联?。 int i2c_add_numbered_adapter(struct i2c_adapter *adap){ int id; int status; if (adap->nr & ~MAX_ID_MASK) return -EINVAL;retry: if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0) return -ENOMEM; mutex_lock(&core_lock); /* "above" here means "above or equal to", sigh; * we need the "equal to" result to force the result */ status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id); if (status == 0 && id != adap->nr) { status = -EBUSY; idr_remove(&i2c_adapter_idr, id); } mutex_unlock(&core_lock); if (status == -EAGAIN) goto retry; if (status == 0)//注册adapter设备 status = i2c_register_adapter(adap); return status;}/////////////////////////////////////////////////////////////////////////////////////static int i2c_register_adapter(struct i2c_adapter *adap){ int res = 0, dummy; /* Can't register until after driver model init */ if (unlikely(WARN_ON(!i2c_bus_type.p))) return -EAGAIN; mutex_init(&adap->bus_lock); mutex_init(&adap->clist_lock); INIT_LIST_HEAD(&adap->clients); mutex_lock(&core_lock); /* Add the adapter to the driver core. * If the parent pointer is not set up, * we add this adapter to the host bus. */ if (adap->dev.parent == NULL) { adap->dev.parent = &platform_bus; pr_debug("I2C adapter driver [%s] forgot to specify " "physical device\n", adap->name); }// /sys/bus/i2c/devices/i2c-0// /sys/bus/i2c/devices/i2c-1//i2c-0 就是adapter device sprintf(adap->dev.bus_id, "i2c-%d", adap->nr); adap->dev.release = &i2c_adapter_dev_release;// 看看 driver->driver.bus = &i2c_bus_type;//struct i2c_adapter ------>绑定i2c_adapter_class//struct i2c_client（i2c_device）------>绑定i2c_bus_type//struct i2c_driver (at24.c at24_driver) ------>绑定i2c_bus_type adap->dev.class = &i2c_adapter_class;//将名为i2c-0的adapter设备注册 res = device_register(&adap->dev); /* create pre-declared device nodes for new-style drivers */ if (adap->nr i2c_scan_static_board_info(adap); /* Notify drivers *///识别一下，看看有没有///尝试和i2c总线上所有的dev进行一次匹配，只要获取的dev为adapter时，就可执行后续操作//bus_for_each_drv()是对BUS上所有的Driver都进行__device_attach()操作；//同样的，bus_for_each_dev()是对BUS上所有的Device都进行__driver_attach()操作 dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap, i2c_do_add_adapter);}//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////首先从__i2c_board_list链表上获取一个devinfo信息结构体，此结构体由前面的smdk6410_machine_init函数调用i2c_register_board_info()添加到i2c设备链表上的。结构体中包含板上的i2cat24c02设备相关信息。然后在此函数中调用i2c_new_device()以从链表上获取的devinfo作为参数，i2c_new_device函数根据devinfo中的设备相关信息来创建client，内核中使用client来代表at24c02设备。static void i2c_scan_static_board_info(struct i2c_adapter *adapter){ struct i2c_devinfo *devinfo; mutex_lock(&__i2c_board_lock);//遍历__i2c_board_list链表////static struct i2c_board_info i2c_devs0[]//smdk6410_machine_init()--->// i2c_register_board_info(0, i2c_devs0, ARRAY_SIZE(i2c_devs0)); // i2c_register_board_info(1, i2c_devs1, ARRAY_SIZE(i2c_devs1));//此处的0和1是+1后就是devinfo->busnum,也就是adapter->nr，应该就是代表第几组寄存器组吧？//i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len) list_for_each_entry(devinfo, &__i2c_board_list, list) {//// s3c24xx_i2c_probe函数 i2c->adap.nr = pdata->bus_num;//如果adapter的号码和节点中的号码相同，才会调用i2c_new_device创建i2c clien if (devinfo->busnum == adapter->nr && !i2c_new_device(adapter, &devinfo->board_info)) printk(KERN_ERR "i2c-core: can't create i2c%d-%04x\n", i2c_adapter_id(adapter), devinfo->board_info.addr); } mutex_unlock(&__i2c_board_lock);}//////////////////////////////////////////////////////////////////////////////////////** * i2c_new_device - instantiate an i2c device for use with a new style driver * @adap: the adapter managing the device * @info: describes one I2C device; bus_num is ignored * Context: can sleep * * Create a device to work with a new style i2c driver, where binding is * handled through driver model probe()/remove() methods. This call is not * appropriate for use by mainboad initialization logic, which usually runs * during an arch_initcall() long before any i2c_adapter could exist. * * This returns the new i2c client, which may be saved for later use with * i2c_unregister_device(); or NULL to indicate an error. */struct i2c_client *i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info){ struct i2c_client *client; int status; client = kzalloc(sizeof *client, GFP_KERNEL); if (!client) return NULL;//client 和adap是相互关联到一起的。 