devres: device resource management

Implement device resource management, in short, devres.  A device
driver can allocate arbirary size of devres data which is associated
with a release function.  On driver detach, release function is
invoked on the devres data, then, devres data is freed.

devreses are typed by associated release functions.  Some devreses are
better represented by single instance of the type while others need
multiple instances sharing the same release function.  Both usages are
supported.

devreses can be grouped using devres group such that a device driver
can easily release acquired resources halfway through initialization
or selectively release resources (e.g. resources for port 1 out of 4
ports).

This patch adds devres core including documentation and the following
managed interfaces.

* alloc/free	: devm_kzalloc(), devm_kzfree()
* IO region	: devm_request_region(), devm_release_region()
* IRQ		: devm_request_irq(), devm_free_irq()
* DMA		: dmam_alloc_coherent(), dmam_free_coherent(),
		  dmam_declare_coherent_memory(), dmam_pool_create(),
		  dmam_pool_destroy()
* PCI		: pcim_enable_device(), pcim_pin_device(), pci_is_managed()
* iomap		: devm_ioport_map(), devm_ioport_unmap(), devm_ioremap(),
		  devm_ioremap_nocache(), devm_iounmap(), pcim_iomap_table(),
		  pcim_iomap(), pcim_iounmap()

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 644 insertions, 0 deletions

