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linux-pinenote/arch/mips/kernel/smtc.c
Robert P. J. Day 5255366403 MIPS: Initialize an atomic_t properly with ATOMIC_INIT(0). 
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1008/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-04-12 17:26:12 +01:00

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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) 2004 Mips Technologies, Inc
* Copyright (C) 2008 Kevin D. Kissell
*/
#include <linux/clockchips.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/slab.h>
#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/hardirq.h>
#include <asm/hazards.h>
#include <asm/irq.h>
#include <asm/mmu_context.h>
#include <asm/mipsregs.h>
#include <asm/cacheflush.h>
#include <asm/time.h>
#include <asm/addrspace.h>
#include <asm/smtc.h>
#include <asm/smtc_proc.h>
/*
* SMTC Kernel needs to manipulate low-level CPU interrupt mask
* in do_IRQ. These are passed in setup_irq_smtc() and stored
* in this table.
*/
unsigned long irq_hwmask[NR_IRQS];
#define LOCK_MT_PRA() \
local_irq_save(flags); \
mtflags = dmt()
#define UNLOCK_MT_PRA() \
emt(mtflags); \
local_irq_restore(flags)
#define LOCK_CORE_PRA() \
local_irq_save(flags); \
mtflags = dvpe()
#define UNLOCK_CORE_PRA() \
evpe(mtflags); \
local_irq_restore(flags)
/*
* Data structures purely associated with SMTC parallelism
*/
/*
* Table for tracking ASIDs whose lifetime is prolonged.
*/
asiduse smtc_live_asid[MAX_SMTC_TLBS][MAX_SMTC_ASIDS];
/*
* Number of InterProcessor Interrupt (IPI) message buffers to allocate
*/
#define IPIBUF_PER_CPU 4
struct smtc_ipi_q IPIQ[NR_CPUS];
static struct smtc_ipi_q freeIPIq;
/* Forward declarations */
void ipi_decode(struct smtc_ipi *);
static void post_direct_ipi(int cpu, struct smtc_ipi *pipi);
static void setup_cross_vpe_interrupts(unsigned int nvpe);
void init_smtc_stats(void);
/* Global SMTC Status */
unsigned int smtc_status;
/* Boot command line configuration overrides */
static int vpe0limit;
static int ipibuffers;
static int nostlb;
static int asidmask;
unsigned long smtc_asid_mask = 0xff;
static int __init vpe0tcs(char *str)
{
get_option(&str, &vpe0limit);
return 1;
}
static int __init ipibufs(char *str)
{
get_option(&str, &ipibuffers);
return 1;
}
static int __init stlb_disable(char *s)
{
nostlb = 1;
return 1;
}
static int __init asidmask_set(char *str)
{
get_option(&str, &asidmask);
switch (asidmask) {
case 0x1:
case 0x3:
case 0x7:
case 0xf:
case 0x1f:
case 0x3f:
case 0x7f:
case 0xff:
smtc_asid_mask = (unsigned long)asidmask;
break;
default:
printk("ILLEGAL ASID mask 0x%x from command line\n", asidmask);
}
return 1;
}
__setup("vpe0tcs=", vpe0tcs);
__setup("ipibufs=", ipibufs);
__setup("nostlb", stlb_disable);
__setup("asidmask=", asidmask_set);
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
static int hang_trig;
static int __init hangtrig_enable(char *s)
{
hang_trig = 1;
return 1;
}
__setup("hangtrig", hangtrig_enable);
#define DEFAULT_BLOCKED_IPI_LIMIT 32
static int timerq_limit = DEFAULT_BLOCKED_IPI_LIMIT;
static int __init tintq(char *str)
{
get_option(&str, &timerq_limit);
return 1;
}
__setup("tintq=", tintq);
static int imstuckcount[2][8];
/* vpemask represents IM/IE bits of per-VPE Status registers, low-to-high */
static int vpemask[2][8] = {
{0, 0, 1, 0, 0, 0, 0, 1},
{0, 0, 0, 0, 0, 0, 0, 1}
};
int tcnoprog[NR_CPUS];
static atomic_t idle_hook_initialized = ATOMIC_INIT(0);
static int clock_hang_reported[NR_CPUS];
#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
/*
* Configure shared TLB - VPC configuration bit must be set by caller
*/
static void smtc_configure_tlb(void)
{
int i, tlbsiz, vpes;
unsigned long mvpconf0;
unsigned long config1val;
/* Set up ASID preservation table */
for (vpes=0; vpes<MAX_SMTC_TLBS; vpes++) {
for(i = 0; i < MAX_SMTC_ASIDS; i++) {
smtc_live_asid[vpes][i] = 0;
}
}
mvpconf0 = read_c0_mvpconf0();
if ((vpes = ((mvpconf0 & MVPCONF0_PVPE)
>> MVPCONF0_PVPE_SHIFT) + 1) > 1) {
/* If we have multiple VPEs, try to share the TLB */
if ((mvpconf0 & MVPCONF0_TLBS) && !nostlb) {
/*
* If TLB sizing is programmable, shared TLB
* size is the total available complement.
* Otherwise, we have to take the sum of all
* static VPE TLB entries.
*/
if ((tlbsiz = ((mvpconf0 & MVPCONF0_PTLBE)
>> MVPCONF0_PTLBE_SHIFT)) == 0) {
/*
* If there's more than one VPE, there had better
* be more than one TC, because we need one to bind
* to each VPE in turn to be able to read
* its configuration state!
