drivers/clocksource/owl-timer.c

   1 /*
   2  * Actions Semi Owl timer
   3  *
   4  * Copyright 2012 Actions Semi Inc.
   5  * Author: Actions Semi, Inc.
   6  *
   7  * Copyright (c) 2017 SUSE Linux GmbH
   8  * Author: Andreas Färber
   9  *
  10  * This program is free software; you can redistribute  it and/or modify it
  11  * under  the terms of  the GNU General  Public License as published by the
  12  * Free Software Foundation;  either version 2 of the  License, or (at your
  13  * option) any later version.
  14  */
  15
  16 #include <linux/clk.h>
  17 #include <linux/clockchips.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/irq.h>
  20 #include <linux/irqreturn.h>
  21 #include <linux/sched_clock.h>
  22 #include <linux/of.h>
  23 #include <linux/of_address.h>
  24 #include <linux/of_irq.h>
  25
  26 #define OWL_Tx_CTL              0x0
  27 #define OWL_Tx_CMP              0x4
  28 #define OWL_Tx_VAL              0x8
  29
  30 #define OWL_Tx_CTL_PD           BIT(0)
  31 #define OWL_Tx_CTL_INTEN        BIT(1)
  32 #define OWL_Tx_CTL_EN           BIT(2)
  33
  34 static void __iomem *owl_timer_base;
  35 static void __iomem *owl_clksrc_base;
  36 static void __iomem *owl_clkevt_base;
  37
  38 static inline void owl_timer_reset(void __iomem *base)
  39 {
  40         writel(0, base + OWL_Tx_CTL);
  41         writel(0, base + OWL_Tx_VAL);
  42         writel(0, base + OWL_Tx_CMP);
  43 }
  44
  45 static inline void owl_timer_set_enabled(void __iomem *base, bool enabled)
  46 {
  47         u32 ctl = readl(base + OWL_Tx_CTL);
  48
  49         /* PD bit is cleared when set */
  50         ctl &= ~OWL_Tx_CTL_PD;
  51
  52         if (enabled)
  53                 ctl |= OWL_Tx_CTL_EN;
  54         else
  55                 ctl &= ~OWL_Tx_CTL_EN;
  56
  57         writel(ctl, base + OWL_Tx_CTL);
  58 }
  59
  60 static u64 notrace owl_timer_sched_read(void)
  61 {
  62         return (u64)readl(owl_clksrc_base + OWL_Tx_VAL);
  63 }
  64
  65 static int owl_timer_set_state_shutdown(struct clock_event_device *evt)
  66 {
  67         owl_timer_set_enabled(owl_clkevt_base, false);
  68
  69         return 0;
  70 }
  71
  72 static int owl_timer_set_state_oneshot(struct clock_event_device *evt)
  73 {
  74         owl_timer_reset(owl_clkevt_base);
  75
  76         return 0;
  77 }
  78
  79 static int owl_timer_tick_resume(struct clock_event_device *evt)
  80 {
  81         return 0;
  82 }
  83
  84 static int owl_timer_set_next_event(unsigned long evt,
  85                                     struct clock_event_device *ev)
  86 {
  87         void __iomem *base = owl_clkevt_base;
  88
  89         owl_timer_set_enabled(base, false);
  90         writel(OWL_Tx_CTL_INTEN, base + OWL_Tx_CTL);
  91         writel(0, base + OWL_Tx_VAL);
  92         writel(evt, base + OWL_Tx_CMP);
  93         owl_timer_set_enabled(base, true);
  94
  95         return 0;
  96 }
  97
  98 static struct clock_event_device owl_clockevent = {
  99         .name                   = "owl_tick",
 100         .rating                 = 200,
 101         .features               = CLOCK_EVT_FEAT_ONESHOT |
 102                                   CLOCK_EVT_FEAT_DYNIRQ,
 103         .set_state_shutdown     = owl_timer_set_state_shutdown,
 104         .set_state_oneshot      = owl_timer_set_state_oneshot,
 105         .tick_resume            = owl_timer_tick_resume,
 106         .set_next_event         = owl_timer_set_next_event,
 107 };
 108
 109 static irqreturn_t owl_timer1_interrupt(int irq, void *dev_id)
 110 {
 111         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 112
 113         writel(OWL_Tx_CTL_PD, owl_clkevt_base + OWL_Tx_CTL);
 114
 115         evt->event_handler(evt);
 116
 117         return IRQ_HANDLED;
 118 }
 119
 120 static int __init owl_timer_init(struct device_node *node)
 121 {
 122         struct clk *clk;
 123         unsigned long rate;
 124         int timer1_irq, ret;
 125
 126         owl_timer_base = of_io_request_and_map(node, 0, "owl-timer");
 127         if (IS_ERR(owl_timer_base)) {
 128                 pr_err("Can't map timer registers");
 129                 return PTR_ERR(owl_timer_base);
 130         }
 131
 132         owl_clksrc_base = owl_timer_base + 0x08;
 133         owl_clkevt_base = owl_timer_base + 0x14;
 134
 135         timer1_irq = of_irq_get_byname(node, "timer1");
 136         if (timer1_irq <= 0) {
 137                 pr_err("Can't parse timer1 IRQ");
 138                 return -EINVAL;
 139         }
 140
 141         clk = of_clk_get(node, 0);
 142         if (IS_ERR(clk))
 143                 return PTR_ERR(clk);
 144
 145         rate = clk_get_rate(clk);
 146
 147         owl_timer_reset(owl_clksrc_base);
 148         owl_timer_set_enabled(owl_clksrc_base, true);
 149
 150         sched_clock_register(owl_timer_sched_read, 32, rate);
 151         clocksource_mmio_init(owl_clksrc_base + OWL_Tx_VAL, node->name,
 152                               rate, 200, 32, clocksource_mmio_readl_up);
 153
 154         owl_timer_reset(owl_clkevt_base);
 155
 156         ret = request_irq(timer1_irq, owl_timer1_interrupt, IRQF_TIMER,
 157                           "owl-timer", &owl_clockevent);
 158         if (ret) {
 159                 pr_err("failed to request irq %d\n", timer1_irq);
 160                 return ret;
 161         }
 162
 163         owl_clockevent.cpumask = cpumask_of(0);
 164         owl_clockevent.irq = timer1_irq;
 165
 166         clockevents_config_and_register(&owl_clockevent, rate,
 167                                         0xf, 0xffffffff);
 168
 169         return 0;
 170 }
 171 CLOCKSOURCE_OF_DECLARE(owl_s500, "actions,s500-timer", owl_timer_init);
 172 CLOCKSOURCE_OF_DECLARE(owl_s900, "actions,s900-timer", owl_timer_init);