i2c: i2c stack can probe()
One of a series of I2C infrastructure updates to support enumeration using the standard Linux driver model. This patch updates probe() and associated hotplug/coldplug support, but not remove(). Nothing yet _uses_ it to create I2C devices, so those hotplug/coldplug mechanisms will be the only externally visible change. This patch will be an overall NOP since the I2C stack doesn't yet create clients/devices except as part of binding them to legacy drivers. Some code is moved earlier in the source code, helping group more of the per-device infrastructure in one place and simplifying handling per-device attributes. Terminology being adopted: "legacy drivers" create devices (i2c_client) themselves, while "new style" ones follow the driver model (the i2c_client is handed to the probe routine). It's an either/or thing; the two models don't mix, and drivers that try mixing them won't even be registered. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
David Brownell
Jean Delvare
parent
5cedb05db3
commit
7b4fbc50fa
@ -44,15 +44,58 @@ static DEFINE_IDR(i2c_adapter_idr);
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/* ------------------------------------------------------------------------- */
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/* match always succeeds, as we want the probe() to tell if we really accept this match */
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static int i2c_device_match(struct device *dev, struct device_driver *drv)
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{
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return 1;
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struct i2c_client *client = to_i2c_client(dev);
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struct i2c_driver *driver = to_i2c_driver(drv);
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/* make legacy i2c drivers bypass driver model probing entirely;
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* such drivers scan each i2c adapter/bus themselves.
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*/
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if (!driver->probe)
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return 0;
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/* new style drivers use the same kind of driver matching policy
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* as platform devices or SPI: compare device and driver IDs.
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*/
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return strcmp(client->driver_name, drv->name) == 0;
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}
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#ifdef CONFIG_HOTPLUG
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/* uevent helps with hotplug: modprobe -q $(MODALIAS) */
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static int i2c_device_uevent(struct device *dev, char **envp, int num_envp,
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char *buffer, int buffer_size)
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{
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struct i2c_client *client = to_i2c_client(dev);
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int i = 0, length = 0;
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/* by definition, legacy drivers can't hotplug */
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if (dev->driver || !client->driver_name)
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return 0;
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if (add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
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"MODALIAS=%s", client->driver_name))
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return -ENOMEM;
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envp[i] = NULL;
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dev_dbg(dev, "uevent\n");
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return 0;
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}
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#else
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#define i2c_device_uevent NULL
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#endif /* CONFIG_HOTPLUG */
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static int i2c_device_probe(struct device *dev)
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{
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return -ENODEV;
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struct i2c_client *client = to_i2c_client(dev);
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struct i2c_driver *driver = to_i2c_driver(dev->driver);
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if (!driver->probe)
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return -ENODEV;
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client->driver = driver;
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dev_dbg(dev, "probe\n");
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return driver->probe(client);
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}
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static int i2c_device_remove(struct device *dev)
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@ -95,9 +138,38 @@ static int i2c_device_resume(struct device * dev)
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return driver->resume(to_i2c_client(dev));
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}
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static void i2c_client_release(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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complete(&client->released);
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}
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static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return sprintf(buf, "%s\n", client->name);
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}
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static ssize_t show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return client->driver_name
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? sprintf(buf, "%s\n", client->driver_name)
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: 0;
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}
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static struct device_attribute i2c_dev_attrs[] = {
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__ATTR(name, S_IRUGO, show_client_name, NULL),
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/* modalias helps coldplug: modprobe $(cat .../modalias) */
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__ATTR(modalias, S_IRUGO, show_modalias, NULL),
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{ },
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};
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struct bus_type i2c_bus_type = {
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.name = "i2c",
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.dev_attrs = i2c_dev_attrs,
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.match = i2c_device_match,
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.uevent = i2c_device_uevent,
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.probe = i2c_device_probe,
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.remove = i2c_device_remove,
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.shutdown = i2c_device_shutdown,
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@ -134,31 +206,6 @@ struct class i2c_adapter_class = {
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};
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static void i2c_client_release(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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complete(&client->released);
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}
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static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return sprintf(buf, "%s\n", client->name);
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}
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/*
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* We can't use the DEVICE_ATTR() macro here, as we used the same name for
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* an i2c adapter attribute (above).
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*/
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static struct device_attribute dev_attr_client_name =
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__ATTR(name, S_IRUGO, &show_client_name, NULL);
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/* ---------------------------------------------------
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* registering functions
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* ---------------------------------------------------
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*/
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/* -----
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* i2c_add_adapter is called from within the algorithm layer,
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* when a new hw adapter registers. A new device is register to be
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@ -208,7 +255,7 @@ int i2c_add_adapter(struct i2c_adapter *adap)
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dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
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/* inform drivers of new adapters */
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/* let legacy drivers scan this bus for matching devices */
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list_for_each(item,&drivers) {
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driver = list_entry(item, struct i2c_driver, list);
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if (driver->attach_adapter)
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@ -292,16 +339,32 @@ int i2c_del_adapter(struct i2c_adapter *adap)
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}
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/* -----
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* What follows is the "upwards" interface: commands for talking to clients,
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* which implement the functions to access the physical information of the
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* chips.
