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/platform_data/clocksource-nomadik-mtu.h>
  24 #include <linux/sched_clock.h>
  25 #include <asm/mach/time.h>
  26
  27 /*
  28  * The MTU device hosts four different counters, with 4 set of
  29  * registers. These are register names.
  30  */
  31
  32 #define MTU_IMSC        0x00    /* Interrupt mask set/clear */
  33 #define MTU_RIS         0x04    /* Raw interrupt status */
  34 #define MTU_MIS         0x08    /* Masked interrupt status */
  35 #define MTU_ICR         0x0C    /* Interrupt clear register */
  36
  37 /* per-timer registers take 0..3 as argument */
  38 #define MTU_LR(x)       (0x10 + 0x10 * (x) + 0x00)      /* Load value */
  39 #define MTU_VAL(x)      (0x10 + 0x10 * (x) + 0x04)      /* Current value */
  40 #define MTU_CR(x)       (0x10 + 0x10 * (x) + 0x08)      /* Control reg */
  41 #define MTU_BGLR(x)     (0x10 + 0x10 * (x) + 0x0c)      /* At next overflow */
  42
  43 /* bits for the control register */
  44 #define MTU_CRn_ENA             0x80
  45 #define MTU_CRn_PERIODIC        0x40    /* if 0 = free-running */
  46 #define MTU_CRn_PRESCALE_MASK   0x0c
  47 #define MTU_CRn_PRESCALE_1              0x00
  48 #define MTU_CRn_PRESCALE_16             0x04
  49 #define MTU_CRn_PRESCALE_256            0x08
  50 #define MTU_CRn_32BITS          0x02
  51 #define MTU_CRn_ONESHOT         0x01    /* if 0 = wraps reloading from BGLR*/
  52
  53 /* Other registers are usual amba/primecell registers, currently not used */
  54 #define MTU_ITCR        0xff0
  55 #define MTU_ITOP        0xff4
  56
  57 #define MTU_PERIPH_ID0  0xfe0
  58 #define MTU_PERIPH_ID1  0xfe4
  59 #define MTU_PERIPH_ID2  0xfe8
  60 #define MTU_PERIPH_ID3  0xfeC
  61
  62 #define MTU_PCELL0      0xff0
  63 #define MTU_PCELL1      0xff4
  64 #define MTU_PCELL2      0xff8
  65 #define MTU_PCELL3      0xffC
  66
  67 static void __iomem *mtu_base;
  68 static bool clkevt_periodic;
  69 static u32 clk_prescale;
  70 static u32 nmdk_cycle;          /* write-once */
  71 static struct delay_timer mtu_delay_timer;
  72
  73 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
  74 /*
  75  * Override the global weak sched_clock symbol with this
  76  * local implementation which uses the clocksource to get some
  77  * better resolution when scheduling the kernel.
  78  */
  79 static u32 notrace nomadik_read_sched_clock(void)
  80 {
  81         if (unlikely(!mtu_base))
  82                 return 0;
  83
  84         return -readl(mtu_base + MTU_VAL(0));
  85 }
  86 #endif
  87
  88 static unsigned long nmdk_timer_read_current_timer(void)
  89 {
  90         return ~readl_relaxed(mtu_base + MTU_VAL(0));
  91 }
  92
  93 /* Clockevent device: use one-shot mode */
  94 static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
  95 {
  96         writel(1 << 1, mtu_base + MTU_IMSC);
  97         writel(evt, mtu_base + MTU_LR(1));
  98         /* Load highest value, enable device, enable interrupts */
  99         writel(MTU_CRn_ONESHOT | clk_prescale |
 100                MTU_CRn_32BITS | MTU_CRn_ENA,
 101                mtu_base + MTU_CR(1));
 102
 103         return 0;
 104 }
 105
 106 void nmdk_clkevt_reset(void)
 107 {
 108         if (clkevt_periodic) {
 109                 /* Timer: configure load and background-load, and fire it up */
 110                 writel(nmdk_cycle, mtu_base + MTU_LR(1));
 111                 writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
 112
 113                 writel(MTU_CRn_PERIODIC | clk_prescale |
 114                        MTU_CRn_32BITS | MTU_CRn_ENA,
 115                        mtu_base + MTU_CR(1));
 116                 writel(1 << 1, mtu_base + MTU_IMSC);
 117         } else {
 118                 /* Generate an interrupt to start the clockevent again */
 119                 (void) nmdk_clkevt_next(nmdk_cycle, NULL);
 120         }
 121 }
 122
 123 static void nmdk_clkevt_mode(enum clock_event_mode mode,
 124                              struct clock_event_device *dev)
 125 {
 126         switch (mode) {
 127         case CLOCK_EVT_MODE_PERIODIC:
 128                 clkevt_periodic = true;
 129                 nmdk_clkevt_reset();
 130                 break;
 131         case CLOCK_EVT_MODE_ONESHOT:
 132                 clkevt_periodic = false;
 133                 break;
 134         case CLOCK_EVT_MODE_SHUTDOWN:
 135         case CLOCK_EVT_MODE_UNUSED:
 136                 writel(0, mtu_base + MTU_IMSC);
 137                 /* disable timer */
 138                 writel(0, mtu_base + MTU_CR(1));
 139                 /* load some high default value */
 140                 writel(0xffffffff, mtu_base + MTU_LR(1));
 141                 break;
 142         case CLOCK_EVT_MODE_RESUME:
 143                 break;
 144         }
 145 }
 146
 147 void nmdk_clksrc_reset(void)
 148 {
 149         /* Disable */
 150         writel(0, mtu_base + MTU_CR(0));
 151
 152         /* ClockSource: configure load and background-load, and fire it up */
 153         writel(nmdk_cycle, mtu_base + MTU_LR(0));
 154         writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
 155
 156         writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
 157                mtu_base + MTU_CR(0));
 158 }
 159
 160 static void nmdk_clkevt_resume(struct clock_event_device *cedev)
 161 {
 162         nmdk_clkevt_reset();
 163         nmdk_clksrc_reset();
 164 }
 165
 166 static struct clock_event_device nmdk_clkevt = {
 167         .name           = "mtu_1",
 168         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC |
 169                           CLOCK_EVT_FEAT_DYNIRQ,
 170         .rating         = 200,
 171         .set_mode       = nmdk_clkevt_mode,
 172         .set_next_event = nmdk_clkevt_next,
 173         .resume         = nmdk_clkevt_resume,
 174 };
 175
 176 /*
 177  * IRQ Handler for timer 1 of the MTU block.
