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 #include <asm/hardware/arm_timer.h>
  30
  31 static void __iomem * sched_clk_base;
  32
  33 static u64 notrace integrator_read_sched_clock(void)
  34 {
  35         return -readl(sched_clk_base + TIMER_VALUE);
  36 }
  37
  38 static void integrator_clocksource_init(unsigned long inrate,
  39                                         void __iomem *base)
  40 {
  41         u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
  42         unsigned long rate = inrate;
  43
  44         if (rate >= 1500000) {
  45                 rate /= 16;
  46                 ctrl |= TIMER_CTRL_DIV16;
  47         }
  48
  49         writel(0xffff, base + TIMER_LOAD);
  50         writel(ctrl, base + TIMER_CTRL);
  51
  52         clocksource_mmio_init(base + TIMER_VALUE, "timer2",
  53                         rate, 200, 16, clocksource_mmio_readl_down);
  54
  55         sched_clk_base = base;
  56         sched_clock_register(integrator_read_sched_clock, 16, rate);
  57 }
  58
  59 static unsigned long timer_reload;
  60 static void __iomem * clkevt_base;
  61
  62 /*
  63  * IRQ handler for the timer
  64  */
  65 static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id)
  66 {
  67         struct clock_event_device *evt = dev_id;
  68
  69         /* clear the interrupt */
  70         writel(1, clkevt_base + TIMER_INTCLR);
  71
  72         evt->event_handler(evt);
  73
  74         return IRQ_HANDLED;
  75 }
  76
  77 static void clkevt_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
  78 {
  79         u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
  80
  81         /* Disable timer */
  82         writel(ctrl, clkevt_base + TIMER_CTRL);
  83
  84         switch (mode) {
  85         case CLOCK_EVT_MODE_PERIODIC:
  86                 /* Enable the timer and start the periodic tick */
  87                 writel(timer_reload, clkevt_base + TIMER_LOAD);
  88                 ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;
  89                 writel(ctrl, clkevt_base + TIMER_CTRL);
  90                 break;
  91         case CLOCK_EVT_MODE_ONESHOT:
  92                 /* Leave the timer disabled, .set_next_event will enable it */
  93                 ctrl &= ~TIMER_CTRL_PERIODIC;
  94                 writel(ctrl, clkevt_base + TIMER_CTRL);
  95                 break;
  96         case CLOCK_EVT_MODE_UNUSED:
  97         case CLOCK_EVT_MODE_SHUTDOWN:
  98         case CLOCK_EVT_MODE_RESUME:
  99         default:
 100                 /* Just leave in disabled state */
 101                 break;
 102         }
 103
 104 }
 105
 106 static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
 107 {
 108         unsigned long ctrl = readl(clkevt_base + TIMER_CTRL);
 109
 110         writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 111         writel(next, clkevt_base + TIMER_LOAD);
 112         writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
 113
 114         return 0;
 115 }
 116
 117 static struct clock_event_device integrator_clockevent = {
 118         .name           = "timer1",
 119         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 120         .set_mode       = clkevt_set_mode,
 121         .set_next_event = clkevt_set_next_event,
 122         .rating         = 300,
 123 };
 124
 125 static struct irqaction integrator_timer_irq = {
 126         .name           = "timer",
 127         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 128         .handler        = integrator_timer_interrupt,
 129         .dev_id         = &integrator_clockevent,
 130 };
 131
 132 static void integrator_clockevent_init(unsigned long inrate,
 133                                 void __iomem *base, int irq)
 134 {
 135         unsigned long rate = inrate;
 136         unsigned int ctrl = 0;
 137
 138         clkevt_base = base;
 139         /* Calculate and program a divisor */
 140         if (rate > 0x100000 * HZ) {
 141                 rate /= 256;
 142                 ctrl |= TIMER_CTRL_DIV256;
 143         } else if (rate > 0x10000 * HZ) {
 144                 rate /= 16;
 145                 ctrl |= TIMER_CTRL_DIV16;
 146         }
 147         timer_reload = rate / HZ;
 148         writel(ctrl, clkevt_base + TIMER_CTRL);
 149
 150         setup_irq(irq, &integrator_timer_irq);
 151         clockevents_config_and_register(&integrator_clockevent,
 152                                         rate,
 153                                         1,
 154                                         0xffffU);
 155 }
 156
 157 static void __init integrator_ap_timer_init_of(struct device_node *node)
 158 {
 159         const char *path;
 160         void __iomem *base;
 161         int err;
 162         int irq;
 163         struct clk *clk;
 164         unsigned long rate;
 165         struct device_node *pri_node;
 166         struct device_node *sec_node;
 167
 168         base = of_io_request_and_map(node, 0, "integrator-timer");
 169         if (!base)
 170                 return;
 171
 172         clk = of_clk_get(node, 0);
 173         if (IS_ERR(clk)) {
 174                 pr_err("No clock for %s\n", node->name);
 175                 return;
 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 (WARN_ON(err))
 184                 return;
 185         pri_node = of_find_node_by_path(path);
 186         err = of_property_read_string(of_aliases,
 187                                 "arm,timer-secondary", &path);
 188         if (WARN_ON(err))
 189                 return;
 190         sec_node = of_find_node_by_path(path);
 191
 192         if (node == pri_node) {
 193                 /* The primary timer lacks IRQ, use as clocksource */
 194                 integrator_clocksource_init(rate, base);
 195                 return;
 196         }
 197
 198         if (node == sec_node) {
 199                 /* The secondary timer will drive the clock event */
 200                 irq = irq_of_parse_and_map(node, 0);
 201                 integrator_clockevent_init(rate, base, irq);
 202                 return;
 203         }
 204
 205         pr_info("Timer @%p unused\n", base);
 206         clk_disable_unprepare(clk);
 207 }
 208
 209 CLOCKSOURCE_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
 210                        integrator_ap_timer_init_of);