client->adapter = adap; client->dev.platform_data = info->platform_data; if (info->archdata) client->dev.archdata = *info->archdata; client->flags = info->flags;//这里是从设备地址 client->addr = info->addr; client->irq = info->irq;// i2c_board_info中的名字给了client////static struct i2c_board_info i2c_devs0[] __initdata = {// { I2C_BOARD_INFO("24c08", 0x50), }, //0x50为IIC芯片设备地址 //"24c08"这个名字就是用来创建i2c_client来和里static struct i2c_driver at24_driver进行匹配的。 strlcpy(client->name, info->type, sizeof(client->name)); /* a new style driver may be bound to this device when we * return from this function, or any later moment (e.g. maybe * hotplugging will load the driver module). and the device * refcount model is the standard driver model one. */ status = i2c_attach_client(client); if (status kfree(client); client = NULL; } return client;}/////////////////////////////////////////////////////////////////////////////////////int i2c_attach_client(struct i2c_client *client){ struct i2c_adapter *adapter = client->adapter; int res; /* Check for address business */ res = i2c_check_addr(adapter, client->addr); if (res) return res; client->dev.parent = &client->adapter->dev;//struct i2c_adapter ------>绑定i2c_adapter_class//struct i2c_client（i2c_device）------>绑定i2c_bus_type//struct i2c_driver (at24.c at24_driver) ------>绑定i2c_bus_type//client被注册到i2c_bus_type总线//static struct i2c_driver dummy_driver 这个也是注册到i2c_bus_type总线 client->dev.bus = &i2c_bus_type; if (client->driver) client->dev.driver = &client->driver->driver; if (client->driver && !is_newstyle_driver(client->driver)) { client->dev.release = i2c_client_release; client->dev.uevent_suppress = 1; } else client->dev.release = i2c_client_dev_release;///sys/bus/i2c/devices # ls // 0-001b 0-0050 i2c-0 i2c-1 i2c-2// /sys/bus/i2c/devices/0-001b// /sys/bus/i2c/devices/0-0050//0-001b就是client device snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id), "%d-%04x", i2c_adapter_id(adapter), client->addr);//注册client的父类到内核//int i2c_register_driver(struct module *owner, struct i2c_driver *driver)// driver->driver.bus = &i2c_bus_type;// res = driver_register(&driver->driver);//这么像，应该能猜到client->dev就是device->dev res = device_register(&client->dev); if (res) goto out_err; mutex_lock(&adapter->clist_lock); list_add_tail(&client->list, &adapter->clients); mutex_unlock(&adapter->clist_lock); dev_dbg(&adapter->dev, "client [%s] registered with bus id %s\n", client->name, client->dev.bus_id); if (adapter->client_register) { if (adapter->client_register(client)) { dev_dbg(&adapter->dev, "client_register " "failed for client [%s] at 0x%02x\n", client->name, client->addr); } } return 0;out_err: dev_err(&adapter->dev, "Failed to attach i2c client %s at 0x%02x " "(%d)\n", client->name, client->addr, res); return res;}///////////////////////////////////////////////////////////////////////////////////////////////static int i2c_do_add_adapter(struct device_driver *d, void *data){ struct i2c_driver *driver = to_i2c_driver(d); struct i2c_adapter *adap = data; /* Detect supported devices on that bus, and instantiate them */ i2c_detect(adap, driver); /* Let legacy drivers scan this bus for matching devices */ if (driver->attach_adapter) { /* We ignore the return code; if it fails, too bad *///调用//static struct i2c_driver i2cdev_driver = {// .attach_adapter = i2cdev_attach_adapter,//此处调用i2cdev_attach_adapter函数 driver->attach_adapter(adap); } return 0;}/////////////////////////////////////////////////////////////////////////////////////////////////和 i2c_do_add_adapter对比一下，就^_^static int __attach_adapter(struct device *dev, void *data){ struct i2c_adapter *adapter = to_i2c_adapter(dev); struct i2c_driver *driver = data; i2c_detect(adapter, driver); /* Legacy drivers scan i2c busses directly */ if (driver->attach_adapter) driver->attach_adapter(adapter); return 0;}////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////static inline int i2c_add_driver(struct i2c_driver *driver){ return i2c_register_driver(THIS_MODULE, driver);}/////////////////////////////////////////////* * An i2c_driver is used with one or more i2c_client (device) nodes