arch/mips/ralink/timer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Ralink RT2880 timer
   4  * Author: John Crispin
   5  *
   6  * Copyright (C) 2013 John Crispin <john@phrozen.org>
   7 */
   8
   9 #include <linux/bits.h>
  10 #include <linux/clk.h>
  11 #include <linux/device.h>
  12 #include <linux/err.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/io.h>
  15 #include <linux/mod_devicetable.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/timer.h>
  18 #include <linux/types.h>
  19
  20 #include <asm/mach-ralink/ralink_regs.h>
  21
  22 #define TIMER_REG_TMRSTAT               0x00
  23 #define TIMER_REG_TMR0LOAD              0x10
  24 #define TIMER_REG_TMR0CTL               0x18
  25
  26 #define TMRSTAT_TMR0INT                 BIT(0)
  27
  28 #define TMR0CTL_ENABLE                  BIT(7)
  29 #define TMR0CTL_MODE_PERIODIC           BIT(4)
  30 #define TMR0CTL_PRESCALER               1
  31 #define TMR0CTL_PRESCALE_VAL            (0xf - TMR0CTL_PRESCALER)
  32 #define TMR0CTL_PRESCALE_DIV            (65536 / BIT(TMR0CTL_PRESCALER))
  33
  34 struct rt_timer {
  35         struct device   *dev;
  36         void __iomem    *membase;
  37         int             irq;
  38         unsigned long   timer_freq;
  39         unsigned long   timer_div;
  40 };
  41
  42 static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
  43 {
  44         __raw_writel(val, rt->membase + reg);
  45 }
  46
  47 static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
  48 {
  49         return __raw_readl(rt->membase + reg);
  50 }
  51
  52 static irqreturn_t rt_timer_irq(int irq, void *_rt)
  53 {
  54         struct rt_timer *rt =  (struct rt_timer *) _rt;
  55
  56         rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
  57         rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);
  58
  59         return IRQ_HANDLED;
  60 }
  61
  62
  63 static int rt_timer_request(struct rt_timer *rt)
  64 {
  65         int err = request_irq(rt->irq, rt_timer_irq, 0,
  66                                                 dev_name(rt->dev), rt);
  67         if (err) {
  68                 dev_err(rt->dev, "failed to request irq\n");
  69         } else {
  70                 u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL;
  71                 rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
  72         }
  73         return err;
  74 }
  75
  76 static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
  77 {
  78         if (rt->timer_freq < divisor)
  79                 rt->timer_div = rt->timer_freq;
  80         else
  81                 rt->timer_div = divisor;
  82
  83         rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
  84
  85         return 0;
  86 }
  87
  88 static int rt_timer_enable(struct rt_timer *rt)
  89 {
  90         u32 t;
  91
  92         rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
  93
  94         t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
  95         t |= TMR0CTL_ENABLE;
  96         rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
  97
  98         return 0;
  99 }
 100
 101 static int rt_timer_probe(struct platform_device *pdev)
 102 {
 103         struct rt_timer *rt;
 104         struct clk *clk;
 105
 106         rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
 107         if (!rt) {
 108                 dev_err(&pdev->dev, "failed to allocate memory\n");
 109                 return -ENOMEM;
 110         }
 111
 112         rt->irq = platform_get_irq(pdev, 0);
 113         if (rt->irq < 0)
 114                 return rt->irq;
 115
 116         rt->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
 117         if (IS_ERR(rt->membase))
 118                 return PTR_ERR(rt->membase);
 119
 120         clk = devm_clk_get(&pdev->dev, NULL);
 121         if (IS_ERR(clk)) {
 122                 dev_err(&pdev->dev, "failed get clock rate\n");
 123                 return PTR_ERR(clk);
 124         }
 125
 126         rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
 127         if (!rt->timer_freq)
 128                 return -EINVAL;
 129
 130         rt->dev = &pdev->dev;
 131         platform_set_drvdata(pdev, rt);
 132
 133         rt_timer_request(rt);
 134         rt_timer_config(rt, 2);
 135         rt_timer_enable(rt);
 136
 137         dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
 138
 139         return 0;
 140 }
 141
 142 static const struct of_device_id rt_timer_match[] = {
 143         { .compatible = "ralink,rt2880-timer" },
 144         {},
 145 };
 146
 147 static struct platform_driver rt_timer_driver = {
 148         .probe = rt_timer_probe,
 149         .driver = {
 150                 .name                   = "rt-timer",
 151                 .of_match_table         = rt_timer_match,
 152                 .suppress_bind_attrs    = true,
 153         },
 154 };
 155 builtin_platform_driver(rt_timer_driver);