kernel/drivers/clocksource/timer-integrator-ap.c

   1 /*
   2  * Integrator/AP timer driver
   3  * Copyright (C) 2000-2003 Deep Blue Solutions Ltd
   4  * Copyright (c) 2014, Linaro Limited
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/clk.h>
  22 #include <linux/clocksource.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/of_address.h>
  25 #include <linux/of_platform.h>
  26 #include <linux/clockchips.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/sched_clock.h>
  29
  30 #include "timer-sp.h"
  31
  32 static void __iomem * sched_clk_base;
  33
  34 static u64 notrace integrator_read_sched_clock(void)
  35 {
  36         return -readl(sched_clk_base + TIMER_VALUE);
  37 }
  38
  39 static void integrator_clocksource_init(unsigned long inrate,
  40                                         void __iomem *base)
  41 {
  42         u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
  43         unsigned long rate = inrate;
  44
  45         if (rate >= 1500000) {
  46                 rate /= 16;
  47                 ctrl |= TIMER_CTRL_DIV16;
  48         }
  49
  50         writel(0xffff, base + TIMER_LOAD);
  51         writel(ctrl, base + TIMER_CTRL);
  52
  53         clocksource_mmio_init(base + TIMER_VALUE, "timer2",
  54                         rate, 200, 16, clocksource_mmio_readl_down);
  55
  56         sched_clk_base = base;
  57         sched_clock_register(integrator_read_sched_clock, 16, rate);
  58 }
  59
  60 static unsigned long timer_reload;
  61 static void __iomem * clkevt_base;
  62
  63 /*
  64  * IRQ handler for the timer
  65  */
  66 static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id)
  67 {
  68         struct clock_event_device *evt = dev_id;
  69
  70         /* clear the interrupt */
  71         writel(1, clkevt_base + TIMER_INTCLR);
  72
  73         evt->event_handler(evt);
  74
  75         return IRQ_HANDLED;
  76 }
  77
  78 static int clkevt_shutdown(struct clock_event_device *evt)
  79 {
  80         u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
  81
  82         /* Disable timer */
  83         writel(ctrl, clkevt_base + TIMER_CTRL);
  84         return 0;
  85 }
  86
  87 static int clkevt_set_oneshot(struct clock_event_device *evt)
  88 {
  89         u32 ctrl = readl(clkevt_base + TIMER_CTRL) &
  90                    ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC);
  91
  92         /* Leave the timer disabled, .set_next_event will enable it */
  93         writel(ctrl, clkevt_base + TIMER_CTRL);
  94         return 0;
  95 }
  96
  97 static int clkevt_set_periodic(struct clock_event_device *evt)
  98 {
  99         u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
 100
 101         /* Disable timer */
 102         writel(ctrl, clkevt_base + TIMER_CTRL);
 103
 104         /* Enable the timer and start the periodic tick */
 105         writel(timer_reload, clkevt_base + TIMER_LOAD);
 106         ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;
 107         writel(ctrl, clkevt_base + TIMER_CTRL);
 108         return 0;
 109 }
 110
 111 static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
 112 {
 113         unsigned long ctrl = readl(clkevt_base + TIMER_CTRL);
 114
 115         writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 116         writel(next, clkevt_base + TIMER_LOAD);
 117         writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 118
 119         return 0;
 120 }
 121
 122 static struct clock_event_device integrator_clockevent = {
 123         .name                   = "timer1",
 124         .features               = CLOCK_EVT_FEAT_PERIODIC |
 125                                   CLOCK_EVT_FEAT_ONESHOT,
 126         .set_state_shutdown     = clkevt_shutdown,
 127         .set_state_periodic     = clkevt_set_periodic,
 128         .set_state_oneshot      = clkevt_set_oneshot,
 129         .tick_resume            = clkevt_shutdown,
 130         .set_next_event         = clkevt_set_next_event,
 131         .rating                 = 300,
 132 };
 133
 134 static struct irqaction integrator_timer_irq = {
 135         .name           = "timer",
 136         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 137         .handler        = integrator_timer_interrupt,
 138         .dev_id         = &integrator_clockevent,
 139 };
 140
 141 static void integrator_clockevent_init(unsigned long inrate,
 142                                 void __iomem *base, int irq)
 143 {
 144         unsigned long rate = inrate;
 145         unsigned int ctrl = 0;
 146
 147         clkevt_base = base;
 148         /* Calculate and program a divisor */
 149         if (rate > 0x100000 * HZ) {
 150                 rate /= 256;
 151                 ctrl |= TIMER_CTRL_DIV256;
 152         } else if (rate > 0x10000 * HZ) {
 153                 rate /= 16;
 154                 ctrl |= TIMER_CTRL_DIV16;
 155         }
 156         timer_reload = rate / HZ;
 157         writel(ctrl, clkevt_base + TIMER_CTRL);
 158
 159         setup_irq(irq, &integrator_timer_irq);
 160         clockevents_config_and_register(&integrator_clockevent,
 161                                         rate,
 162                                         1,
 163                                         0xffffU);
 164 }
 165
 166 static void __init integrator_ap_timer_init_of(struct device_node *node)
 167 {
 168         const char *path;
 169         void __iomem *base;
 170         int err;
 171         int irq;
 172         struct clk *clk;
 173         unsigned long rate;
 174         struct device_node *pri_node;
 175         struct device_node *sec_node;
 176
 177         base = of_io_request_and_map(node, 0, "integrator-timer");
 178         if (IS_ERR(base))
 179                 return;
 180
 181         clk = of_clk_get(node, 0);
 182         if (IS_ERR(clk)) {
 183                 pr_err("No clock for %s\n", node->name);
 184                 return;
 185         }
 186         clk_prepare_enable(clk);
 187         rate = clk_get_rate(clk);
 188         writel(0, base + TIMER_CTRL);
 189
 190         err = of_property_read_string(of_aliases,
 191                                 "arm,timer-primary", &path);
 192         if (WARN_ON(err))
 193                 return;
 194         pri_node = of_find_node_by_path(path);
 195         err = of_property_read_string(of_aliases,
 196                                 "arm,timer-secondary", &path);
 197         if (WARN_ON(err))
 198                 return;
 199         sec_node = of_find_node_by_path(path);
 200
 201         if (node == pri_node) {
 202                 /* The primary timer lacks IRQ, use as clocksource */
 203                 integrator_clocksource_init(rate, base);
 204                 return;
 205         }
 206
 207         if (node == sec_node) {
 208                 /* The secondary timer will drive the clock event */
 209                 irq = irq_of_parse_and_map(node, 0);
 210                 integrator_clockevent_init(rate, base, irq);
 211                 return;
 212         }
 213
 214         pr_info("Timer @%p unused\n", base);
 215         clk_disable_unprepare(clk);
 216 }
 217
 218 CLOCKSOURCE_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
 219                        integrator_ap_timer_init_of);