[U-Boot] [PATCH v2 06/14] devres: introduce Devres (Managed Device Resource) framework

Masahiro Yamada
2015-07-13T04:17:09Z

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 memory on their own in case they cannot statically
know how much memory is needed. Moreover, I am afraid the failure
paths of driver model core parts are getting messier as more and
more memory size members are supported, .per_child_auto_alloc_size,
.per_child_platdata_auto_alloc_size... So, I believe it is
reasonable enough to port Devres into U-boot.

As you know, 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>
---

Changes in v2:
- Add more APIs: _free, _find, _get, _remove, _destroy, _release
- Move devres_release_probe() and devres_release_all() decrlarations
to dm/device-internal.h
- Move comments to headers

drivers/core/Kconfig | 10 +++
drivers/core/Makefile | 2 +-
drivers/core/device-remove.c | 5 ++
drivers/core/device.c | 3 +
drivers/core/devres.c | 187 +++++++++++++++++++++++++++++++++++++++++++
include/dm/device-internal.h | 19 +++++
include/dm/device.h | 140 ++++++++++++++++++++++++++++++++
7 files changed, 365 insertions(+), 1 deletion(-)
create mode 100644 drivers/core/devres.c

diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index 2861b43..5966801 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -55,3 +55,13 @@ config DM_SEQ_ALIAS
Most boards will have a '/aliases' node containing the path to
numbered devices (e.g. serial0 = &serial0). This feature can be
disabled if it is not required, to save code space in SPL.
+
+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 a3fec38..cd8c104 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -4,7 +4,7 @@
# SPDX-License-Identifier: GPL-2.0+
#

-obj-$(CONFIG_DM) += device.o lists.o root.o uclass.o util.o
+obj-$(CONFIG_DM) += 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 20b56f9..e1714b2 100644
--- a/drivers/core/device-remove.c
+++ b/drivers/core/device-remove.c
@@ -109,6 +109,9 @@ int device_unbind(struct udevice *dev)

if (dev->parent)
list_del(&dev->sibling_node);
+
+ devres_release_all(dev);
+
free(dev);

return 0;
@@ -142,6 +145,8 @@ 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 39cc2f3..83b47d8 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..e7330b3
--- /dev/null
+++ b/drivers/core/devres.c
@@ -0,0 +1,187 @@
+/*
+ * 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 {
+ 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 687462b..409c687 100644
--- a/include/dm/device-internal.h
+++ b/include/dm/device-internal.h
@@ -117,4 +117,23 @@ static inline void device_free(struct udevice *dev) {}
#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 3674d19..c266c7d 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 */
@@ -449,4 +450,143 @@ 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
--
1.9.1