drivers/clocksource/rockchip_timer.c

   1 /*
   2  * Rockchip timer support
   3  *
   4  * Copyright (C) Daniel Lezcano <daniel.lezcano@linaro.org>
   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 #include <linux/clk.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/init.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17
  18 #define TIMER_NAME "rk_timer"
  19
  20 #define TIMER_LOAD_COUNT0 0x00
  21 #define TIMER_LOAD_COUNT1 0x04
  22 #define TIMER_CONTROL_REG 0x10
  23 #define TIMER_INT_STATUS 0x18
  24
  25 #define TIMER_DISABLE 0x0
  26 #define TIMER_ENABLE 0x1
  27 #define TIMER_MODE_FREE_RUNNING (0 << 1)
  28 #define TIMER_MODE_USER_DEFINED_COUNT (1 << 1)
  29 #define TIMER_INT_UNMASK (1 << 2)
  30
  31 struct bc_timer {
  32         struct clock_event_device ce;
  33         void __iomem *base;
  34         u32 freq;
  35 };
  36
  37 static struct bc_timer bc_timer;
  38
  39 static inline struct bc_timer *rk_timer(struct clock_event_device *ce)
  40 {
  41         return container_of(ce, struct bc_timer, ce);
  42 }
  43
  44 static inline void __iomem *rk_base(struct clock_event_device *ce)
  45 {
  46         return rk_timer(ce)->base;
  47 }
  48
  49 static inline void rk_timer_disable(struct clock_event_device *ce)
  50 {
  51         writel_relaxed(TIMER_DISABLE, rk_base(ce) + TIMER_CONTROL_REG);
  52         dsb();
  53 }
  54
  55 static inline void rk_timer_enable(struct clock_event_device *ce, u32 flags)
  56 {
  57         writel_relaxed(TIMER_ENABLE | TIMER_INT_UNMASK | flags,
  58                        rk_base(ce) + TIMER_CONTROL_REG);
  59         dsb();
  60 }
  61
  62 static void rk_timer_update_counter(unsigned long cycles,
  63                                     struct clock_event_device *ce)
  64 {
  65         writel_relaxed(cycles, rk_base(ce) + TIMER_LOAD_COUNT0);
  66         writel_relaxed(0, rk_base(ce) + TIMER_LOAD_COUNT1);
  67         dsb();
  68 }
  69
  70 static void rk_timer_interrupt_clear(struct clock_event_device *ce)
  71 {
  72         writel_relaxed(1, rk_base(ce) + TIMER_INT_STATUS);
  73         dsb();
  74 }
  75
  76 static inline int rk_timer_set_next_event(unsigned long cycles,
  77                                           struct clock_event_device *ce)
  78 {
  79         rk_timer_disable(ce);
  80         rk_timer_update_counter(cycles, ce);
  81         rk_timer_enable(ce, TIMER_MODE_USER_DEFINED_COUNT);
  82         return 0;
  83 }
  84
  85 static int rk_timer_shutdown(struct clock_event_device *ce)
  86 {
  87         rk_timer_disable(ce);
  88         return 0;
  89 }
  90
  91 static int rk_timer_set_periodic(struct clock_event_device *ce)
  92 {
  93         rk_timer_disable(ce);
  94         rk_timer_update_counter(rk_timer(ce)->freq / HZ - 1, ce);
  95         rk_timer_enable(ce, TIMER_MODE_FREE_RUNNING);
  96         return 0;
  97 }
  98
  99 static irqreturn_t rk_timer_interrupt(int irq, void *dev_id)
 100 {
 101         struct clock_event_device *ce = dev_id;
 102
 103         rk_timer_interrupt_clear(ce);
 104
 105         if (clockevent_state_oneshot(ce))
 106                 rk_timer_disable(ce);
 107
 108         ce->event_handler(ce);
 109
 110         return IRQ_HANDLED;
 111 }
 112
 113 static void __init rk_timer_init(struct device_node *np)
 114 {
 115         struct clock_event_device *ce = &bc_timer.ce;
 116         struct clk *timer_clk;
 117         struct clk *pclk;
 118         int ret, irq;
 119
 120         bc_timer.base = of_iomap(np, 0);
 121         if (!bc_timer.base) {
 122                 pr_err("Failed to get base address for '%s'\n", TIMER_NAME);
 123                 return;
 124         }
 125
 126         pclk = of_clk_get_by_name(np, "pclk");
 127         if (IS_ERR(pclk)) {
 128                 pr_err("Failed to get pclk for '%s'\n", TIMER_NAME);
 129                 return;
 130         }
 131
 132         if (clk_prepare_enable(pclk)) {
 133                 pr_err("Failed to enable pclk for '%s'\n", TIMER_NAME);
 134                 return;
 135         }
 136
 137         timer_clk = of_clk_get_by_name(np, "timer");
 138         if (IS_ERR(timer_clk)) {
 139                 pr_err("Failed to get timer clock for '%s'\n", TIMER_NAME);
 140                 return;
 141         }
 142
 143         if (clk_prepare_enable(timer_clk)) {
 144                 pr_err("Failed to enable timer clock\n");
 145                 return;
 146         }
 147
 148         bc_timer.freq = clk_get_rate(timer_clk);
 149
 150         irq = irq_of_parse_and_map(np, 0);
 151         if (!irq) {
 152                 pr_err("Failed to map interrupts for '%s'\n", TIMER_NAME);
 153                 return;
 154         }
 155
 156         ce->name = TIMER_NAME;
 157         ce->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 158         ce->set_next_event = rk_timer_set_next_event;
 159         ce->set_state_shutdown = rk_timer_shutdown;
 160         ce->set_state_periodic = rk_timer_set_periodic;
 161         ce->irq = irq;
 162         ce->cpumask = cpumask_of(0);
 163         ce->rating = 250;
 164
 165         rk_timer_interrupt_clear(ce);
 166         rk_timer_disable(ce);
 167
 168         ret = request_irq(irq, rk_timer_interrupt, IRQF_TIMER, TIMER_NAME, ce);
 169         if (ret) {
 170                 pr_err("Failed to initialize '%s': %d\n", TIMER_NAME, ret);
 171                 return;
 172         }
 173
 174         clockevents_config_and_register(ce, bc_timer.freq, 1, UINT_MAX);
 175 }
 176 CLOCKSOURCE_OF_DECLARE(rk_timer, "rockchip,rk3288-timer", rk_timer_init);