Re: [PATCH v2 1/8] dma-buf: heaps: Initialize a secure heap

Initialize a secure heap. Currently just add a null heap, Prepare for
the later patches.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/dma-buf/heaps/Kconfig       |  7 +++
 drivers/dma-buf/heaps/Makefile      |  1 +
 drivers/dma-buf/heaps/secure_heap.c | 98 +++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 drivers/dma-buf/heaps/secure_heap.c

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index a5eef06c4226..e358bf711145 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig

@@ -12,3 +12,10 @@ config DMABUF_HEAPS_CMA
          Choose this option to enable dma-buf CMA heap. This heap is backed
          by the Contiguous Memory Allocator (CMA). If your system has these
          regions, you should say Y here.
+
+config DMABUF_HEAPS_SECURE
+       bool "DMA-BUF Secure Heap"
+       depends on DMABUF_HEAPS && TEE
+       help
+         Choose this option to enable dma-buf secure heap. This heap is backed by
+         TEE client interfaces or CMA. If in doubt, say N.

diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
index 974467791032..b1ad9d1f2fbe 100644
--- a/drivers/dma-buf/heaps/Makefile
+++ b/drivers/dma-buf/heaps/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_DMABUF_HEAPS_SECURE)      += secure_heap.o
 obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)      += system_heap.o
 obj-$(CONFIG_DMABUF_HEAPS_CMA)         += cma_heap.o

diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
new file mode 100644
index 000000000000..a634051a0a67
--- /dev/null
+++ b/drivers/dma-buf/heaps/secure_heap.c

@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DMABUF secure heap exporter
+ *
+ * Copyright (C) 2023 MediaTek Inc.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+enum secure_memory_type {
+       /*
+        * MediaTek static chunk memory carved out for TrustZone. The memory
+        * management is inside the TEE.
+        */
+       SECURE_MEMORY_TYPE_MTK_CM_TZ    = 1,

+};
+
+struct secure_buffer {
+       struct dma_heap                 *heap;
+       size_t                          size;
+};
+
+struct secure_heap {
+       const char                      *name;
+       const enum secure_memory_type   mem_type;

+
+static struct dma_buf *
+secure_heap_allocate(struct dma_heap *heap, unsigned long size,
+                    unsigned long fd_flags, unsigned long heap_flags)
+{
+       struct secure_buffer *sec_buf;
+       DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+       struct dma_buf *dmabuf;
+       int ret;
+
+       sec_buf = kzalloc(sizeof(*sec_buf), GFP_KERNEL);
+       if (!sec_buf)
+               return ERR_PTR(-ENOMEM);
+
+       sec_buf->size = ALIGN(size, PAGE_SIZE);
+       sec_buf->heap = heap;
+
+       exp_info.exp_name = dma_heap_get_name(heap);
+       exp_info.size = sec_buf->size;
+       exp_info.flags = fd_flags;
+       exp_info.priv = sec_buf;
+
+       dmabuf = dma_buf_export(&exp_info);
+       if (IS_ERR(dmabuf)) {
+               ret = PTR_ERR(dmabuf);
+               goto err_free_buf;
+       }
+
+       return dmabuf;
+
+err_free_buf:
+       kfree(sec_buf);
+       return ERR_PTR(ret);
+}
+
+static const struct dma_heap_ops sec_heap_ops = {
+       .allocate = secure_heap_allocate,
+};
+
+static struct secure_heap secure_heaps[] = {
+       {
+               .name           = "secure_mtk_cm",
+               .mem_type       = SECURE_MEMORY_TYPE_MTK_CM_TZ,
+       },
+};

+
+static int secure_heap_init(void)
+{
+       struct secure_heap *sec_heap = secure_heaps;
+       struct dma_heap_export_info exp_info;
+       struct dma_heap *heap;
+       unsigned int i;
+
+       for (i = 0; i < ARRAY_SIZE(secure_heaps); i++, sec_heap++) {
+               exp_info.name = sec_heap->name;
+               exp_info.ops = &sec_heap_ops;
+               exp_info.priv = (void *)sec_heap;
+
+               heap = dma_heap_add(&exp_info);
+               if (IS_ERR(heap))
+                       return PTR_ERR(heap);
+       }
+       return 0;
+}

+
+module_init(secure_heap_init);
+MODULE_DESCRIPTION("Secure Heap Driver");
+MODULE_LICENSE("GPL");