iommu: introduce generic page table allocation framework
This patch introduces a generic framework for allocating page tables for
an IOMMU. There are a number of reasons we want to do this:
- It avoids duplication of complex table management code in IOMMU
drivers that use the same page table format
- It removes any coupling with the CPU table format (and even the
architecture!)
- It defines an API for IOMMU TLB maintenance
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
new file mode 100644
index 0000000..f664a1c
--- /dev/null
+++ b/drivers/iommu/io-pgtable.c
@@ -0,0 +1,71 @@
+/*
+ * Generic page table allocator for IOMMUs.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (C) 2014 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+#include "io-pgtable.h"
+
+static const struct io_pgtable_init_fns *
+io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] =
+{
+};
+
+struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
+ struct io_pgtable_cfg *cfg,
+ void *cookie)
+{
+ struct io_pgtable *iop;
+ const struct io_pgtable_init_fns *fns;
+
+ if (fmt >= IO_PGTABLE_NUM_FMTS)
+ return NULL;
+
+ fns = io_pgtable_init_table[fmt];
+ if (!fns)
+ return NULL;
+
+ iop = fns->alloc(cfg, cookie);
+ if (!iop)
+ return NULL;
+
+ iop->fmt = fmt;
+ iop->cookie = cookie;
+ iop->cfg = *cfg;
+
+ return &iop->ops;
+}
+
+/*
+ * It is the IOMMU driver's responsibility to ensure that the page table
+ * is no longer accessible to the walker by this point.
+ */
+void free_io_pgtable_ops(struct io_pgtable_ops *ops)
+{
+ struct io_pgtable *iop;
+
+ if (!ops)
+ return;
+
+ iop = container_of(ops, struct io_pgtable, ops);
+ iop->cfg.tlb->tlb_flush_all(iop->cookie);
+ io_pgtable_init_table[iop->fmt]->free(iop);
+}