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>

drivers/Makefile

@@ -58,7 +58,7 @@ obj-$(CONFIG_GAMEPORT)		+= input/gameport/
 obj-$(CONFIG_INPUT)		+= input/
 obj-$(CONFIG_I2O)		+= message/
 obj-$(CONFIG_RTC_LIB)		+= rtc/
-obj-$(CONFIG_I2C)		+= i2c/
+obj-y				+= i2c/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_HWMON)		+= hwmon/
 obj-$(CONFIG_PHONE)		+= telephony/

drivers/i2c/Kconfig

@@ -22,6 +22,11 @@ config I2C
 	  This I2C support can also be built as a module.  If so, the module
 	  will be called i2c-core.
 
+config I2C_BOARDINFO
+	boolean
+	depends on I2C
+	default y
+
 config I2C_CHARDEV
 	tristate "I2C device interface"
 	depends on I2C

drivers/i2c/Makefile

@@ -2,6 +2,7 @@
 # Makefile for the i2c core.
 #
 
+obj-$(CONFIG_I2C_BOARDINFO)	+= i2c-boardinfo.o
 obj-$(CONFIG_I2C)		+= i2c-core.o
 obj-$(CONFIG_I2C_CHARDEV)	+= i2c-dev.o
 obj-y				+= busses/ chips/ algos/

drivers/i2c/i2c-boardinfo.c

@@ -0,0 +1,90 @@
+/*
+ * i2c-boardinfo.h - collect pre-declarations of I2C devices
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+
+#include "i2c-core.h"
+
+
+/* These symbols are exported ONLY FOR the i2c core.
+ * No other users will be supported.
+ */
+DEFINE_MUTEX(__i2c_board_lock);
+EXPORT_SYMBOL_GPL(__i2c_board_lock);
+
+LIST_HEAD(__i2c_board_list);
+EXPORT_SYMBOL_GPL(__i2c_board_list);
+
+int __i2c_first_dynamic_bus_num;
+EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
+
+
+/**
+ * i2c_register_board_info - statically declare I2C devices
+ * @busnum: identifies the bus to which these devices belong
+ * @info: vector of i2c device descriptors
+ * @len: how many descriptors in the vector; may be zero to reserve
+ *	the specified bus number.
+ *
+ * Systems using the Linux I2C driver stack can declare tables of board info
+ * while they initialize.  This should be done in board-specific init code
+ * near arch_initcall() time, or equivalent, before any I2C adapter driver is
+ * registered.  For example, mainboard init code could define several devices,
+ * as could the init code for each daughtercard in a board stack.
+ *
+ * The I2C devices will be created later, after the adapter for the relevant
+ * bus has been registered.  After that moment, standard driver model tools
+ * are used to bind "new style" I2C drivers to the devices.  The bus number
+ * for any device declared using this routine is not available for dynamic
+ * allocation.
+ *
+ * The board info passed can safely be __initdata, but be careful of embedded
+ * pointers (for platform_data, functions, etc) since that won't be copied.
+ */
+int __init
+i2c_register_board_info(int busnum,
+	struct i2c_board_info const *info, unsigned len)
+{
+	int status;
+
+	mutex_lock(&__i2c_board_lock);
+
+	/* dynamic bus numbers will be assigned after the last static one */
+	if (busnum >= __i2c_first_dynamic_bus_num)
+		__i2c_first_dynamic_bus_num = busnum + 1;
+
+	for (status = 0; len; len--, info++) {
+		struct i2c_devinfo	*devinfo;
+
+		devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
+		if (!devinfo) {
+			pr_debug("i2c-core: can't register boardinfo!\n");
+			status = -ENOMEM;
+			break;
+		}
+
+		devinfo->busnum = busnum;
+		devinfo->board_info = *info;
+		list_add_tail(&devinfo->list, &__i2c_board_list);
+	}
+
+	mutex_unlock(&__i2c_board_lock);
+
+	return status;
+}

drivers/i2c/i2c-core.c

@@ -35,6 +35,8 @@
 #include <linux/completion.h>
 #include <asm/uaccess.h>
 
+#include "i2c-core.h"
+
 
 static LIST_HEAD(adapters);
 static LIST_HEAD(drivers);
@@ -162,6 +164,11 @@ static void i2c_client_release(struct device *dev)
 	complete(&client->released);
 }
 
