devres: introduce Devres (Managed Device Resource) framework

In U-Boot's driver model, memory is basically allocated and freed
in the core framework.  So, low level drivers generally only have
to specify the size of needed memory with .priv_auto_alloc_size,
.platdata_auto_alloc_size, etc.  Nevertheless, some drivers still
need to allocate/free memory on their own in case they cannot
statically know the necessary memory size.  So, I believe it is
reasonable enough to port Devres into U-boot.

Devres, which originates in Linux, manages device resources for each
device and automatically releases them on driver detach.  With devres,
device resources are guaranteed to be freed whether initialization
fails half-way or the device gets detached.

The basic idea is totally the same to that of Linux, but I tweaked
it a bit so that it fits in U-Boot's driver model.

In U-Boot, drivers are activated in two steps: binding and probing.
Binding puts a driver and a device together.  It is just data
manipulation on the system memory, so nothing has happened on the
hardware device at this moment.  When the device is really used, it
is probed.  Probing initializes the real hardware device to make it
really ready for use.

So, the resources acquired during the probing process must be freed
when the device is removed.  Likewise, what has been allocated in
binding should be released when the device is unbound.  The struct
devres has a member "probe" to remember when the resource was
allocated.

CONFIG_DEBUG_DEVRES is also supported for easier debugging.
If enabled, debug messages are printed each time a resource is
allocated/freed.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>

2 files changed, 159 insertions, 0 deletions

diff --git a/include/dm/device-internal.h b/include/dm/device-internal.h
index 1a9ba01b3b..a2bf0579ff 100644
--- a/include/dm/device-internal.h
+++ b/include/dm/device-internal.h
@@ -155,4 +155,23 @@ fdt_addr_t simple_bus_translate(struct udevice *dev, fdt_addr_t addr);
 #define DM_ROOT_NON_CONST		(((gd_t *)gd)->dm_root)
 #define DM_UCLASS_ROOT_NON_CONST	(((gd_t *)gd)->uclass_root)
 
+/* device resource management */
+/**
+ * devres_release_probe - Release managed resources allocated after probing
+ * @dev: Device to release resources for
+ *
+ * Release all resources allocated for @dev when it was probed or later.
+ * This function is called on driver removal.
+ */
+void devres_release_probe(struct udevice *dev);
+
+/**
+ * devres_release_all - Release all managed resources
+ * @dev: Device to release resources for
+ *
+ * Release all resources associated with @dev.  This function is
+ * called on driver unbinding.
+ */
+void devres_release_all(struct udevice *dev);
+
 #endif
diff --git a/include/dm/device.h b/include/dm/device.h
index 4cd7ba3386..85513e10ee 100644
--- a/include/dm/device.h
+++ b/include/dm/device.h
@@ -96,6 +96,7 @@ struct udevice {
 	uint32_t flags;
 	int req_seq;
 	int seq;
+	struct list_head devres_head;
 };
 
 /* Maximum sequence number supported */
@@ -465,4 +466,143 @@ bool device_has_active_children(struct udevice *dev);
  */
 bool device_is_last_sibling(struct udevice *dev);
 