 178  */
 179 static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
 180 {
 181         struct clock_event_device *evdev = dev_id;
 182
 183         writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
 184         evdev->event_handler(evdev);
 185         return IRQ_HANDLED;
 186 }
 187
 188 static struct irqaction nmdk_timer_irq = {
 189         .name           = "Nomadik Timer Tick",
 190         .flags          = IRQF_DISABLED | IRQF_TIMER,
 191         .handler        = nmdk_timer_interrupt,
 192         .dev_id         = &nmdk_clkevt,
 193 };
 194
 195 static void __init __nmdk_timer_init(void __iomem *base, int irq,
 196                                      struct clk *pclk, struct clk *clk)
 197 {
 198         unsigned long rate;
 199
 200         mtu_base = base;
 201
 202         BUG_ON(clk_prepare_enable(pclk));
 203         BUG_ON(clk_prepare_enable(clk));
 204
 205         /*
 206          * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
 207          * for ux500.
 208          * Use a divide-by-16 counter if the tick rate is more than 32MHz.
 209          * At 32 MHz, the timer (with 32 bit counter) can be programmed
 210          * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
 211          * with 16 gives too low timer resolution.
 212          */
 213         rate = clk_get_rate(clk);
 214         if (rate > 32000000) {
 215                 rate /= 16;
 216                 clk_prescale = MTU_CRn_PRESCALE_16;
 217         } else {
 218                 clk_prescale = MTU_CRn_PRESCALE_1;
 219         }
 220
 221         /* Cycles for periodic mode */
 222         nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
 223
 224
 225         /* Timer 0 is the free running clocksource */
 226         nmdk_clksrc_reset();
 227
 228         if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
 229                         rate, 200, 32, clocksource_mmio_readl_down))
 230                 pr_err("timer: failed to initialize clock source %s\n",
 231                        "mtu_0");
 232
 233 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
 234         setup_sched_clock(nomadik_read_sched_clock, 32, rate);
 235 #endif
 236
 237         /* Timer 1 is used for events, register irq and clockevents */
 238         setup_irq(irq, &nmdk_timer_irq);
 239         nmdk_clkevt.cpumask = cpumask_of(0);
 240         nmdk_clkevt.irq = irq;
 241         clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU);
 242
 243         mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
 244         mtu_delay_timer.freq = rate;
 245         register_current_timer_delay(&mtu_delay_timer);
 246 }
 247
 248 void __init nmdk_timer_init(void __iomem *base, int irq)
 249 {
 250         struct clk *clk0, *pclk0;
 251
 252         pclk0 = clk_get_sys("mtu0", "apb_pclk");
 253         BUG_ON(IS_ERR(pclk0));
 254         clk0 = clk_get_sys("mtu0", NULL);
 255         BUG_ON(IS_ERR(clk0));
 256
 257         __nmdk_timer_init(base, irq, pclk0, clk0);
 258 }
 259
 260 static void __init nmdk_timer_of_init(struct device_node *node)
 261 {
 262         struct clk *pclk;
 263         struct clk *clk;
 264         void __iomem *base;
 265         int irq;
 266
 267         base = of_iomap(node, 0);
 268         if (!base)
 269                 panic("Can't remap registers");
 270
 271         pclk = of_clk_get_by_name(node, "apb_pclk");
 272         if (IS_ERR(pclk))
 273                 panic("could not get apb_pclk");
 274
 275         clk = of_clk_get_by_name(node, "timclk");
 276         if (IS_ERR(clk))
 277                 panic("could not get timclk");
 278
 279         irq = irq_of_parse_and_map(node, 0);
 280         if (irq <= 0)
 281                 panic("Can't parse IRQ");
 282
 283         __nmdk_timer_init(base, irq, pclk, clk);
 284 }
 285 CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
 286                        nmdk_timer_of_init);