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>

1 files changed, 11 insertions, 2 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 563c9651dd37..8dcccc0f4822 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -113,7 +113,7 @@ struct i2c_driver {
          * can be used by the driver to test if the bus meets its conditions
          * & seek for the presence of the chip(s) it supports. If found, it
          * registers the client(s) that are on the bus to the i2c admin. via
-         * i2c_attach_client.
+         * i2c_attach_client.  (LEGACY I2C DRIVERS ONLY)
          */
         int (*attach_adapter)(struct i2c_adapter *);
         int (*detach_adapter)(struct i2c_adapter *);
@@ -121,10 +121,16 @@ struct i2c_driver {
         /* tells the driver that a client is about to be deleted & gives it
          * the chance to remove its private data. Also, if the client struct
          * has been dynamically allocated by the driver in the function above,
-         * it must be freed here.
+         * it must be freed here.  (LEGACY I2C DRIVERS ONLY)
          */
         int (*detach_client)(struct i2c_client *);
 
+        /* Standard driver model interfaces, for "new style" i2c drivers.
+         * With the driver model, device enumeration is NEVER done by drivers;
+         * it's done by infrastructure.  (NEW STYLE DRIVERS ONLY)
+         */
+        int (*probe)(struct i2c_client *);
+
         /* driver model interfaces that don't relate to enumeration  */
         void (*shutdown)(struct i2c_client *);
         int (*suspend)(struct i2c_client *, pm_message_t mesg);
@@ -148,6 +154,8 @@ struct i2c_driver {
  * @name: Indicates the type of the device, usually a chip name that's
  *      generic enough to hide second-sourcing and compatible revisions.
  * @dev: Driver model device node for the slave.
+ * @driver_name: Identifies new-style driver used with this device; also
+ *      used as the module name for hotplug/coldplug modprobe support.
  *
  * An i2c_client identifies a single device (i.e. chip) connected to an
  * i2c bus. The behaviour is defined by the routines of the driver.
@@ -163,6 +171,7 @@ struct i2c_client {
         int usage_count;                /* How many accesses currently  */
                                         /* to the client                */
         struct device dev;              /* the device structure         */
+        char driver_name[KOBJ_NAME_LEN];
         struct list_head list;
         struct completion released;
 };