*/
settc(1);
/* Stop the TC from doing anything foolish */
write_tc_c0_tchalt(TCHALT_H);
mips_ihb();
/* No need to un-Halt - that happens later anyway */
for (i=0; i < vpes; i++) {
write_tc_c0_tcbind(i);
/*
* To be 100% sure we're really getting the right
* information, we exit the configuration state
* and do an IHB after each rebinding.
*/
write_c0_mvpcontrol(
read_c0_mvpcontrol() & ~ MVPCONTROL_VPC );
mips_ihb();
/*
* Only count if the MMU Type indicated is TLB
*/
if (((read_vpe_c0_config() & MIPS_CONF_MT) >> 7) == 1) {
config1val = read_vpe_c0_config1();
tlbsiz += ((config1val >> 25) & 0x3f) + 1;
}
/* Put core back in configuration state */
write_c0_mvpcontrol(
read_c0_mvpcontrol() | MVPCONTROL_VPC );
mips_ihb();
}
}
write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_STLB);
ehb();
/*
* Setup kernel data structures to use software total,
* rather than read the per-VPE Config1 value. The values
* for "CPU 0" gets copied to all the other CPUs as part
* of their initialization in smtc_cpu_setup().
*/
/* MIPS32 limits TLB indices to 64 */
if (tlbsiz > 64)
tlbsiz = 64;
cpu_data[0].tlbsize = current_cpu_data.tlbsize = tlbsiz;
smtc_status |= SMTC_TLB_SHARED;
local_flush_tlb_all();
printk("TLB of %d entry pairs shared by %d VPEs\n",
tlbsiz, vpes);
} else {
printk("WARNING: TLB Not Sharable on SMTC Boot!\n");
}
}
}
/*
* Incrementally build the CPU map out of constituent MIPS MT cores,
* using the specified available VPEs and TCs. Plaform code needs
* to ensure that each MIPS MT core invokes this routine on reset,
* one at a time(!).
*
* This version of the build_cpu_map and prepare_cpus routines assumes
* that *all* TCs of a MIPS MT core will be used for Linux, and that
* they will be spread across *all* available VPEs (to minimise the
* loss of efficiency due to exception service serialization).
* An improved version would pick up configuration information and
* possibly leave some TCs/VPEs as "slave" processors.
*
* Use c0_MVPConf0 to find out how many TCs are available, setting up
* cpu_possible_map and the logical/physical mappings.
*/
int __init smtc_build_cpu_map(int start_cpu_slot)
{
int i, ntcs;
/*
* The CPU map isn't actually used for anything at this point,
* so it's not clear what else we should do apart from set
* everything up so that "logical" = "physical".
*/
ntcs = ((read_c0_mvpconf0() & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
for (i=start_cpu_slot; i<NR_CPUS && i<ntcs; i++) {
set_cpu_possible(i, true);
__cpu_number_map[i] = i;
__cpu_logical_map[i] = i;
}
#ifdef CONFIG_MIPS_MT_FPAFF
/* Initialize map of CPUs with FPUs */
cpus_clear(mt_fpu_cpumask);
#endif
/* One of those TC's is the one booting, and not a secondary... */
printk("%i available secondary CPU TC(s)\n", i - 1);
return i;
}
/*
* Common setup before any secondaries are started
* Make sure all CPU's are in a sensible state before we boot any of the
* secondaries.
*
* For MIPS MT "SMTC" operation, we set up all TCs, spread as evenly
* as possible across the available VPEs.
*/
static void smtc_tc_setup(int vpe, int tc, int cpu)
{
settc(tc);
write_tc_c0_tchalt(TCHALT_H);
mips_ihb();
write_tc_c0_tcstatus((read_tc_c0_tcstatus()
& ~(TCSTATUS_TKSU | TCSTATUS_DA | TCSTATUS_IXMT))
| TCSTATUS_A);
/*
* TCContext gets an offset from the base of the IPIQ array
* to be used in low-level code to detect the presence of
* an active IPI queue
*/
write_tc_c0_tccontext((sizeof(struct smtc_ipi_q) * cpu) << 16);
/* Bind tc to vpe */
write_tc_c0_tcbind(vpe);
/* In general, all TCs should have the same cpu_data indications */
memcpy(&cpu_data[cpu], &cpu_data[0], sizeof(struct cpuinfo_mips));
/* For 34Kf, start with TC/CPU 0 as sole owner of single FPU context */
if (cpu_data[0].cputype == CPU_34K ||
cpu_data[0].cputype == CPU_1004K)
cpu_data[cpu].options &= ~MIPS_CPU_FPU;
cpu_data[cpu].vpe_id = vpe;
cpu_data[cpu].tc_id = tc;
/* Multi-core SMTC hasn't been tested, but be prepared */
cpu_data[cpu].core = (read_vpe_c0_ebase() >> 1) & 0xff;
}
/*
* Tweak to get Count registes in as close a sync as possible.
* Value seems good for 34K-class cores.
*/
#define CP0_SKEW 8
void smtc_prepare_cpus(int cpus)
{
int i, vpe, tc, ntc, nvpe, tcpervpe[NR_CPUS], slop, cpu;
unsigned long flags;
unsigned long val;
int nipi;
struct smtc_ipi *pipi;
/* disable interrupts so we can disable MT */
local_irq_save(flags);
/* disable MT so we can configure */
dvpe();
dmt();
spin_lock_init(&freeIPIq.lock);
/*
* We probably don't have as many VPEs as we do SMP "CPUs",
* but it's possible - and in any case we'll never use more!
