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Subject[PATCH v2 17/18] powerpc/vas: Define vas_win_id()
Date
Define an interface to return a system-wide unique id for a given VAS
window.

The vas_win_id() will be used in a follow-on patch to generate an unique
handle for a user space receive window. Applications can use this handle
to pair send and receive windows for fast thread-wakeup.

The hardware refers to this system-wide unique id as a Partition Send
Window ID which is expected to be used during fault handling. Hence the
"pswid" in the function names.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/vas.h | 5 +++++
arch/powerpc/platforms/powernv/vas-window.c | 9 +++++++++
arch/powerpc/platforms/powernv/vas.h | 28 ++++++++++++++++++++++++++++
3 files changed, 42 insertions(+)

diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
index f98ade8..7714562 100644
--- a/arch/powerpc/include/asm/vas.h
+++ b/arch/powerpc/include/asm/vas.h
@@ -168,6 +168,11 @@ int vas_copy_crb(void *crb, int offset);
int vas_paste_crb(struct vas_window *win, int offset, bool re);

/*
+ * Return a system-wide unique id for the VAS window @win.
+ */
+extern u32 vas_win_id(struct vas_window *win);
+
+/*
* Return the power bus paste address associated with @win so the caller
* can map that address into their address space.
*/
diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index e4a9c7b..1d08b64 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1239,3 +1239,12 @@ int vas_win_close(struct vas_window *window)
return 0;
}
EXPORT_SYMBOL_GPL(vas_win_close);
+
+/*
+ * Return a system-wide unique window id for the window @win.
+ */
+u32 vas_win_id(struct vas_window *win)
+{
+ return encode_pswid(win->vinst->vas_id, win->winid);
+}
+EXPORT_SYMBOL_GPL(vas_win_id);
diff --git a/arch/powerpc/platforms/powernv/vas.h b/arch/powerpc/platforms/powernv/vas.h
index 145749a..78a8926 100644
--- a/arch/powerpc/platforms/powernv/vas.h
+++ b/arch/powerpc/platforms/powernv/vas.h
@@ -447,4 +447,32 @@ static inline u64 read_hvwc_reg(struct vas_window *win,
return in_be64(win->hvwc_map+reg);
}

+/*
+ * Encode/decode the Partition Send Window ID (PSWID) for a window in
+ * a way that we can uniquely identify any window in the system. i.e.
+ * we should be able to locate the 'struct vas_window' given the PSWID.
+ *
+ * Bits Usage
+ * 0:7 VAS id (8 bits)
+ * 8:15 Unused, 0 (3 bits)
+ * 16:31 Window id (16 bits)
+ */
+static inline u32 encode_pswid(int vasid, int winid)
+{
+ u32 pswid = 0;
+
+ pswid |= vasid << (31 - 7);
+ pswid |= winid;
+
+ return pswid;
+}
+
+static inline void decode_pswid(u32 pswid, int *vasid, int *winid)
+{
+ if (vasid)
+ *vasid = pswid >> (31 - 7) & 0xFF;
+
+ if (winid)
+ *winid = pswid & 0xFFFF;
+}
#endif /* _VAS_H */
--
2.7.4
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