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>

7 files changed, 374 insertions, 1 deletions

diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index 5d0e949..a002d69 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -78,3 +78,13 @@ config SYSCON
 	  as a group by a single driver. Some common functionality is provided
 	  by this uclass, including accessing registers via regmap and
 	  assigning a unique number to each.
+
+config DEBUG_DEVRES
+	bool "Managed device resources verbose debug messages"
+	depends on DM
+	help
+	  If this option is enabled, devres debug messages are printed.
+	  Select this if you are having a problem with devres or want to
+	  debug resource management for a managed device.
+
+	  If you are unsure about this, Say N here.
diff --git a/drivers/core/Makefile b/drivers/core/Makefile
index ce3027a..260833e 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -4,7 +4,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y	+= device.o lists.o root.o uclass.o util.o
+obj-y	+= device.o lists.o root.o uclass.o util.o devres.o
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_OF_CONTROL) += simple-bus.o
 endif
diff --git a/drivers/core/device-remove.c b/drivers/core/device-remove.c
index 45d6543..bd6d406 100644
--- a/drivers/core/device-remove.c
+++ b/drivers/core/device-remove.c
@@ -95,6 +95,9 @@ int device_unbind(struct udevice *dev)
 
 	if (dev->parent)
 		list_del(&dev->sibling_node);
+
+	devres_release_all(dev);
+
 	free(dev);
 
 	return 0;
@@ -128,6 +131,8 @@ void device_free(struct udevice *dev)
 			dev->parent_priv = NULL;
 		}
 	}
+
+	devres_release_probe(dev);
 }
 
 int device_remove(struct udevice *dev)
diff --git a/drivers/core/device.c b/drivers/core/device.c
index bf6f271..e3a42dc 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -47,6 +47,7 @@ int device_bind(struct udevice *parent, const struct driver *drv,
 	INIT_LIST_HEAD(&dev->sibling_node);
 	INIT_LIST_HEAD(&dev->child_head);
 	INIT_LIST_HEAD(&dev->uclass_node);
+	INIT_LIST_HEAD(&dev->devres_head);
 	dev->platdata = platdata;
 	dev->name = name;
 	dev->of_offset = of_offset;
@@ -170,6 +171,8 @@ fail_alloc2:
 		dev->platdata = NULL;
 	}
 fail_alloc1:
+	devres_release_all(dev);
+
 	free(dev);
 