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/* ------------------------------------------------------------------------- */
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/*
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* An i2c_driver is used with one or more i2c_client (device) nodes to access
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* i2c slave chips, on a bus instance associated with some i2c_adapter. There
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* are two models for binding the driver to its device: "new style" drivers
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* follow the standard Linux driver model and just respond to probe() calls
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* issued if the driver core sees they match(); "legacy" drivers create device
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* nodes themselves.
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*/
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int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
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{
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int res;
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/* new style driver methods can't mix with legacy ones */
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if (driver->probe) {
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if (driver->attach_adapter || driver->detach_adapter
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|| driver->detach_client) {
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printk(KERN_WARNING
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"i2c-core: driver [%s] is confused\n",
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driver->driver.name);
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return -EINVAL;
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}
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}
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/* add the driver to the list of i2c drivers in the driver core */
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driver->driver.owner = owner;
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driver->driver.bus = &i2c_bus_type;
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@ -315,7 +378,7 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
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list_add_tail(&driver->list,&drivers);
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pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
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/* now look for instances of driver on our adapters */
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/* legacy drivers scan i2c busses directly */
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if (driver->attach_adapter) {
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struct i2c_adapter *adapter;
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@ -380,6 +443,8 @@ int i2c_del_driver(struct i2c_driver *driver)
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return 0;
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}
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/* ------------------------------------------------------------------------- */
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static int __i2c_check_addr(struct i2c_adapter *adapter, unsigned int addr)
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{
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struct list_head *item;
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@ -430,9 +495,6 @@ int i2c_attach_client(struct i2c_client *client)
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res = device_register(&client->dev);
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if (res)
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goto out_list;
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res = device_create_file(&client->dev, &dev_attr_client_name);
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if (res)
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goto out_unregister;
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mutex_unlock(&adapter->clist_lock);
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if (adapter->client_register) {
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@ -445,10 +507,6 @@ int i2c_attach_client(struct i2c_client *client)
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return 0;
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out_unregister:
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init_completion(&client->released); /* Needed? */
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device_unregister(&client->dev);
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wait_for_completion(&client->released);
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out_list:
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list_del(&client->list);
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dev_err(&adapter->dev, "Failed to attach i2c client %s at 0x%02x "
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@ -483,7 +541,6 @@ int i2c_detach_client(struct i2c_client *client)
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mutex_lock(&adapter->clist_lock);
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list_del(&client->list);
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init_completion(&client->released);
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device_remove_file(&client->dev, &dev_attr_client_name);
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device_unregister(&client->dev);
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mutex_unlock(&adapter->clist_lock);
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wait_for_completion(&client->released);
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@ -113,7 +113,7 @@ struct i2c_driver {
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* can be used by the driver to test if the bus meets its conditions
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* & seek for the presence of the chip(s) it supports. If found, it
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* registers the client(s) that are on the bus to the i2c admin. via
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* i2c_attach_client.
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* i2c_attach_client. (LEGACY I2C DRIVERS ONLY)
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*/
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int (*attach_adapter)(struct i2c_adapter *);
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int (*detach_adapter)(struct i2c_adapter *);
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@ -121,10 +121,16 @@ struct i2c_driver {
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/* tells the driver that a client is about to be deleted & gives it
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* the chance to remove its private data. Also, if the client struct
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* has been dynamically allocated by the driver in the function above,
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* it must be freed here.
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* it must be freed here. (LEGACY I2C DRIVERS ONLY)
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*/
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int (*detach_client)(struct i2c_client *);
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/* Standard driver model interfaces, for "new style" i2c drivers.
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* With the driver model, device enumeration is NEVER done by drivers;
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* it's done by infrastructure. (NEW STYLE DRIVERS ONLY)
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*/
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int (*probe)(struct i2c_client *);
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/* driver model interfaces that don't relate to enumeration */
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void (*shutdown)(struct i2c_client *);
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int (*suspend)(struct i2c_client *, pm_message_t mesg);
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@ -148,6 +154,8 @@ struct i2c_driver {
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* @name: Indicates the type of the device, usually a chip name that's
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* generic enough to hide second-sourcing and compatible revisions.
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* @dev: Driver model device node for the slave.
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* @driver_name: Identifies new-style driver used with this device; also
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* used as the module name for hotplug/coldplug modprobe support.
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*
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* An i2c_client identifies a single device (i.e. chip) connected to an
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* i2c bus. The behaviour is defined by the routines of the driver.
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@ -163,6 +171,7 @@ struct i2c_client {
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int usage_count; /* How many accesses currently */
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/* to the client */
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struct device dev; /* the device structure */
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char driver_name[KOBJ_NAME_LEN];
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struct list_head list;
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struct completion released;
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};
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