5 files changed, 125 insertions, 0 deletions

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 119d58db8342..0300bf612946 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -181,6 +181,12 @@ config ACPI_DOCK
           This driver supports ACPI-controlled docking stations and removable
           drive bays such as the IBM Ultrabay and the Dell Module Bay.
 
+config ACPI_I2C
+        def_tristate I2C
+        depends on I2C
+        help
+          ACPI I2C enumeration support.
+
 config ACPI_PROCESSOR
         tristate "Processor"
         select THERMAL
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 3223edfb23b6..7198b6d6b763 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_ACPI_HED)		+= hed.o
 obj-$(CONFIG_ACPI_EC_DEBUGFS)   += ec_sys.o
 obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
 obj-$(CONFIG_ACPI_BGRT)         += bgrt.o
+obj-$(CONFIG_ACPI_I2C)          += acpi_i2c.o
 
 # processor has its own "processor." module_param namespace
 processor-y                     := processor_driver.o processor_throttling.o
diff --git a/drivers/acpi/acpi_i2c.c b/drivers/acpi/acpi_i2c.c
new file mode 100644
index 000000000000..82045e3f5cac
--- /dev/null
+++ b/drivers/acpi/acpi_i2c.c
@@ -0,0 +1,103 @@
+/*
+ * ACPI I2C enumeration support
+ *
+ * Copyright (C) 2012, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/i2c.h>
+#include <linux/ioport.h>
+
+ACPI_MODULE_NAME("i2c");
+
+static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
+{
+        struct i2c_board_info *info = data;
+
+        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+                struct acpi_resource_i2c_serialbus *sb;
+
+                sb = &ares->data.i2c_serial_bus;
+                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+                        info->addr = sb->slave_address;
+                        if (sb->access_mode == ACPI_I2C_10BIT_MODE)
+                                info->flags |= I2C_CLIENT_TEN;
+                }
+        } else if (info->irq < 0) {
+                struct resource r;
+
+                if (acpi_dev_resource_interrupt(ares, 0, &r))
+                        info->irq = r.start;
+        }
+
+        /* Tell the ACPI core to skip this resource */
+        return 1;
+}
+
+static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
+                                       void *data, void **return_value)
+{
+        struct i2c_adapter *adapter = data;
+        struct list_head resource_list;
+        struct i2c_board_info info;
+        struct acpi_device *adev;
+        int ret;
+
+        if (acpi_bus_get_device(handle, &adev))
+                return AE_OK;
+        if (acpi_bus_get_status(adev) || !adev->status.present)
+                return AE_OK;
+
+        memset(&info, 0, sizeof(info));
+        info.acpi_node.handle = handle;
+        info.irq = -1;
+
+        INIT_LIST_HEAD(&resource_list);
+        ret = acpi_dev_get_resources(adev, &resource_list,
+                                     acpi_i2c_add_resource, &info);
+        acpi_dev_free_resource_list(&resource_list);
+
+        if (ret < 0 || !info.addr)
+                return AE_OK;
+
+        strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
+        if (!i2c_new_device(adapter, &info)) {
+                dev_err(&adapter->dev,
+                        "failed to add I2C device %s from ACPI\n",
+                        dev_name(&adev->dev));
+        }
+
+        return AE_OK;
+}
+
+/**
+ * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
+ * @adapter: pointer to adapter
+ *
+ * Enumerate all I2C slave devices behind this adapter by walking the ACPI
+ * namespace. When a device is found it will be added to the Linux device
+ * model and bound to the corresponding ACPI handle.
+ */
+void acpi_i2c_register_devices(struct i2c_adapter *adapter)
+{
+        acpi_handle handle;
+        acpi_status status;
+
+        handle = ACPI_HANDLE(&adapter->dev);
+        if (!handle)
+                return;
+
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+                                     acpi_i2c_add_device, NULL,
+                                     adapter, NULL);
+        if (ACPI_FAILURE(status))
+                dev_warn(&adapter->dev, "failed to enumerate I2C slaves\n");
+}
+EXPORT_SYMBOL_GPL(acpi_i2c_register_devices);
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index a7edf987a339..e388590b44ab 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -39,6 +39,7 @@
 #include <linux/irqflags.h>
 #include <linux/rwsem.h>
 #include <linux/pm_runtime.h>
+#include <linux/acpi.h>
 #include <asm/uaccess.h>
 
 #include "i2c-core.h"
@@ -78,6 +79,10 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
         if (of_driver_match_device(dev, drv))
                 return 1;
 
+        /* Then ACPI style match */
+        if (acpi_driver_match_device(dev, drv))
+                return 1;
+
         driver = to_i2c_driver(drv);
         /* match on an id table if there is one */
         if (driver->id_table)
@@ -539,6 +544,7 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
         client->dev.bus = &i2c_bus_type;
         client->dev.type = &i2c_client_type;
         client->dev.of_node = info->of_node;
+        ACPI_HANDLE_SET(&client->dev, info->acpi_node.handle);
 
         /* For 10-bit clients, add an arbitrary offset to avoid collisions */
         dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 800de224336b..d0c4db7b4872 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -259,6 +259,7 @@ static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
  * @platform_data: stored in i2c_client.dev.platform_data
  * @archdata: copied into i2c_client.dev.archdata
  * @of_node: pointer to OpenFirmware device node
+ * @acpi_node: ACPI device node
  * @irq: stored in i2c_client.irq
  *
  * I2C doesn't actually support hardware probing, although controllers and
@@ -279,6 +280,7 @@ struct i2c_board_info {
         void            *platform_data;
         struct dev_archdata     *archdata;
         struct device_node *of_node;
+        struct acpi_dev_node acpi_node;
         int             irq;
 };
 
@@ -501,4 +503,11 @@ static inline int i2c_adapter_id(struct i2c_adapter *adap)
                         i2c_del_driver)
 
 #endif /* I2C */
+
+#if IS_ENABLED(CONFIG_ACPI_I2C)
+extern void acpi_i2c_register_devices(struct i2c_adapter *adap);
+#else
+static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) {}
+#endif
+
 #endif /* _LINUX_I2C_H */