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| 1 | +/* |
| 2 | + * Copyright (C) 2015 ARM Limited |
| 3 | + * |
| 4 | + * Author: Vladimir Murzin <[email protected]> |
| 5 | + * |
| 6 | + * This program is free software; you can redistribute it and/or modify |
| 7 | + * it under the terms of the GNU General Public License version 2 as |
| 8 | + * published by the Free Software Foundation. |
| 9 | + * |
| 10 | + */ |
| 11 | + |
| 12 | +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 13 | + |
| 14 | +#include <linux/clk.h> |
| 15 | +#include <linux/clockchips.h> |
| 16 | +#include <linux/clocksource.h> |
| 17 | +#include <linux/err.h> |
| 18 | +#include <linux/interrupt.h> |
| 19 | +#include <linux/io.h> |
| 20 | +#include <linux/irq.h> |
| 21 | +#include <linux/of_address.h> |
| 22 | +#include <linux/of.h> |
| 23 | +#include <linux/of_irq.h> |
| 24 | +#include <linux/sched_clock.h> |
| 25 | +#include <linux/slab.h> |
| 26 | + |
| 27 | +#define TIMER_CTRL 0x0 |
| 28 | +#define TIMER_CTRL_ENABLE BIT(0) |
| 29 | +#define TIMER_CTRL_IE BIT(3) |
| 30 | + |
| 31 | +#define TIMER_VALUE 0x4 |
| 32 | +#define TIMER_RELOAD 0x8 |
| 33 | +#define TIMER_INT 0xc |
| 34 | + |
| 35 | +struct clockevent_mps2 { |
| 36 | + void __iomem *reg; |
| 37 | + u32 clock_count_per_tick; |
| 38 | + struct clock_event_device clkevt; |
| 39 | +}; |
| 40 | + |
| 41 | +static void __iomem *sched_clock_base; |
| 42 | + |
| 43 | +static u64 notrace mps2_sched_read(void) |
| 44 | +{ |
| 45 | + return ~readl_relaxed(sched_clock_base + TIMER_VALUE); |
| 46 | +} |
| 47 | + |
| 48 | +static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c) |
| 49 | +{ |
| 50 | + return container_of(c, struct clockevent_mps2, clkevt); |
| 51 | +} |
| 52 | + |
| 53 | +static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset) |
| 54 | +{ |
| 55 | + writel_relaxed(val, to_mps2_clkevt(c)->reg + offset); |
| 56 | +} |
| 57 | + |
| 58 | +static int mps2_timer_shutdown(struct clock_event_device *ce) |
| 59 | +{ |
| 60 | + clockevent_mps2_writel(0, ce, TIMER_RELOAD); |
| 61 | + clockevent_mps2_writel(0, ce, TIMER_CTRL); |
| 62 | + |
| 63 | + return 0; |
| 64 | +} |
| 65 | + |
| 66 | +static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce) |
| 67 | +{ |
| 68 | + clockevent_mps2_writel(next, ce, TIMER_VALUE); |
| 69 | + clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL); |
| 70 | + |
| 71 | + return 0; |
| 72 | +} |
| 73 | + |
| 74 | +static int mps2_timer_set_periodic(struct clock_event_device *ce) |
| 75 | +{ |
| 76 | + u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick; |
| 77 | + |
| 78 | + clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD); |
| 79 | + clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE); |
| 80 | + clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL); |
| 81 | + |
| 82 | + return 0; |
| 83 | +} |
| 84 | + |
| 85 | +static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id) |
| 86 | +{ |
| 87 | + struct clockevent_mps2 *ce = dev_id; |
| 88 | + u32 status = readl_relaxed(ce->reg + TIMER_INT); |
