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>

5 files changed, 213 insertions, 4 deletions

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 11935f66fcd8..74c8518b69e7 100644
--- a/drivers/i2c/Kconfig
+++ b/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
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 71c5a854ac5d..ba26e6cbe74e 100644
--- a/drivers/i2c/Makefile
+++ b/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/
diff --git a/drivers/i2c/i2c-boardinfo.c b/drivers/i2c/i2c-boardinfo.c
new file mode 100644
index 000000000000..ffb35f09df03
--- /dev/null
+++ b/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;
+}
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3aac1b5c7cbd..a7dcdc69b9e7 100644
--- a/drivers/i2c/i2c-core.c
+++ b/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);
diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h
new file mode 100644
index 000000000000..cd5bff874855
--- /dev/null
+++ b/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;
+