*/
for (i=0; i<NR_CPUS; i++) {
IPIQ[i].head = IPIQ[i].tail = NULL;
spin_lock_init(&IPIQ[i].lock);
IPIQ[i].depth = 0;
IPIQ[i].resched_flag = 0; /* No reschedules queued initially */
}
/* cpu_data index starts at zero */
cpu = 0;
cpu_data[cpu].vpe_id = 0;
cpu_data[cpu].tc_id = 0;
cpu_data[cpu].core = (read_c0_ebase() >> 1) & 0xff;
cpu++;
/* Report on boot-time options */
mips_mt_set_cpuoptions();
if (vpelimit > 0)
printk("Limit of %d VPEs set\n", vpelimit);
if (tclimit > 0)
printk("Limit of %d TCs set\n", tclimit);
if (nostlb) {
printk("Shared TLB Use Inhibited - UNSAFE for Multi-VPE Operation\n");
}
if (asidmask)
printk("ASID mask value override to 0x%x\n", asidmask);
/* Temporary */
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
if (hang_trig)
printk("Logic Analyser Trigger on suspected TC hang\n");
#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
/* Put MVPE's into 'configuration state' */
write_c0_mvpcontrol( read_c0_mvpcontrol() | MVPCONTROL_VPC );
val = read_c0_mvpconf0();
nvpe = ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
if (vpelimit > 0 && nvpe > vpelimit)
nvpe = vpelimit;
ntc = ((val & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
if (ntc > NR_CPUS)
ntc = NR_CPUS;
if (tclimit > 0 && ntc > tclimit)
ntc = tclimit;
slop = ntc % nvpe;
for (i = 0; i < nvpe; i++) {
tcpervpe[i] = ntc / nvpe;
if (slop) {
if((slop - i) > 0) tcpervpe[i]++;
}
}
/* Handle command line override for VPE0 */
if (vpe0limit > ntc) vpe0limit = ntc;
if (vpe0limit > 0) {
int slopslop;
if (vpe0limit < tcpervpe[0]) {
/* Reducing TC count - distribute to others */
slop = tcpervpe[0] - vpe0limit;
slopslop = slop % (nvpe - 1);
tcpervpe[0] = vpe0limit;
for (i = 1; i < nvpe; i++) {
tcpervpe[i] += slop / (nvpe - 1);
if(slopslop && ((slopslop - (i - 1) > 0)))
tcpervpe[i]++;
}
} else if (vpe0limit > tcpervpe[0]) {
/* Increasing TC count - steal from others */
slop = vpe0limit - tcpervpe[0];
slopslop = slop % (nvpe - 1);
tcpervpe[0] = vpe0limit;
for (i = 1; i < nvpe; i++) {
tcpervpe[i] -= slop / (nvpe - 1);
if(slopslop && ((slopslop - (i - 1) > 0)))
tcpervpe[i]--;
}
}
}
/* Set up shared TLB */
smtc_configure_tlb();
for (tc = 0, vpe = 0 ; (vpe < nvpe) && (tc < ntc) ; vpe++) {
if (tcpervpe[vpe] == 0)
continue;
if (vpe != 0)
printk(", ");
printk("VPE %d: TC", vpe);
for (i = 0; i < tcpervpe[vpe]; i++) {
/*
* TC 0 is bound to VPE 0 at reset,
* and is presumably executing this
* code. Leave it alone!
*/
if (tc != 0) {
smtc_tc_setup(vpe, tc, cpu);
cpu++;
}
printk(" %d", tc);
tc++;
}
if (vpe != 0) {
/*
* Allow this VPE to control others.
*/
write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() |
VPECONF0_MVP);
/*
* Clear any stale software interrupts from VPE's Cause
*/
write_vpe_c0_cause(0);
/*
* Clear ERL/EXL of VPEs other than 0
* and set restricted interrupt enable/mask.
*/
write_vpe_c0_status((read_vpe_c0_status()
& ~(ST0_BEV | ST0_ERL | ST0_EXL | ST0_IM))
| (STATUSF_IP0 | STATUSF_IP1 | STATUSF_IP7
| ST0_IE));
/*
* set config to be the same as vpe0,
* particularly kseg0 coherency alg
*/
write_vpe_c0_config(read_c0_config());
/* Clear any pending timer interrupt */
write_vpe_c0_compare(0);
/* Propagate Config7 */
write_vpe_c0_config7(read_c0_config7());
write_vpe_c0_count(read_c0_count() + CP0_SKEW);
ehb();
}
/* enable multi-threading within VPE */
write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() | VPECONTROL_TE);
/* enable the VPE */
write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);
}
/*
* Pull any physically present but unused TCs out of circulation.
*/
while (tc < (((val & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1)) {
set_cpu_possible(tc, false);
set_cpu_present(tc, false);
tc++;
}
/* release config state */
write_c0_mvpcontrol( read_c0_mvpcontrol() & ~ MVPCONTROL_VPC );
printk("\n");
/* Set up coprocessor affinity CPU mask(s) */
#ifdef CONFIG_MIPS_MT_FPAFF
for (tc = 0; tc < ntc; tc++) {
if (cpu_data[tc].options & MIPS_CPU_FPU)
cpu_set(tc, mt_fpu_cpumask);
}
#endif
/* set up ipi interrupts... */
/* If we have multiple VPEs running, set up the cross-VPE interrupt */
setup_cross_vpe_interrupts(nvpe);
/* Set up queue of free IPI "messages". */
nipi = NR_CPUS * IPIBUF_PER_CPU;
if (ipibuffers > 0)
nipi = ipibuffers;
pipi = kmalloc(nipi *sizeof(struct smtc_ipi), GFP_KERNEL);
if (pipi == NULL)
panic("kmalloc of IPI message buffers failed\n");
else
printk("IPI buffer pool of %d buffers\n", nipi);
for (i = 0; i < nipi; i++) {
smtc_ipi_nq(&freeIPIq, pipi);
pipi++;
}
/* Arm multithreading and enable other VPEs - but all TCs are Halted */
emt(EMT_ENABLE);
evpe(EVPE_ENABLE);
local_irq_restore(flags);
/* Initialize SMTC /proc statistics/diagnostics */
init_smtc_stats();
}
/*
* Setup the PC, SP, and GP of a secondary processor and start it
* running!
