Commit 689ae231 authored by Jean Delvare's avatar Jean Delvare Committed by Greg Kroah-Hartman
Browse files

platform: Add support for automatic device IDs 



Right now we have support for explicit platform device IDs, as well as
ID-less platform devices when a given device type can only have one
instance. However there are cases where multiple instances of a device
type can exist, and their IDs aren't (and can't be) known in advance
and do not matter. In that case we need automatic device IDs to avoid
device name collisions.

I am using magic ID value -2 (PLATFORM_DEVID_AUTO) for this, similar
to -1 for ID-less devices. The automatically allocated device IDs are
global (to avoid an additional per-driver cost.) We keep note that the
ID was automatically allocated so that it can be freed later.

Note that we also restore the ID to PLATFORM_DEVID_AUTO on error and
device deletion, to avoid avoid unexpected behavior on retry. I don't
really expect retries on platform device addition, but better safe
than sorry.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a525a3dd

drivers/base/platform.c

+35 −3
Original line number Diff line number Diff line
@@ -20,9 +20,13 @@ 
#include <linux/err.h>

#include <linux/slab.h>

#include <linux/pm_runtime.h>

#include <linux/idr.h>



#include "base.h"



/* For automatically allocated device IDs */

static DEFINE_IDA(platform_devid_ida);



#define to_platform_driver(drv)	(container_of((drv), struct platform_driver, \

				 driver))
@@ -263,7 +267,7 @@ EXPORT_SYMBOL_GPL(platform_device_add_data); 
 */

int platform_device_add(struct platform_device *pdev)

{

	int i, ret = 0;

	int i, ret;



	if (!pdev)

		return -EINVAL;
@@ -273,10 +277,27 @@ int platform_device_add(struct platform_device *pdev) 


	pdev->dev.bus = &platform_bus_type;



	if (pdev->id != -1)

	switch (pdev->id) {

	default:

		dev_set_name(&pdev->dev, "%s.%d", pdev->name,  pdev->id);

	else

		break;

	case PLATFORM_DEVID_NONE:

		dev_set_name(&pdev->dev, "%s", pdev->name);

		break;

	case PLATFORM_DEVID_AUTO:

		/*

		 * Automatically allocated device ID. We mark it as such so

		 * that we remember it must be freed, and we append a suffix

		 * to avoid namespace collision with explicit IDs.

		 */

		ret = ida_simple_get(&platform_devid_ida, 0, 0, GFP_KERNEL);

		if (ret < 0)

			goto err_out;

		pdev->id = ret;

		pdev->id_auto = true;

		dev_set_name(&pdev->dev, "%s.%d.auto", pdev->name, pdev->id);

		break;

	}



	for (i = 0; i < pdev->num_resources; i++) {

		struct resource *p, *r = &pdev->resource[i];
@@ -309,6 +330,11 @@ int platform_device_add(struct platform_device *pdev) 
		return ret;



 failed:

	if (pdev->id_auto) {

		ida_simple_remove(&platform_devid_ida, pdev->id);

		pdev->id = PLATFORM_DEVID_AUTO;

	}



	while (--i >= 0) {

		struct resource *r = &pdev->resource[i];

		unsigned long type = resource_type(r);
@@ -317,6 +343,7 @@ int platform_device_add(struct platform_device *pdev) 
			release_resource(r);

	}



 err_out:

	return ret;

}

EXPORT_SYMBOL_GPL(platform_device_add);
@@ -336,6 +363,11 @@ void platform_device_del(struct platform_device *pdev) 
	if (pdev) {

		device_del(&pdev->dev);



		if (pdev->id_auto) {

			ida_simple_remove(&platform_devid_ida, pdev->id);

			pdev->id = PLATFORM_DEVID_AUTO;

		}



		for (i = 0; i < pdev->num_resources; i++) {

			struct resource *r = &pdev->resource[i];

			unsigned long type = resource_type(r);

include/linux/platform_device.h

+4 −0
Original line number Diff line number Diff line
@@ -14,11 +14,15 @@ 
#include <linux/device.h>

#include <linux/mod_devicetable.h>



#define PLATFORM_DEVID_NONE	(-1)

#define PLATFORM_DEVID_AUTO	(-2)



struct mfd_cell;



struct platform_device {

	const char	* name;

	int		id;

	bool		id_auto;

	struct device	dev;

	u32		num_resources;

	struct resource	* resource;

CRA Git | Maintained and supported by SUSTech CRA and CCSE