1 /*
2 * System timer for CSR SiRFprimaII
3 *
4 * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
5 *
6 * Licensed under GPLv2 or later.
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/interrupt.h>
11 #include <linux/clockchips.h>
12 #include <linux/clocksource.h>
13 #include <linux/bitops.h>
14 #include <linux/irq.h>
15 #include <linux/clk.h>
16 #include <linux/err.h>
17 #include <linux/slab.h>
18 #include <linux/of.h>
19 #include <linux/of_irq.h>
20 #include <linux/of_address.h>
21 #include <linux/sched_clock.h>
22
23 #define PRIMA2_CLOCK_FREQ 1000000
24
25 #define SIRFSOC_TIMER_COUNTER_LO 0x0000
26 #define SIRFSOC_TIMER_COUNTER_HI 0x0004
27 #define SIRFSOC_TIMER_MATCH_0 0x0008
28 #define SIRFSOC_TIMER_MATCH_1 0x000C
29 #define SIRFSOC_TIMER_MATCH_2 0x0010
30 #define SIRFSOC_TIMER_MATCH_3 0x0014
31 #define SIRFSOC_TIMER_MATCH_4 0x0018
32 #define SIRFSOC_TIMER_MATCH_5 0x001C
33 #define SIRFSOC_TIMER_STATUS 0x0020
34 #define SIRFSOC_TIMER_INT_EN 0x0024
35 #define SIRFSOC_TIMER_WATCHDOG_EN 0x0028
36 #define SIRFSOC_TIMER_DIV 0x002C
37 #define SIRFSOC_TIMER_LATCH 0x0030
38 #define SIRFSOC_TIMER_LATCHED_LO 0x0034
39 #define SIRFSOC_TIMER_LATCHED_HI 0x0038
40
41 #define SIRFSOC_TIMER_WDT_INDEX 5
42
43 #define SIRFSOC_TIMER_LATCH_BIT BIT(0)
44
45 #define SIRFSOC_TIMER_REG_CNT 11
46
47 static const u32 sirfsoc_timer_reg_list[SIRFSOC_TIMER_REG_CNT] = {
48 SIRFSOC_TIMER_MATCH_0, SIRFSOC_TIMER_MATCH_1, SIRFSOC_TIMER_MATCH_2,
49 SIRFSOC_TIMER_MATCH_3, SIRFSOC_TIMER_MATCH_4, SIRFSOC_TIMER_MATCH_5,
50 SIRFSOC_TIMER_INT_EN, SIRFSOC_TIMER_WATCHDOG_EN, SIRFSOC_TIMER_DIV,
51 SIRFSOC_TIMER_LATCHED_LO, SIRFSOC_TIMER_LATCHED_HI,
52 };
53
54 static u32 sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT];
55
56 static void __iomem *sirfsoc_timer_base;
57
58 /* timer0 interrupt handler */
sirfsoc_timer_interrupt(int irq,void * dev_id)59 static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id)
60 {
61 struct clock_event_device *ce = dev_id;
62
63 WARN_ON(!(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_STATUS) &
64 BIT(0)));
65
66 /* clear timer0 interrupt */
67 writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
68
69 ce->event_handler(ce);
70
71 return IRQ_HANDLED;
72 }
73
74 /* read 64-bit timer counter */
sirfsoc_timer_read(struct clocksource * cs)75 static u64 notrace sirfsoc_timer_read(struct clocksource *cs)
76 {
77 u64 cycles;
78
79 /* latch the 64-bit timer counter */
80 writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
81 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
82 cycles = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_HI);
83 cycles = (cycles << 32) |
84 readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
85
86 return cycles;
87 }
88
sirfsoc_timer_set_next_event(unsigned long delta,struct clock_event_device * ce)89 static int sirfsoc_timer_set_next_event(unsigned long delta,
90 struct clock_event_device *ce)
91 {
92 unsigned long now, next;
93
94 writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
95 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
96 now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
97 next = now + delta;
98 writel_relaxed(next, sirfsoc_timer_base + SIRFSOC_TIMER_MATCH_0);
99 writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
100 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
101 now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
102
103 return next - now > delta ? -ETIME : 0;
104 }
105
sirfsoc_timer_shutdown(struct clock_event_device * evt)106 static int sirfsoc_timer_shutdown(struct clock_event_device *evt)
107 {
108 u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
109
110 writel_relaxed(val & ~BIT(0),
111 sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
112 return 0;
113 }
114
sirfsoc_timer_set_oneshot(struct clock_event_device * evt)115 static int sirfsoc_timer_set_oneshot(struct clock_event_device *evt)
116 {
117 u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
118
119 writel_relaxed(val | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
