From 689ae231afbac8979f96100b372a5a73458baaa9 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Fri, 27 Jul 2012 22:14:59 +0200 Subject: [PATCH] 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: Jean Delvare Signed-off-by: Greg Kroah-Hartman --- drivers/base/platform.c | 38 +++++++++++++++++++++++++++++++++++--- include/linux/platform_device.h | 4 ++++ 2 files changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/base/platform.c b/drivers/base/platform.c index a1a7225..3f8077c 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -20,9 +20,13 @@ #include #include #include +#include #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); diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 60e9994..5711e95 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -14,11 +14,15 @@ #include #include +#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; -- 2.7.4