to access * i2c slave chips, on a bus instance associated with some i2c_adapter. There * are two models for binding the driver to its device: "new style" drivers * follow the standard Linux driver model and just respond to probe() calls * issued if the driver core sees they match(); "legacy" drivers create device * nodes themselves. *///对比//static int i2c_register_adapter(struct i2c_adapter *adap)//这两个函数里面是何其形似，所以 i2c_register_adapter相当于 i2c_register_device,和i2c_register_driver匹配int i2c_register_driver(struct module *owner, struct i2c_driver *driver){ int res; /* Can't register until after driver model init */ if (unlikely(WARN_ON(!i2c_bus_type.p))) return -EAGAIN; /* new style driver methods can't mix with legacy ones */ if (is_newstyle_driver(driver)) { if (driver->attach_adapter || driver->detach_adapter || driver->detach_client) { printk(KERN_WARNING "i2c-core: driver [%s] is confused\n", driver->driver.name); return -EINVAL; } } /* add the driver to the list of i2c drivers in the driver core */ driver->driver.owner = owner;////int i2c_attach_client(struct i2c_client *client)// client->dev.bus = &i2c_bus_type;//client被注册到i2c_bus_type总线//static struct i2c_driver dummy_driver 这个也是注册到i2c_bus_type总线//struct i2c_adapter ------>绑定i2c_adapter_class//struct i2c_client（i2c_device）------>绑定i2c_bus_type//struct i2c_driver ------>绑定i2c_bus_type driver->driver.bus = &i2c_bus_type; //见//int i2c_attach_client(struct i2c_client *client)//---> client->dev.parent = &client->adapter->dev;// client->dev.bus = &i2c_bus_type;// res = device_register(&client->dev);//这么像，是不是必须client是device.呵呵 /* for new style drivers, when registration returns the driver core * will have called probe() for all matching-but-unbound devices. */ res = driver_register(&driver->driver); if (res) return res; mutex_lock(&core_lock); pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name); INIT_LIST_HEAD(&driver->clients); /* Walk the adapters that are already present */// i2c_register_adapter里也有一个 bus_for_each_drv class_for_each_device(&i2c_adapter_class, NULL, driver, __attach_adapter); mutex_unlock(&core_lock); return 0;}/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////** * i2c_transfer - execute a single or combined I2C message * @adap: Handle to I2C bus * @msgs: One or more messages to execute before STOP is issued to * terminate the operation; each message begins with a START. * @num: Number of messages to be executed. * * Returns negative errno, else the number of messages executed. * * Note that there is no requirement that each message be sent to * the same slave address, although that is the most common model. */ at24_eeprom_read调用i2c_transferint i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num){ int ret; /* REVISIT the fault reporting model here is weak: * * - When we get an error after receiving N bytes from a slave, * there is no way to report "N". * * - When we get a NAK after transmitting N bytes to a slave, * there is no way to report "N" ... or to let the master * continue executing the rest of this combined message, if * that's the appropriate response. * * - When for example "num" is two and we successfully complete * the first message but get an error part way through the * second, it's unclear whether that should be reported as * one (discarding status on the second message) or errno * (discarding status on the first one). */ if (adap->algo->master_xfer) {#ifdef DEBUG for (ret = 0; ret dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, " "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD) ? 'R' : 'W', msgs[ret].addr, msgs[ret].len, (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : ""); }#endif if (in_atomic() || irqs_disabled()) { ret = mutex_trylock(&adap->bus_lock); if (!ret) /* I2C activity is ongoing. */ return -EAGAIN; } else { mutex_lock_nested(&adap->bus_lock, adap->level); }//发送数据////static const struct i2c_algorithm s3c24xx_i2c_algorithm = {// .master_xfer = s3c24xx_i2c_xfer,//此处调用 s3c24xx_i2c_xfer函数 ret = adap->algo->master_xfer(adap,msgs,num); mutex_unlock(&adap->bus_lock); return ret; } else { dev_dbg(&adap->dev, "I2C level transfers not supported\n"); return -EOPNOTSUPP; }}
