i2c / ACPI: add ACPI enumeration support

ACPI 5 introduced I2cSerialBus resource that makes it possible to enumerate
and configure the I2C slave devices behind the I2C controller. This patch
adds helper functions to support I2C slave enumeration.

An ACPI enabled I2C controller driver only needs to call acpi_i2c_register_devices()
in order to get its slave devices enumerated, created and bound to the
corresponding ACPI handle.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 110 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);