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
new file mode 100644
index 000000000000..e177c9533b6c
--- /dev/null
+++ b/drivers/base/devres.c
@@ -0,0 +1,644 @@
+/*
+ * drivers/base/devres.c - device resource management
+ *
+ * Copyright (c) 2006  SUSE Linux Products GmbH
+ * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+
+struct devres_node {
+        struct list_head                entry;
+        dr_release_t                    release;
+#ifdef CONFIG_DEBUG_DEVRES
+        const char                      *name;
+        size_t                          size;
+#endif
+};
+
+struct devres {
+        struct devres_node              node;
+        /* -- 3 pointers */
+        unsigned long long              data[]; /* guarantee ull alignment */
+};
+
+struct devres_group {
+        struct devres_node              node[2];
+        void                            *id;
+        int                             color;
+        /* -- 8 pointers */
+};
+
+#ifdef CONFIG_DEBUG_DEVRES
+static int log_devres = 0;
+module_param_named(log, log_devres, int, S_IRUGO | S_IWUSR);
+
+static void set_node_dbginfo(struct devres_node *node, const char *name,
+                             size_t size)
+{
+        node->name = name;
+        node->size = size;
+}
+
+static void devres_log(struct device *dev, struct devres_node *node,
+                       const char *op)
+{
+        if (unlikely(log_devres))
+                dev_printk(KERN_ERR, dev, "DEVRES %3s %p %s (%lu bytes)\n",
+                           op, node, node->name, (unsigned long)node->size);
+}
+#else /* CONFIG_DEBUG_DEVRES */
+#define set_node_dbginfo(node, n, s)    do {} while (0)
+#define devres_log(dev, node, op)       do {} while (0)
+#endif /* CONFIG_DEBUG_DEVRES */
+
+/*
+ * Release functions for devres group.  These callbacks are used only
+ * for identification.
+ */
+static void group_open_release(struct device *dev, void *res)
+{
+        /* noop */
+}
+
+static void group_close_release(struct device *dev, void *res)
+{
+        /* noop */
+}
+
+static struct devres_group * node_to_group(struct devres_node *node)
+{
+        if (node->release == &group_open_release)
+                return container_of(node, struct devres_group, node[0]);
+        if (node->release == &group_close_release)
+                return container_of(node, struct devres_group, node[1]);
+        return NULL;
+}
+
+static __always_inline struct devres * alloc_dr(dr_release_t release,
+                                                size_t size, gfp_t gfp)
+{
+        size_t tot_size = sizeof(struct devres) + size;
+        struct devres *dr;
+
+        dr = kmalloc_track_caller(tot_size, gfp);
+        if (unlikely(!dr))
+                return NULL;
+
+        memset(dr, 0, tot_size);
+        INIT_LIST_HEAD(&dr->node.entry);
+        dr->node.release = release;
+        return dr;
+}
+
+static void add_dr(struct device *dev, struct devres_node *node)
+{
+        devres_log(dev, node, "ADD");
+        BUG_ON(!list_empty(&node->entry));
+        list_add_tail(&node->entry, &dev->devres_head);
+}
+
+/**
+ * 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 zeroed, then
+ * associated with @release.  The returned pointer can be passed to
+ * other devres_*() functions.
+ *
+ * RETURNS:
+ * Pointer to allocated devres on success, NULL on failure.
+ */
+#ifdef CONFIG_DEBUG_DEVRES
+void * __devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
+                      const char *name)
+{
+        struct devres *dr;
+
+        dr = alloc_dr(release, size, gfp);
+        if (unlikely(!dr))
+                return NULL;
+        set_node_dbginfo(&dr->node, name, size);
+        return dr->data;
+}
+EXPORT_SYMBOL_GPL(__devres_alloc);
+#else
+void * devres_alloc(dr_release_t release, size_t size, gfp_t gfp)
+{
+        struct devres *dr;
+
+        dr = alloc_dr(release, size, gfp);
+        if (unlikely(!dr))
+                return NULL;
+        return dr->data;
+}
+EXPORT_SYMBOL_GPL(devres_alloc);
+#endif
+
+/**
+ * devres_free - Free device resource data
+ * @res: Pointer to devres data to free
+ *
+ * Free devres created with devres_alloc().
+ */
+void devres_free(void *res)
+{
+        if (res) {
+                struct devres *dr = container_of(res, struct devres, data);
+
+                BUG_ON(!list_empty(&dr->node.entry));
+                kfree(dr);
+        }
+}
+EXPORT_SYMBOL_GPL(devres_free);
+
+/**
+ * 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 device *dev, void *res)
+{
+        struct devres *dr = container_of(res, struct devres, data);
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        add_dr(dev, &dr->node);
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+}
+EXPORT_SYMBOL_GPL(devres_add);
+
+static struct devres *find_dr(struct device *dev, dr_release_t release,
+                              dr_match_t match, void *match_data)
+{
+        struct devres_node *node;
+
+        list_for_each_entry_reverse(node, &dev->devres_head, entry) {
+                struct devres *dr = container_of(node, struct devres, node);
+
+                if (node->release != release)
+                        continue;
+                if (match && !match(dev, dr->data, match_data))
+                        continue;
+                return dr;
+        }
+
+        return NULL;
+}
+
+/**
+ * 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 device *dev, dr_release_t release,
+                   dr_match_t match, void *match_data)
+{
+        struct devres *dr;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        dr = find_dr(dev, release, match, match_data);
