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 int zevio_timer_shutdown(struct clock_event_device *dev)
  80 {
  81         struct zevio_timer *timer = container_of(dev, struct zevio_timer,
  82                                                  clkevt);
  83
  84         /* Disable timer interrupts */
  85         writel(0, timer->interrupt_regs + IO_INTR_MSK);
  86         writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
  87         /* Stop timer */
  88         writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
  89         return 0;
  90 }
  91
  92 static int zevio_timer_set_oneshot(struct clock_event_device *dev)
  93 {
  94         struct zevio_timer *timer = container_of(dev, struct zevio_timer,
  95                                                  clkevt);
  96
  97         /* Enable timer interrupts */
  98         writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_MSK);
  99         writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
 100         return 0;
 101 }
 102
 103 static irqreturn_t zevio_timer_interrupt(int irq, void *dev_id)
 104 {
 105         struct zevio_timer *timer = dev_id;
 106         u32 intr;
 107
 108         intr = readl(timer->interrupt_regs + IO_INTR_ACK);
 109         if (!(intr & TIMER_INTR_MSK))
 110                 return IRQ_NONE;
 111
 112         writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
 113         writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
 114
 115         if (timer->clkevt.event_handler)
 116                 timer->clkevt.event_handler(&timer->clkevt);
 117
 118         return IRQ_HANDLED;
 119 }
 120
 121 static int __init zevio_timer_add(struct device_node *node)
 122 {
 123         struct zevio_timer *timer;
 124         struct resource res;
 125         int irqnr, ret;
 126
 127         timer = kzalloc(sizeof(*timer), GFP_KERNEL);
 128         if (!timer)
 129                 return -ENOMEM;
 130
 131         timer->base = of_iomap(node, 0);
 132         if (!timer->base) {
 133                 ret = -EINVAL;
 134                 goto error_free;
 135         }
 136         timer->timer1 = timer->base + IO_TIMER1;
 137         timer->timer2 = timer->base + IO_TIMER2;
 138
 139         timer->clk = of_clk_get(node, 0);
 140         if (IS_ERR(timer->clk)) {
 141                 ret = PTR_ERR(timer->clk);
 142                 pr_err("Timer clock not found! (error %d)\n", ret);
 143                 goto error_unmap;
 144         }
 145
 146         timer->interrupt_regs = of_iomap(node, 1);
 147         irqnr = irq_of_parse_and_map(node, 0);
 148
 149         of_address_to_resource(node, 0, &res);
 150         scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
 151                         "%llx.%s_clocksource",
 152                         (unsigned long long)res.start, node->name);
 153
 154         scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
 155                         "%llx.%s_clockevent",
 156                         (unsigned long long)res.start, node->name);
 157
 158         if (timer->interrupt_regs && irqnr) {
 159                 timer->clkevt.name              = timer->clockevent_name;
 160                 timer->clkevt.set_next_event    = zevio_timer_set_event;
 161                 timer->clkevt.set_state_shutdown = zevio_timer_shutdown;
 162                 timer->clkevt.set_state_oneshot = zevio_timer_set_oneshot;
 163                 timer->clkevt.tick_resume       = zevio_timer_set_oneshot;
 164                 timer->clkevt.rating            = 200;
 165                 timer->clkevt.cpumask           = cpu_all_mask;
 166                 timer->clkevt.features          = CLOCK_EVT_FEAT_ONESHOT;
 167                 timer->clkevt.irq               = irqnr;
 168
 169                 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
 170                 writel(0, timer->timer1 + IO_DIVIDER);
 171
 172                 /* Start with timer interrupts disabled */
 173                 writel(0, timer->interrupt_regs + IO_INTR_MSK);
 174                 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
 175
 176                 /* Interrupt to occur when timer value matches 0 */
 177                 writel(0, timer->base + IO_MATCH(TIMER_MATCH));
 178
 179                 timer->clkevt_irq.name          = timer->clockevent_name;
 180                 timer->clkevt_irq.handler       = zevio_timer_interrupt;
 181                 timer->clkevt_irq.dev_id        = timer;
 182                 timer->clkevt_irq.flags         = IRQF_TIMER | IRQF_IRQPOLL;
 183
 184                 setup_irq(irqnr, &timer->clkevt_irq);
 185
 186                 clockevents_config_and_register(&timer->clkevt,
 187                                 clk_get_rate(timer->clk), 0x0001, 0xffff);
 188                 pr_info("Added %s as clockevent\n", timer->clockevent_name);
 189         }
 190
 191         writel(CNTL_STOP_TIMER, timer->timer2 + IO_CONTROL);
 192         writel(0, timer->timer2 + IO_CURRENT_VAL);
 193         writel(0, timer->timer2 + IO_DIVIDER);
 194         writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
 195                         timer->timer2 + IO_CONTROL);
 196
 197         clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
 198                         timer->clocksource_name,
 199                         clk_get_rate(timer->clk),
 200                         200, 16,
 201                         clocksource_mmio_readw_up);
 202
 203         pr_info("Added %s as clocksource\n", timer->clocksource_name);
 204
 205         return 0;
 206 error_unmap:
 207         iounmap(timer->base);
 208 error_free:
 209         kfree(timer);
 210         return ret;
 211 }
 212
 213 static void __init zevio_timer_init(struct device_node *node)
 214 {
 215         BUG_ON(zevio_timer_add(node));
 216 }
 217
 218 CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);