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_timer_set_mode(enum clock_event_mode mode,struct clock_event_device * evt)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
metag_clocksource_read(struct clocksource * cs)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
metag_timer_interrupt(int irq,void * dummy)91 static irqreturn_t metag_timer_interrupt(int irq, void *dummy)
92 {
93 struct clock_event_device *evt = this_cpu_ptr(&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
sched_clock(void)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
arch_timer_setup(unsigned int cpu)112 static void 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
arch_timer_cpu_notify(struct notifier_block * self,unsigned long action,void * hcpu)157 static int 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 arch_timer_cpu_nb = {
173 .notifier_call = arch_timer_cpu_notify,
174 };
175
metag_generic_timer_init(void)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 pr_info("Timer frequency: %u Hz\n", hwtimer_freq);
188
189 clocksource_register_hz(&clocksource_metag, hwtimer_freq);
190
191 setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
192
193 /* Configure timer on boot CPU */
194 arch_timer_setup(smp_processor_id());
195
196 /* Hook cpu boot to configure other CPU's timers */
197 register_cpu_notifier(&arch_timer_cpu_nb);
198
199 return 0;
200 }
201