From: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
This commit adds a VCM driver that instead of using real
hardware MMU emulates one and uses CMA for allocating
contiguous memory chunks.
Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
Documentation/virtual-contiguous-memory.txt | 12 +++-
include/linux/vcm-cma.h | 38 ++++++++++
mm/Kconfig | 14 ++++
mm/Makefile | 1 +
mm/vcm-cma.c | 99 +++++++++++++++++++++++++++
5 files changed, 163 insertions(+), 1 deletions(-)
create mode 100644 include/linux/vcm-cma.h
create mode 100644 mm/vcm-cma.c
diff --git a/Documentation/virtual-contiguous-memory.txt b/Documentation/virtual-contiguous-memory.txt
index 070685b..46edaee 100644
--- a/Documentation/virtual-contiguous-memory.txt
+++ b/Documentation/virtual-contiguous-memory.txt
@@ -552,7 +552,17 @@ well:
If one uses vcm_unbind() then vcm_bind() on the same reservation,
physical memory pair should also work.
-There are no One-to-One drivers at this time.
+*** VCM CMA
+
+VCM CMA driver is a One-to-One driver which uses CMA (see
+[[file:contiguous-memory.txt][contiguous-memory.txt]]) to allocate physically contiguous memory. VCM
+CMA context is created by calling:
+
+ struct vcm *__must_check
+ vcm_cma_create(const char *regions, dma_addr_t alignment);
+
+Its first argument is the list of regions that CMA should try to
+allocate memory from. The second argument is required alignment.
* Writing a VCM driver
diff --git a/include/linux/vcm-cma.h b/include/linux/vcm-cma.h
new file mode 100644
index 0000000..57c2cc9
--- /dev/null
+++ b/include/linux/vcm-cma.h
@@ -0,0 +1,38 @@
+/*
+ * Virtual Contiguous Memory driver for CMA header
+ * Copyright (c) 2010 by Samsung Electronics.
+ * Written by Michal Nazarewicz (m.nazarewicz@xxxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License or (at your optional) any later version of the license.
+ */
+
+/*
+ * See Documentation/virtual-contiguous-memory.txt for details.
+ */
+
+#ifndef __LINUX_VCM_CMA_H
+#define __LINUX_VCM_CMA_H
+
+#include <linux/types.h>
+
+struct vcm;
+
+/**
+ * vcm_cma_create() - creates a VCM context that fakes a hardware MMU
+ * @ctx: the cma context that is defined by the machine's implementation.
+ * from.
+ * @alignment: required alignment of allocations.
+ *
+ * This creates VCM context that can be used on platforms with no
+ * hardware MMU or for devices that aro conected to the bus directly.
+ * Because it does not represent real MMU it has some limitations:
+ * basically, vcm_alloc(), vcm_reserve() and vcm_bind() are likely to
+ * fail so vcm_make_binding() should be used instead.
+ */
+struct vcm *__must_check
+vcm_cma_create(struct cma *ctx, unsigned long alignment);
+
+#endif
diff --git a/mm/Kconfig b/mm/Kconfig
index 53328d2..5cd25e7 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -390,6 +390,20 @@ config VCM_O2O
it if you are going to build external modules that will use this
functionality.
+config VCM_CMA
+ bool "VCM CMA driver"
+ depends on VCM && CMA
+ select VCM_O2O
+ help
+ This enables VCM driver that instead of using a real hardware
+ MMU fakes one and uses a direct mapping. It provides a subset
+ of functionalities of a real MMU but if drivers limits their
+ use of VCM to only supported operations they can work on
+ both systems with and without MMU with no changes.
+
+ For more information see
+ <Documentation/virtual-contiguous-memory.txt>. If unsure, say "n".
+
#
# UP and nommu archs use km based percpu allocator
#
diff --git a/mm/Makefile b/mm/Makefile
index b96a6cb..6663fc2 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -44,3 +44,4 @@ obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
obj-$(CONFIG_CMA) += cma.o
obj-$(CONFIG_VCM) += vcm.o
+obj-$(CONFIG_VCM_CMA) += vcm-cma.o
diff --git a/mm/vcm-cma.c b/mm/vcm-cma.c
new file mode 100644
index 0000000..dcdc751
--- /dev/null
+++ b/mm/vcm-cma.c
@@ -0,0 +1,99 @@
+/*
+ * Virtual Contiguous Memory driver for CMA
+ * Copyright (c) 2010 by Samsung Electronics.
+ * Written by Michal Nazarewicz (m.nazarewicz@xxxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License or (at your optional) any later version of the license.
+ */
+
+/*
+ * See Documentation/virtual-contiguous-memory.txt for details.
+ */
+
+#include <linux/vcm-drv.h>
+#include <linux/cma.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+struct vcm_cma {
+ struct vcm_o2o o2o;
+ struct cma *ctx;
+ unsigned long alignment;
+};
+
+struct vcm_cma_phys {
+ struct cm *chunk;
+ struct vcm_phys phys;
+};
+
+static void vcm_cma_free(struct vcm_phys *_phys)
+{
+ struct vcm_cma_phys *phys =
+ container_of(_phys, struct vcm_cma_phys, phys);
+ cm_unpin(phys->chunk);
+ cm_free(phys->chunk);
+ kfree(phys);
+}
+
+static struct vcm_phys *
+vcm_cma_phys(struct vcm *vcm, resource_size_t size, unsigned flags)
+{
+ struct vcm_cma *cma = container_of(vcm, struct vcm_cma, o2o.vcm);
+ struct vcm_cma_phys *phys;
+ struct cm *chunk;
+
+ phys = kmalloc(sizeof *phys + sizeof *phys->phys.parts, GFP_KERNEL);
+ if (!phys)
+ return ERR_PTR(-ENOMEM);
+
+ chunk = cm_alloc(cma->ctx, size, cma->alignment);
+ if (IS_ERR(chunk)) {
+ kfree(phys);
+ return ERR_CAST(chunk);
+ }
+
+ phys->chunk = chunk;
+ phys->phys.count = 1;
+ phys->phys.free = vcm_cma_free;
+ phys->phys.parts->start = cm_pin(chunk);
+ phys->phys.parts->size = size;
+ return &phys->phys;
+}
+
+struct vcm *__must_check
+vcm_cma_create(struct cma *ctx, unsigned long alignment)
+{
+ static const struct vcm_o2o_driver driver = {
+ .phys = vcm_cma_phys,
+ };
+
+ struct vcm_cma *cma;
+ struct vcm *vcm;
+
+ if (alignment & (alignment - 1))
+ return ERR_PTR(-EINVAL);
+
+ cma = kmalloc(sizeof *cma, GFP_KERNEL);
+ if (!cma)
+ return ERR_PTR(-ENOMEM);
+
+ cma->o2o.driver = &driver;
+ /* dummy size and start address!
+ * to be accepted by vcm_init()
+ * vcm_cma does not use these members.
+ */
+ cma->o2o.vcm.start = 0;
+ cma->o2o.vcm.size = PAGE_SIZE;
+ cma->ctx = ctx;
+ cma->alignment = alignment;
+ vcm = vcm_o2o_init(&cma->o2o);
+ if (IS_ERR(vcm))
+ kfree(cma);
+ return vcm;
+}
+EXPORT_SYMBOL_GPL(vcm_cma_create);
--
1.6.2.5
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