drivers/clocksource/mps2-timer.c

   1 /*
   2  * Copyright (C) 2015 ARM Limited
   3  *
   4  * Author: Vladimir Murzin <vladimir.murzin@arm.com>
   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 int __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 0;
 263                 }
 264         }
 265
 266         if (!has_clockevent) {
 267                 ret = mps2_clockevent_init(np);
 268                 if (!ret) {
 269                         has_clockevent = 1;
 270                         return 0;
 271                 }
 272         }
 273
 274         return 0;
 275 }
 276
 277 CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);