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9995f4f1 RF |
1 | /* |
2 | * J-Core SoC PIT/clocksource driver | |
3 | * | |
4 | * Copyright (C) 2015-2016 Smart Energy Instruments, Inc. | |
5 | * | |
6 | * This file is subject to the terms and conditions of the GNU General Public | |
7 | * License. See the file "COPYING" in the main directory of this archive | |
8 | * for more details. | |
9 | */ | |
10 | ||
11 | #include <linux/kernel.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/interrupt.h> | |
14 | #include <linux/clockchips.h> | |
15 | #include <linux/clocksource.h> | |
16 | #include <linux/sched_clock.h> | |
17 | #include <linux/cpu.h> | |
18 | #include <linux/cpuhotplug.h> | |
19 | #include <linux/of_address.h> | |
20 | #include <linux/of_irq.h> | |
21 | ||
22 | #define PIT_IRQ_SHIFT 12 | |
23 | #define PIT_PRIO_SHIFT 20 | |
24 | #define PIT_ENABLE_SHIFT 26 | |
25 | #define PIT_PRIO_MASK 0xf | |
26 | ||
27 | #define REG_PITEN 0x00 | |
28 | #define REG_THROT 0x10 | |
29 | #define REG_COUNT 0x14 | |
30 | #define REG_BUSPD 0x18 | |
31 | #define REG_SECHI 0x20 | |
32 | #define REG_SECLO 0x24 | |
33 | #define REG_NSEC 0x28 | |
34 | ||
35 | struct jcore_pit { | |
36 | struct clock_event_device ced; | |
37 | void __iomem *base; | |
38 | unsigned long periodic_delta; | |
39 | u32 enable_val; | |
40 | }; | |
41 | ||
42 | static void __iomem *jcore_pit_base; | |
43 | static struct jcore_pit __percpu *jcore_pit_percpu; | |
44 | ||
45 | static notrace u64 jcore_sched_clock_read(void) | |
46 | { | |
47 | u32 seclo, nsec, seclo0; | |
48 | __iomem void *base = jcore_pit_base; | |
49 | ||
50 | seclo = readl(base + REG_SECLO); | |
51 | do { | |
52 | seclo0 = seclo; | |
53 | nsec = readl(base + REG_NSEC); | |
54 | seclo = readl(base + REG_SECLO); | |
55 | } while (seclo0 != seclo); | |
56 | ||
57 | return seclo * NSEC_PER_SEC + nsec; | |
58 | } | |
59 | ||
a5a1d1c2 | 60 | static u64 jcore_clocksource_read(struct clocksource *cs) |
9995f4f1 RF |
61 | { |
62 | return jcore_sched_clock_read(); | |
63 | } | |
64 | ||
65 | static int jcore_pit_disable(struct jcore_pit *pit) | |
66 | { | |
67 | writel(0, pit->base + REG_PITEN); | |
68 | return 0; | |
69 | } | |
70 | ||
71 | static int jcore_pit_set(unsigned long delta, struct jcore_pit *pit) | |
72 | { | |
73 | jcore_pit_disable(pit); | |
74 | writel(delta, pit->base + REG_THROT); | |
75 | writel(pit->enable_val, pit->base + REG_PITEN); | |
76 | return 0; | |
77 | } | |
78 | ||
79 | static int jcore_pit_set_state_shutdown(struct clock_event_device *ced) | |
80 | { | |
81 | struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); | |
82 | ||
83 | return jcore_pit_disable(pit); | |
84 | } | |
85 | ||
86 | static int jcore_pit_set_state_oneshot(struct clock_event_device *ced) | |
87 | { | |
88 | struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); | |
89 | ||
90 | return jcore_pit_disable(pit); | |
91 | } | |
92 | ||
93 | static int jcore_pit_set_state_periodic(struct clock_event_device *ced) | |
94 | { | |
95 | struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); | |
96 | ||
97 | return jcore_pit_set(pit->periodic_delta, pit); | |
98 | } | |
99 | ||
100 | static int jcore_pit_set_next_event(unsigned long delta, | |
101 | struct clock_event_device *ced) | |
102 | { | |
103 | struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); | |
104 | ||
105 | return jcore_pit_set(delta, pit); | |
106 | } | |
107 | ||
108 | static int jcore_pit_local_init(unsigned cpu) | |
109 | { | |
110 | struct jcore_pit *pit = this_cpu_ptr(jcore_pit_percpu); | |
111 | unsigned buspd, freq; | |
112 | ||
113 | pr_info("Local J-Core PIT init on cpu %u\n", cpu); | |
114 | ||
115 | buspd = readl(pit->base + REG_BUSPD); | |
116 | freq = DIV_ROUND_CLOSEST(NSEC_PER_SEC, buspd); | |
117 | pit->periodic_delta = DIV_ROUND_CLOSEST(NSEC_PER_SEC, HZ * buspd); | |
118 | ||
119 | clockevents_config_and_register(&pit->ced, freq, 1, ULONG_MAX); | |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
124 | static irqreturn_t jcore_timer_interrupt(int irq, void *dev_id) | |
125 | { | |
126 | struct jcore_pit *pit = this_cpu_ptr(dev_id); | |
127 | ||
128 | if (clockevent_state_oneshot(&pit->ced)) | |
129 | jcore_pit_disable(pit); | |
130 | ||
131 | pit->ced.event_handler(&pit->ced); | |
132 | ||
133 | return IRQ_HANDLED; | |
134 | } | |
135 | ||
136 | static int __init jcore_pit_init(struct device_node *node) | |
