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
  66 static void __iomem *mtu_base;
  67 static bool clkevt_periodic;
  68 static u32 clk_prescale;
  69 static u32 nmdk_cycle;          /* write-once */
  70 static 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  */
  78 static 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
  87 static 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 */
  93 static 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
 105 static 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
 122 static 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
 132 static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt)
 133 {
 134         clkevt_periodic = false;
 135         return 0;
 136 }
 137
 138 static int nmdk_clkevt_set_periodic(struct clock_event_device *evt)
 139 {
 140         clkevt_periodic = true;
 141         nmdk_clkevt_reset();
 142         return 0;
 143 }
 144
 145 static 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
 158 static void nmdk_clkevt_resume(struct clock_event_device *cedev)
 159 {
 160         nmdk_clkevt_reset();
 161         nmdk_clksrc_reset();
 162 }
 163
 164 static 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  */
 180 static 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
 189 static 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
 196 static int __init nmdk_timer_init(void __iomem *base, int irq,
 197                                    struct clk *pclk, struct clk *clk)
 198 {
 199         unsigned long rate;
 200         int ret;
 201
 202         mtu_base = base;
 203
 204         BUG_ON(clk_prepare_enable(pclk));
 205         BUG_ON(clk_prepare_enable(clk));
 206
 207         /*
 208          * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
 209          * for ux500.
 210          * Use a divide-by-16 counter if the tick rate is more than 32MHz.
 211          * At 32 MHz, the timer (with 32 bit counter) can be programmed
 212          * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
 213          * with 16 gives too low timer resolution.
 214          */
 215         rate = clk_get_rate(clk);
 216         if (rate > 32000000) {
 217                 rate /= 16;
 218                 clk_prescale = MTU_CRn_PRESCALE_16;
 219         } else {
 220                 clk_prescale = MTU_CRn_PRESCALE_1;
 221         }
 222
 223         /* Cycles for periodic mode */
 224         nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
 225
 226
 227         /* Timer 0 is the free running clocksource */
 228         nmdk_clksrc_reset();
 229
 230         ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
 231                                     rate, 200, 32, clocksource_mmio_readl_down);
 232         if (ret) {
 233                 pr_err("timer: failed to initialize clock source %s\n", "mtu_0");
 234                 return ret;
 235         }
 236
 237 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
 238         sched_clock_register(nomadik_read_sched_clock, 32, rate);
 239 #endif
 240
 241         /* Timer 1 is used for events, register irq and clockevents */
 242         setup_irq(irq, &nmdk_timer_irq);
 243         nmdk_clkevt.cpumask = cpumask_of(0);
 244         nmdk_clkevt.irq = irq;
 245         clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU);
 246
 247         mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
 248         mtu_delay_timer.freq = rate;
 249         register_current_timer_delay(&mtu_delay_timer);
 250
 251         return 0;
 252 }
 253
 254 static int __init nmdk_timer_of_init(struct device_node *node)
 255 {
 256         struct clk *pclk;
 257         struct clk *clk;
 258         void __iomem *base;
 259         int irq;
 260
 261         base = of_iomap(node, 0);
 262         if (!base) {
 263                 pr_err("Can't remap registers");
 264                 return -ENXIO;
 265         }
 266
 267         pclk = of_clk_get_by_name(node, "apb_pclk");
 268         if (IS_ERR(pclk)) {
 269                 pr_err("could not get apb_pclk");
 270                 return PTR_ERR(pclk);
 271         }
 272
 273         clk = of_clk_get_by_name(node, "timclk");
 274         if (IS_ERR(clk)) {
 275                 pr_err("could not get timclk");
 276                 return PTR_ERR(clk);
 277         }
 278
 279         irq = irq_of_parse_and_map(node, 0);
 280         if (irq <= 0) {
 281                 pr_err("Can't parse IRQ");
 282                 return -EINVAL;
 283         }
 284
 285         return nmdk_timer_init(base, irq, pclk, clk);
 286 }
 287 CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
 288                        nmdk_timer_of_init);