[PATCH v2 3/3] i2c / ACPI: add ACPI enumeration support

[Mika Westerberg]

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@xxxxxxxxxxxxxxx>
---
 drivers/acpi/Kconfig     |    6 ++
 drivers/acpi/Makefile    |    1 +
 drivers/acpi/acpi_i2c.c  |  212 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/i2c/i2c-core.c   |   10 +++
 include/linux/acpi_i2c.h |   27 ++++++
 5 files changed, 256 insertions(+)
 create mode 100644 drivers/acpi/acpi_i2c.c
 create mode 100644 include/linux/acpi_i2c.h

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 119d58d..0300bf6 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 7289828..2a4502b 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -70,6 +70,7 @@ 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 0000000..5bf2dad
--- /dev/null
+++ b/drivers/acpi/acpi_i2c.c
@@ -0,0 +1,212 @@
+/*
+ * ACPI I2C enumeration support
+ *
+ * Copyright (C) 2012, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
+ *
+ * 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/err.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 acpi_resource_i2c_serialbus *sb;
+	struct i2c_board_info *info = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return 0;
+
+	sb = &ares->data.i2c_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
+		return 0;
+
+	info->addr = sb->slave_address;
+	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
+		info->flags |= I2C_CLIENT_TEN;
+
+	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 resource_list_entry *rentry;
+	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));
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_i2c_add_resource, &info);
+	if (ret < 0)
+		return AE_OK;
+
+	list_for_each_entry(rentry, &resource_list, node) {
+		struct resource *r = &rentry->res;
+
+		if (resource_type(r) == IORESOURCE_IRQ) {
+			info.irq = r->start;
+			break;
+		}
+	}
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (!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 = adapter->dev.acpi_handle;
+	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);
+
+struct acpi_i2c_find {
+	acpi_handle handle;
+	u16 addr;
+	bool found;
+};
+
+static int acpi_i2c_find_child_address(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_i2c_serialbus *sb;
+	struct acpi_i2c_find *i2c_find = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return 1;
+
+	sb = &ares->data.i2c_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
+		return 1;
+
+	if (sb->slave_address == i2c_find->addr)
+		i2c_find->found = true;
+
+	return 1;
+}
+
+static acpi_status acpi_i2c_find_child(acpi_handle handle, u32 level,
+				       void *data, void **return_value)
+{
+	struct acpi_i2c_find *i2c_find = data;
+	struct list_head resource_list;
+	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;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_i2c_find_child_address, i2c_find);
+	if (ret < 0)
+		return AE_OK;
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (i2c_find->found) {
+		i2c_find->handle = handle;
+		return AE_CTRL_TERMINATE;
+	}
+	return AE_OK;
+}
+
+static int acpi_i2c_find_device(struct device *dev, acpi_handle *handle)
+{
+	struct acpi_i2c_find i2c_find;
+	struct i2c_adapter *adapter;
+	struct i2c_client *client;
+	acpi_handle parent;
+	acpi_status status;
+
+	client = i2c_verify_client(dev);
+	if (!client)
+		return -ENODEV;
+
+	adapter = client->adapter;
+	if (!adapter)
+		return -ENODEV;
+
+	parent = adapter->dev.acpi_handle;
+	if (!parent)
+		return -ENODEV;
+
+	memset(&i2c_find, 0, sizeof(i2c_find));
+	i2c_find.addr = client->addr;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1,
+				     acpi_i2c_find_child, NULL,
+				     &i2c_find, NULL);
+	if (ACPI_FAILURE(status) || !i2c_find.handle)
+		return -ENODEV;
+
+	*handle = i2c_find.handle;
+	return 0;
+}
+
+static struct acpi_bus_type acpi_i2c_bus = {
+	.bus = &i2c_bus_type,
+	.find_device = acpi_i2c_find_device,
+};
+
+void acpi_i2c_bus_register(void)
+{
+	register_acpi_bus_type(&acpi_i2c_bus);
+}
+EXPORT_SYMBOL_GPL(acpi_i2c_bus_register);
+
+void acpi_i2c_bus_unregister(void)
+{
+	unregister_acpi_bus_type(&acpi_i2c_bus);
+}
+EXPORT_SYMBOL_GPL(acpi_i2c_bus_unregister);
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index a7edf98..7385de2f 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -39,6 +39,8 @@
 #include <linux/irqflags.h>
 #include <linux/rwsem.h>
 #include <linux/pm_runtime.h>
+#include <linux/acpi.h>
+#include <linux/acpi_i2c.h>
 #include <asm/uaccess.h>
 
 #include "i2c-core.h"
@@ -78,6 +80,10 @@ 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)
@@ -1298,6 +1304,8 @@ static int __init i2c_init(void)
 	retval = i2c_add_driver(&dummy_driver);
 	if (retval)
 		goto class_err;
+
+	acpi_i2c_bus_register();
 	return 0;
 
 class_err:
@@ -1311,6 +1319,8 @@ bus_err:
 
 static void __exit i2c_exit(void)
 {
+	acpi_i2c_bus_unregister();
+
 	i2c_del_driver(&dummy_driver);
 #ifdef CONFIG_I2C_COMPAT
 	class_compat_unregister(i2c_adapter_compat_class);
diff --git a/include/linux/acpi_i2c.h b/include/linux/acpi_i2c.h
new file mode 100644
index 0000000..cf2233f
--- /dev/null
+++ b/include/linux/acpi_i2c.h
@@ -0,0 +1,27 @@
+/*
+ * ACPI I2C enumeration support
+ *
+ * Copyright (C) 2012, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
+ *
+ * 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.
+ */
+
+#ifndef LINUX_ACPI_I2C_H
+#define LINUX_ACPI_I2C_H
+
+struct i2c_adapter;
+
+#if IS_ENABLED(CONFIG_ACPI_I2C)
+extern void acpi_i2c_register_devices(struct i2c_adapter *adap);
+extern void acpi_i2c_bus_register(void);
+extern void acpi_i2c_bus_unregister(void);
+#else
+static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) {}
+static inline void acpi_i2c_bus_register(void) {}
+static inline void acpi_i2c_bus_unregister(void) {}
+#endif /* IS_ENABLED(CONFIG_ACPI_I2C) */
+
+#endif /* LINUX_ACPI_I2C_H */
-- 
1.7.10.4

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