LXR linux/drivers/clocksource/nomadik-mtu.c

   1/*
   2 * Copyright (C) 2008 STMicroelectronics
   3 * Copyright (C) 2010 Alessandro Rubini
   4 * Copyright (C) 2010 Linus Walleij for ST-Ericsson
   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/init.h>
  11#include <linux/interrupt.h>
  12#include <linux/irq.h>
  13#include <linux/io.h>
  14#include <linux/clockchips.h>
  15#include <linux/clocksource.h>
  16#include <linux/of_address.h>
  17#include <linux/of_irq.h>
  18#include <linux/of_platform.h>
  19#include <linux/clk.h>
  20#include <linux/jiffies.h>
  21#include <linux/delay.h>
  22#include <linux/err.h>
  23#include <linux/sched_clock.h>
  24#include <asm/mach/time.h>
  25
  26/*
  27 * The MTU device hosts four different counters, with 4 set of
  28 * registers. These are register names.
  29 */
  30
  31#define MTU_IMSC        0x00    /* Interrupt mask set/clear */
  32#define MTU_RIS         0x04    /* Raw interrupt status */
  33#define MTU_MIS         0x08    /* Masked interrupt status */
  34#define MTU_ICR         0x0C    /* Interrupt clear register */
  35
  36/* per-timer registers take 0..3 as argument */
  37#define MTU_LR(x)       (0x10 + 0x10 * (x) + 0x00)      /* Load value */
  38#define MTU_VAL(x)      (0x10 + 0x10 * (x) + 0x04)      /* Current value */
  39#define MTU_CR(x)       (0x10 + 0x10 * (x) + 0x08)      /* Control reg */
  40#define MTU_BGLR(x)     (0x10 + 0x10 * (x) + 0x0c)      /* At next overflow */
  41
  42/* bits for the control register */
  43#define MTU_CRn_ENA             0x80
  44#define MTU_CRn_PERIODIC        0x40    /* if 0 = free-running */
  45#define MTU_CRn_PRESCALE_MASK   0x0c
  46#define MTU_CRn_PRESCALE_1              0x00
  47#define MTU_CRn_PRESCALE_16             0x04
  48#define MTU_CRn_PRESCALE_256            0x08
  49#define MTU_CRn_32BITS          0x02
  50#define MTU_CRn_ONESHOT         0x01    /* if 0 = wraps reloading from BGLR*/
  51
  52/* Other registers are usual amba/primecell registers, currently not used */
  53#define MTU_ITCR        0xff0
  54#define MTU_ITOP        0xff4
  55
  56#define MTU_PERIPH_ID0  0xfe0
  57#define MTU_PERIPH_ID1  0xfe4
  58#define MTU_PERIPH_ID2  0xfe8
  59#define MTU_PERIPH_ID3  0xfeC
  60
  61#define MTU_PCELL0      0xff0
  62#define MTU_PCELL1      0xff4
  63#define MTU_PCELL2      0xff8
  64#define MTU_PCELL3      0xffC
  65
  66static void __iomem *mtu_base;
  67static bool clkevt_periodic;
  68static u32 clk_prescale;
  69static u32 nmdk_cycle;          /* write-once */
  70static struct delay_timer mtu_delay_timer;
  71
  72#ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
  73/*
  74 * Override the global weak sched_clock symbol with this
  75 * local implementation which uses the clocksource to get some
  76 * better resolution when scheduling the kernel.
  77 */
  78static u64 notrace nomadik_read_sched_clock(void)
  79{
  80        if (unlikely(!mtu_base))
  81                return 0;
  82
  83        return -readl(mtu_base + MTU_VAL(0));
  84}
  85#endif
  86
  87static unsigned long nmdk_timer_read_current_timer(void)
  88{
  89        return ~readl_relaxed(mtu_base + MTU_VAL(0));
  90}
  91
  92/* Clockevent device: use one-shot mode */
  93static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
  94{
  95        writel(1 << 1, mtu_base + MTU_IMSC);
  96        writel(evt, mtu_base + MTU_LR(1));
  97        /* Load highest value, enable device, enable interrupts */
  98        writel(MTU_CRn_ONESHOT | clk_prescale |
  99               MTU_CRn_32BITS | MTU_CRn_ENA,
 100               mtu_base + MTU_CR(1));
 101
 102        return 0;
 103}
 104
 105static void nmdk_clkevt_reset(void)
 106{
 107        if (clkevt_periodic) {
 108                /* Timer: configure load and background-load, and fire it up */
 109                writel(nmdk_cycle, mtu_base + MTU_LR(1));
 110                writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
 111
 112                writel(MTU_CRn_PERIODIC | clk_prescale |
 113                       MTU_CRn_32BITS | MTU_CRn_ENA,
 114                       mtu_base + MTU_CR(1));
 115                writel(1 << 1, mtu_base + MTU_IMSC);
 116        } else {
 117                /* Generate an interrupt to start the clockevent again */
 118                (void) nmdk_clkevt_next(nmdk_cycle, NULL);
 119        }
 120}
 121
 122static int nmdk_clkevt_shutdown(struct clock_event_device *evt)
 123{
 124        writel(0, mtu_base + MTU_IMSC);
 125        /* disable timer */
 126        writel(0, mtu_base + MTU_CR(1));
 127        /* load some high default value */
 128        writel(0xffffffff, mtu_base + MTU_LR(1));
 129        return 0;
 130}
 131
 132static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt)
 133{
 134        clkevt_periodic = false;
 135        return 0;
 136}
 137
 138static int nmdk_clkevt_set_periodic(struct clock_event_device *evt)
