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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (C) 2020 Western Digital Corporation or its affiliates. | |
4 | * | |
5 | * Most of the M-mode (i.e. NoMMU) RISC-V systems usually have a | |
6 | * CLINT MMIO timer device. | |
7 | */ | |
8 | ||
9 | #define pr_fmt(fmt) "clint: " fmt | |
10 | #include <linux/bitops.h> | |
11 | #include <linux/clocksource.h> | |
12 | #include <linux/clockchips.h> | |
13 | #include <linux/cpu.h> | |
14 | #include <linux/delay.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/of_address.h> | |
17 | #include <linux/sched_clock.h> | |
18 | #include <linux/io-64-nonatomic-lo-hi.h> | |
19 | #include <linux/interrupt.h> | |
20 | #include <linux/of_irq.h> | |
21 | #include <linux/smp.h> | |
22 | ||
23 | #define CLINT_IPI_OFF 0 | |
24 | #define CLINT_TIMER_CMP_OFF 0x4000 | |
25 | #define CLINT_TIMER_VAL_OFF 0xbff8 | |
26 | ||
27 | /* CLINT manages IPI and Timer for RISC-V M-mode */ | |
28 | static u32 __iomem *clint_ipi_base; | |
29 | static u64 __iomem *clint_timer_cmp; | |
30 | static u64 __iomem *clint_timer_val; | |
31 | static unsigned long clint_timer_freq; | |
32 | static unsigned int clint_timer_irq; | |
33 | ||
34 | static void clint_send_ipi(const struct cpumask *target) | |
35 | { | |
36 | unsigned int cpu; | |
37 | ||
38 | for_each_cpu(cpu, target) | |
39 | writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu)); | |
40 | } | |
41 | ||
42 | static void clint_clear_ipi(void) | |
43 | { | |
44 | writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id())); | |
45 | } | |
46 | ||
47 | static struct riscv_ipi_ops clint_ipi_ops = { | |
48 | .ipi_inject = clint_send_ipi, | |
49 | .ipi_clear = clint_clear_ipi, | |
50 | }; | |
51 | ||
52 | #ifdef CONFIG_64BIT | |
53 | #define clint_get_cycles() readq_relaxed(clint_timer_val) | |
54 | #else | |
55 | #define clint_get_cycles() readl_relaxed(clint_timer_val) | |
56 | #define clint_get_cycles_hi() readl_relaxed(((u32 *)clint_timer_val) + 1) | |
57 | #endif | |
58 | ||
59 | #ifdef CONFIG_64BIT | |
60 | static u64 notrace clint_get_cycles64(void) | |
61 | { | |
62 | return clint_get_cycles(); | |
63 | } | |
64 | #else /* CONFIG_64BIT */ | |
65 | static u64 notrace clint_get_cycles64(void) | |
66 | { | |
67 | u32 hi, lo; | |
68 | ||
69 | do { | |
70 | hi = clint_get_cycles_hi(); | |
71 | lo = clint_get_cycles(); | |
72 | } while (hi != clint_get_cycles_hi()); | |
73 | ||
74 | return ((u64)hi << 32) | lo; | |
75 | } | |
76 | #endif /* CONFIG_64BIT */ | |
77 | ||
78 | static u64 clint_rdtime(struct clocksource *cs) | |
79 | { | |
80 | return clint_get_cycles64(); | |
81 | } | |
82 | ||
83 | static struct clocksource clint_clocksource = { | |
84 | .name = "clint_clocksource", | |
85 | .rating = 300, | |
86 | .mask = CLOCKSOURCE_MASK(64), | |
87 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
88 | .read = clint_rdtime, | |
89 | }; | |
90 | ||
91 | static int clint_clock_next_event(unsigned long delta, | |
92 | struct clock_event_device *ce) | |
93 | { | |
94 | void __iomem *r = clint_timer_cmp + | |
95 | cpuid_to_hartid_map(smp_processor_id()); | |
96 | ||
97 | csr_set(CSR_IE, IE_TIE); | |
98 | writeq_relaxed(clint_get_cycles64() + delta, r); | |
99 | return 0; | |
100 | } | |
101 | ||
102 | static DEFINE_PER_CPU(struct clock_event_device, clint_clock_event) = { | |
103 | .name = "clint_clockevent", | |
104 | .features = CLOCK_EVT_FEAT_ONESHOT, | |
105 | .rating = 100, | |
106 | .set_next_event = clint_clock_next_event, | |
107 | }; | |
108 | ||
109 | static int clint_timer_starting_cpu(unsigned int cpu) | |
110 | { | |
111 | struct clock_event_device *ce = per_cpu_ptr(&clint_clock_event, cpu); | |
112 | ||
113 | ce->cpumask = cpumask_of(cpu); | |