| 89 | + |
| 90 | + if (!status) { |
| 91 | + pr_warn("spurious interrupt\n"); |
| 92 | + return IRQ_NONE; |
| 93 | + } |
| 94 | + |
| 95 | + writel_relaxed(1, ce->reg + TIMER_INT); |
| 96 | + |
| 97 | + ce->clkevt.event_handler(&ce->clkevt); |
| 98 | + |
| 99 | + return IRQ_HANDLED; |
| 100 | +} |
| 101 | + |
| 102 | +static int __init mps2_clockevent_init(struct device_node *np) |
| 103 | +{ |
| 104 | + void __iomem *base; |
| 105 | + struct clk *clk = NULL; |
| 106 | + struct clockevent_mps2 *ce; |
| 107 | + u32 rate; |
| 108 | + int irq, ret; |
| 109 | + const char *name = "mps2-clkevt"; |
| 110 | + |
| 111 | + ret = of_property_read_u32(np, "clock-frequency", &rate); |
| 112 | + if (ret) { |
| 113 | + clk = of_clk_get(np, 0); |
| 114 | + if (IS_ERR(clk)) { |
| 115 | + ret = PTR_ERR(clk); |
| 116 | + pr_err("failed to get clock for clockevent: %d\n", ret); |
| 117 | + goto out; |
| 118 | + } |
| 119 | + |
| 120 | + ret = clk_prepare_enable(clk); |
| 121 | + if (ret) { |
| 122 | + pr_err("failed to enable clock for clockevent: %d\n", ret); |
| 123 | + goto out_clk_put; |
| 124 | + } |
| 125 | + |
| 126 | + rate = clk_get_rate(clk); |
| 127 | + } |
| 128 | + |
| 129 | + base = of_iomap(np, 0); |
| 130 | + if (!base) { |
| 131 | + ret = -EADDRNOTAVAIL; |
| 132 | + pr_err("failed to map register for clockevent: %d\n", ret); |
| 133 | + goto out_clk_disable; |
| 134 | + } |
| 135 | + |
| 136 | + irq = irq_of_parse_and_map(np, 0); |
| 137 | + if (!irq) { |
| 138 | + ret = -ENOENT; |
| 139 | + pr_err("failed to get irq for clockevent: %d\n", ret); |
| 140 | + goto out_iounmap; |
| 141 | + } |
| 142 | + |
| 143 | + ce = kzalloc(sizeof(*ce), GFP_KERNEL); |
| 144 | + if (!ce) { |
| 145 | + ret = -ENOMEM; |
| 146 | + goto out_iounmap; |
| 147 | + } |
| 148 | + |
| 149 | + ce->reg = base; |
| 150 | + ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ); |
| 151 | + ce->clkevt.irq = irq; |
| 152 | + ce->clkevt.name = name; |
| 153 | + ce->clkevt.rating = 200; |
| 154 | + ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; |
| 155 | + ce->clkevt.cpumask = cpu_possible_mask; |
| 156 | + ce->clkevt.set_state_shutdown = mps2_timer_shutdown, |
| 157 | + ce->clkevt.set_state_periodic = mps2_timer_set_periodic, |
| 158 | + ce->clkevt.set_state_oneshot = mps2_timer_shutdown, |
| 159 | + ce->clkevt.set_next_event = mps2_timer_set_next_event; |
| 160 | + |
| 161 | + /* Ensure timer is disabled */ |
| 162 | + writel_relaxed(0, base + TIMER_CTRL); |
| 163 | + |
| 164 | + ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce); |
| 165 | + if (ret) { |
| 166 | + pr_err("failed to request irq for clockevent: %d\n", ret); |
| 167 | + goto out_kfree; |
| 168 | + } |
| 169 | + |
| 170 | + clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff); |
| 171 | + |
| 172 | + return 0; |
| 173 | + |
| 174 | +out_kfree: |
| 175 | + kfree(ce); |
| 176 | +out_iounmap: |
| 177 | + iounmap(base); |
| 178 | +out_clk_disable: |
| 179 | + /* clk_{disable, unprepare, put}() can handle NULL as a parameter */ |