* smp_bootstrap is the place to resume from
* __KSTK_TOS(idle) is apparently the stack pointer
* (unsigned long)idle->thread_info the gp
*
*/
void __cpuinit smtc_boot_secondary(int cpu, struct task_struct *idle)
{
extern u32 kernelsp[NR_CPUS];
unsigned long flags;
int mtflags;
LOCK_MT_PRA();
if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
dvpe();
}
settc(cpu_data[cpu].tc_id);
/* pc */
write_tc_c0_tcrestart((unsigned long)&smp_bootstrap);
/* stack pointer */
kernelsp[cpu] = __KSTK_TOS(idle);
write_tc_gpr_sp(__KSTK_TOS(idle));
/* global pointer */
write_tc_gpr_gp((unsigned long)task_thread_info(idle));
smtc_status |= SMTC_MTC_ACTIVE;
write_tc_c0_tchalt(0);
if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
evpe(EVPE_ENABLE);
}
UNLOCK_MT_PRA();
}
void smtc_init_secondary(void)
{
local_irq_enable();
}
void smtc_smp_finish(void)
{
int cpu = smp_processor_id();
/*
* Lowest-numbered CPU per VPE starts a clock tick.
* Like per_cpu_trap_init() hack, this assumes that
* SMTC init code assigns TCs consdecutively and
* in ascending order across available VPEs.
*/
if (cpu > 0 && (cpu_data[cpu].vpe_id != cpu_data[cpu - 1].vpe_id))
write_c0_compare(read_c0_count() + mips_hpt_frequency/HZ);
printk("TC %d going on-line as CPU %d\n",
cpu_data[smp_processor_id()].tc_id, smp_processor_id());
}
void smtc_cpus_done(void)
{
}
/*
* Support for SMTC-optimized driver IRQ registration
*/
/*
* SMTC Kernel needs to manipulate low-level CPU interrupt mask
* in do_IRQ. These are passed in setup_irq_smtc() and stored
* in this table.
*/
int setup_irq_smtc(unsigned int irq, struct irqaction * new,
unsigned long hwmask)
{
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
unsigned int vpe = current_cpu_data.vpe_id;
vpemask[vpe][irq - MIPS_CPU_IRQ_BASE] = 1;
#endif
irq_hwmask[irq] = hwmask;
return setup_irq(irq, new);
}
#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
/*
* Support for IRQ affinity to TCs
*/
void smtc_set_irq_affinity(unsigned int irq, cpumask_t affinity)
{
/*
* If a "fast path" cache of quickly decodable affinity state
* is maintained, this is where it gets done, on a call up
* from the platform affinity code.
*/
}
void smtc_forward_irq(unsigned int irq)
{
int target;
/*
* OK wise guy, now figure out how to get the IRQ
* to be serviced on an authorized "CPU".
*
* Ideally, to handle the situation where an IRQ has multiple
* eligible CPUS, we would maintain state per IRQ that would
* allow a fair distribution of service requests. Since the
* expected use model is any-or-only-one, for simplicity
* and efficiency, we just pick the easiest one to find.
*/
target = cpumask_first(irq_desc[irq].affinity);
/*
* We depend on the platform code to have correctly processed
* IRQ affinity change requests to ensure that the IRQ affinity
* mask has been purged of bits corresponding to nonexistent and
* offline "CPUs", and to TCs bound to VPEs other than the VPE
* connected to the physical interrupt input for the interrupt
* in question. Otherwise we have a nasty problem with interrupt
* mask management. This is best handled in non-performance-critical
* platform IRQ affinity setting code, to minimize interrupt-time
* checks.
*/
/* If no one is eligible, service locally */
if (target >= NR_CPUS) {
do_IRQ_no_affinity(irq);
return;
}
smtc_send_ipi(target, IRQ_AFFINITY_IPI, irq);
}
#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
/*
* IPI model for SMTC is tricky, because interrupts aren't TC-specific.
* Within a VPE one TC can interrupt another by different approaches.
* The easiest to get right would probably be to make all TCs except
* the target IXMT and set a software interrupt, but an IXMT-based
* scheme requires that a handler must run before a new IPI could
* be sent, which would break the "broadcast" loops in MIPS MT.
* A more gonzo approach within a VPE is to halt the TC, extract
* its Restart, Status, and a couple of GPRs, and program the Restart
* address to emulate an interrupt.
*
* Within a VPE, one can be confident that the target TC isn't in
* a critical EXL state when halted, since the write to the Halt
* register could not have issued on the writing thread if the
* halting thread had EXL set. So k0 and k1 of the target TC
* can be used by the injection code. Across VPEs, one can't
* be certain that the target TC isn't in a critical exception
* state. So we try a two-step process of sending a software
* interrupt to the target VPE, which either handles the event
* itself (if it was the target) or injects the event within
* the VPE.