114 | clockevents_config_and_register(ce, clint_timer_freq, 100, 0x7fffffff); | |
115 | ||
116 | enable_percpu_irq(clint_timer_irq, | |
117 | irq_get_trigger_type(clint_timer_irq)); | |
118 | return 0; | |
119 | } | |
120 | ||
121 | static int clint_timer_dying_cpu(unsigned int cpu) | |
122 | { | |
123 | disable_percpu_irq(clint_timer_irq); | |
124 | return 0; | |
125 | } | |
126 | ||
127 | static irqreturn_t clint_timer_interrupt(int irq, void *dev_id) | |
128 | { | |
129 | struct clock_event_device *evdev = this_cpu_ptr(&clint_clock_event); | |
130 | ||
131 | csr_clear(CSR_IE, IE_TIE); | |
132 | evdev->event_handler(evdev); | |
133 | ||
134 | return IRQ_HANDLED; | |
135 | } | |
136 | ||
137 | static int __init clint_timer_init_dt(struct device_node *np) | |
138 | { | |
139 | int rc; | |
140 | u32 i, nr_irqs; | |
141 | void __iomem *base; | |
142 | struct of_phandle_args oirq; | |
143 | ||
144 | /* | |
145 | * Ensure that CLINT device interrupts are either RV_IRQ_TIMER or | |
146 | * RV_IRQ_SOFT. If it's anything else then we ignore the device. | |
147 | */ | |
148 | nr_irqs = of_irq_count(np); | |
149 | for (i = 0; i < nr_irqs; i++) { | |
150 | if (of_irq_parse_one(np, i, &oirq)) { | |
151 | pr_err("%pOFP: failed to parse irq %d.\n", np, i); | |
152 | continue; | |
153 | } | |
154 | ||
155 | if ((oirq.args_count != 1) || | |
156 | (oirq.args[0] != RV_IRQ_TIMER && | |
157 | oirq.args[0] != RV_IRQ_SOFT)) { | |
158 | pr_err("%pOFP: invalid irq %d (hwirq %d)\n", | |
159 | np, i, oirq.args[0]); | |
160 | return -ENODEV; | |
161 | } | |
162 | ||
163 | /* Find parent irq domain and map timer irq */ | |
164 | if (!clint_timer_irq && | |
165 | oirq.args[0] == RV_IRQ_TIMER && | |
166 | irq_find_host(oirq.np)) | |
167 | clint_timer_irq = irq_of_parse_and_map(np, i); | |
168 | } | |
169 | ||
170 | /* If CLINT timer irq not found then fail */ | |
171 | if (!clint_timer_irq) { | |
172 | pr_err("%pOFP: timer irq not found\n", np); | |
173 | return -ENODEV; | |
174 | } | |
175 | ||
176 | base = of_iomap(np, 0); | |
177 | if (!base) { | |
178 | pr_err("%pOFP: could not map registers\n", np); | |
179 | return -ENODEV; | |
180 | } | |
181 | ||
182 | clint_ipi_base = base + CLINT_IPI_OFF; | |
183 | clint_timer_cmp = base + CLINT_TIMER_CMP_OFF; | |
184 | clint_timer_val = base + CLINT_TIMER_VAL_OFF; | |
185 | clint_timer_freq = riscv_timebase; | |
186 | ||
187 | pr_info("%pOFP: timer running at %ld Hz\n", np, clint_timer_freq); | |
188 | ||
189 | rc = clocksource_register_hz(&clint_clocksource, clint_timer_freq); | |
190 | if (rc) { | |
191 | pr_err("%pOFP: clocksource register failed [%d]\n", np, rc); | |
192 | goto fail_iounmap; | |
193 | } | |
194 | ||
195 | sched_clock_register(clint_get_cycles64, 64, clint_timer_freq); | |
196 | ||
197 | rc = request_percpu_irq(clint_timer_irq, clint_timer_interrupt, | |
198 | "clint-timer", &clint_clock_event); | |
199 | if (rc) { | |
200 | pr_err("registering percpu irq failed [%d]\n", rc); | |
201 | goto fail_iounmap; | |
202 | } | |
203 | ||
204 | rc = cpuhp_setup_state(CPUHP_AP_CLINT_TIMER_STARTING, | |
205 | "clockevents/clint/timer:starting", | |
206 | clint_timer_starting_cpu, | |
207 | clint_timer_dying_cpu); | |
208 | if (rc) { | |
209 | pr_err("%pOFP: cpuhp setup state failed [%d]\n", np, rc); | |
210 | goto fail_free_irq; | |
211 | } | |
212 | ||
213 | riscv_set_ipi_ops(&clint_ipi_ops); | |
214 | clint_clear_ipi(); | |
215 | ||
216 | return 0; | |
217 | ||
218 | fail_free_irq: | |
219 | free_irq(clint_timer_irq, &clint_clock_event); | |
220 | fail_iounmap: | |
221 | iounmap(base); | |
222 | return rc; | |
223 | } | |
224 | ||
225 | TIMER_OF_DECLARE(clint_timer, "riscv,clint0", clint_timer_init_dt); | |
226 | TIMER_OF_DECLARE(clint_timer1, "sifive,clint0", clint_timer_init_dt); |