linux-kernel - Re: [RFC PATCH 5/6] ACPI: Introduce ACPI I2C controller enumeration driver

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Date:	Tue, 2 Oct 2012 09:12:53 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	"Zhang, Rui" <rui.zhang@...el.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-pm <linux-pm@...ts.linux-foundation.org>,
	linux-i2c <linux-i2c@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Len, Brown" <lenb@...nel.org>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Grant Likely <grant.likely@...retlab.ca>,
	Dirk Brandewie <dirk.brandewie@...il.com>
Subject: Re: [RFC PATCH 5/6] ACPI: Introduce ACPI I2C controller enumeration
 driver

On Mon, Oct 01, 2012 at 02:19:49PM +0000, Zhang, Rui wrote:
> 
> 
> > -----Original Message-----
> > From: linux-i2c-owner@...r.kernel.org [mailto:linux-i2c-
> > owner@...r.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@...r.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:
> > > +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))
> > {
> > > +		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) {
> > > +				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.

It would have been good idea to mention this in the cover letter at least.

> 
> > 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.
> 
> > > +				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.

Yes but if some vendor is not setting it (as it is optional) you still want
your code to work, right?
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