+/* device resource management */
+typedef void (*dr_release_t)(struct udevice *dev, void *res);
+typedef int (*dr_match_t)(struct udevice *dev, void *res, void *match_data);
+
+#ifdef CONFIG_DEBUG_DEVRES
+void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
+		     const char *name);
+#define _devres_alloc(release, size, gfp) \
+	__devres_alloc(release, size, gfp, #release)
+#else
+void *_devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
+#endif
+
+/**
+ * devres_alloc - Allocate device resource data
+ * @release: Release function devres will be associated with
+ * @size: Allocation size
+ * @gfp: Allocation flags
+ *
+ * Allocate devres of @size bytes.  The allocated area is associated
+ * with @release.  The returned pointer can be passed to
+ * other devres_*() functions.
+ *
+ * RETURNS:
+ * Pointer to allocated devres on success, NULL on failure.
+ */
+#define devres_alloc(release, size, gfp) \
+	_devres_alloc(release, size, gfp | __GFP_ZERO)
+
+/**
+ * devres_free - Free device resource data
+ * @res: Pointer to devres data to free
+ *
+ * Free devres created with devres_alloc().
+ */
+void devres_free(void *res);
+
+/**
+ * devres_add - Register device resource
+ * @dev: Device to add resource to
+ * @res: Resource to register
+ *
+ * Register devres @res to @dev.  @res should have been allocated
+ * using devres_alloc().  On driver detach, the associated release
+ * function will be invoked and devres will be freed automatically.
+ */
+void devres_add(struct udevice *dev, void *res);
+
+/**
+ * devres_find - Find device resource
+ * @dev: Device to lookup resource from
+ * @release: Look for resources associated with this release function
+ * @match: Match function (optional)
+ * @match_data: Data for the match function
+ *
+ * Find the latest devres of @dev which is associated with @release
+ * and for which @match returns 1.  If @match is NULL, it's considered
+ * to match all.
+ *
+ * RETURNS:
+ * Pointer to found devres, NULL if not found.
+ */
+void *devres_find(struct udevice *dev, dr_release_t release,
+		  dr_match_t match, void *match_data);
+
+/**
+ * devres_get - Find devres, if non-existent, add one atomically
+ * @dev: Device to lookup or add devres for
+ * @new_res: Pointer to new initialized devres to add if not found
+ * @match: Match function (optional)
+ * @match_data: Data for the match function
+ *
+ * Find the latest devres of @dev which has the same release function
+ * as @new_res and for which @match return 1.  If found, @new_res is
+ * freed; otherwise, @new_res is added atomically.
+ *
+ * RETURNS:
+ * Pointer to found or added devres.
+ */
+void *devres_get(struct udevice *dev, void *new_res,
+		 dr_match_t match, void *match_data);
+
+/**
+ * devres_remove - Find a device resource and remove it
+ * @dev: Device to find resource from
+ * @release: Look for resources associated with this release function
+ * @match: Match function (optional)
+ * @match_data: Data for the match function
+ *
+ * Find the latest devres of @dev associated with @release and for
+ * which @match returns 1.  If @match is NULL, it's considered to
+ * match all.  If found, the resource is removed atomically and
+ * returned.
+ *
+ * RETURNS:
+ * Pointer to removed devres on success, NULL if not found.
+ */
+void *devres_remove(struct udevice *dev, dr_release_t release,
+		    dr_match_t match, void *match_data);
+
+/**
+ * devres_destroy - Find a device resource and destroy it
+ * @dev: Device to find resource from
+ * @release: Look for resources associated with this release function
+ * @match: Match function (optional)
+ * @match_data: Data for the match function
+ *
+ * Find the latest devres of @dev associated with @release and for
+ * which @match returns 1.  If @match is NULL, it's considered to
+ * match all.  If found, the resource is removed atomically and freed.
+ *
+ * Note that the release function for the resource will not be called,
+ * only the devres-allocated data will be freed.  The caller becomes
+ * responsible for freeing any other data.
+ *
+ * RETURNS:
+ * 0 if devres is found and freed, -ENOENT if not found.
+ */
+int devres_destroy(struct udevice *dev, dr_release_t release,
+		   dr_match_t match, void *match_data);
+
+/**
+ * devres_release - Find a device resource and destroy it, calling release
+ * @dev: Device to find resource from
+ * @release: Look for resources associated with this release function
+ * @match: Match function (optional)
+ * @match_data: Data for the match function
+ *
+ * Find the latest devres of @dev associated with @release and for
+ * which @match returns 1.  If @match is NULL, it's considered to
+ * match all.  If found, the resource is removed atomically, the
+ * release function called and the resource freed.
+ *
+ * RETURNS:
+ * 0 if devres is found and freed, -ENOENT if not found.
+ */
+int devres_release(struct udevice *dev, dr_release_t release,
+		   dr_match_t match, void *match_data);
+
 #endif