*/
static void smtc_ipi_qdump(void)
{
int i;
struct smtc_ipi *temp;
for (i = 0; i < NR_CPUS ;i++) {
pr_info("IPIQ[%d]: head = 0x%x, tail = 0x%x, depth = %d\n",
i, (unsigned)IPIQ[i].head, (unsigned)IPIQ[i].tail,
IPIQ[i].depth);
temp = IPIQ[i].head;
while (temp != IPIQ[i].tail) {
pr_debug("%d %d %d: ", temp->type, temp->dest,
(int)temp->arg);
#ifdef SMTC_IPI_DEBUG
pr_debug("%u %lu\n", temp->sender, temp->stamp);
#else
pr_debug("\n");
#endif
temp = temp->flink;
}
}
}
/*
* The standard atomic.h primitives don't quite do what we want
* here: We need an atomic add-and-return-previous-value (which
* could be done with atomic_add_return and a decrement) and an
* atomic set/zero-and-return-previous-value (which can't really
* be done with the atomic.h primitives). And since this is
* MIPS MT, we can assume that we have LL/SC.
*/
static inline int atomic_postincrement(atomic_t *v)
{
unsigned long result;
unsigned long temp;
__asm__ __volatile__(
"1: ll %0, %2 \n"
" addu %1, %0, 1 \n"
" sc %1, %2 \n"
" beqz %1, 1b \n"
__WEAK_LLSC_MB
: "=&r" (result), "=&r" (temp), "=m" (v->counter)
: "m" (v->counter)
: "memory");
return result;
}
void smtc_send_ipi(int cpu, int type, unsigned int action)
{
int tcstatus;
struct smtc_ipi *pipi;
unsigned long flags;
int mtflags;
unsigned long tcrestart;
extern void r4k_wait_irqoff(void), __pastwait(void);
int set_resched_flag = (type == LINUX_SMP_IPI &&
action == SMP_RESCHEDULE_YOURSELF);
if (cpu == smp_processor_id()) {
printk("Cannot Send IPI to self!\n");
return;
}
if (set_resched_flag && IPIQ[cpu].resched_flag != 0)
return; /* There is a reschedule queued already */
/* Set up a descriptor, to be delivered either promptly or queued */
pipi = smtc_ipi_dq(&freeIPIq);
if (pipi == NULL) {
bust_spinlocks(1);
mips_mt_regdump(dvpe());
panic("IPI Msg. Buffers Depleted\n");
}
pipi->type = type;
pipi->arg = (void *)action;
pipi->dest = cpu;
if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
/* If not on same VPE, enqueue and send cross-VPE interrupt */
IPIQ[cpu].resched_flag |= set_resched_flag;
smtc_ipi_nq(&IPIQ[cpu], pipi);
LOCK_CORE_PRA();
settc(cpu_data[cpu].tc_id);
write_vpe_c0_cause(read_vpe_c0_cause() | C_SW1);
UNLOCK_CORE_PRA();
} else {
/*
* Not sufficient to do a LOCK_MT_PRA (dmt) here,
* since ASID shootdown on the other VPE may
* collide with this operation.
*/
LOCK_CORE_PRA();
settc(cpu_data[cpu].tc_id);
/* Halt the targeted TC */
write_tc_c0_tchalt(TCHALT_H);
mips_ihb();
/*
* Inspect TCStatus - if IXMT is set, we have to queue
* a message. Otherwise, we set up the "interrupt"
* of the other TC
*/
tcstatus = read_tc_c0_tcstatus();
if ((tcstatus & TCSTATUS_IXMT) != 0) {
/*
* If we're in the the irq-off version of the wait
* loop, we need to force exit from the wait and
* do a direct post of the IPI.
*/
if (cpu_wait == r4k_wait_irqoff) {
tcrestart = read_tc_c0_tcrestart();
if (tcrestart >= (unsigned long)r4k_wait_irqoff
&& tcrestart < (unsigned long)__pastwait) {
write_tc_c0_tcrestart(__pastwait);
tcstatus &= ~TCSTATUS_IXMT;
write_tc_c0_tcstatus(tcstatus);
goto postdirect;
}
}
/*
* Otherwise we queue the message for the target TC
* to pick up when he does a local_irq_restore()
*/
write_tc_c0_tchalt(0);
UNLOCK_CORE_PRA();
IPIQ[cpu].resched_flag |= set_resched_flag;
smtc_ipi_nq(&IPIQ[cpu], pipi);
} else {
postdirect:
post_direct_ipi(cpu, pipi);
write_tc_c0_tchalt(0);
UNLOCK_CORE_PRA();
}
}
}
/*
* Send IPI message to Halted TC, TargTC/TargVPE already having been set
*/
static void post_direct_ipi(int cpu, struct smtc_ipi *pipi)
{
struct pt_regs *kstack;
unsigned long tcstatus;
unsigned long tcrestart;
extern u32 kernelsp[NR_CPUS];
extern void __smtc_ipi_vector(void);
//printk("%s: on %d for %d\n", __func__, smp_processor_id(), cpu);
/* Extract Status, EPC from halted TC */
tcstatus = read_tc_c0_tcstatus();
tcrestart = read_tc_c0_tcrestart();
/* If TCRestart indicates a WAIT instruction, advance the PC */
if ((tcrestart & 0x80000000)
&& ((*(unsigned int *)tcrestart & 0xfe00003f) == 0x42000020)) {
tcrestart += 4;
}
/*
* Save on TC's future kernel stack
*
* CU bit of Status is indicator that TC was
* already running on a kernel stack...
