ARM: dma-mapping: split out vmregion code from dma coherent mapping code

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 131 insertions, 0 deletions

diff --git a/arch/arm/mm/vmregion.c b/arch/arm/mm/vmregion.c
new file mode 100644
index 00000000000..19e09bdb1b8
--- /dev/null
+++ b/arch/arm/mm/vmregion.c
@@ -0,0 +1,131 @@
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include "vmregion.h"
+
+/*
+ * VM region handling support.
+ *
+ * This should become something generic, handling VM region allocations for
+ * vmalloc and similar (ioremap, module space, etc).
+ *
+ * I envisage vmalloc()'s supporting vm_struct becoming:
+ *
+ *  struct vm_struct {
+ *    struct vmregion	region;
+ *    unsigned long	flags;
+ *    struct page	**pages;
+ *    unsigned int	nr_pages;
+ *    unsigned long	phys_addr;
+ *  };
+ *
+ * get_vm_area() would then call vmregion_alloc with an appropriate
+ * struct vmregion head (eg):
+ *
+ *  struct vmregion vmalloc_head = {
+ *	.vm_list	= LIST_HEAD_INIT(vmalloc_head.vm_list),
+ *	.vm_start	= VMALLOC_START,
+ *	.vm_end		= VMALLOC_END,
+ *  };
+ *
+ * However, vmalloc_head.vm_start is variable (typically, it is dependent on
+ * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
+ * would have to initialise this each time prior to calling vmregion_alloc().
+ */
+
+struct arm_vmregion *
+arm_vmregion_alloc(struct arm_vmregion_head *head, size_t size, gfp_t gfp)
+{
+	unsigned long addr = head->vm_start, end = head->vm_end - size;
+	unsigned long flags;
+	struct arm_vmregion *c, *new;
+
+	if (head->vm_end - head->vm_start < size) {
+		printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
+			__func__, size);
+		goto out;
+	}
+
+	new = kmalloc(sizeof(struct arm_vmregion), gfp);
+	if (!new)
+		goto out;
+
+	spin_lock_irqsave(&head->vm_lock, flags);
+
+	list_for_each_entry(c, &head->vm_list, vm_list) {
+		if ((addr + size) < addr)
+			goto nospc;
+		if ((addr + size) <= c->vm_start)
+			goto found;
+		addr = c->vm_end;
+		if (addr > end)
+			goto nospc;
+	}
+
+ found:
+	/*
+	 * Insert this entry _before_ the one we found.
+	 */
+	list_add_tail(&new->vm_list, &c->vm_list);
+	new->vm_start = addr;
+	new->vm_end = addr + size;
+	new->vm_active = 1;
+
+	spin_unlock_irqrestore(&head->vm_lock, flags);
+	return new;
+
+ nospc:
+	spin_unlock_irqrestore(&head->vm_lock, flags);
+	kfree(new);
+ out:
+	return NULL;
+}
+
+static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
+{
+	struct arm_vmregion *c;
+
+	list_for_each_entry(c, &head->vm_list, vm_list) {
+		if (c->vm_active && c->vm_start == addr)
+			goto out;
+	}
+	c = NULL;
+ out:
+	return c;
+}
+
+struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
+{
+	struct arm_vmregion *c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&head->vm_lock, flags);
+	c = __arm_vmregion_find(head, addr);
+	spin_unlock_irqrestore(&head->vm_lock, flags);
+	return c;
+}
+
+struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
+{
+	struct arm_vmregion *c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&head->vm_lock, flags);
+	c = __arm_vmregion_find(head, addr);
+	if (c)
+		c->vm_active = 0;
+	spin_unlock_irqrestore(&head->vm_lock, flags);
+	return c;
+}
+
+void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&head->vm_lock, flags);
+	list_del(&c->vm_list);
+	spin_unlock_irqrestore(&head->vm_lock, flags);
+
+	kfree(c);
+}