drivers/clocksource/zevio-timer.c

   1 /*
   2  *  linux/drivers/clocksource/zevio-timer.c
   3  *
   4  *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
   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 #include <linux/io.h>
  13 #include <linux/irq.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <linux/clk.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/cpumask.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/slab.h>
  22
  23 #define IO_CURRENT_VAL  0x00
  24 #define IO_DIVIDER      0x04
  25 #define IO_CONTROL      0x08
  26
  27 #define IO_TIMER1       0x00
  28 #define IO_TIMER2       0x0C
  29
  30 #define IO_MATCH_BEGIN  0x18
  31 #define IO_MATCH(x)     (IO_MATCH_BEGIN + ((x) << 2))
  32
  33 #define IO_INTR_STS     0x00
  34 #define IO_INTR_ACK     0x00
  35 #define IO_INTR_MSK     0x04
  36
  37 #define CNTL_STOP_TIMER (1 << 4)
  38 #define CNTL_RUN_TIMER  (0 << 4)
  39
  40 #define CNTL_INC        (1 << 3)
  41 #define CNTL_DEC        (0 << 3)
  42
  43 #define CNTL_TOZERO     0
  44 #define CNTL_MATCH(x)   ((x) + 1)
  45 #define CNTL_FOREVER    7
  46
  47 /* There are 6 match registers but we only use one. */
  48 #define TIMER_MATCH     0
  49
  50 #define TIMER_INTR_MSK  (1 << (TIMER_MATCH))
  51 #define TIMER_INTR_ALL  0x3F
  52
  53 struct zevio_timer {
  54         void __iomem *base;
  55         void __iomem *timer1, *timer2;
  56         void __iomem *interrupt_regs;
  57
  58         struct clk *clk;
  59         struct clock_event_device clkevt;
  60         struct irqaction clkevt_irq;
  61
  62         char clocksource_name[64];
  63         char clockevent_name[64];
  64 };
  65
  66 static int zevio_timer_set_event(unsigned long delta,
  67                                  struct clock_event_device *dev)
  68 {
  69         struct zevio_timer *timer = container_of(dev, struct zevio_timer,
  70                                                  clkevt);
  71
  72         writel(delta, timer->timer1 + IO_CURRENT_VAL);
  73         writel(CNTL_RUN_TIMER | CNTL_DEC | CNTL_MATCH(TIMER_MATCH),
  74                         timer->timer1 + IO_CONTROL);
  75
  76         return 0;
  77 }
  78
  79 static void zevio_timer_set_mode(enum clock_event_mode mode,
  80                                  struct clock_event_device *dev)
  81 {
  82         struct zevio_timer *timer = container_of(dev, struct zevio_timer,
  83                                                  clkevt);
  84
  85         switch (mode) {
  86         case CLOCK_EVT_MODE_RESUME:
  87         case CLOCK_EVT_MODE_ONESHOT:
  88                 /* Enable timer interrupts */
  89                 writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_MSK);
  90                 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
  91                 break;
  92         case CLOCK_EVT_MODE_SHUTDOWN:
  93         case CLOCK_EVT_MODE_UNUSED:
  94                 /* Disable timer interrupts */
  95                 writel(0, timer->interrupt_regs + IO_INTR_MSK);
  96                 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
  97                 /* Stop timer */
  98                 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
  99                 break;
 100         case CLOCK_EVT_MODE_PERIODIC:
 101         default:
 102                 /* Unsupported */
 103                 break;
 104         }
 105 }
 106
 107 static irqreturn_t zevio_timer_interrupt(int irq, void *dev_id)
 108 {
 109         struct zevio_timer *timer = dev_id;
 110         u32 intr;
 111
 112         intr = readl(timer->interrupt_regs + IO_INTR_ACK);
 113         if (!(intr & TIMER_INTR_MSK))
 114                 return IRQ_NONE;
 115
 116         writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
 117         writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
 118
 119         if (timer->clkevt.event_handler)
 120                 timer->clkevt.event_handler(&timer->clkevt);
 121
 122         return IRQ_HANDLED;
