drivers/clocksource/timer-gx6605s.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
   3
   4 #include <linux/init.h>
   5 #include <linux/interrupt.h>
   6 #include <linux/sched_clock.h>
   7
   8 #include "timer-of.h"
   9
  10 #define CLKSRC_OFFSET   0x40
  11
  12 #define TIMER_STATUS    0x00
  13 #define TIMER_VALUE     0x04
  14 #define TIMER_CONTRL    0x10
  15 #define TIMER_CONFIG    0x20
  16 #define TIMER_DIV       0x24
  17 #define TIMER_INI       0x28
  18
  19 #define GX6605S_STATUS_CLR      BIT(0)
  20 #define GX6605S_CONTRL_RST      BIT(0)
  21 #define GX6605S_CONTRL_START    BIT(1)
  22 #define GX6605S_CONFIG_EN       BIT(0)
  23 #define GX6605S_CONFIG_IRQ_EN   BIT(1)
  24
  25 static irqreturn_t gx6605s_timer_interrupt(int irq, void *dev)
  26 {
  27         struct clock_event_device *ce = dev;
  28         void __iomem *base = timer_of_base(to_timer_of(ce));
  29
  30         writel_relaxed(GX6605S_STATUS_CLR, base + TIMER_STATUS);
  31
  32         ce->event_handler(ce);
  33
  34         return IRQ_HANDLED;
  35 }
  36
  37 static int gx6605s_timer_set_oneshot(struct clock_event_device *ce)
  38 {
  39         void __iomem *base = timer_of_base(to_timer_of(ce));
  40
  41         /* reset and stop counter */
  42         writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
  43
  44         /* enable with irq and start */
  45         writel_relaxed(GX6605S_CONFIG_EN | GX6605S_CONFIG_IRQ_EN,
  46                        base + TIMER_CONFIG);
  47
  48         return 0;
  49 }
  50
  51 static int gx6605s_timer_set_next_event(unsigned long delta,
  52                                         struct clock_event_device *ce)
  53 {
  54         void __iomem *base = timer_of_base(to_timer_of(ce));
  55
  56         /* use reset to pause timer */
  57         writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
  58
  59         /* config next timeout value */
  60         writel_relaxed(ULONG_MAX - delta, base + TIMER_INI);
  61         writel_relaxed(GX6605S_CONTRL_START, base + TIMER_CONTRL);
  62
  63         return 0;
  64 }
  65
  66 static int gx6605s_timer_shutdown(struct clock_event_device *ce)
  67 {
  68         void __iomem *base = timer_of_base(to_timer_of(ce));
  69
  70         writel_relaxed(0, base + TIMER_CONTRL);
  71         writel_relaxed(0, base + TIMER_CONFIG);
  72
  73         return 0;
  74 }
  75
  76 static struct timer_of to = {
  77         .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
  78         .clkevt = {
  79                 .rating                 = 300,
  80                 .features               = CLOCK_EVT_FEAT_DYNIRQ |
  81                                           CLOCK_EVT_FEAT_ONESHOT,
  82                 .set_state_shutdown     = gx6605s_timer_shutdown,
  83                 .set_state_oneshot      = gx6605s_timer_set_oneshot,
  84                 .set_next_event         = gx6605s_timer_set_next_event,
  85                 .cpumask                = cpu_possible_mask,
  86         },
  87         .of_irq = {
  88                 .handler                = gx6605s_timer_interrupt,
  89                 .flags                  = IRQF_TIMER | IRQF_IRQPOLL,
  90         },
  91 };
  92
  93 static u64 notrace gx6605s_sched_clock_read(void)
  94 {
  95         void __iomem *base;
  96
  97         base = timer_of_base(&to) + CLKSRC_OFFSET;
  98
  99         return (u64)readl_relaxed(base + TIMER_VALUE);
 100 }
 101
 102 static void gx6605s_clkevt_init(void __iomem *base)
 103 {
 104         writel_relaxed(0, base + TIMER_DIV);
 105         writel_relaxed(0, base + TIMER_CONFIG);
 106
 107         clockevents_config_and_register(&to.clkevt, timer_of_rate(&to), 2,
 108                                         ULONG_MAX);
 109 }
 110
 111 static int gx6605s_clksrc_init(void __iomem *base)
 112 {
 113         writel_relaxed(0, base + TIMER_DIV);
 114         writel_relaxed(0, base + TIMER_INI);
 115
 116         writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
 117
 118         writel_relaxed(GX6605S_CONFIG_EN, base + TIMER_CONFIG);
 119
 120         writel_relaxed(GX6605S_CONTRL_START, base + TIMER_CONTRL);
 121
 122         sched_clock_register(gx6605s_sched_clock_read, 32, timer_of_rate(&to));
 123
 124         return clocksource_mmio_init(base + TIMER_VALUE, "gx6605s",
 125                         timer_of_rate(&to), 200, 32, clocksource_mmio_readl_up);
 126 }
 127
 128 static int __init gx6605s_timer_init(struct device_node *np)
 129 {
 130         int ret;
 131
 132         /*
 133          * The timer driver is for nationalchip gx6605s SOC and there are two
 134          * same timer in gx6605s. We use one for clkevt and another for clksrc.
 135          *
 136          * The timer is mmio map to access, so we need give mmio address in dts.
 137          *
 138          * It provides a 32bit countup timer and interrupt will be caused by
 139          * count-overflow.
 140          * So we need set-next-event by ULONG_MAX - delta in TIMER_INI reg.
 141          *
 142          * The counter at 0x0  offset is clock event.
 143          * The counter at 0x40 offset is clock source.
 144          * They are the same in hardware, just different used by driver.
 145          */
 146         ret = timer_of_init(np, &to);
 147         if (ret)
 148                 return ret;
 149
 150         gx6605s_clkevt_init(timer_of_base(&to));
 151
 152         return gx6605s_clksrc_init(timer_of_base(&to) + CLKSRC_OFFSET);
 153 }
 154 TIMER_OF_DECLARE(csky_gx6605s_timer, "csky,gx6605s-timer", gx6605s_timer_init);