*/
if (tcstatus & ST0_CU0) {
/* Note that this "- 1" is pointer arithmetic */
kstack = ((struct pt_regs *)read_tc_gpr_sp()) - 1;
} else {
kstack = ((struct pt_regs *)kernelsp[cpu]) - 1;
}
kstack->cp0_epc = (long)tcrestart;
/* Save TCStatus */
kstack->cp0_tcstatus = tcstatus;
/* Pass token of operation to be performed kernel stack pad area */
kstack->pad0[4] = (unsigned long)pipi;
/* Pass address of function to be called likewise */
kstack->pad0[5] = (unsigned long)&ipi_decode;
/* Set interrupt exempt and kernel mode */
tcstatus |= TCSTATUS_IXMT;
tcstatus &= ~TCSTATUS_TKSU;
write_tc_c0_tcstatus(tcstatus);
ehb();
/* Set TC Restart address to be SMTC IPI vector */
write_tc_c0_tcrestart(__smtc_ipi_vector);
}
static void ipi_resched_interrupt(void)
{
/* Return from interrupt should be enough to cause scheduler check */
}
static void ipi_call_interrupt(void)
{
/* Invoke generic function invocation code in smp.c */
smp_call_function_interrupt();
}
DECLARE_PER_CPU(struct clock_event_device, mips_clockevent_device);
static void __irq_entry smtc_clock_tick_interrupt(void)
{
unsigned int cpu = smp_processor_id();
struct clock_event_device *cd;
int irq = MIPS_CPU_IRQ_BASE + 1;
irq_enter();
kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
cd = &per_cpu(mips_clockevent_device, cpu);
cd->event_handler(cd);
irq_exit();
}
void ipi_decode(struct smtc_ipi *pipi)
{
void *arg_copy = pipi->arg;
int type_copy = pipi->type;
smtc_ipi_nq(&freeIPIq, pipi);
switch (type_copy) {
case SMTC_CLOCK_TICK:
smtc_clock_tick_interrupt();
break;
case LINUX_SMP_IPI:
switch ((int)arg_copy) {
case SMP_RESCHEDULE_YOURSELF:
ipi_resched_interrupt();
break;
case SMP_CALL_FUNCTION:
ipi_call_interrupt();
break;
default:
printk("Impossible SMTC IPI Argument 0x%x\n",
(int)arg_copy);
break;
}
break;
#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
case IRQ_AFFINITY_IPI:
/*
* Accept a "forwarded" interrupt that was initially
* taken by a TC who doesn't have affinity for the IRQ.
*/
do_IRQ_no_affinity((int)arg_copy);
break;
#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
default:
printk("Impossible SMTC IPI Type 0x%x\n", type_copy);
break;
}
}
/*
* Similar to smtc_ipi_replay(), but invoked from context restore,
* so it reuses the current exception frame rather than set up a
* new one with self_ipi.
*/
void deferred_smtc_ipi(void)
{
int cpu = smp_processor_id();
/*
* Test is not atomic, but much faster than a dequeue,
* and the vast majority of invocations will have a null queue.
* If irq_disabled when this was called, then any IPIs queued
* after we test last will be taken on the next irq_enable/restore.
* If interrupts were enabled, then any IPIs added after the
* last test will be taken directly.
*/
while (IPIQ[cpu].head != NULL) {
struct smtc_ipi_q *q = &IPIQ[cpu];
struct smtc_ipi *pipi;
unsigned long flags;
/*
* It may be possible we'll come in with interrupts
* already enabled.
*/
local_irq_save(flags);
spin_lock(&q->lock);
pipi = __smtc_ipi_dq(q);
spin_unlock(&q->lock);
if (pipi != NULL) {
if (pipi->type == LINUX_SMP_IPI &&
(int)pipi->arg == SMP_RESCHEDULE_YOURSELF)
IPIQ[cpu].resched_flag = 0;
ipi_decode(pipi);
}
/*
* The use of the __raw_local restore isn't
* as obviously necessary here as in smtc_ipi_replay(),
* but it's more efficient, given that we're already
* running down the IPI queue.
*/
__raw_local_irq_restore(flags);
}
}
/*
* Cross-VPE interrupts in the SMTC prototype use "software interrupts"
* set via cross-VPE MTTR manipulation of the Cause register. It would be
* in some regards preferable to have external logic for "doorbell" hardware
* interrupts.
*/
static int cpu_ipi_irq = MIPS_CPU_IRQ_BASE + MIPS_CPU_IPI_IRQ;
static irqreturn_t ipi_interrupt(int irq, void *dev_idm)
{
int my_vpe = cpu_data[smp_processor_id()].vpe_id;
int my_tc = cpu_data[smp_processor_id()].tc_id;
int cpu;
struct smtc_ipi *pipi;
unsigned long tcstatus;
int sent;
unsigned long flags;
unsigned int mtflags;
unsigned int vpflags;
/*
* So long as cross-VPE interrupts are done via
* MFTR/MTTR read-modify-writes of Cause, we need
* to stop other VPEs whenever the local VPE does
* anything similar.
*/
local_irq_save(flags);
vpflags = dvpe();
clear_c0_cause(0x100 << MIPS_CPU_IPI_IRQ);
set_c0_status(0x100 << MIPS_CPU_IPI_IRQ);
irq_enable_hazard();
evpe(vpflags);
local_irq_restore(flags);
/*
* Cross-VPE Interrupt handler: Try to directly deliver IPIs
* queued for TCs on this VPE other than the current one.
* Return-from-interrupt should cause us to drain the queue
* for the current TC, so we ought not to have to do it explicitly here.