| 180 | + clk_disable_unprepare(clk); |
| 181 | +out_clk_put: |
| 182 | + clk_put(clk); |
| 183 | +out: |
| 184 | + return ret; |
| 185 | +} |
| 186 | + |
| 187 | +static int __init mps2_clocksource_init(struct device_node *np) |
| 188 | +{ |
| 189 | + void __iomem *base; |
| 190 | + struct clk *clk = NULL; |
| 191 | + u32 rate; |
| 192 | + int ret; |
| 193 | + const char *name = "mps2-clksrc"; |
| 194 | + |
| 195 | + ret = of_property_read_u32(np, "clock-frequency", &rate); |
| 196 | + if (ret) { |
| 197 | + clk = of_clk_get(np, 0); |
| 198 | + if (IS_ERR(clk)) { |
| 199 | + ret = PTR_ERR(clk); |
| 200 | + pr_err("failed to get clock for clocksource: %d\n", ret); |
| 201 | + goto out; |
| 202 | + } |
| 203 | + |
| 204 | + ret = clk_prepare_enable(clk); |
| 205 | + if (ret) { |
| 206 | + pr_err("failed to enable clock for clocksource: %d\n", ret); |
| 207 | + goto out_clk_put; |
| 208 | + } |
| 209 | + |
| 210 | + rate = clk_get_rate(clk); |
| 211 | + } |
| 212 | + |
| 213 | + base = of_iomap(np, 0); |
| 214 | + if (!base) { |
| 215 | + ret = -EADDRNOTAVAIL; |
| 216 | + pr_err("failed to map register for clocksource: %d\n", ret); |
| 217 | + goto out_clk_disable; |
| 218 | + } |
| 219 | + |
| 220 | + /* Ensure timer is disabled */ |
| 221 | + writel_relaxed(0, base + TIMER_CTRL); |
| 222 | + |
| 223 | + /* ... and set it up as free-running clocksource */ |
| 224 | + writel_relaxed(0xffffffff, base + TIMER_VALUE); |
| 225 | + writel_relaxed(0xffffffff, base + TIMER_RELOAD); |
| 226 | + |
| 227 | + writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL); |
| 228 | + |
| 229 | + ret = clocksource_mmio_init(base + TIMER_VALUE, name, |
| 230 | + rate, 200, 32, |
| 231 | + clocksource_mmio_readl_down); |
| 232 | + if (ret) { |
| 233 | + pr_err("failed to init clocksource: %d\n", ret); |
| 234 | + goto out_iounmap; |
| 235 | + } |
| 236 | + |
| 237 | + sched_clock_base = base; |
| 238 | + sched_clock_register(mps2_sched_read, 32, rate); |
| 239 | + |
| 240 | + return 0; |
| 241 | + |
| 242 | +out_iounmap: |
| 243 | + iounmap(base); |
| 244 | +out_clk_disable: |
| 245 | + /* clk_{disable, unprepare, put}() can handle NULL as a parameter */ |
| 246 | + clk_disable_unprepare(clk); |
| 247 | +out_clk_put: |
| 248 | + clk_put(clk); |
| 249 | +out: |
| 250 | + return ret; |
| 251 | +} |
| 252 | + |
| 253 | +static void __init mps2_timer_init(struct device_node *np) |
| 254 | +{ |
| 255 | + static int has_clocksource, has_clockevent; |
| 256 | + int ret; |
| 257 | + |
| 258 | + if (!has_clocksource) { |
| 259 | + ret = mps2_clocksource_init(np); |
| 260 | + if (!ret) { |
| 261 | + has_clocksource = 1; |
| 262 | + return; |
| 263 | + } |
| 264 | + } |
| 265 | + |
| 266 | + if (!has_clockevent) { |
| 267 | + ret = mps2_clockevent_init(np); |
| 268 | + if (!ret) { |
| 269 | + has_clockevent = 1; |
| 270 | + return; |
| 271 | + } |
| 272 | + } |
| 273 | +} |
| 274 | + |
| 275 | +CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init); |
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