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Subject[RFCv5 8/9] mm: vcm: Sample driver added
This commit adds a sample Virtual Contiguous Memory framework
driver. It handles no real hardware and is there only for
demonstrating purposes.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
Documentation/virtual-contiguous-memory.txt | 3 +
include/linux/vcm-sample.h | 30 +++++++
mm/Kconfig | 9 ++
mm/Makefile | 1 +
mm/vcm-sample.c | 120 +++++++++++++++++++++++++++
5 files changed, 163 insertions(+), 0 deletions(-)
create mode 100644 include/linux/vcm-sample.h
create mode 100644 mm/vcm-sample.c
diff --git a/Documentation/virtual-contiguous-memory.txt b/Documentation/virtual-contiguous-memory.txt
index 0c0e90c..6d1014c 100644
--- a/Documentation/virtual-contiguous-memory.txt
+++ b/Documentation/virtual-contiguous-memory.txt
@@ -730,6 +730,9 @@ already there.
If you want to use this wrapper, you need to select VCM_MMU Kconfig
option.

+There is a sample driver provided which provides a template for real
+drivers. It can be found in [[file:../mm/vcm-sample.c][mm/vcm-sample.c]] file.
+
*** Context creation

Similarly to normal drivers, MMU driver needs to provide a context
diff --git a/include/linux/vcm-sample.h b/include/linux/vcm-sample.h
new file mode 100644
index 0000000..9a79403
--- /dev/null
+++ b/include/linux/vcm-sample.h
@@ -0,0 +1,30 @@
+/*
+ * Virtual Contiguous Memory driver driver template header
+ * Copyright (c) 2010 by Samsung Electronics.
+ * Written by Michal Nazarewicz (m.nazarewicz@samsung.com)
+ *
+ * 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_SAMPLE_H
+#define __LINUX_VCM_SAMPLE_H
+
+#include <linux/vcm.h>
+
+struct vcm;
+
+/**
+ * vcm_samp_create() - creates a VCM context
+ *
+ * ... Documentation goes here ...
+ */
+struct vcm *__must_check vcm_samp_create(/* ... */);
+
+#endif
diff --git a/mm/Kconfig b/mm/Kconfig
index 0445f68..be040e7 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -401,3 +401,12 @@ config VCM_O2O
# Select if you need vcm_phys_alloc() or vcm_phys_walk() functions
config VCM_PHYS
bool
+
+config VCM_SAMP
+ bool "VCM sample driver"
+ depends on VCM
+ select VCM_MMU
+ help
+ This enables a sample driver for the VCM framework. This driver
+ does not handle any real harwdare. It's merely an template of
+ how for real drivers.
diff --git a/mm/Makefile b/mm/Makefile
index e908202..c465dfa 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -50,3 +50,4 @@ obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
obj-$(CONFIG_CMA) += cma.o
obj-$(CONFIG_CMA_BEST_FIT) += cma-best-fit.o
obj-$(CONFIG_VCM) += vcm.o
+obj-$(CONFIG_VCM_SAMPLE) += vcm-sample.o
diff --git a/mm/vcm-sample.c b/mm/vcm-sample.c
new file mode 100644
index 0000000..e265a73
--- /dev/null
+++ b/mm/vcm-sample.c
@@ -0,0 +1,120 @@
+/*
+ * Virtual Contiguous Memory driver template
+ * Copyright (c) 2010 by Samsung Electronics.
+ * Written by Michal Nazarewicz (m.nazarewicz@samsung.com)
+ *
+ * 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.
+ */
+
+/*
+ * This is just a sample code. It does nothing useful other then
+ * presenting a template for VCM driver.
+ */
+
+/*
+ * See Documentation/virtual-contiguous-memory.txt for details.
+ */
+
+#include <linux/vcm-drv.h>
+#include <linux/vcm-sample.h>
+
+struct vcm_samp {
+ struct vcm_mmu mmu;
+ /* ... */
+};
+
+static const unsigned vcm_samp_orders[] = {
+ 4 + 20 - PAGES_SHIFT, /* 16MiB pages */
+ 0 + 20 - PAGES_SHIFT, /* 1MiB pages */
+ 6 + 10 - PAGES_SHIFT, /* 64KiB pages */
+ 2 + 10 - PAGES_SHIFT, /* 4KiB pages */
+};
+
+static int vcm_samp_activate_page(dma_addr_t vaddr, dma_addr_t paddr,
+ unsigned order, void *priv)
+{
+ struct vcm_samp *samp =
+ container_of((struct vcm *)priv, struct vcm_samp, mmu.vcm);
+
+ /*
+ * Handle adding a mapping from virtual page at @vaddr to
+ * physical page ad @paddr. The page is of order @order which
+ * means that it's (PAGE_SIZE << @order) bytes.
+ */
+
+ return -EOPNOTSUPP;
+}
+
+static int vcm_samp_deactivate_page(dma_addr_t vaddr, dma_addr_t paddr,
+ unsigned order, void *priv)
+{
+ struct vcm_samp *samp =
+ container_of((struct vcm *)priv, struct vcm_samp, mmu.vcm);
+
+ /*
+ * Handle removing a mapping from virtual page at @vaddr to
+ * physical page ad @paddr. The page is of order @order which
+ * means that it's (PAGE_SIZE << @order) bytes.
+ */
+
+ /* It's best not to fail here */
+ return 0;
+}
+
+static void vcm_samp_cleanup(struct vcm *vcm)
+{
+ struct vcm_samp *samp =
+ container_of(res->vcm, struct vcm_samp, mmu.vcm);
+
+ /* Clean ups ... */
+
+ kfree(samp);
+}
+
+struct vcm *__must_check vcm_samp_create(/* ... */)
+{
+ static const struct vcm_mmu_driver driver = {
+ .order = vcm_samp_orders,
+ .cleanup = vcm_samp_cleanup,
+ .activate_page = vcm_samp_activate_page,
+ .deactivate_page = vcm_samp_deactivate_page,
+ };
+
+ struct vcm_samp *samp;
+ struct vcm *vcm;
+
+ switch (0) {
+ case 0:
+ case PAGE_SHIFT == 12:
+ /*
+ * If you have a compilation error here it means you
+ * are compiling for a very strange platfrom where
+ * PAGE_SHIFT is not 12 (ie. PAGE_SIZE is not 4KiB).
+ * This driver assumes PAGE_SHIFT is 12.
+ */
+ };
+
+ samp = kzalloc(sizeof *samp, GFP_KERNEL);
+ if (!samp)
+ return ERR_PTR(-ENOMEM);
+
+ /* ... Set things up ... */
+
+ samp->mmu.driver = &driver;
+ /* skip first 64K so that zero address will be a NULL pointer */
+ samp->mmu.vcm.start = (64 << 10);
+ samp->mmu.vcm.size = -(64 << 10);
+
+ vcm = vcm_mmu_init(&samp->mmu);
+ if (!IS_ERR(vcm))
+ return vcm;
+
+ /* ... Error recovery ... */
+
+ kfree(samp);
+ return vcm;
+}
+EXPORT_SYMBOL_GPL(vcm_samp_create);
--
1.7.1


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