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>
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index fd921ce..a2ad83a 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -44,15 +44,58 @@
/* ------------------------------------------------------------------------- */
-/* match always succeeds, as we want the probe() to tell if we really accept this match */
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
- return 1;
+ 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 (!driver->probe)
+ return 0;
+
+ /* new style drivers use the same kind of driver matching policy
+ * as platform devices or SPI: compare device and driver IDs.
+ */
+ return strcmp(client->driver_name, drv->name) == 0;
}
+#ifdef CONFIG_HOTPLUG
+
+/* uevent helps with hotplug: modprobe -q $(MODALIAS) */
+static int i2c_device_uevent(struct device *dev, char **envp, int num_envp,
+ char *buffer, int buffer_size)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ int i = 0, length = 0;
+
+ /* by definition, legacy drivers can't hotplug */
+ if (dev->driver || !client->driver_name)
+ return 0;
+
+ if (add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
+ "MODALIAS=%s", client->driver_name))
+ return -ENOMEM;
+ envp[i] = NULL;
+ dev_dbg(dev, "uevent\n");
+ return 0;
+}
+
+#else
+#define i2c_device_uevent NULL
+#endif /* CONFIG_HOTPLUG */
+
static int i2c_device_probe(struct device *dev)
{
- return -ENODEV;
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_driver *driver = to_i2c_driver(dev->driver);
+
+ if (!driver->probe)
+ return -ENODEV;
+ client->driver = driver;
+ dev_dbg(dev, "probe\n");
+ return driver->probe(client);
}
static int i2c_device_remove(struct device *dev)
@@ -95,9 +138,38 @@
return driver->resume(to_i2c_client(dev));
}
+static void i2c_client_release(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ complete(&client->released);
+}
+
+static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ return sprintf(buf, "%s\n", client->name);
+}
+
+static ssize_t show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ return client->driver_name
+ ? sprintf(buf, "%s\n", client->driver_name)
+ : 0;
+}
+
+static struct device_attribute i2c_dev_attrs[] = {
+ __ATTR(name, S_IRUGO, show_client_name, NULL),
+ /* modalias helps coldplug: modprobe $(cat .../modalias) */
+ __ATTR(modalias, S_IRUGO, show_modalias, NULL),
+ { },
+};
+
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,
@@ -134,31 +206,6 @@
};
-static void i2c_client_release(struct device *dev)
-{
- struct i2c_client *client = to_i2c_client(dev);
- complete(&client->released);
-}
-
-static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
-{
- struct i2c_client *client = to_i2c_client(dev);
- return sprintf(buf, "%s\n", client->name);
-}
-
-/*
- * We can't use the DEVICE_ATTR() macro here, as we used the same name for
- * an i2c adapter attribute (above).
- */
-static struct device_attribute dev_attr_client_name =
- __ATTR(name, S_IRUGO, &show_client_name, NULL);
-
-
-/* ---------------------------------------------------
- * registering functions
- * ---------------------------------------------------
- */
-
/* -----
* i2c_add_adapter is called from within the algorithm layer,
* when a new hw adapter registers. A new device is register to be
@@ -208,7 +255,7 @@
dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
- /* inform drivers of new adapters */
+ /* let legacy drivers scan this bus for matching devices */
list_for_each(item,&drivers) {
driver = list_entry(item, struct i2c_driver, list);
if (driver->attach_adapter)
@@ -292,16 +339,32 @@
}
-/* -----
- * What follows is the "upwards" interface: commands for talking to clients,
- * which implement the functions to access the physical information of the
- * chips.
+/* ------------------------------------------------------------------------- */
+
+/*
+ * 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.
*/
int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
{
int res;
+ /* new style driver methods can't mix with legacy ones */
+ if (driver->probe) {
+ 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;
driver->driver.bus = &i2c_bus_type;
@@ -315,7 +378,7 @@
list_add_tail(&driver->list,&drivers);
pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
- /* now look for instances of driver on our adapters */
+ /* legacy drivers scan i2c busses directly */
if (driver->attach_adapter) {
struct i2c_adapter *adapter;
@@ -380,6 +443,8 @@
return 0;
}
+/* ------------------------------------------------------------------------- */
+
static int __i2c_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
struct list_head *item;
@@ -430,9 +495,6 @@
res = device_register(&client->dev);
if (res)
goto out_list;
- res = device_create_file(&client->dev, &dev_attr_client_name);
- if (res)
- goto out_unregister;
mutex_unlock(&adapter->clist_lock);
if (adapter->client_register) {
@@ -445,10 +507,6 @@
return 0;
-out_unregister:
- init_completion(&client->released); /* Needed? */
- device_unregister(&client->dev);
- wait_for_completion(&client->released);
out_list:
list_del(&client->list);
dev_err(&adapter->dev, "Failed to attach i2c client %s at 0x%02x "
@@ -483,7 +541,6 @@
mutex_lock(&adapter->clist_lock);
list_del(&client->list);
init_completion(&client->released);
- device_remove_file(&client->dev, &dev_attr_client_name);
device_unregister(&client->dev);
mutex_unlock(&adapter->clist_lock);
wait_for_completion(&client->released);