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