Merge branch 'rework/kthreads' into for-linus
[platform/kernel/linux-starfive.git] / drivers / clocksource / bcm_kona_timer.c
1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2012 Broadcom Corporation
3
4 #include <linux/init.h>
5 #include <linux/irq.h>
6 #include <linux/interrupt.h>
7 #include <linux/jiffies.h>
8 #include <linux/clockchips.h>
9 #include <linux/types.h>
10 #include <linux/clk.h>
11
12 #include <linux/io.h>
13
14 #include <linux/of.h>
15 #include <linux/of_address.h>
16 #include <linux/of_irq.h>
17
18
19 #define KONA_GPTIMER_STCS_OFFSET                        0x00000000
20 #define KONA_GPTIMER_STCLO_OFFSET                       0x00000004
21 #define KONA_GPTIMER_STCHI_OFFSET                       0x00000008
22 #define KONA_GPTIMER_STCM0_OFFSET                       0x0000000C
23
24 #define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT             0
25 #define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT          4
26
27 struct kona_bcm_timers {
28         int tmr_irq;
29         void __iomem *tmr_regs;
30 };
31
32 static struct kona_bcm_timers timers;
33
34 static u32 arch_timer_rate;
35
36 /*
37  * We use the peripheral timers for system tick, the cpu global timer for
38  * profile tick
39  */
40 static void kona_timer_disable_and_clear(void __iomem *base)
41 {
42         uint32_t reg;
43
44         /*
45          * clear and disable interrupts
46          * We are using compare/match register 0 for our system interrupts
47          */
48         reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
49
50         /* Clear compare (0) interrupt */
51         reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
52         /* disable compare */
53         reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
54
55         writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
56
57 }
58
59 static int
60 kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
61 {
62         int loop_limit = 3;
63
64         /*
65          * Read 64-bit free running counter
66          * 1. Read hi-word
67          * 2. Read low-word
68          * 3. Read hi-word again
69          * 4.1
70          *      if new hi-word is not equal to previously read hi-word, then
71          *      start from #1
72          * 4.2
73          *      if new hi-word is equal to previously read hi-word then stop.
74          */
75
76         do {
77                 *msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
78                 *lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
79                 if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
80                         break;
81         } while (--loop_limit);
82         if (!loop_limit) {
83                 pr_err("bcm_kona_timer: getting counter failed.\n");
84                 pr_err(" Timer will be impacted\n");
85                 return -ETIMEDOUT;
86         }
87
88         return 0;
89 }
90
91 static int kona_timer_set_next_event(unsigned long clc,
92                                   struct clock_event_device *unused)
93 {
94         /*
95          * timer (0) is disabled by the timer interrupt already
96          * so, here we reload the next event value and re-enable
97          * the timer.
98          *
99          * This way, we are potentially losing the time between
100          * timer-interrupt->set_next_event. CPU local timers, when
101          * they come in should get rid of skew.
102          */
103
104         uint32_t lsw, msw;
105         uint32_t reg;
106         int ret;
107
108         ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
109         if (ret)
110                 return ret;
111
112         /* Load the "next" event tick value */
113         writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
114
115         /* Enable compare */
116         reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
117         reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
118         writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
119
120         return 0;
121 }
122
123 static int kona_timer_shutdown(struct clock_event_device *evt)
124 {
125         kona_timer_disable_and_clear(timers.tmr_regs);
126         return 0;
127 }
128
129 static struct clock_event_device kona_clockevent_timer = {
130         .name = "timer 1",
131         .features = CLOCK_EVT_FEAT_ONESHOT,
132         .set_next_event = kona_timer_set_next_event,
133         .set_state_shutdown = kona_timer_shutdown,
134         .tick_resume = kona_timer_shutdown,
135 };
136
137 static void __init kona_timer_clockevents_init(void)
138 {
139         kona_clockevent_timer.cpumask = cpumask_of(0);
140         clockevents_config_and_register(&kona_clockevent_timer,
141                 arch_timer_rate, 6, 0xffffffff);
142 }
143
144 static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
145 {
146         struct clock_event_device *evt = &kona_clockevent_timer;
147
148         kona_timer_disable_and_clear(timers.tmr_regs);
149         evt->event_handler(evt);
150         return IRQ_HANDLED;
151 }
152
153 static int __init kona_timer_init(struct device_node *node)
154 {
155         u32 freq;
156         struct clk *external_clk;
157
158         external_clk = of_clk_get_by_name(node, NULL);
159
160         if (!IS_ERR(external_clk)) {
161                 arch_timer_rate = clk_get_rate(external_clk);
162                 clk_prepare_enable(external_clk);
163         } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
164                 arch_timer_rate = freq;
165         } else {
166                 pr_err("Kona Timer v1 unable to determine clock-frequency\n");
167                 return -EINVAL;
168         }
169
170         /* Setup IRQ numbers */
171         timers.tmr_irq = irq_of_parse_and_map(node, 0);
172
173         /* Setup IO addresses */
174         timers.tmr_regs = of_iomap(node, 0);
175
176         kona_timer_disable_and_clear(timers.tmr_regs);
177
178         kona_timer_clockevents_init();
179         if (request_irq(timers.tmr_irq, kona_timer_interrupt, IRQF_TIMER,
180                         "Kona Timer Tick", NULL))
181                 pr_err("%s: request_irq() failed\n", "Kona Timer Tick");
182         kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
183
184         return 0;
185 }
186
187 TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
188 /*
189  * bcm,kona-timer is deprecated by brcm,kona-timer
190  * being kept here for driver compatibility
191  */
192 TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);