137 | { | |
138 | int err; | |
139 | unsigned pit_irq, cpu; | |
140 | unsigned long hwirq; | |
141 | u32 irqprio, enable_val; | |
142 | ||
143 | jcore_pit_base = of_iomap(node, 0); | |
144 | if (!jcore_pit_base) { | |
145 | pr_err("Error: Cannot map base address for J-Core PIT\n"); | |
146 | return -ENXIO; | |
147 | } | |
148 | ||
149 | pit_irq = irq_of_parse_and_map(node, 0); | |
150 | if (!pit_irq) { | |
151 | pr_err("Error: J-Core PIT has no IRQ\n"); | |
152 | return -ENXIO; | |
153 | } | |
154 | ||
155 | pr_info("Initializing J-Core PIT at %p IRQ %d\n", | |
156 | jcore_pit_base, pit_irq); | |
157 | ||
158 | err = clocksource_mmio_init(jcore_pit_base, "jcore_pit_cs", | |
159 | NSEC_PER_SEC, 400, 32, | |
160 | jcore_clocksource_read); | |
161 | if (err) { | |
162 | pr_err("Error registering clocksource device: %d\n", err); | |
163 | return err; | |
164 | } | |
165 | ||
166 | sched_clock_register(jcore_sched_clock_read, 32, NSEC_PER_SEC); | |
167 | ||
168 | jcore_pit_percpu = alloc_percpu(struct jcore_pit); | |
169 | if (!jcore_pit_percpu) { | |
170 | pr_err("Failed to allocate memory for clock event device\n"); | |
171 | return -ENOMEM; | |
172 | } | |
173 | ||
174 | err = request_irq(pit_irq, jcore_timer_interrupt, | |
175 | IRQF_TIMER | IRQF_PERCPU, | |
176 | "jcore_pit", jcore_pit_percpu); | |
177 | if (err) { | |
178 | pr_err("pit irq request failed: %d\n", err); | |
179 | free_percpu(jcore_pit_percpu); | |
180 | return err; | |
181 | } | |
182 | ||
183 | /* | |
184 | * The J-Core PIT is not hard-wired to a particular IRQ, but | |
185 | * integrated with the interrupt controller such that the IRQ it | |
186 | * generates is programmable, as follows: | |
187 | * | |
188 | * The bit layout of the PIT enable register is: | |
189 | * | |
190 | * .....e..ppppiiiiiiii............ | |
191 | * | |
192 | * where the .'s indicate unrelated/unused bits, e is enable, | |
193 | * p is priority, and i is hard irq number. | |
194 | * | |
195 | * For the PIT included in AIC1 (obsolete but still in use), | |
196 | * any hard irq (trap number) can be programmed via the 8 | |
197 | * iiiiiiii bits, and a priority (0-15) is programmable | |
198 | * separately in the pppp bits. | |
199 | * | |
200 | * For the PIT included in AIC2 (current), the programming | |
201 | * interface is equivalent modulo interrupt mapping. This is | |
202 | * why a different compatible tag was not used. However only | |
203 | * traps 64-127 (the ones actually intended to be used for | |
204 | * interrupts, rather than syscalls/exceptions/etc.) can be | |
205 | * programmed (the high 2 bits of i are ignored) and the | |
206 | * priority pppp is <<2'd and or'd onto the irq number. This | |
207 | * choice seems to have been made on the hardware engineering | |
208 | * side under an assumption that preserving old AIC1 priority | |
209 | * mappings was important. Future models will likely ignore | |
210 | * the pppp field. | |
211 | */ | |
212 | hwirq = irq_get_irq_data(pit_irq)->hwirq; | |
213 | irqprio = (hwirq >> 2) & PIT_PRIO_MASK; | |
214 | enable_val = (1U << PIT_ENABLE_SHIFT) | |
215 | | (hwirq << PIT_IRQ_SHIFT) | |
216 | | (irqprio << PIT_PRIO_SHIFT); | |
217 | ||
218 | for_each_present_cpu(cpu) { | |
219 | struct jcore_pit *pit = per_cpu_ptr(jcore_pit_percpu, cpu); | |
220 | ||
221 | pit->base = of_iomap(node, cpu); | |
222 | if (!pit->base) { | |
223 | pr_err("Unable to map PIT for cpu %u\n", cpu); | |
224 | continue; | |
225 | } | |
226 | ||
227 | pit->ced.name = "jcore_pit"; | |
228 | pit->ced.features = CLOCK_EVT_FEAT_PERIODIC | |
229 | | CLOCK_EVT_FEAT_ONESHOT | |
230 | | CLOCK_EVT_FEAT_PERCPU; | |
231 | pit->ced.cpumask = cpumask_of(cpu); | |
232 | pit->ced.rating = 400; | |
233 | pit->ced.irq = pit_irq; | |
234 | pit->ced.set_state_shutdown = jcore_pit_set_state_shutdown; | |
235 | pit->ced.set_state_periodic = jcore_pit_set_state_periodic; | |
236 | pit->ced.set_state_oneshot = jcore_pit_set_state_oneshot; | |
237 | pit->ced.set_next_event = jcore_pit_set_next_event; | |
238 | ||
239 | pit->enable_val = enable_val; | |
240 | } | |
241 | ||
242 | cpuhp_setup_state(CPUHP_AP_JCORE_TIMER_STARTING, | |
73c1b41e | 243 | "clockevents/jcore:starting", |
9995f4f1 RF |
244 | jcore_pit_local_init, NULL); |
245 | ||
246 | return 0; | |
247 | } | |
248 | ||
249 | CLOCKSOURCE_OF_DECLARE(jcore_pit, "jcore,pit", jcore_pit_init); |