 	return ret;
diff --git a/drivers/core/devres.c b/drivers/core/devres.c
new file mode 100644
index 0000000..49c270c
--- /dev/null
+++ b/drivers/core/devres.c
@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * Based on the original work in Linux by
+ * Copyright (c) 2006  SUSE Linux Products GmbH
+ * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <linux/compat.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <dm/device.h>
+
+/**
+ * struct devres - Bookkeeping info for managed device resource
+ * @entry: List to associate this structure with a device
+ * @release: Callback invoked when this resource is released
+ * @probe: Flag to show when this resource was allocated
+	   (true = probe, false = bind)
+ * @name: Name of release function
+ * @size: Size of resource data
+ * @data: Resource data
+ */
+struct devres {
+	struct list_head		entry;
+	dr_release_t			release;
+	bool				probe;
+#ifdef CONFIG_DEBUG_DEVRES
+	const char			*name;
+	size_t				size;
+#endif
+	unsigned long long		data[];
+};
+
+#ifdef CONFIG_DEBUG_DEVRES
+static void set_node_dbginfo(struct devres *dr, const char *name, size_t size)
+{
+	dr->name = name;
+	dr->size = size;
+}
+
+static void devres_log(struct udevice *dev, struct devres *dr,
+		       const char *op)
+{
+	printf("%s: DEVRES %3s %p %s (%lu bytes)\n",
+	       dev->name, op, dr, dr->name, (unsigned long)dr->size);
+}
+#else /* CONFIG_DEBUG_DEVRES */
+#define set_node_dbginfo(dr, n, s)	do {} while (0)
+#define devres_log(dev, dr, op)		do {} while (0)
+#endif
+
+#if CONFIG_DEBUG_DEVRES
+void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
+		     const char *name)
+#else
+void *_devres_alloc(dr_release_t release, size_t size, gfp_t gfp)
+#endif
+{
+	size_t tot_size = sizeof(struct devres) + size;
+	struct devres *dr;
+
+	dr = kmalloc(tot_size, gfp);
+	if (unlikely(!dr))
+		return NULL;
+
+	INIT_LIST_HEAD(&dr->entry);
+	dr->release = release;
+	set_node_dbginfo(dr, name, size);
+
+	return dr->data;
+}
+
+void devres_free(void *res)
+{
+	if (res) {
+		struct devres *dr = container_of(res, struct devres, data);
+
+		BUG_ON(!list_empty(&dr->entry));
+		kfree(dr);
+	}
+}
+
+void devres_add(struct udevice *dev, void *res)
+{
+	struct devres *dr = container_of(res, struct devres, data);
+
+	devres_log(dev, dr, "ADD");
+	BUG_ON(!list_empty(&dr->entry));
+	dr->probe = dev->flags & DM_FLAG_BOUND ? true : false;
+	list_add_tail(&dr->entry, &dev->devres_head);
+}
+
+void *devres_find(struct udevice *dev, dr_release_t release,
+		  dr_match_t match, void *match_data)
+{
+	struct devres *dr;
+
+	list_for_each_entry_reverse(dr, &dev->devres_head, entry) {
+		if (dr->release != release)
+			continue;
+		if (match && !match(dev, dr->data, match_data))
+			continue;
+		return dr->data;
+	}
+
+	return NULL;
+}
+
+void *devres_get(struct udevice *dev, void *new_res,
+		 dr_match_t match, void *match_data)
+{
+	struct devres *new_dr = container_of(new_res, struct devres, data);
+	void *res;
+
+	res = devres_find(dev, new_dr->release, match, match_data);
+	if (!res) {
+		devres_add(dev, new_res);
+		res = new_res;
+		new_res = NULL;
+	}
+	devres_free(new_res);
+
+	return res;
+}
+
+void *devres_remove(struct udevice *dev, dr_release_t release,
+		    dr_match_t match, void *match_data)
+{
+	void *res;
+
+	res = devres_find(dev, release, match, match_data);
+	if (res) {
+		struct devres *dr = container_of(res, struct devres, data);
+
+		list_del_init(&dr->entry);
+		devres_log(dev, dr, "REM");
+	}
+
+	return res;
+}
+
+int devres_destroy(struct udevice *dev, dr_release_t release,
+		   dr_match_t match, void *match_data)
+{
+	void *res;
+
+	res = devres_remove(dev, release, match, match_data);
+	if (unlikely(!res))
+		return -ENOENT;
+
+	devres_free(res);
+	return 0;
+}
+
+int devres_release(struct udevice *dev, dr_release_t release,
+		   dr_match_t match, void *match_data)
+{
+	void *res;
+
+	res = devres_remove(dev, release, match, match_data);
+	if (unlikely(!res))
+		return -ENOENT;
+
+	(*release)(dev, res);
+	devres_free(res);
+	return 0;
+}
+
+static void release_nodes(struct udevice *dev, struct list_head *head,
+			  bool probe_only)
+{
+	struct devres *dr, *tmp;
+
+	list_for_each_entry_safe_reverse(dr, tmp, head, entry)  {
+		if (probe_only && !dr->probe)
+			break;
+		devres_log(dev, dr, "REL");
+		dr->release(dev, dr->data);
+		list_del(&dr->entry);
+		kfree(dr);
+	}
+}
+
+void devres_release_probe(struct udevice *dev)
+{
+	release_nodes(dev, &dev->devres_head, true);
+}
+
+void devres_release_all(struct udevice *dev)
+{
+	release_nodes(dev, &dev->devres_head, false);
+}
diff --git a/include/dm/device-internal.h b/include/dm/device-internal.h
index 1a9ba01..a2bf057 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 4cd7ba3..85513e1 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