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+        if (dr)
+                return dr->data;
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(devres_find);
+
+/**
+ * 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 device *dev, void *new_res,
+                  dr_match_t match, void *match_data)
+{
+        struct devres *new_dr = container_of(new_res, struct devres, data);
+        struct devres *dr;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        dr = find_dr(dev, new_dr->node.release, match, match_data);
+        if (!dr) {
+                add_dr(dev, &new_dr->node);
+                dr = new_dr;
+                new_dr = NULL;
+        }
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+        devres_free(new_dr);
+
+        return dr->data;
+}
+EXPORT_SYMBOL_GPL(devres_get);
+
+/**
+ * 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 device *dev, dr_release_t release,
+                     dr_match_t match, void *match_data)
+{
+        struct devres *dr;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        dr = find_dr(dev, release, match, match_data);
+        if (dr) {
+                list_del_init(&dr->node.entry);
+                devres_log(dev, &dr->node, "REM");
+        }
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+        if (dr)
+                return dr->data;
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(devres_remove);
+
+/**
+ * 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.
+ *
+ * RETURNS:
+ * 0 if devres is found and freed, -ENOENT if not found.
+ */
+int devres_destroy(struct device *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;
+}
+EXPORT_SYMBOL_GPL(devres_destroy);
+
+static int remove_nodes(struct device *dev,
+                        struct list_head *first, struct list_head *end,
+                        struct list_head *todo)
+{
+        int cnt = 0, nr_groups = 0;
+        struct list_head *cur;
+
+        /* First pass - move normal devres entries to @todo and clear
+         * devres_group colors.
+         */
+        cur = first;
+        while (cur != end) {
+                struct devres_node *node;
+                struct devres_group *grp;
+
+                node = list_entry(cur, struct devres_node, entry);
+                cur = cur->next;
+
+                grp = node_to_group(node);
+                if (grp) {
+                        /* clear color of group markers in the first pass */
+                        grp->color = 0;
+                        nr_groups++;
+                } else {
+                        /* regular devres entry */
+                        if (&node->entry == first)
+                                first = first->next;
+                        list_move_tail(&node->entry, todo);
+                        cnt++;
+                }
+        }
+
+        if (!nr_groups)
+                return cnt;
+
+        /* Second pass - Scan groups and color them.  A group gets
+         * color value of two iff the group is wholly contained in
+         * [cur, end).  That is, for a closed group, both opening and
+         * closing markers should be in the range, while just the
+         * opening marker is enough for an open group.
+         */
+        cur = first;
+        while (cur != end) {
+                struct devres_node *node;
+                struct devres_group *grp;
+
+                node = list_entry(cur, struct devres_node, entry);
+                cur = cur->next;
+
+                grp = node_to_group(node);
+                BUG_ON(!grp || list_empty(&grp->node[0].entry));
+
+                grp->color++;
+                if (list_empty(&grp->node[1].entry))
+                        grp->color++;
+
+                BUG_ON(grp->color <= 0 || grp->color > 2);
+                if (grp->color == 2) {
+                        /* No need to update cur or end.  The removed
+                         * nodes are always before both.
+                         */
+                        list_move_tail(&grp->node[0].entry, todo);
+                        list_del_init(&grp->node[1].entry);
+                }
+        }
+
+        return cnt;
+}
+
+static int release_nodes(struct device *dev, struct list_head *first,
+                         struct list_head *end, unsigned long flags)
+{
+        LIST_HEAD(todo);
+        int cnt;
+        struct devres *dr, *tmp;
+
+        cnt = remove_nodes(dev, first, end, &todo);
+
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+        /* Release.  Note that both devres and devres_group are
+         * handled as devres in the following loop.  This is safe.
+         */
+        list_for_each_entry_safe_reverse(dr, tmp, &todo, node.entry) {
+                devres_log(dev, &dr->node, "REL");
+                dr->node.release(dev, dr->data);
+                kfree(dr);
+        }
+
+        return cnt;
+}
+
+/**
+ * devres_release_all - Release all resources
+ * @dev: Device to release resources for
+ *
+ * Release all resources associated with @dev.  This function is
+ * called on driver detach.
+ */
+int devres_release_all(struct device *dev)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        return release_nodes(dev, dev->devres_head.next, &dev->devres_head,
+                             flags);
+}
+
+/**
+ * devres_open_group - Open a new devres group
+ * @dev: Device to open devres group for
+ * @id: Separator ID
+ * @gfp: Allocation flags
+ *
+ * Open a new devres group for @dev with @id.  For @id, using a
+ * pointer to an object which won't be used for another group is
+ * recommended.  If @id is NULL, address-wise unique ID is created.
+ *
+ * RETURNS:
+ * ID of the new group, NULL on failure.
