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From:   Oded Gabbay <oded.gabbay@gmail.com>
To:     linux-kernel@vger.kernel.org, SW_Drivers@habana.ai
Subject: [PATCH 1/3] habanalabs: restructure hl_mmap
Date:   Sat, 29 Aug 2020 17:43:50 +0300
Message-Id: <20200829144352.17171-1-oded.gabbay@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Arrange the hl_mmap code to be more structured and expandable for the
future. Add better defines that describe our usage of the vm_pgoff.

Note that I shamelessly took the code and defines from the amdkfd driver
(my previous driver).

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
---
 drivers/misc/habanalabs/common/command_buffer.c |  2 +-
 drivers/misc/habanalabs/common/device.c         |  8 ++++++--
 drivers/misc/habanalabs/common/habanalabs.h     | 14 +++++++++++++-
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_buffer.c b/drivers/misc/habanalabs/common/command_buffer.c
index e4bbe6a8e00f..68dfbafe3354 100644
--- a/drivers/misc/habanalabs/common/command_buffer.c
+++ b/drivers/misc/habanalabs/common/command_buffer.c
@@ -183,7 +183,7 @@ int hl_cb_create(struct hl_device *hdev, struct hl_cb_mgr *mgr,
 	 * idr is 32-bit so we can safely OR it with a mask that is above
 	 * 32 bit
 	 */
-	*handle = cb->id | HL_MMAP_CB_MASK;
+	*handle = cb->id | HL_MMAP_TYPE_CB;
 	*handle <<= PAGE_SHIFT;
 
 	hl_debugfs_add_cb(cb);
diff --git a/drivers/misc/habanalabs/common/device.c b/drivers/misc/habanalabs/common/device.c
index 6e916cc22a4c..aa7fa9e94651 100644
--- a/drivers/misc/habanalabs/common/device.c
+++ b/drivers/misc/habanalabs/common/device.c
@@ -123,9 +123,13 @@ static int hl_device_release_ctrl(struct inode *inode, struct file *filp)
 static int hl_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct hl_fpriv *hpriv = filp->private_data;
+	unsigned long vm_pgoff;
 
-	if ((vma->vm_pgoff & HL_MMAP_CB_MASK) == HL_MMAP_CB_MASK) {
-		vma->vm_pgoff ^= HL_MMAP_CB_MASK;
+	vm_pgoff = vma->vm_pgoff;
+	vma->vm_pgoff = HL_MMAP_OFFSET_VALUE_GET(vm_pgoff);
+
+	switch (vm_pgoff & HL_MMAP_TYPE_MASK) {
+	case HL_MMAP_TYPE_CB:
 		return hl_cb_mmap(hpriv, vma);
 	}
 
diff --git a/drivers/misc/habanalabs/common/habanalabs.h b/drivers/misc/habanalabs/common/habanalabs.h
index 6912f88a4b01..cdb7a672ed30 100644
--- a/drivers/misc/habanalabs/common/habanalabs.h
+++ b/drivers/misc/habanalabs/common/habanalabs.h
@@ -22,7 +22,19 @@
 
 #define HL_NAME				"habanalabs"
 
-#define HL_MMAP_CB_MASK			(0x8000000000000000ull >> PAGE_SHIFT)
+/* Use upper bits of mmap offset to store habana driver specific information.
+ * bits[63:62] - Encode mmap type
+ * bits[45:0]  - mmap offset value
+ *
+ * NOTE: struct vm_area_struct.vm_pgoff uses offset in pages. Hence, these
+ *  defines are w.r.t to PAGE_SIZE
+ */
+#define HL_MMAP_TYPE_SHIFT		(62 - PAGE_SHIFT)
+#define HL_MMAP_TYPE_MASK		(0x3ull << HL_MMAP_TYPE_SHIFT)
+#define HL_MMAP_TYPE_CB			(0x2ull << HL_MMAP_TYPE_SHIFT)
+
+#define HL_MMAP_OFFSET_VALUE_MASK	(0x3FFFFFFFFFFFull >> PAGE_SHIFT)
+#define HL_MMAP_OFFSET_VALUE_GET(off)	(off & HL_MMAP_OFFSET_VALUE_MASK)
 
 #define HL_PENDING_RESET_PER_SEC	30
 
-- 
2.17.1