*/
for_each_online_cpu(cpu) {
if (cpu_data[cpu].vpe_id != my_vpe)
continue;
pipi = smtc_ipi_dq(&IPIQ[cpu]);
if (pipi != NULL) {
if (cpu_data[cpu].tc_id != my_tc) {
sent = 0;
LOCK_MT_PRA();
settc(cpu_data[cpu].tc_id);
write_tc_c0_tchalt(TCHALT_H);
mips_ihb();
tcstatus = read_tc_c0_tcstatus();
if ((tcstatus & TCSTATUS_IXMT) == 0) {
post_direct_ipi(cpu, pipi);
sent = 1;
}
write_tc_c0_tchalt(0);
UNLOCK_MT_PRA();
if (!sent) {
smtc_ipi_req(&IPIQ[cpu], pipi);
}
} else {
/*
* ipi_decode() should be called
* with interrupts off
*/
local_irq_save(flags);
if (pipi->type == LINUX_SMP_IPI &&
(int)pipi->arg == SMP_RESCHEDULE_YOURSELF)
IPIQ[cpu].resched_flag = 0;
ipi_decode(pipi);
local_irq_restore(flags);
}
}
}
return IRQ_HANDLED;
}
static void ipi_irq_dispatch(void)
{
do_IRQ(cpu_ipi_irq);
}
static struct irqaction irq_ipi = {
.handler = ipi_interrupt,
.flags = IRQF_DISABLED | IRQF_PERCPU,
.name = "SMTC_IPI"
};
static void setup_cross_vpe_interrupts(unsigned int nvpe)
{
if (nvpe < 1)
return;
if (!cpu_has_vint)
panic("SMTC Kernel requires Vectored Interrupt support");
set_vi_handler(MIPS_CPU_IPI_IRQ, ipi_irq_dispatch);
setup_irq_smtc(cpu_ipi_irq, &irq_ipi, (0x100 << MIPS_CPU_IPI_IRQ));
set_irq_handler(cpu_ipi_irq, handle_percpu_irq);
}
/*
* SMTC-specific hacks invoked from elsewhere in the kernel.
*/
/*
* smtc_ipi_replay is called from raw_local_irq_restore
*/
void smtc_ipi_replay(void)
{
unsigned int cpu = smp_processor_id();
/*
* To the extent that we've ever turned interrupts off,
* we may have accumulated deferred IPIs. This is subtle.
* we should be OK: If we pick up something and dispatch
* it here, that's great. If we see nothing, but concurrent
* with this operation, another TC sends us an IPI, IXMT
* is clear, and we'll handle it as a real pseudo-interrupt
* and not a pseudo-pseudo interrupt. The important thing
* is to do the last check for queued message *after* the
* re-enabling of interrupts.
*/
while (IPIQ[cpu].head != NULL) {
struct smtc_ipi_q *q = &IPIQ[cpu];
struct smtc_ipi *pipi;
unsigned long flags;
/*
* It's just possible we'll come in with interrupts
* already enabled.
*/
local_irq_save(flags);
spin_lock(&q->lock);
pipi = __smtc_ipi_dq(q);
spin_unlock(&q->lock);
/*
** But use a raw restore here to avoid recursion.
*/
__raw_local_irq_restore(flags);
if (pipi) {
self_ipi(pipi);
smtc_cpu_stats[cpu].selfipis++;
}
}
}
EXPORT_SYMBOL(smtc_ipi_replay);
void smtc_idle_loop_hook(void)
{
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
int im;
int flags;
int mtflags;
int bit;
int vpe;
int tc;
int hook_ntcs;
/*
* printk within DMT-protected regions can deadlock,
* so buffer diagnostic messages for later output.
*/
char *pdb_msg;
char id_ho_db_msg[768]; /* worst-case use should be less than 700 */
if (atomic_read(&idle_hook_initialized) == 0) { /* fast test */
if (atomic_add_return(1, &idle_hook_initialized) == 1) {
int mvpconf0;
/* Tedious stuff to just do once */
mvpconf0 = read_c0_mvpconf0();
hook_ntcs = ((mvpconf0 & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
if (hook_ntcs > NR_CPUS)
hook_ntcs = NR_CPUS;
for (tc = 0; tc < hook_ntcs; tc++) {
tcnoprog[tc] = 0;
clock_hang_reported[tc] = 0;
}
for (vpe = 0; vpe < 2; vpe++)
for (im = 0; im < 8; im++)
imstuckcount[vpe][im] = 0;
printk("Idle loop test hook initialized for %d TCs\n", hook_ntcs);
atomic_set(&idle_hook_initialized, 1000);
} else {
/* Someone else is initializing in parallel - let 'em finish */
while (atomic_read(&idle_hook_initialized) < 1000)
;
}
}
/* Have we stupidly left IXMT set somewhere? */
if (read_c0_tcstatus() & 0x400) {
write_c0_tcstatus(read_c0_tcstatus() & ~0x400);
ehb();
printk("Dangling IXMT in cpu_idle()\n");
}
/* Have we stupidly left an IM bit turned off? */
#define IM_LIMIT 2000
local_irq_save(flags);
mtflags = dmt();
pdb_msg = &id_ho_db_msg[0];
im = read_c0_status();
vpe = current_cpu_data.vpe_id;
for (bit = 0; bit < 8; bit++) {
/*
* In current prototype, I/O interrupts
* are masked for VPE > 0
*/
if (vpemask[vpe][bit]) {
if (!(im & (0x100 << bit)))
imstuckcount[vpe][bit]++;
else
imstuckcount[vpe][bit] = 0;
if (imstuckcount[vpe][bit] > IM_LIMIT) {
set_c0_status(0x100 << bit);
ehb();
imstuckcount[vpe][bit] = 0;
pdb_msg += sprintf(pdb_msg,
"Dangling IM %d fixed for VPE %d\n", bit,
vpe);
}
}
}
emt(mtflags);
local_irq_restore(flags);
if (pdb_msg != &id_ho_db_msg[0])
printk("CPU%d: %s", smp_processor_id(), id_ho_db_msg);
#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
smtc_ipi_replay();
}
void smtc_soft_dump(void)
{
int i;
printk("Counter Interrupts taken per CPU (TC)\n");
for (i=0; i < NR_CPUS; i++) {
printk("%d: %ld\n", i, smtc_cpu_stats[i].timerints);
}
printk("Self-IPI invocations:\n");
for (i=0; i < NR_CPUS; i++) {
printk("%d: %ld\n", i, smtc_cpu_stats[i].selfipis);
}
smtc_ipi_qdump();
printk("%d Recoveries of \"stolen\" FPU\n",
atomic_read(&smtc_fpu_recoveries));
}
/*
* TLB management routines special to SMTC
*/
void smtc_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
{
unsigned long flags, mtflags, tcstat, prevhalt, asid;
int tlb, i;
/*
* It would be nice to be able to use a spinlock here,
* but this is invoked from within TLB flush routines
* that protect themselves with DVPE, so if a lock is
* held by another TC, it'll never be freed.