+ */
+void * devres_open_group(struct device *dev, void *id, gfp_t gfp)
+{
+        struct devres_group *grp;
+        unsigned long flags;
+
+        grp = kmalloc(sizeof(*grp), gfp);
+        if (unlikely(!grp))
+                return NULL;
+
+        grp->node[0].release = &group_open_release;
+        grp->node[1].release = &group_close_release;
+        INIT_LIST_HEAD(&grp->node[0].entry);
+        INIT_LIST_HEAD(&grp->node[1].entry);
+        set_node_dbginfo(&grp->node[0], "grp<", 0);
+        set_node_dbginfo(&grp->node[1], "grp>", 0);
+        grp->id = grp;
+        if (id)
+                grp->id = id;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+        add_dr(dev, &grp->node[0]);
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+        return grp->id;
+}
+EXPORT_SYMBOL_GPL(devres_open_group);
+
+/* Find devres group with ID @id.  If @id is NULL, look for the latest. */
+static struct devres_group * find_group(struct device *dev, void *id)
+{
+        struct devres_node *node;
+
+        list_for_each_entry_reverse(node, &dev->devres_head, entry) {
+                struct devres_group *grp;
+
+                if (node->release != &group_open_release)
+                        continue;
+
+                grp = container_of(node, struct devres_group, node[0]);
+
+                if (id) {
+                        if (grp->id == id)
+                                return grp;
+                } else if (list_empty(&grp->node[1].entry))
+                        return grp;
+        }
+
+        return NULL;
+}
+
+/**
+ * devres_close_group - Close a devres group
+ * @dev: Device to close devres group for
+ * @id: ID of target group, can be NULL
+ *
+ * Close the group identified by @id.  If @id is NULL, the latest open
+ * group is selected.
+ */
+void devres_close_group(struct device *dev, void *id)
+{
+        struct devres_group *grp;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+
+        grp = find_group(dev, id);
+        if (grp)
+                add_dr(dev, &grp->node[1]);
+        else
+                WARN_ON(1);
+
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+}
+EXPORT_SYMBOL_GPL(devres_close_group);
+
+/**
+ * devres_remove_group - Remove a devres group
+ * @dev: Device to remove group for
+ * @id: ID of target group, can be NULL
+ *
+ * Remove the group identified by @id.  If @id is NULL, the latest
+ * open group is selected.  Note that removing a group doesn't affect
+ * any other resources.
+ */
+void devres_remove_group(struct device *dev, void *id)
+{
+        struct devres_group *grp;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+
+        grp = find_group(dev, id);
+        if (grp) {
+                list_del_init(&grp->node[0].entry);
+                list_del_init(&grp->node[1].entry);
+                devres_log(dev, &grp->node[0], "REM");
+        } else
+                WARN_ON(1);
+
+        spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+        kfree(grp);
+}
+EXPORT_SYMBOL_GPL(devres_remove_group);
+
+/**
+ * devres_release_group - Release resources in a devres group
+ * @dev: Device to release group for
+ * @id: ID of target group, can be NULL
+ *
+ * Release all resources in the group identified by @id.  If @id is
+ * NULL, the latest open group is selected.  The selected group and
+ * groups properly nested inside the selected group are removed.
+ *
+ * RETURNS:
+ * The number of released non-group resources.
+ */
+int devres_release_group(struct device *dev, void *id)
+{
+        struct devres_group *grp;
+        unsigned long flags;
+        int cnt = 0;
+
+        spin_lock_irqsave(&dev->devres_lock, flags);
+
+        grp = find_group(dev, id);
+        if (grp) {
+                struct list_head *first = &grp->node[0].entry;
+                struct list_head *end = &dev->devres_head;
+
+                if (!list_empty(&grp->node[1].entry))
+                        end = grp->node[1].entry.next;
+
+                cnt = release_nodes(dev, first, end, flags);
+        } else {
+                WARN_ON(1);
+                spin_unlock_irqrestore(&dev->devres_lock, flags);
+        }
+
+        return cnt;
+}
+EXPORT_SYMBOL_GPL(devres_release_group);
+
+/*
+ * Managed kzalloc/kfree
+ */
+static void devm_kzalloc_release(struct device *dev, void *res)
+{
+        /* noop */
+}
+
+static int devm_kzalloc_match(struct device *dev, void *res, void *data)
+{
+        return res == data;
+}
+
+/**
+ * devm_kzalloc - Managed kzalloc
+ * @dev: Device to allocate memory for
+ * @size: Allocation size
+ * @gfp: Allocation gfp flags
+ *
+ * Managed kzalloc.  Memory allocated with this function is
+ * automatically freed on driver detach.  Like all other devres
+ * resources, guaranteed alignment is unsigned long long.
+ *
+ * RETURNS:
+ * Pointer to allocated memory on success, NULL on failure.
+ */
+void * devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
+{
+        struct devres *dr;
+
+        /* use raw alloc_dr for kmalloc caller tracing */
+        dr = alloc_dr(devm_kzalloc_release, size, gfp);
+        if (unlikely(!dr))
+                return NULL;
+
+        set_node_dbginfo(&dr->node, "devm_kzalloc_release", size);
+        devres_add(dev, dr->data);
+        return dr->data;
+}
+EXPORT_SYMBOL_GPL(devm_kzalloc);
+
+/**
+ * devm_kfree - Managed kfree
+ * @dev: Device this memory belongs to
+ * @p: Memory to free
+ *
+ * Free memory allocated with dev_kzalloc().
+ */
+void devm_kfree(struct device *dev, void *p)
+{
+        int rc;
+
+        rc = devres_destroy(dev, devm_kzalloc_release, devm_kzalloc_match, p);
+        WARN_ON(rc);
+}
+EXPORT_SYMBOL_GPL(devm_kfree);