RE: [RFC PATCH 5/6] ACPI: Introduce ACPI I2C controller enumeration driver

-----Original Message-----
From: linux-i2c-owner@vger.kernel.org [mailto:linux-i2c-
owner@vger.kernel.org] On Behalf Of Mika Westerberg
Sent: Monday, October 01, 2012 2:55 PM
To: Zhang, Rui
Cc: LKML; linux-pm; linux-i2c; linux-acpi@vger.kernel.org; Len, Brown;
Rafael J. Wysocki; Grant Likely; Dirk Brandewie
Subject: Re: [RFC PATCH 5/6] ACPI: Introduce ACPI I2C controller
enumeration driver
Importance: High

On Fri, Sep 28, 2012 at 03:40:32PM +0800, Zhang Rui wrote:

quoted

+acpi_status __init i2c_enumerate_slave(acpi_handle handle, u32 level,
+				       void *data, void **return_value) {
+	int result;
+	acpi_status status;
+	struct acpi_buffer buffer;
+	struct acpi_resource *resource;
+	struct acpi_resource_gpio *gpio;
+	struct acpi_resource_i2c_serialbus *i2c;
+	int i;
+	struct acpi_i2c_root *root = data;
+	struct i2c_board_info info;
+	struct acpi_device *device;
+
+	if (acpi_bus_get_device(handle, &device))
+		return AE_OK;
+
+	status = acpi_get_current_resources(handle, &buffer);
+	if (ACPI_FAILURE(status)) {
+		dev_err(&device->dev, "Failed to get ACPI resources\n");
+		return AE_OK;
+	}
+
+	for (i = 0; i < buffer.length; i += sizeof(struct acpi_resource))

{

quoted

+		resource = (struct acpi_resource *)(buffer.pointer + i);
+
+		switch (resource->type) {
+		case ACPI_RESOURCE_TYPE_GPIO:
+			gpio = &resource->data.gpio;
+
+			if (gpio->connection_type ==

ACPI_RESOURCE_GPIO_TYPE_INT) {

quoted

+				result =
+				    acpi_device_get_gpio_irq
+				    (gpio->resource_source.string_ptr,
+				     gpio->pin_table[0], &info.irq);

acpi_device_get_gpio_irq() is not defined in this patch series?

ACPI GPIO controller patch has already been sent out, but in ACPI mailing list only.

Also you need to do the gpio_request()/gpio_to_irq() things somewhere.
Are they handled in acpi_device_get_gpio_irq()?

Yep.
 

How about GpioIo resources?

This is not covered in this patch set, but will be in the next patch set.

quoted

+				if (result)
+					dev_err(&device->dev,
+						"Failed to get IRQ\n");
+			}
+			break;
+		case ACPI_RESOURCE_TYPE_SERIAL_BUS:
+			i2c = &resource->data.i2c_serial_bus;
+
+			info.addr = i2c->slave_address;
+			break;
+		default:
+			break;
+		}
+	}
+
+	add_slave(root, &info);
+
+	kfree(buffer.pointer);
+	return AE_OK;
+}
+
+static int __devinit acpi_i2c_root_add(struct acpi_device *device) {
+	acpi_status status;
+	struct acpi_i2c_root *root;
+	struct resource *resources;
+	int result;
+
+	if (!device->pnp.unique_id) {
+		dev_err(&device->dev,
+			"Unsupported ACPI I2C controller. No UID\n");

Where does this restriction come from? As far as I understand UID is
optional.

_UID is optional.
But it seems to be required for SPB buses that need ACPI device enumeration.
At least this is true for the ACPI 5 compatible ACPI tables I have.

Thanks,
rui