blob: 0595dc6c453e6ee4a97cfb4dd30865f76c351366 [file] [log] [blame]
Christian Daudt80116572013-03-13 14:27:27 -07001/*
2 * Copyright (C) 2012 Broadcom Corporation
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
7 *
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14#include <linux/init.h>
15#include <linux/irq.h>
16#include <linux/interrupt.h>
17#include <linux/jiffies.h>
18#include <linux/clockchips.h>
19#include <linux/types.h>
Tim Kryger50ac2062013-12-05 11:20:43 -080020#include <linux/clk.h>
Christian Daudt80116572013-03-13 14:27:27 -070021
22#include <linux/io.h>
23#include <asm/mach/time.h>
24
25#include <linux/of.h>
26#include <linux/of_address.h>
27#include <linux/of_irq.h>
28
29
30#define KONA_GPTIMER_STCS_OFFSET 0x00000000
31#define KONA_GPTIMER_STCLO_OFFSET 0x00000004
32#define KONA_GPTIMER_STCHI_OFFSET 0x00000008
33#define KONA_GPTIMER_STCM0_OFFSET 0x0000000C
34
35#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0
36#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4
37
38struct kona_bcm_timers {
39 int tmr_irq;
40 void __iomem *tmr_regs;
41};
42
43static struct kona_bcm_timers timers;
44
45static u32 arch_timer_rate;
46
47/*
48 * We use the peripheral timers for system tick, the cpu global timer for
49 * profile tick
50 */
51static void kona_timer_disable_and_clear(void __iomem *base)
52{
53 uint32_t reg;
54
55 /*
56 * clear and disable interrupts
57 * We are using compare/match register 0 for our system interrupts
58 */
59 reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
60
61 /* Clear compare (0) interrupt */
62 reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
63 /* disable compare */
64 reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
65
66 writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
67
68}
69
70static void
71kona_timer_get_counter(void *timer_base, uint32_t *msw, uint32_t *lsw)
72{
73 void __iomem *base = IOMEM(timer_base);
74 int loop_limit = 4;
75
76 /*
77 * Read 64-bit free running counter
78 * 1. Read hi-word
79 * 2. Read low-word
80 * 3. Read hi-word again
81 * 4.1
82 * if new hi-word is not equal to previously read hi-word, then
83 * start from #1
84 * 4.2
85 * if new hi-word is equal to previously read hi-word then stop.
86 */
87
88 while (--loop_limit) {
89 *msw = readl(base + KONA_GPTIMER_STCHI_OFFSET);
90 *lsw = readl(base + KONA_GPTIMER_STCLO_OFFSET);
91 if (*msw == readl(base + KONA_GPTIMER_STCHI_OFFSET))
92 break;
93 }
94 if (!loop_limit) {
95 pr_err("bcm_kona_timer: getting counter failed.\n");
96 pr_err(" Timer will be impacted\n");
97 }
98
99 return;
100}
101
Christian Daudt80116572013-03-13 14:27:27 -0700102static int kona_timer_set_next_event(unsigned long clc,
103 struct clock_event_device *unused)
104{
105 /*
106 * timer (0) is disabled by the timer interrupt already
107 * so, here we reload the next event value and re-enable
108 * the timer.
109 *
110 * This way, we are potentially losing the time between
111 * timer-interrupt->set_next_event. CPU local timers, when
112 * they come in should get rid of skew.
113 */
114
115 uint32_t lsw, msw;
116 uint32_t reg;
117
118 kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
119
120 /* Load the "next" event tick value */
121 writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
122
123 /* Enable compare */
124 reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
125 reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
126 writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
127
128 return 0;
129}
130
131static void kona_timer_set_mode(enum clock_event_mode mode,
132 struct clock_event_device *unused)
133{
134 switch (mode) {
135 case CLOCK_EVT_MODE_ONESHOT:
136 /* by default mode is one shot don't do any thing */
137 break;
138 case CLOCK_EVT_MODE_UNUSED:
139 case CLOCK_EVT_MODE_SHUTDOWN:
140 default:
141 kona_timer_disable_and_clear(timers.tmr_regs);
142 }
143}
144
145static struct clock_event_device kona_clockevent_timer = {
146 .name = "timer 1",
147 .features = CLOCK_EVT_FEAT_ONESHOT,
148 .set_next_event = kona_timer_set_next_event,
149 .set_mode = kona_timer_set_mode
150};
151
152static void __init kona_timer_clockevents_init(void)
153{
154 kona_clockevent_timer.cpumask = cpumask_of(0);
155 clockevents_config_and_register(&kona_clockevent_timer,
156 arch_timer_rate, 6, 0xffffffff);
157}
158
159static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
160{
161 struct clock_event_device *evt = &kona_clockevent_timer;
162
163 kona_timer_disable_and_clear(timers.tmr_regs);
164 evt->event_handler(evt);
165 return IRQ_HANDLED;
166}
167
168static struct irqaction kona_timer_irq = {
169 .name = "Kona Timer Tick",
170 .flags = IRQF_TIMER,
171 .handler = kona_timer_interrupt,
172};
173
Arnd Bergmann9682bcd2013-04-23 16:04:14 +0200174static void __init kona_timer_init(struct device_node *node)
Christian Daudt80116572013-03-13 14:27:27 -0700175{
Tim Krygerad037c12014-02-04 16:15:04 -0800176 u32 freq;
177 struct clk *external_clk;
178
179 if (!of_device_is_available(node)) {
180 pr_info("Kona Timer v1 marked as disabled in device tree\n");
181 return;
182 }
183
184 external_clk = of_clk_get_by_name(node, NULL);
185
186 if (!IS_ERR(external_clk)) {
187 arch_timer_rate = clk_get_rate(external_clk);
188 clk_prepare_enable(external_clk);
189 } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
190 arch_timer_rate = freq;
191 } else {
192 pr_err("Kona Timer v1 unable to determine clock-frequency");
193 return;
194 }
195
196 /* Setup IRQ numbers */
197 timers.tmr_irq = irq_of_parse_and_map(node, 0);
198
199 /* Setup IO addresses */
200 timers.tmr_regs = of_iomap(node, 0);
201
202 kona_timer_disable_and_clear(timers.tmr_regs);
203
Christian Daudt80116572013-03-13 14:27:27 -0700204 kona_timer_clockevents_init();
205 setup_irq(timers.tmr_irq, &kona_timer_irq);
206 kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
207}
208
Christian Daudtaea237b2013-08-20 08:37:19 -0700209CLOCKSOURCE_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
210/*
211 * bcm,kona-timer is deprecated by brcm,kona-timer
212 * being kept here for driver compatibility
213 */
Arnd Bergmann9682bcd2013-04-23 16:04:14 +0200214CLOCKSOURCE_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);