 123 }
 124
 125 static int __init zevio_timer_add(struct device_node *node)
 126 {
 127         struct zevio_timer *timer;
 128         struct resource res;
 129         int irqnr, ret;
 130
 131         timer = kzalloc(sizeof(*timer), GFP_KERNEL);
 132         if (!timer)
 133                 return -ENOMEM;
 134
 135         timer->base = of_iomap(node, 0);
 136         if (!timer->base) {
 137                 ret = -EINVAL;
 138                 goto error_free;
 139         }
 140         timer->timer1 = timer->base + IO_TIMER1;
 141         timer->timer2 = timer->base + IO_TIMER2;
 142
 143         timer->clk = of_clk_get(node, 0);
 144         if (IS_ERR(timer->clk)) {
 145                 ret = PTR_ERR(timer->clk);
 146                 pr_err("Timer clock not found! (error %d)\n", ret);
 147                 goto error_unmap;
 148         }
 149
 150         timer->interrupt_regs = of_iomap(node, 1);
 151         irqnr = irq_of_parse_and_map(node, 0);
 152
 153         of_address_to_resource(node, 0, &res);
 154         scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
 155                         "%llx.%s_clocksource",
 156                         (unsigned long long)res.start, node->name);
 157
 158         scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
 159                         "%llx.%s_clockevent",
 160                         (unsigned long long)res.start, node->name);
 161
 162         if (timer->interrupt_regs && irqnr) {
 163                 timer->clkevt.name              = timer->clockevent_name;
 164                 timer->clkevt.set_next_event    = zevio_timer_set_event;
 165                 timer->clkevt.set_mode          = zevio_timer_set_mode;
 166                 timer->clkevt.rating            = 200;
 167                 timer->clkevt.cpumask           = cpu_all_mask;
 168                 timer->clkevt.features          = CLOCK_EVT_FEAT_ONESHOT;
 169                 timer->clkevt.irq               = irqnr;
 170
 171                 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
 172                 writel(0, timer->timer1 + IO_DIVIDER);
 173
 174                 /* Start with timer interrupts disabled */
 175                 writel(0, timer->interrupt_regs + IO_INTR_MSK);
 176                 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
 177
 178                 /* Interrupt to occur when timer value matches 0 */
 179                 writel(0, timer->base + IO_MATCH(TIMER_MATCH));
 180
 181                 timer->clkevt_irq.name          = timer->clockevent_name;
 182                 timer->clkevt_irq.handler       = zevio_timer_interrupt;
 183                 timer->clkevt_irq.dev_id        = timer;
 184                 timer->clkevt_irq.flags         = IRQF_TIMER | IRQF_IRQPOLL;
 185
 186                 setup_irq(irqnr, &timer->clkevt_irq);
 187
 188                 clockevents_config_and_register(&timer->clkevt,
 189                                 clk_get_rate(timer->clk), 0x0001, 0xffff);
 190                 pr_info("Added %s as clockevent\n", timer->clockevent_name);
 191         }
 192
 193         writel(CNTL_STOP_TIMER, timer->timer2 + IO_CONTROL);
 194         writel(0, timer->timer2 + IO_CURRENT_VAL);
 195         writel(0, timer->timer2 + IO_DIVIDER);
 196         writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
 197                         timer->timer2 + IO_CONTROL);
 198
 199         clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
 200                         timer->clocksource_name,
 201                         clk_get_rate(timer->clk),
 202                         200, 16,
 203                         clocksource_mmio_readw_up);
 204
 205         pr_info("Added %s as clocksource\n", timer->clocksource_name);
 206
 207         return 0;
 208 error_unmap:
 209         iounmap(timer->base);
 210 error_free:
 211         kfree(timer);
 212         return ret;
 213 }
 214
 215 CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_add);