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authorKevin D. Kissell <kevink@paralogos.com>2008-09-09 15:48:52 -0400
committerRalf Baechle <ralf@linux-mips.org>2008-10-03 12:58:58 -0400
commit8531a35e5e275b17c57c39b7911bc2b37025f28c (patch)
treec593e23c875d0639a8f422c0ceb8b2a7738d143e /arch/mips/kernel/cevt-r4k.c
parentd2bb01b042a38219fbddaafc214c5beb96248d2f (diff)
[MIPS] SMTC: Fix SMTC dyntick support.
Rework of SMTC support to make it work with the new clock event system, allowing "tickless" operation, and to make it compatible with the use of the "wait_irqoff" idle loop. The new clocking scheme means that the previously optional IPI instant replay mechanism is now required, and has been made more robust. Signed-off-by: Kevin D. Kissell <kevink@paralogos.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/cevt-r4k.c')
-rw-r--r--arch/mips/kernel/cevt-r4k.c173
1 files changed, 48 insertions, 125 deletions
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 24a2d907aa0d..4a4c59f2737a 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -12,6 +12,14 @@
12 12
13#include <asm/smtc_ipi.h> 13#include <asm/smtc_ipi.h>
14#include <asm/time.h> 14#include <asm/time.h>
15#include <asm/cevt-r4k.h>
16
17/*
18 * The SMTC Kernel for the 34K, 1004K, et. al. replaces several
19 * of these routines with SMTC-specific variants.
20 */
21
22#ifndef CONFIG_MIPS_MT_SMTC
15 23
16static int mips_next_event(unsigned long delta, 24static int mips_next_event(unsigned long delta,
17 struct clock_event_device *evt) 25 struct clock_event_device *evt)
@@ -19,60 +27,27 @@ static int mips_next_event(unsigned long delta,
19 unsigned int cnt; 27 unsigned int cnt;
20 int res; 28 int res;
21 29
22#ifdef CONFIG_MIPS_MT_SMTC
23 {
24 unsigned long flags, vpflags;
25 local_irq_save(flags);
26 vpflags = dvpe();
27#endif
28 cnt = read_c0_count(); 30 cnt = read_c0_count();
29 cnt += delta; 31 cnt += delta;
30 write_c0_compare(cnt); 32 write_c0_compare(cnt);
31 res = ((int)(read_c0_count() - cnt) > 0) ? -ETIME : 0; 33 res = ((int)(read_c0_count() - cnt) > 0) ? -ETIME : 0;
32#ifdef CONFIG_MIPS_MT_SMTC
33 evpe(vpflags);
34 local_irq_restore(flags);
35 }
36#endif
37 return res; 34 return res;
38} 35}
39 36
40static void mips_set_mode(enum clock_event_mode mode, 37#endif /* CONFIG_MIPS_MT_SMTC */
41 struct clock_event_device *evt) 38
39void mips_set_clock_mode(enum clock_event_mode mode,
40 struct clock_event_device *evt)
42{ 41{
43 /* Nothing to do ... */ 42 /* Nothing to do ... */
44} 43}
45 44
46static DEFINE_PER_CPU(struct clock_event_device, mips_clockevent_device); 45DEFINE_PER_CPU(struct clock_event_device, mips_clockevent_device);
47static int cp0_timer_irq_installed; 46int cp0_timer_irq_installed;
48 47
49/* 48#ifndef CONFIG_MIPS_MT_SMTC
50 * Timer ack for an R4k-compatible timer of a known frequency.
51 */
52static void c0_timer_ack(void)
53{
54 write_c0_compare(read_c0_compare());
55}
56 49
57/* 50irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
58 * Possibly handle a performance counter interrupt.
59 * Return true if the timer interrupt should not be checked
60 */
61static inline int handle_perf_irq(int r2)
62{
63 /*
64 * The performance counter overflow interrupt may be shared with the
65 * timer interrupt (cp0_perfcount_irq < 0). If it is and a
66 * performance counter has overflowed (perf_irq() == IRQ_HANDLED)
67 * and we can't reliably determine if a counter interrupt has also
68 * happened (!r2) then don't check for a timer interrupt.
69 */
70 return (cp0_perfcount_irq < 0) &&
71 perf_irq() == IRQ_HANDLED &&
72 !r2;
73}
74
75static irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
76{ 51{
77 const int r2 = cpu_has_mips_r2; 52 const int r2 = cpu_has_mips_r2;
78 struct clock_event_device *cd; 53 struct clock_event_device *cd;
@@ -93,12 +68,8 @@ static irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
93 * interrupt. Being the paranoiacs we are we check anyway. 68 * interrupt. Being the paranoiacs we are we check anyway.
94 */ 69 */
95 if (!r2 || (read_c0_cause() & (1 << 30))) { 70 if (!r2 || (read_c0_cause() & (1 << 30))) {
96 c0_timer_ack(); 71 /* Clear Count/Compare Interrupt */
97#ifdef CONFIG_MIPS_MT_SMTC 72 write_c0_compare(read_c0_compare());
98 if (cpu_data[cpu].vpe_id)
99 goto out;
100 cpu = 0;
101#endif
102 cd = &per_cpu(mips_clockevent_device, cpu); 73 cd = &per_cpu(mips_clockevent_device, cpu);
103 cd->event_handler(cd); 74 cd->event_handler(cd);
104 } 75 }
@@ -107,65 +78,16 @@ out:
107 return IRQ_HANDLED; 78 return IRQ_HANDLED;
108} 79}
109 80
110static struct irqaction c0_compare_irqaction = { 81#endif /* Not CONFIG_MIPS_MT_SMTC */
82
83struct irqaction c0_compare_irqaction = {
111 .handler = c0_compare_interrupt, 84 .handler = c0_compare_interrupt,
112#ifdef CONFIG_MIPS_MT_SMTC
113 .flags = IRQF_DISABLED,
114#else
115 .flags = IRQF_DISABLED | IRQF_PERCPU, 85 .flags = IRQF_DISABLED | IRQF_PERCPU,
116#endif
117 .name = "timer", 86 .name = "timer",
118}; 87};
119 88
120#ifdef CONFIG_MIPS_MT_SMTC
121DEFINE_PER_CPU(struct clock_event_device, smtc_dummy_clockevent_device);
122
123static void smtc_set_mode(enum clock_event_mode mode,
124 struct clock_event_device *evt)
125{
126}
127
128static void mips_broadcast(cpumask_t mask)
129{
130 unsigned int cpu;
131
132 for_each_cpu_mask(cpu, mask)
133 smtc_send_ipi(cpu, SMTC_CLOCK_TICK, 0);
134}
135
136static void setup_smtc_dummy_clockevent_device(void)
137{
138 //uint64_t mips_freq = mips_hpt_^frequency;
139 unsigned int cpu = smp_processor_id();
140 struct clock_event_device *cd;
141 89
142 cd = &per_cpu(smtc_dummy_clockevent_device, cpu); 90void mips_event_handler(struct clock_event_device *dev)
143
144 cd->name = "SMTC";
145 cd->features = CLOCK_EVT_FEAT_DUMMY;
146
147 /* Calculate the min / max delta */
148 cd->mult = 0; //div_sc((unsigned long) mips_freq, NSEC_PER_SEC, 32);
149 cd->shift = 0; //32;
150 cd->max_delta_ns = 0; //clockevent_delta2ns(0x7fffffff, cd);
151 cd->min_delta_ns = 0; //clockevent_delta2ns(0x30, cd);
152
153 cd->rating = 200;
154 cd->irq = 17; //-1;
155// if (cpu)
156// cd->cpumask = CPU_MASK_ALL; // cpumask_of_cpu(cpu);
157// else
158 cd->cpumask = cpumask_of_cpu(cpu);
159
160 cd->set_mode = smtc_set_mode;
161
162 cd->broadcast = mips_broadcast;
163
164 clockevents_register_device(cd);
165}
166#endif
167
168static void mips_event_handler(struct clock_event_device *dev)
169{ 91{
170} 92}
171 93
@@ -177,7 +99,23 @@ static int c0_compare_int_pending(void)
177 return (read_c0_cause() >> cp0_compare_irq) & 0x100; 99 return (read_c0_cause() >> cp0_compare_irq) & 0x100;
178} 100}
179 101
180static int c0_compare_int_usable(void) 102/*
103 * Compare interrupt can be routed and latched outside the core,
104 * so a single execution hazard barrier may not be enough to give
105 * it time to clear as seen in the Cause register. 4 time the
106 * pipeline depth seems reasonably conservative, and empirically
107 * works better in configurations with high CPU/bus clock ratios.
108 */
109
110#define compare_change_hazard() \
111 do { \
112 irq_disable_hazard(); \
113 irq_disable_hazard(); \
114 irq_disable_hazard(); \
115 irq_disable_hazard(); \
116 } while (0)
117
118int c0_compare_int_usable(void)
181{ 119{
182 unsigned int delta; 120 unsigned int delta;
183 unsigned int cnt; 121 unsigned int cnt;
@@ -187,7 +125,7 @@ static int c0_compare_int_usable(void)
187 */ 125 */
188 if (c0_compare_int_pending()) { 126 if (c0_compare_int_pending()) {
189 write_c0_compare(read_c0_count()); 127 write_c0_compare(read_c0_count());
190 irq_disable_hazard(); 128 compare_change_hazard();
191 if (c0_compare_int_pending()) 129 if (c0_compare_int_pending())
192 return 0; 130 return 0;
193 } 131 }
@@ -196,7 +134,7 @@ static int c0_compare_int_usable(void)
196 cnt = read_c0_count(); 134 cnt = read_c0_count();
197 cnt += delta; 135 cnt += delta;
198 write_c0_compare(cnt); 136 write_c0_compare(cnt);
199 irq_disable_hazard(); 137 compare_change_hazard();
200 if ((int)(read_c0_count() - cnt) < 0) 138 if ((int)(read_c0_count() - cnt) < 0)
201 break; 139 break;
202 /* increase delta if the timer was already expired */ 140 /* increase delta if the timer was already expired */
@@ -205,11 +143,12 @@ static int c0_compare_int_usable(void)
205 while ((int)(read_c0_count() - cnt) <= 0) 143 while ((int)(read_c0_count() - cnt) <= 0)
206 ; /* Wait for expiry */ 144 ; /* Wait for expiry */
207 145
146 compare_change_hazard();
208 if (!c0_compare_int_pending()) 147 if (!c0_compare_int_pending())
209 return 0; 148 return 0;
210 149
211 write_c0_compare(read_c0_count()); 150 write_c0_compare(read_c0_count());
212 irq_disable_hazard(); 151 compare_change_hazard();
213 if (c0_compare_int_pending()) 152 if (c0_compare_int_pending())
214 return 0; 153 return 0;
215 154
@@ -219,6 +158,8 @@ static int c0_compare_int_usable(void)
219 return 1; 158 return 1;
220} 159}
221 160
161#ifndef CONFIG_MIPS_MT_SMTC
162
222int __cpuinit mips_clockevent_init(void) 163int __cpuinit mips_clockevent_init(void)
223{ 164{
224 uint64_t mips_freq = mips_hpt_frequency; 165 uint64_t mips_freq = mips_hpt_frequency;
@@ -229,17 +170,6 @@ int __cpuinit mips_clockevent_init(void)
229 if (!cpu_has_counter || !mips_hpt_frequency) 170 if (!cpu_has_counter || !mips_hpt_frequency)
230 return -ENXIO; 171 return -ENXIO;
231 172
232#ifdef CONFIG_MIPS_MT_SMTC
233 setup_smtc_dummy_clockevent_device();
234
235 /*
236 * On SMTC we only register VPE0's compare interrupt as clockevent
237 * device.
238 */
239 if (cpu)
240 return 0;
241#endif
242
243 if (!c0_compare_int_usable()) 173 if (!c0_compare_int_usable())
244 return -ENXIO; 174 return -ENXIO;
245 175
@@ -265,13 +195,9 @@ int __cpuinit mips_clockevent_init(void)
265 195
266 cd->rating = 300; 196 cd->rating = 300;
267 cd->irq = irq; 197 cd->irq = irq;
268#ifdef CONFIG_MIPS_MT_SMTC
269 cd->cpumask = CPU_MASK_ALL;
270#else
271 cd->cpumask = cpumask_of_cpu(cpu); 198 cd->cpumask = cpumask_of_cpu(cpu);
272#endif
273 cd->set_next_event = mips_next_event; 199 cd->set_next_event = mips_next_event;
274 cd->set_mode = mips_set_mode; 200 cd->set_mode = mips_set_clock_mode;
275 cd->event_handler = mips_event_handler; 201 cd->event_handler = mips_event_handler;
276 202
277 clockevents_register_device(cd); 203 clockevents_register_device(cd);
@@ -281,12 +207,9 @@ int __cpuinit mips_clockevent_init(void)
281 207
282 cp0_timer_irq_installed = 1; 208 cp0_timer_irq_installed = 1;
283 209
284#ifdef CONFIG_MIPS_MT_SMTC
285#define CPUCTR_IMASKBIT (0x100 << cp0_compare_irq)
286 setup_irq_smtc(irq, &c0_compare_irqaction, CPUCTR_IMASKBIT);
287#else
288 setup_irq(irq, &c0_compare_irqaction); 210 setup_irq(irq, &c0_compare_irqaction);
289#endif
290 211
291 return 0; 212 return 0;
292} 213}
214
215#endif /* Not CONFIG_MIPS_MT_SMTC */