i2c: Add i2c_board_info and i2c_new_device()
This provides partial support for new-style I2C driver binding. It builds
on "struct i2c_board_info" declarations that identify I2C devices on a given
board. This is needed on systems with I2C devices that can't be fully probed
and/or autoconfigured, such as many embedded Linux configurations where the
way a given I2C device is wired may affect how it must be used.
There are two models for declaring such devices:
* LATE -- using a public function i2c_new_device(). This lets modules
declare I2C devices found *AFTER* a given I2C adapter becomes available.
For example, a PCI card could create adapters giving access to utility
chips on that card, and this would be used to associate those chips with
those adapters.
* EARLY -- from arch_initcall() level code, using a non-exported function
i2c_register_board_info(). This copies the declarations *BEFORE* such
an i2c_adapter becomes available, arranging that i2c_new_device() will
be called later when i2c-core registers the relevant i2c_adapter.
For example, arch/.../.../board-*.c files would declare the I2C devices
along with their platform data, and I2C devices would behave much like
PNPACPI devices. (That is, both enumerate from board-specific tables.)
To match the exported i2c_new_device(), the previously-private function
i2c_unregister_device() is now exported.
Pending later patches using these new APIs, this is effectively a NOP.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 6802c3a..382a43b 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -172,6 +172,7 @@
int usage_count; /* How many accesses currently */
/* to the client */
struct device dev; /* the device structure */
+ int irq; /* irq issued by device (or -1) */
char driver_name[KOBJ_NAME_LEN];
struct list_head list;
struct completion released;
@@ -193,6 +194,67 @@
dev_set_drvdata (&dev->dev, data);
}
+/**
+ * struct i2c_board_info - template for device creation
+ * @driver_name: identifies the driver to be bound to the device
+ * @type: optional chip type information, to initialize i2c_client.name
+ * @flags: to initialize i2c_client.flags
+ * @addr: stored in i2c_client.addr
+ * @platform_data: stored in i2c_client.dev.platform_data
+ * @irq: stored in i2c_client.irq
+
+ * I2C doesn't actually support hardware probing, although controllers and
+ * devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
+ * a device at a given address. Drivers commonly need more information than
+ * that, such as chip type, configuration, associated IRQ, and so on.
+ *
+ * i2c_board_info is used to build tables of information listing I2C devices
+ * that are present. This information is used to grow the driver model tree
+ * for "new style" I2C drivers. For mainboards this is done statically using
+ * i2c_register_board_info(), where @bus_num represents an adapter that isn't
+ * yet available. For add-on boards, i2c_new_device() does this dynamically
+ * with the adapter already known.
+ */
+struct i2c_board_info {
+ char driver_name[KOBJ_NAME_LEN];
+ char type[I2C_NAME_SIZE];
+ unsigned short flags;
+ unsigned short addr;
+ void *platform_data;
+ int irq;
+};
+
+/**
+ * I2C_BOARD_INFO - macro used to list an i2c device and its driver
+ * @driver: identifies the driver to use with the device
+ * @dev_addr: the device's address on the bus.
+ *
+ * This macro initializes essential fields of a struct i2c_board_info,
+ * declaring what has been provided on a particular board. Optional
+ * fields (such as the chip type, its associated irq, or device-specific
+ * platform_data) are provided using conventional syntax.
+ */
+#define I2C_BOARD_INFO(driver,dev_addr) \
+ .driver_name = (driver), .addr = (dev_addr)
+
+
+/* Add-on boards should register/unregister their devices; e.g. a board
+ * with integrated I2C, a config eeprom, sensors, and a codec that's
+ * used in conjunction with the primary hardware.
+ */
+extern struct i2c_client *
+i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);
+
+extern void i2c_unregister_device(struct i2c_client *);
+
+/* Mainboard arch_initcall() code should register all its I2C devices.
+ * This is done at arch_initcall time, before declaring any i2c adapters.
+ * Modules for add-on boards must use other calls.
+ */
+extern int
+i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned n);
+
+
/*
* The following structs are for those who like to implement new bus drivers:
* i2c_algorithm is the interface to a class of hardware solutions which can