i2c: move ACPI helpers into the core

This follows what has already been done for the DeviceTree helpers. Move
the ACPI helpers from drivers/acpi/acpi_i2c.c to the I2C core and update
documentation accordingly.

This also solves a problem reported by Jerry Snitselaar that we can't build
the ACPI I2C helpers as a module.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 91 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index e874b052b4f8..29d3f045a2bf 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1058,6 +1058,96 @@ EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
 static void of_i2c_register_devices(struct i2c_adapter *adap) { }
 #endif /* CONFIG_OF */
 
+/* ACPI support code */
+
+#if IS_ENABLED(CONFIG_ACPI)
+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
+ * @adap: 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.
+ */
+static void acpi_i2c_register_devices(struct i2c_adapter *adap)
+{
+        acpi_handle handle;
+        acpi_status status;
+
+        handle = ACPI_HANDLE(adap->dev.parent);
+        if (!handle)
+                return;
+
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+                                     acpi_i2c_add_device, NULL,
+                                     adap, NULL);
+        if (ACPI_FAILURE(status))
+                dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
+}
+#else
+static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) {}
+#endif /* CONFIG_ACPI */
+
 static int i2c_do_add_adapter(struct i2c_driver *driver,
                               struct i2c_adapter *adap)
 {
@@ -1163,6 +1253,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 exit_recovery:
         /* create pre-declared device nodes */
         of_i2c_register_devices(adap);
+        acpi_i2c_register_devices(adap);
 
         if (adap->nr < __i2c_first_dynamic_bus_num)
                 i2c_scan_static_board_info(adap);