120 return 0;
121 }
122
sirfsoc_clocksource_suspend(struct clocksource * cs)123 static void sirfsoc_clocksource_suspend(struct clocksource *cs)
124 {
125 int i;
126
127 writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
128 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
129
130 for (i = 0; i < SIRFSOC_TIMER_REG_CNT; i++)
131 sirfsoc_timer_reg_val[i] =
132 readl_relaxed(sirfsoc_timer_base +
133 sirfsoc_timer_reg_list[i]);
134 }
135
sirfsoc_clocksource_resume(struct clocksource * cs)136 static void sirfsoc_clocksource_resume(struct clocksource *cs)
137 {
138 int i;
139
140 for (i = 0; i < SIRFSOC_TIMER_REG_CNT - 2; i++)
141 writel_relaxed(sirfsoc_timer_reg_val[i],
142 sirfsoc_timer_base + sirfsoc_timer_reg_list[i]);
143
144 writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 2],
145 sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
146 writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 1],
147 sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
148 }
149
150 static struct clock_event_device sirfsoc_clockevent = {
151 .name = "sirfsoc_clockevent",
152 .rating = 200,
153 .features = CLOCK_EVT_FEAT_ONESHOT,
154 .set_state_shutdown = sirfsoc_timer_shutdown,
155 .set_state_oneshot = sirfsoc_timer_set_oneshot,
156 .set_next_event = sirfsoc_timer_set_next_event,
157 };
158
159 static struct clocksource sirfsoc_clocksource = {
160 .name = "sirfsoc_clocksource",
161 .rating = 200,
162 .mask = CLOCKSOURCE_MASK(64),
163 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
164 .read = sirfsoc_timer_read,
165 .suspend = sirfsoc_clocksource_suspend,
166 .resume = sirfsoc_clocksource_resume,
167 };
168
169 static struct irqaction sirfsoc_timer_irq = {
170 .name = "sirfsoc_timer0",
171 .flags = IRQF_TIMER,
172 .irq = 0,
173 .handler = sirfsoc_timer_interrupt,
174 .dev_id = &sirfsoc_clockevent,
175 };
176
177 /* Overwrite weak default sched_clock with more precise one */
sirfsoc_read_sched_clock(void)178 static u64 notrace sirfsoc_read_sched_clock(void)
179 {
180 return sirfsoc_timer_read(NULL);
181 }
182
sirfsoc_clockevent_init(void)183 static void __init sirfsoc_clockevent_init(void)
184 {
185 sirfsoc_clockevent.cpumask = cpumask_of(0);
186 clockevents_config_and_register(&sirfsoc_clockevent, PRIMA2_CLOCK_FREQ,
187 2, -2);
188 }
189
190 /* initialize the kernel jiffy timer source */
sirfsoc_prima2_timer_init(struct device_node * np)191 static int __init sirfsoc_prima2_timer_init(struct device_node *np)
192 {
193 unsigned long rate;
194 struct clk *clk;
195 int ret;
196
197 clk = of_clk_get(np, 0);
198 if (IS_ERR(clk)) {
199 pr_err("Failed to get clock\n");
200 return PTR_ERR(clk);
201 }
202
203 ret = clk_prepare_enable(clk);
204 if (ret) {
205 pr_err("Failed to enable clock\n");
206 return ret;
207 }
208
209 rate = clk_get_rate(clk);
210
211 if (rate < PRIMA2_CLOCK_FREQ || rate % PRIMA2_CLOCK_FREQ) {
212 pr_err("Invalid clock rate\n");
213 return -EINVAL;
214 }
215
216 sirfsoc_timer_base = of_iomap(np, 0);
217 if (!sirfsoc_timer_base) {
218 pr_err("unable to map timer cpu registers\n");
219 return -ENXIO;
220 }
221
222 sirfsoc_timer_irq.irq = irq_of_parse_and_map(np, 0);
223
224 writel_relaxed(rate / PRIMA2_CLOCK_FREQ / 2 - 1,
225 sirfsoc_timer_base + SIRFSOC_TIMER_DIV);
226 writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
227 writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
228 writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
229
230 ret = clocksource_register_hz(&sirfsoc_clocksource, PRIMA2_CLOCK_FREQ);
231 if (ret) {
232 pr_err("Failed to register clocksource\n");
233 return ret;
234 }
235
236 sched_clock_register(sirfsoc_read_sched_clock, 64, PRIMA2_CLOCK_FREQ);
237
238 ret = setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq);
239 if (ret) {
240 pr_err("Failed to setup irq\n");
241 return ret;
242 }
243
244 sirfsoc_clockevent_init();
245
246 return 0;
247 }
248 TIMER_OF_DECLARE(sirfsoc_prima2_timer,
249 "sirf,prima2-tick", sirfsoc_prima2_timer_init);
250
