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
metag_timer_set_next_event(unsigned long delta,struct clock_event_device * dev)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
metag_clocksource_read(struct clocksource * cs)59 static u64 metag_clocksource_read(struct clocksource *cs)
60 {
61 return __core_reg_get(TXTIMER);
62 }
63
64 static struct clocksource clocksource_metag = {
65 .name = "META",
66 .rating = 200,
67 .mask = CLOCKSOURCE_MASK(32),
68 .read = metag_clocksource_read,
69 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
70 };
71
metag_timer_interrupt(int irq,void * dummy)72 static irqreturn_t metag_timer_interrupt(int irq, void *dummy)
73 {
74 struct clock_event_device *evt = this_cpu_ptr(&local_clockevent);
75
76 evt->event_handler(evt);
77
78 return IRQ_HANDLED;
79 }
80
81 static struct irqaction metag_timer_irq = {
82 .name = "META core timer",
83 .handler = metag_timer_interrupt,
84 .flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_PERCPU,
85 };
86
sched_clock(void)87 unsigned long long sched_clock(void)
88 {
89 unsigned long long ticks = __core_reg_get(TXTIMER);
90 return ticks << HARDWARE_TO_NS_SHIFT;
91 }
92
arch_timer_starting_cpu(unsigned int cpu)93 static int arch_timer_starting_cpu(unsigned int cpu)
94 {
95 unsigned int txdivtime;
96 struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
97 char *name = per_cpu(local_clockevent_name, cpu);
98
99 txdivtime = __core_reg_get(TXDIVTIME);
100
101 txdivtime &= ~TXDIVTIME_DIV_BITS;
102 txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS);
103
104 __core_reg_set(TXDIVTIME, txdivtime);
105
106 sprintf(name, "META %d", cpu);
107 clk->name = name;
108 clk->features = CLOCK_EVT_FEAT_ONESHOT,
109
110 clk->rating = 200,
111 clk->shift = 12,
112 clk->irq = tbisig_map(TBID_SIGNUM_TRT),
113 clk->set_next_event = metag_timer_set_next_event,
114
115 clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift);
116 clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk);
117 clk->max_delta_ticks = 0x7fffffff;
118 clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
119 clk->min_delta_ticks = 0xf;
120 clk->cpumask = cpumask_of(cpu);
121
122 clockevents_register_device(clk);
123
124 /*
125 * For all non-boot CPUs we need to synchronize our free
126 * running clock (TXTIMER) with the boot CPU's clock.
127 *
128 * While this won't be accurate, it should be close enough.
129 */
130 if (cpu) {
131 unsigned int thread0 = cpu_2_hwthread_id[0];
132 unsigned long val;
133
134 val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0);
135 __core_reg_set(TXTIMER, val);
136 }
137 return 0;
138 }
139
metag_generic_timer_init(void)140 int __init metag_generic_timer_init(void)
141 {
142 /*
143 * On Meta 2 SoCs, the actual frequency of the timer is based on the
144 * Meta core clock speed divided by an integer, so it is only
145 * approximately 1MHz. Calculating the real frequency here drastically
146 * reduces clock skew on these SoCs.
147 */
148 #ifdef CONFIG_METAG_META21
149 hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1);
150 #endif
151 pr_info("Timer frequency: %u Hz\n", hwtimer_freq);
152
153 clocksource_register_hz(&clocksource_metag, hwtimer_freq);
154
155 setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
156
157 /* Hook cpu boot to configure the CPU's timers */
158 return cpuhp_setup_state(CPUHP_AP_METAG_TIMER_STARTING,
159 "clockevents/metag:starting",
160 arch_timer_starting_cpu, NULL);
161 }
162