*
* DVPE/DMT must not be done with interrupts enabled,
* so even so most callers will already have disabled
* them, let's be really careful...
*/
local_irq_save(flags);
if (smtc_status & SMTC_TLB_SHARED) {
mtflags = dvpe();
tlb = 0;
} else {
mtflags = dmt();
tlb = cpu_data[cpu].vpe_id;
}
asid = asid_cache(cpu);
do {
if (!((asid += ASID_INC) & ASID_MASK) ) {
if (cpu_has_vtag_icache)
flush_icache_all();
/* Traverse all online CPUs (hack requires contiguous range) */
for_each_online_cpu(i) {
/*
* We don't need to worry about our own CPU, nor those of
* CPUs who don't share our TLB.
*/
if ((i != smp_processor_id()) &&
((smtc_status & SMTC_TLB_SHARED) ||
(cpu_data[i].vpe_id == cpu_data[cpu].vpe_id))) {
settc(cpu_data[i].tc_id);
prevhalt = read_tc_c0_tchalt() & TCHALT_H;
if (!prevhalt) {
write_tc_c0_tchalt(TCHALT_H);
mips_ihb();
}
tcstat = read_tc_c0_tcstatus();
smtc_live_asid[tlb][(tcstat & ASID_MASK)] |= (asiduse)(0x1 << i);
if (!prevhalt)
write_tc_c0_tchalt(0);
}
}
if (!asid) /* fix version if needed */
asid = ASID_FIRST_VERSION;
local_flush_tlb_all(); /* start new asid cycle */
}
} while (smtc_live_asid[tlb][(asid & ASID_MASK)]);
/*
* SMTC shares the TLB within VPEs and possibly across all VPEs.
*/
for_each_online_cpu(i) {
if ((smtc_status & SMTC_TLB_SHARED) ||
(cpu_data[i].vpe_id == cpu_data[cpu].vpe_id))
cpu_context(i, mm) = asid_cache(i) = asid;
}
if (smtc_status & SMTC_TLB_SHARED)
evpe(mtflags);
else
emt(mtflags);
local_irq_restore(flags);
}
/*
* Invoked from macros defined in mmu_context.h
* which must already have disabled interrupts
* and done a DVPE or DMT as appropriate.
*/
void smtc_flush_tlb_asid(unsigned long asid)
{
int entry;
unsigned long ehi;
entry = read_c0_wired();
/* Traverse all non-wired entries */
while (entry < current_cpu_data.tlbsize) {
write_c0_index(entry);
ehb();
tlb_read();
ehb();
ehi = read_c0_entryhi();
if ((ehi & ASID_MASK) == asid) {
/*
* Invalidate only entries with specified ASID,
* makiing sure all entries differ.
*/
write_c0_entryhi(CKSEG0 + (entry << (PAGE_SHIFT + 1)));
write_c0_entrylo0(0);
write_c0_entrylo1(0);
mtc0_tlbw_hazard();
tlb_write_indexed();
}
entry++;
}
write_c0_index(PARKED_INDEX);
tlbw_use_hazard();
}
/*
* Support for single-threading cache flush operations.
*/
static int halt_state_save[NR_CPUS];
/*
* To really, really be sure that nothing is being done
* by other TCs, halt them all. This code assumes that
* a DVPE has already been done, so while their Halted
* state is theoretically architecturally unstable, in
* practice, it's not going to change while we're looking
* at it.
*/
void smtc_cflush_lockdown(void)
{
int cpu;
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id()) {
settc(cpu_data[cpu].tc_id);
halt_state_save[cpu] = read_tc_c0_tchalt();
write_tc_c0_tchalt(TCHALT_H);
}
}
mips_ihb();
}
/* It would be cheating to change the cpu_online states during a flush! */
void smtc_cflush_release(void)
{
int cpu;
/*
* Start with a hazard barrier to ensure
* that all CACHE ops have played through.
*/
mips_ihb();
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id()) {
settc(cpu_data[cpu].tc_id);
write_tc_c0_tchalt(halt_state_save[cpu]);
}
}
mips_ihb();
}
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