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powerpc/vas: Define vas_win_id() 

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Sukadev Bhattiprolu 2017-11-07 18:23:57 -08:00 committed by Michael Ellerman
parent 5676be2fb7
commit 61f3cca8cd
3 changed files with 42 additions and 0 deletions
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5
arch/powerpc/include/asm/vas.h
View File

@ -167,6 +167,11 @@ 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.

9
arch/powerpc/platforms/powernv/vas-window.c
View File

@ -1235,3 +1235,12 @@ 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);

28
arch/powerpc/platforms/powernv/vas.h
View File

@ -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 */