 139{
 140        clkevt_periodic = true;
 141        nmdk_clkevt_reset();
 142        return 0;
 143}
 144
 145static void nmdk_clksrc_reset(void)
 146{
 147        /* Disable */
 148        writel(0, mtu_base + MTU_CR(0));
 149
 150        /* ClockSource: configure load and background-load, and fire it up */
 151        writel(nmdk_cycle, mtu_base + MTU_LR(0));
 152        writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
 153
 154        writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
 155               mtu_base + MTU_CR(0));
 156}
 157
 158static void nmdk_clkevt_resume(struct clock_event_device *cedev)
 159{
 160        nmdk_clkevt_reset();
 161        nmdk_clksrc_reset();
 162}
 163
 164static struct clock_event_device nmdk_clkevt = {
 165        .name                   = "mtu_1",
 166        .features               = CLOCK_EVT_FEAT_ONESHOT |
 167                                  CLOCK_EVT_FEAT_PERIODIC |
 168                                  CLOCK_EVT_FEAT_DYNIRQ,
 169        .rating                 = 200,
 170        .set_state_shutdown     = nmdk_clkevt_shutdown,
 171        .set_state_periodic     = nmdk_clkevt_set_periodic,
 172        .set_state_oneshot      = nmdk_clkevt_set_oneshot,
 173        .set_next_event         = nmdk_clkevt_next,
 174        .resume                 = nmdk_clkevt_resume,
 175};
 176
 177/*
 178 * IRQ Handler for timer 1 of the MTU block.
 179 */
 180static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
 181{
 182        struct clock_event_device *evdev = dev_id;
 183
 184        writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
 185        evdev->event_handler(evdev);
 186        return IRQ_HANDLED;
 187}
 188
 189static struct irqaction nmdk_timer_irq = {
 190        .name           = "Nomadik Timer Tick",
 191        .flags          = IRQF_TIMER,
 192        .handler        = nmdk_timer_interrupt,
 193        .dev_id         = &nmdk_clkevt,
 194};
 195
 196static void __init nmdk_timer_init(void __iomem *base, int irq,
 197                                   struct clk *pclk, struct clk *clk)
 198{
 199        unsigned long rate;
 200
 201        mtu_base = base;
 202
 203        BUG_ON(clk_prepare_enable(pclk));
 204        BUG_ON(clk_prepare_enable(clk));
 205
 206        /*
 207         * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
 208         * for ux500.
 209         * Use a divide-by-16 counter if the tick rate is more than 32MHz.
 210         * At 32 MHz, the timer (with 32 bit counter) can be programmed
 211         * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
 212         * with 16 gives too low timer resolution.
 213         */
 214        rate = clk_get_rate(clk);
 215        if (rate > 32000000) {
 216                rate /= 16;
 217                clk_prescale = MTU_CRn_PRESCALE_16;
 218        } else {
 219                clk_prescale = MTU_CRn_PRESCALE_1;
 220        }
 221
 222        /* Cycles for periodic mode */
 223        nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
 224
 225
 226        /* Timer 0 is the free running clocksource */
 227        nmdk_clksrc_reset();
 228
 229        if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
 230                        rate, 200, 32, clocksource_mmio_readl_down))
 231                pr_err("timer: failed to initialize clock source %s\n",
 232                       "mtu_0");
 233
 234#ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
 235        sched_clock_register(nomadik_read_sched_clock, 32, rate);
 236#endif
 237
 238        /* Timer 1 is used for events, register irq and clockevents */
 239        setup_irq(irq, &nmdk_timer_irq);
 240        nmdk_clkevt.cpumask = cpumask_of(0);
 241        nmdk_clkevt.irq = irq;
 242        clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU);
 243
 244        mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
 245        mtu_delay_timer.freq = rate;
 246        register_current_timer_delay(&mtu_delay_timer);
 247}
 248
 249static void __init nmdk_timer_of_init(struct device_node *node)
 250{
 251        struct clk *pclk;
 252        struct clk *clk;
 253        void __iomem *base;
 254        int irq;
 255
 256        base = of_iomap(node, 0);
 257        if (!base)
 258                panic("Can't remap registers");
 259
 260        pclk = of_clk_get_by_name(node, "apb_pclk");
 261        if (IS_ERR(pclk))
 262                panic("could not get apb_pclk");
 263
 264        clk = of_clk_get_by_name(node, "timclk");
 265        if (IS_ERR(clk))
 266                panic("could not get timclk");
 267
 268        irq = irq_of_parse_and_map(node, 0);
 269        if (irq <= 0)
 270                panic("Can't parse IRQ");
 271
 272        nmdk_timer_init(base, irq, pclk, clk);
 273}
 274CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
 275                       nmdk_timer_of_init);
 276