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1 | /* |
2 | * Copyright (C) 2005-2013 Imagination Technologies Ltd. |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify |
5 | * it under the terms of the GNU General Public License version 2 as |
6 | * published by the Free Software Foundation. |
7 | * |
8 | * This program is distributed in the hope that it will be useful, |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
11 | * GNU General Public License for more details. |
12 | * |
13 | * You should have received a copy of the GNU General Public License |
14 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
15 | * |
16 | * |
17 | * Support for Meta per-thread timers. |
18 | * |
19 | * Meta hardware threads have 2 timers. The background timer (TXTIMER) is used |
20 | * as a free-running time base (hz clocksource), and the interrupt timer |
21 | * (TXTIMERI) is used for the timer interrupt (clock event). Both counters |
22 | * traditionally count at approximately 1MHz. |
23 | */ |
24 | |
25 | #include <clocksource/metag_generic.h> |
26 | #include <linux/cpu.h> |
27 | #include <linux/errno.h> |
28 | #include <linux/sched.h> |
29 | #include <linux/kernel.h> |
30 | #include <linux/param.h> |
31 | #include <linux/time.h> |
32 | #include <linux/init.h> |
33 | #include <linux/proc_fs.h> |
34 | #include <linux/clocksource.h> |
35 | #include <linux/clockchips.h> |
36 | #include <linux/interrupt.h> |
37 | |
38 | #include <asm/clock.h> |
39 | #include <asm/hwthread.h> |
40 | #include <asm/core_reg.h> |
41 | #include <asm/metag_mem.h> |
42 | #include <asm/tbx.h> |
43 | |
44 | #define HARDWARE_FREQ 1000000 /* 1MHz */ |
45 | #define HARDWARE_DIV 1 /* divide by 1 = 1MHz clock */ |
46 | #define HARDWARE_TO_NS_SHIFT 10 /* convert ticks to ns */ |
47 | |
48 | static unsigned int hwtimer_freq = HARDWARE_FREQ; |
49 | static DEFINE_PER_CPU(struct clock_event_device, local_clockevent); |
50 | static DEFINE_PER_CPU(char [11], local_clockevent_name); |
51 | |
52 | static int metag_timer_set_next_event(unsigned long delta, |
53 | struct clock_event_device *dev) |
54 | { |
55 | __core_reg_set(TXTIMERI, -delta); |
56 | return 0; |
57 | } |
58 | |
59 | static void metag_timer_set_mode(enum clock_event_mode mode, |
60 | struct clock_event_device *evt) |
61 | { |
62 | switch (mode) { |
63 | case CLOCK_EVT_MODE_ONESHOT: |
64 | case CLOCK_EVT_MODE_RESUME: |
65 | break; |
66 | |
67 | case CLOCK_EVT_MODE_SHUTDOWN: |
68 | /* We should disable the IRQ here */ |
69 | break; |
70 | |
71 | case CLOCK_EVT_MODE_PERIODIC: |
72 | case CLOCK_EVT_MODE_UNUSED: |
73 | WARN_ON(1); |
74 | break; |
75 | }; |
76 | } |
77 | |
78 | static cycle_t metag_clocksource_read(struct clocksource *cs) |
79 | { |
80 | return __core_reg_get(TXTIMER); |
81 | } |
82 | |
83 | static struct clocksource clocksource_metag = { |
84 | .name = "META", |
85 | .rating = 200, |
86 | .mask = CLOCKSOURCE_MASK(32), |
87 | .read = metag_clocksource_read, |
88 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
89 | }; |
90 | |
91 | static irqreturn_t metag_timer_interrupt(int irq, void *dummy) |
92 | { |
93 | struct clock_event_device *evt = &__get_cpu_var(local_clockevent); |
94 | |
95 | evt->event_handler(evt); |
96 | |
97 | return IRQ_HANDLED; |
98 | } |
99 | |
100 | static struct irqaction metag_timer_irq = { |
101 | .name = "META core timer", |
102 | .handler = metag_timer_interrupt, |
103 | .flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_PERCPU, |
104 | }; |
105 | |
106 | unsigned long long sched_clock(void) |
107 | { |
108 | unsigned long long ticks = __core_reg_get(TXTIMER); |
109 | return ticks << HARDWARE_TO_NS_SHIFT; |
110 | } |
111 | |
112 | static void __cpuinit arch_timer_setup(unsigned int cpu) |
113 | { |
114 | unsigned int txdivtime; |
115 | struct clock_event_device *clk = &per_cpu(local_clockevent, cpu); |
116 | char *name = per_cpu(local_clockevent_name, cpu); |
117 | |
118 | txdivtime = __core_reg_get(TXDIVTIME); |
119 | |
120 | txdivtime &= ~TXDIVTIME_DIV_BITS; |
121 | txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS); |
122 | |
123 | __core_reg_set(TXDIVTIME, txdivtime); |
124 | |
125 | sprintf(name, "META %d", cpu); |
126 | clk->name = name; |
127 | clk->features = CLOCK_EVT_FEAT_ONESHOT, |
128 | |
129 | clk->rating = 200, |
130 | clk->shift = 12, |
131 | clk->irq = tbisig_map(TBID_SIGNUM_TRT), |
132 | clk->set_mode = metag_timer_set_mode, |
133 | clk->set_next_event = metag_timer_set_next_event, |
134 | |
135 | clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift); |
136 | clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk); |
137 | clk->min_delta_ns = clockevent_delta2ns(0xf, clk); |
138 | clk->cpumask = cpumask_of(cpu); |
139 | |
140 | clockevents_register_device(clk); |
141 | |
142 | /* |
143 | * For all non-boot CPUs we need to synchronize our free |
144 | * running clock (TXTIMER) with the boot CPU's clock. |
145 | * |
146 | * While this won't be accurate, it should be close enough. |
147 | */ |
148 | if (cpu) { |
149 | unsigned int thread0 = cpu_2_hwthread_id[0]; |
150 | unsigned long val; |
151 | |
152 | val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0); |
153 | __core_reg_set(TXTIMER, val); |
154 | } |
155 | } |
156 | |
157 | static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, |
158 | unsigned long action, void *hcpu) |
159 | { |
160 | int cpu = (long)hcpu; |
161 | |
162 | switch (action) { |
163 | case CPU_STARTING: |
164 | case CPU_STARTING_FROZEN: |
165 | arch_timer_setup(cpu); |
166 | break; |
167 | } |
168 | |
169 | return NOTIFY_OK; |
170 | } |
171 | |
172 | static struct notifier_block __cpuinitdata arch_timer_cpu_nb = { |
173 | .notifier_call = arch_timer_cpu_notify, |
174 | }; |
175 | |
176 | int __init metag_generic_timer_init(void) |
177 | { |
178 | /* |
179 | * On Meta 2 SoCs, the actual frequency of the timer is based on the |
180 | * Meta core clock speed divided by an integer, so it is only |
181 | * approximately 1MHz. Calculating the real frequency here drastically |
182 | * reduces clock skew on these SoCs. |
183 | */ |
184 | #ifdef CONFIG_METAG_META21 |
185 | hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1); |
186 | #endif |
187 | clocksource_register_hz(&clocksource_metag, hwtimer_freq); |
188 | |
189 | setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq); |
190 | |
191 | /* Configure timer on boot CPU */ |
192 | arch_timer_setup(smp_processor_id()); |
193 | |
194 | /* Hook cpu boot to configure other CPU's timers */ |
195 | register_cpu_notifier(&arch_timer_cpu_nb); |
196 | |
197 | return 0; |
198 | } |
199 |
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