+static void i2c_client_dev_release(struct device *dev)
+{
+	kfree(to_i2c_client(dev));
+}
+
 static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
@@ -195,7 +202,60 @@ struct bus_type i2c_bus_type = {
 	.resume		= i2c_device_resume,
 };
 
-static void i2c_unregister_device(struct i2c_client *client)
+/**
+ * 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
+ *
+ * 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->adapter = adap;
+
+	client->dev.platform_data = info->platform_data;
+	client->flags = info->flags;
+	client->addr = info->addr;
+	client->irq = info->irq;
+
+	strlcpy(client->driver_name, info->driver_name,
+		sizeof(client->driver_name));
+	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 < 0) {
+		kfree(client);
+		client = NULL;
+	}
+	return client;
+}
+EXPORT_SYMBOL_GPL(i2c_new_device);
+
+
+/**
+ * i2c_unregister_device - reverse effect of i2c_new_device()
+ * @client: value returned from i2c_new_device()
+ */
+void i2c_unregister_device(struct i2c_client *client)
 {
 	struct i2c_adapter	*adapter = client->adapter;
 	struct i2c_driver	*driver = client->driver;
@@ -213,6 +273,7 @@ static void i2c_unregister_device(struct i2c_client *client)
 
 	device_unregister(&client->dev);
 }
+EXPORT_SYMBOL_GPL(i2c_unregister_device);
 
 
 /* ------------------------------------------------------------------------- */
@@ -243,6 +304,22 @@ struct class i2c_adapter_class = {
 	.dev_attrs		= i2c_adapter_attrs,
 };
 
+static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
+{
+	struct i2c_devinfo	*devinfo;
+
+	mutex_lock(&__i2c_board_lock);
+	list_for_each_entry(devinfo, &__i2c_board_list, list) {
+		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_add_adapter is called from within the algorithm layer,
@@ -311,7 +388,6 @@ out_list:
 	goto out_unlock;
 }
 
-
 int i2c_del_adapter(struct i2c_adapter *adap)
 {
 	struct list_head  *item, *_n;
@@ -541,9 +617,15 @@ int i2c_attach_client(struct i2c_client *client)
 	client->usage_count = 0;
 
 	client->dev.parent = &client->adapter->dev;
-	client->dev.driver = &client->driver->driver;
 	client->dev.bus = &i2c_bus_type;
-	client->dev.release = &i2c_client_release;
+
+	if (client->driver)
+		client->dev.driver = &client->driver->driver;
+
+	if (client->driver && !is_newstyle_driver(client->driver))
+		client->dev.release = i2c_client_release;
+	else
+		client->dev.release = i2c_client_dev_release;
 
 	snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id),
 		"%d-%04x", i2c_adapter_id(adapter), client->addr);

drivers/i2c/i2c-core.h

@@ -0,0 +1,31 @@
+/*
+ * i2c-core.h - interfaces internal to the I2C framework
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+struct i2c_devinfo {
+	struct list_head	list;
+	int			busnum;
+	struct i2c_board_info	board_info;
+};
+
+/* board_lock protects board_list and first_dynamic_bus_num.
+ * only i2c core components are allowed to use these symbols.
+ */
+extern struct mutex	__i2c_board_lock;
+extern struct list_head	__i2c_board_list;
+extern int		__i2c_first_dynamic_bus_num;
+

include/linux/i2c.h

@@ -172,6 +172,7 @@ struct i2c_client {
 	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 @@ static inline void i2c_set_clientdata (struct i2c_client *dev, void *data)
 	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