[PATCH] habanalabs: Add CB IOCTL opcode to retrieve CB information

[Oded Gabbay]

From: Tomer Tayar <tta...@habana.ai>

Add a new CB IOCTL opcode that enables a user to query about a CB and
get its usage count.

Signed-off-by: Tomer Tayar <tta...@habana.ai>
Reviewed-by: Oded Gabbay <ogab...@kernel.org>
Signed-off-by: Oded Gabbay <ogab...@kernel.org>
---
 .../misc/habanalabs/common/command_buffer.c   | 38 +++++++++++++++++++
 include/uapi/misc/habanalabs.h                | 15 +++++++-
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_buffer.c 
b/drivers/misc/habanalabs/common/command_buffer.c
index 2856bb3423ee..6f6a904ab6ca 100644
--- a/drivers/misc/habanalabs/common/command_buffer.c
+++ b/drivers/misc/habanalabs/common/command_buffer.c
@@ -375,12 +375,43 @@ int hl_cb_destroy(struct hl_device *hdev, struct 
hl_cb_mgr *mgr, u64 cb_handle)
        return rc;
 }
 
+static int hl_cb_info(struct hl_device *hdev, struct hl_cb_mgr *mgr,
+                       u64 cb_handle, u32 *usage_cnt)
+{
+       struct hl_cb *cb;
+       u32 handle;
+       int rc = 0;
+
+       /* The CB handle was given to user to do mmap, so need to shift it back
+        * to the value which was allocated by the IDR module.
+        */
+       cb_handle >>= PAGE_SHIFT;
+       handle = (u32) cb_handle;
+
+       spin_lock(&mgr->cb_lock);
+
+       cb = idr_find(&mgr->cb_handles, handle);
+       if (!cb) {
+               dev_err(hdev->dev,
+                       "CB info failed, no match to handle 0x%x\n", handle);
+               rc = -EINVAL;
+               goto out;
+       }
+
+       *usage_cnt = atomic_read(&cb->cs_cnt);
+
+out:
+       spin_unlock(&mgr->cb_lock);
+       return rc;
+}
+
 int hl_cb_ioctl(struct hl_fpriv *hpriv, void *data)
 {
        union hl_cb_args *args = data;
        struct hl_device *hdev = hpriv->hdev;
        enum hl_device_status status;
        u64 handle = 0;
+       u32 usage_cnt = 0;
        int rc;
 
        if (!hl_device_operational(hdev, &status)) {
@@ -413,6 +444,13 @@ int hl_cb_ioctl(struct hl_fpriv *hpriv, void *data)
                                        args->in.cb_handle);
                break;
 
+       case HL_CB_OP_INFO:
+               rc = hl_cb_info(hdev, &hpriv->cb_mgr, args->in.cb_handle,
+                               &usage_cnt);
+               memset(args, 0, sizeof(*args));
+               args->out.usage_cnt = usage_cnt;
+               break;
+
        default:
                rc = -ENOTTY;
                break;
diff --git a/include/uapi/misc/habanalabs.h b/include/uapi/misc/habanalabs.h
index 6eff4e05eccb..8c15a7d336a0 100644
--- a/include/uapi/misc/habanalabs.h
+++ b/include/uapi/misc/habanalabs.h
@@ -483,6 +483,8 @@ struct hl_info_args {
 #define HL_CB_OP_CREATE                0
 /* Opcode to destroy previously created command buffer */
 #define HL_CB_OP_DESTROY       1
+/* Opcode to retrieve information about a command buffer */
+#define HL_CB_OP_INFO          2
 
 /* 2MB minus 32 bytes for 2xMSG_PROT */
 #define HL_MAX_CB_SIZE         (0x200000 - 32)
@@ -506,8 +508,17 @@ struct hl_cb_in {
 };
 
 struct hl_cb_out {
-       /* Handle of CB */
-       __u64 cb_handle;
+       union {
+               /* Handle of CB */
+               __u64 cb_handle;
+
+               /* Information about CB */
+               struct {
+                       /* Usage count of CB */
+                       __u32 usage_cnt;
+                       __u32 pad;
+               };
+       };
 };
 
 union hl_cb_args {
-- 
2.17.1