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metag: handle low level kicks directly 

Kick interrupts trigger the LWK (low level kick) signal, usually handled
by the __TBIDoStdLWK() function which is the only handler inherited from
the bootloader. The LWK signal is converted either to a SWK (plain
software kick) or a SWS (software kick with an attached message).

Linux has kick_handler() to handle SWK and call registered kick handlers
(IPIs and inter-thread comms), but SWS is as far as I'm aware unused
with Linux.

Therefore remove that abstraction and have Linux handle LWK directly.
This will reduce kick latency slightly, and reduce our dependence on the
bootloader, which makes it easier to directly boot a kernel in QEMU
(particularly for SMP).

Signed-off-by: James Hogan <james.hogan@imgtec.com>
This commit is contained in:
James Hogan 2013-11-05 14:42:03 +00:00
parent 5e01dc7b26
commit 95281171a7
4 changed files with 11 additions and 21 deletions
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19
arch/metag/include/asm/tbx.h
View File

@ -150,11 +150,9 @@
#else
/* Reserved 0x04-0x09 */
#endif
#define TBID_SIGNUM_SWS 0x0A /* KICK received with SigMask != 0 */
#define TBID_SIGNUM_SWK 0x0B /* KICK received with SigMask == 0 */
/* Reserved 0x0C-0x0F */
/* Reserved 0x0A-0x0F */
#define TBID_SIGNUM_TRT 0x10 /* Timer trigger */
#define TBID_SIGNUM_LWK 0x11 /* Low level kick (handler provided by TBI) */
#define TBID_SIGNUM_LWK 0x11 /* Low level kick */
#define TBID_SIGNUM_XXF 0x12 /* Fault handler - receives ALL _xxF sigs */
#ifdef TBI_1_4
#define TBID_SIGNUM_DFR 0x13 /* Deferred Exception handler */
@ -183,8 +181,7 @@
each hardware signal, sometimes this is a many-to-one relationship. */
#define TBI_TRIG_BIT(SigNum) (\
((SigNum) >= TBID_SIGNUM_TRT) ? 1<<((SigNum)-TBID_SIGNUM_TRT) :\
( ((SigNum) == TBID_SIGNUM_SWS) || \
((SigNum) == TBID_SIGNUM_SWK) ) ? \
((SigNum) == TBID_SIGNUM_LWK) ? \
TXSTAT_KICK_BIT : TXSTATI_BGNDHALT_BIT )
/* Return the hardware trigger vector number for entries in the
@ -687,10 +684,8 @@ typedef union _tbires_tag_ {
Triggers will indicate the status of TXSTAT or TXSTATI sampled by the
code that called the handler.
InstOrSWSId is defined firstly as 'Inst' if the SigNum is TBID_SIGNUM_SWx
and hold the actual SWITCH instruction detected, secondly if SigNum
is TBID_SIGNUM_SWS the 'SWSId' is defined to hold the Id of the
software signal detected, in other cases the value of this
Inst is defined as 'Inst' if the SigNum is TBID_SIGNUM_SWx and holds the
actual SWITCH instruction detected, in other cases the value of this
parameter is undefined.
pTBI points at the PTBI structure related to the thread and processing
@ -709,7 +704,7 @@ typedef union _tbires_tag_ {
*/
typedef TBIRES (*PTBIAPIFN)( TBIRES State, int SigNum,
int Triggers, int InstOrSWSId,
int Triggers, int Inst,
volatile struct _tbi_tag_ *pTBI );
#endif /* ifndef __ASSEMBLY__ */
@ -757,7 +752,7 @@ typedef volatile struct _tbi_tag_ {
#ifndef __ASSEMBLY__
/* This handler should be used for TBID_SIGNUM_DFR */
extern TBIRES __TBIHandleDFR ( TBIRES State, int SigNum,
int Triggers, int InstOrSWSId,
int Triggers, int Inst,
volatile struct _tbi_tag_ *pTBI );
#endif
#endif

6
arch/metag/kernel/setup.c
View File

@ -302,13 +302,9 @@ void __init setup_arch(char **cmdline_p)
* rather than the version from the bootloader. This makes call
* stacks easier to understand and may allow us to unmap the
* bootloader at some point.
*
* We need to keep the LWK handler that TBI installed in order to
* be able to do inter-thread comms.
*/
for (i = 0; i <= TBID_SIGNUM_MAX; i++)
if (i != TBID_SIGNUM_LWK)
_pTBI->fnSigs[i] = __TBIUnExpXXX;
_pTBI->fnSigs[i] = __TBIUnExpXXX;
/* A Meta requirement is that the kernel is loaded (virtually)
* at the PAGE_OFFSET.

5
arch/metag/kernel/traps.c
View File

@ -819,8 +819,7 @@ void per_cpu_trap_init(unsigned long cpu)
set_trigger_mask(TBI_INTS_INIT(thread) | /* interrupts */
TBI_TRIG_BIT(TBID_SIGNUM_LWK) | /* low level kick */
TBI_TRIG_BIT(TBID_SIGNUM_SW1) |
TBI_TRIG_BIT(TBID_SIGNUM_SWS));
TBI_TRIG_BIT(TBID_SIGNUM_SW1));
/* non-priv - use current stack */
int_context.Sig.pCtx = NULL;
@ -842,7 +841,7 @@ void __init trap_init(void)
_pTBI->fnSigs[TBID_SIGNUM_SW1] = switch1_handler;
_pTBI->fnSigs[TBID_SIGNUM_SW2] = switchx_handler;
_pTBI->fnSigs[TBID_SIGNUM_SW3] = switchx_handler;
_pTBI->fnSigs[TBID_SIGNUM_SWK] = kick_handler;
_pTBI->fnSigs[TBID_SIGNUM_LWK] = kick_handler;
#ifdef CONFIG_METAG_META21
_pTBI->fnSigs[TBID_SIGNUM_DFR] = __TBIHandleDFR;

2
arch/metag/tbx/tbidefr.S
View File

@ -20,7 +20,7 @@
/* D1Ar1:D0Ar2 -- State
* D0Ar3 -- SigNum
* D0Ar4 -- Triggers
* D1Ar5 -- InstOrSWSId
* D1Ar5 -- Inst
* D0Ar6 -- pTBI (volatile)
*/
___TBIHandleDFR: