diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2011-05-14 06:06:36 -0400 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2011-05-14 06:06:36 -0400 |
commit | a18f22a968de17b29f2310cdb7ba69163e65ec15 (patch) | |
tree | a7d56d88fad5e444d7661484109758a2f436129e /arch/x86/kernel/i8253.c | |
parent | a1c57e0fec53defe745e64417eacdbd3618c3e66 (diff) | |
parent | 798778b8653f64b7b2162ac70eca10367cff6ce8 (diff) |
Merge branch 'consolidate-clksrc-i8253' of master.kernel.org:~rmk/linux-2.6-arm into timers/clocksource
Conflicts:
arch/ia64/kernel/cyclone.c
arch/mips/kernel/i8253.c
arch/x86/kernel/i8253.c
Reason: Resolve conflicts so further cleanups do not conflict further
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/i8253.c')
-rw-r--r-- | arch/x86/kernel/i8253.c | 76 |
1 files changed, 1 insertions, 75 deletions
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c index 212fe6590aab..577e90cadaeb 100644 --- a/arch/x86/kernel/i8253.c +++ b/arch/x86/kernel/i8253.c | |||
@@ -117,79 +117,6 @@ void __init setup_pit_timer(void) | |||
117 | } | 117 | } |
118 | 118 | ||
119 | #ifndef CONFIG_X86_64 | 119 | #ifndef CONFIG_X86_64 |
120 | /* | ||
121 | * Since the PIT overflows every tick, its not very useful | ||
122 | * to just read by itself. So use jiffies to emulate a free | ||
123 | * running counter: | ||
124 | */ | ||
125 | static cycle_t pit_read(struct clocksource *cs) | ||
126 | { | ||
127 | static int old_count; | ||
128 | static u32 old_jifs; | ||
129 | unsigned long flags; | ||
130 | int count; | ||
131 | u32 jifs; | ||
132 | |||
133 | raw_spin_lock_irqsave(&i8253_lock, flags); | ||
134 | /* | ||
135 | * Although our caller may have the read side of xtime_lock, | ||
136 | * this is now a seqlock, and we are cheating in this routine | ||
137 | * by having side effects on state that we cannot undo if | ||
138 | * there is a collision on the seqlock and our caller has to | ||
139 | * retry. (Namely, old_jifs and old_count.) So we must treat | ||
140 | * jiffies as volatile despite the lock. We read jiffies | ||
141 | * before latching the timer count to guarantee that although | ||
142 | * the jiffies value might be older than the count (that is, | ||
143 | * the counter may underflow between the last point where | ||
144 | * jiffies was incremented and the point where we latch the | ||
145 | * count), it cannot be newer. | ||
146 | */ | ||
147 | jifs = jiffies; | ||
148 | outb_pit(0x00, PIT_MODE); /* latch the count ASAP */ | ||
149 | count = inb_pit(PIT_CH0); /* read the latched count */ | ||
150 | count |= inb_pit(PIT_CH0) << 8; | ||
151 | |||
152 | /* VIA686a test code... reset the latch if count > max + 1 */ | ||
153 | if (count > LATCH) { | ||
154 | outb_pit(0x34, PIT_MODE); | ||
155 | outb_pit(LATCH & 0xff, PIT_CH0); | ||
156 | outb_pit(LATCH >> 8, PIT_CH0); | ||
157 | count = LATCH - 1; | ||
158 | } | ||
159 | |||
160 | /* | ||
161 | * It's possible for count to appear to go the wrong way for a | ||
162 | * couple of reasons: | ||
163 | * | ||
164 | * 1. The timer counter underflows, but we haven't handled the | ||
165 | * resulting interrupt and incremented jiffies yet. | ||
166 | * 2. Hardware problem with the timer, not giving us continuous time, | ||
167 | * the counter does small "jumps" upwards on some Pentium systems, | ||
168 | * (see c't 95/10 page 335 for Neptun bug.) | ||
169 | * | ||
170 | * Previous attempts to handle these cases intelligently were | ||
171 | * buggy, so we just do the simple thing now. | ||
172 | */ | ||
173 | if (count > old_count && jifs == old_jifs) | ||
174 | count = old_count; | ||
175 | |||
176 | old_count = count; | ||
177 | old_jifs = jifs; | ||
178 | |||
179 | raw_spin_unlock_irqrestore(&i8253_lock, flags); | ||
180 | |||
181 | count = (LATCH - 1) - count; | ||
182 | |||
183 | return (cycle_t)(jifs * LATCH) + count; | ||
184 | } | ||
185 | |||
186 | static struct clocksource pit_cs = { | ||
187 | .name = "pit", | ||
188 | .rating = 110, | ||
189 | .read = pit_read, | ||
190 | .mask = CLOCKSOURCE_MASK(32), | ||
191 | }; | ||
192 | |||
193 | static int __init init_pit_clocksource(void) | 120 | static int __init init_pit_clocksource(void) |
194 | { | 121 | { |
195 | /* | 122 | /* |
@@ -203,8 +130,7 @@ static int __init init_pit_clocksource(void) | |||
203 | pit_ce.mode != CLOCK_EVT_MODE_PERIODIC) | 130 | pit_ce.mode != CLOCK_EVT_MODE_PERIODIC) |
204 | return 0; | 131 | return 0; |
205 | 132 | ||
206 | return clocksource_register_hz(&pit_cs, CLOCK_TICK_RATE); | 133 | return clocksource_i8253_init(); |
207 | } | 134 | } |
208 | arch_initcall(init_pit_clocksource); | 135 | arch_initcall(init_pit_clocksource); |
209 | |||
210 | #endif /* !CONFIG_X86_64 */ | 136 | #endif /* !CONFIG_X86_64 */ |