drivers/clocksource/timer-integrator-ap.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Integrator/AP timer driver
   4  * Copyright (C) 2000-2003 Deep Blue Solutions Ltd
   5  * Copyright (c) 2014, Linaro Limited
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/clocksource.h>
  10 #include <linux/of.h>
  11 #include <linux/of_irq.h>
  12 #include <linux/of_address.h>
  13 #include <linux/clockchips.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/sched_clock.h>
  16
  17 #include "timer-sp.h"
  18
  19 static void __iomem * sched_clk_base;
  20
  21 static u64 notrace integrator_read_sched_clock(void)
  22 {
  23         return -readl(sched_clk_base + TIMER_VALUE);
  24 }
  25
  26 static int __init integrator_clocksource_init(unsigned long inrate,
  27                                               void __iomem *base)
  28 {
  29         u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
  30         unsigned long rate = inrate;
  31         int ret;
  32
  33         if (rate >= 1500000) {
  34                 rate /= 16;
  35                 ctrl |= TIMER_CTRL_DIV16;
  36         }
  37
  38         writel(0xffff, base + TIMER_LOAD);
  39         writel(ctrl, base + TIMER_CTRL);
  40
  41         ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2",
  42                                     rate, 200, 16, clocksource_mmio_readl_down);
  43         if (ret)
  44                 return ret;
  45
  46         sched_clk_base = base;
  47         sched_clock_register(integrator_read_sched_clock, 16, rate);
  48
  49         return 0;
  50 }
  51
  52 static unsigned long timer_reload;
  53 static void __iomem * clkevt_base;
  54
  55 /*
  56  * IRQ handler for the timer
  57  */
  58 static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id)
  59 {
  60         struct clock_event_device *evt = dev_id;
  61
  62         /* clear the interrupt */
  63         writel(1, clkevt_base + TIMER_INTCLR);
  64
  65         evt->event_handler(evt);
  66
  67         return IRQ_HANDLED;
  68 }
  69
  70 static int clkevt_shutdown(struct clock_event_device *evt)
  71 {
  72         u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
  73
  74         /* Disable timer */
  75         writel(ctrl, clkevt_base + TIMER_CTRL);
  76         return 0;
  77 }
  78
  79 static int clkevt_set_oneshot(struct clock_event_device *evt)
  80 {
  81         u32 ctrl = readl(clkevt_base + TIMER_CTRL) &
  82                    ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC);
  83
  84         /* Leave the timer disabled, .set_next_event will enable it */
  85         writel(ctrl, clkevt_base + TIMER_CTRL);
  86         return 0;
  87 }
  88
  89 static int clkevt_set_periodic(struct clock_event_device *evt)
  90 {
  91         u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
  92
  93         /* Disable timer */
  94         writel(ctrl, clkevt_base + TIMER_CTRL);
  95
  96         /* Enable the timer and start the periodic tick */
  97         writel(timer_reload, clkevt_base + TIMER_LOAD);
  98         ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;
  99         writel(ctrl, clkevt_base + TIMER_CTRL);
 100         return 0;
 101 }
 102
 103 static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
 104 {
 105         unsigned long ctrl = readl(clkevt_base + TIMER_CTRL);
 106
 107         writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 108         writel(next, clkevt_base + TIMER_LOAD);
 109         writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 110
 111         return 0;
 112 }
 113
 114 static struct clock_event_device integrator_clockevent = {
 115         .name                   = "timer1",
 116         .features               = CLOCK_EVT_FEAT_PERIODIC |
 117                                   CLOCK_EVT_FEAT_ONESHOT,
 118         .set_state_shutdown     = clkevt_shutdown,
 119         .set_state_periodic     = clkevt_set_periodic,
 120         .set_state_oneshot      = clkevt_set_oneshot,
 121         .tick_resume            = clkevt_shutdown,
 122         .set_next_event         = clkevt_set_next_event,
 123         .rating                 = 300,
 124 };
 125
 126 static int integrator_clockevent_init(unsigned long inrate,
 127                                       void __iomem *base, int irq)
 128 {
 129         unsigned long rate = inrate;
 130         unsigned int ctrl = 0;
 131         int ret;
 132
 133         clkevt_base = base;
 134         /* Calculate and program a divisor */
 135         if (rate > 0x100000 * HZ) {
 136                 rate /= 256;
 137                 ctrl |= TIMER_CTRL_DIV256;
 138         } else if (rate > 0x10000 * HZ) {
 139                 rate /= 16;
 140                 ctrl |= TIMER_CTRL_DIV16;
 141         }
 142         timer_reload = rate / HZ;
 143         writel(ctrl, clkevt_base + TIMER_CTRL);
 144
 145         ret = request_irq(irq, integrator_timer_interrupt,
 146                           IRQF_TIMER | IRQF_IRQPOLL, "timer",
 147                           &integrator_clockevent);
 148         if (ret)
 149                 return ret;
 150
 151         clockevents_config_and_register(&integrator_clockevent,
 152                                         rate,
 153                                         1,
 154                                         0xffffU);
 155         return 0;
 156 }
 157
 158 static int __init integrator_ap_timer_init_of(struct device_node *node)
 159 {
 160         const char *path;
 161         void __iomem *base;
 162         int err;
 163         int irq;
 164         struct clk *clk;
 165         unsigned long rate;
 166         struct device_node *alias_node;
 167
 168         base = of_io_request_and_map(node, 0, "integrator-timer");
 169         if (IS_ERR(base))
 170                 return PTR_ERR(base);
 171
 172         clk = of_clk_get(node, 0);
 173         if (IS_ERR(clk)) {
 174                 pr_err("No clock for %pOFn\n", node);
 175                 return PTR_ERR(clk);
 176         }
 177         clk_prepare_enable(clk);
 178         rate = clk_get_rate(clk);
 179         writel(0, base + TIMER_CTRL);
 180
 181         err = of_property_read_string(of_aliases,
 182                                 "arm,timer-primary", &path);
 183         if (err) {
 184                 pr_warn("Failed to read property\n");
 185                 return err;
 186         }
 187
 188         alias_node = of_find_node_by_path(path);
 189
 190         /*
 191          * The pointer is used as an identifier not as a pointer, we
 192          * can drop the refcount on the of__node immediately after
 193          * getting it.
 194          */
 195         of_node_put(alias_node);
 196
 197         if (node == alias_node)
 198                 /* The primary timer lacks IRQ, use as clocksource */
 199                 return integrator_clocksource_init(rate, base);
 200
 201         err = of_property_read_string(of_aliases,
 202                                 "arm,timer-secondary", &path);
 203         if (err) {
 204                 pr_warn("Failed to read property\n");
 205                 return err;
 206         }
 207
 208         alias_node = of_find_node_by_path(path);
 209
 210         of_node_put(alias_node);
 211
 212         if (node == alias_node) {
 213                 /* The secondary timer will drive the clock event */
 214                 irq = irq_of_parse_and_map(node, 0);
 215                 return integrator_clockevent_init(rate, base, irq);
 216         }
 217
 218         pr_info("Timer @%p unused\n", base);
 219         clk_disable_unprepare(clk);
 220
 221         return 0;
 222 }
 223
 224 TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
 225                        integrator_ap_timer_init_of);