arch/arm/mach-exynos4/time.c

   1 /* linux/arch/arm/mach-exynos4/time.c
   2  *
   3  * Copyright (c) 2010-2011 Samsung Electronics Co., Ltd.
   4  *              http://www.samsung.com
   5  *
   6  * EXYNOS4 (and compatible) HRT support
   7  * PWM 2/4 is used for this feature
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12 */
  13
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/irq.h>
  17 #include <linux/err.h>
  18 #include <linux/clk.h>
  19 #include <linux/clockchips.h>
  20 #include <linux/platform_device.h>
  21
  22 #include <asm/smp_twd.h>
  23
  24 #include <mach/map.h>
  25 #include <plat/regs-timer.h>
  26 #include <asm/mach/time.h>
  27
  28 static unsigned long clock_count_per_tick;
  29
  30 static struct clk *tin2;
  31 static struct clk *tin4;
  32 static struct clk *tdiv2;
  33 static struct clk *tdiv4;
  34 static struct clk *timerclk;
  35
  36 static void exynos4_pwm_stop(unsigned int pwm_id)
  37 {
  38         unsigned long tcon;
  39
  40         tcon = __raw_readl(S3C2410_TCON);
  41
  42         switch (pwm_id) {
  43         case 2:
  44                 tcon &= ~S3C2410_TCON_T2START;
  45                 break;
  46         case 4:
  47                 tcon &= ~S3C2410_TCON_T4START;
  48                 break;
  49         default:
  50                 break;
  51         }
  52         __raw_writel(tcon, S3C2410_TCON);
  53 }
  54
  55 static void exynos4_pwm_init(unsigned int pwm_id, unsigned long tcnt)
  56 {
  57         unsigned long tcon;
  58
  59         tcon = __raw_readl(S3C2410_TCON);
  60
  61         /* timers reload after counting zero, so reduce the count by 1 */
  62         tcnt--;
  63
  64         /* ensure timer is stopped... */
  65         switch (pwm_id) {
  66         case 2:
  67                 tcon &= ~(0xf<<12);
  68                 tcon |= S3C2410_TCON_T2MANUALUPD;
  69
  70                 __raw_writel(tcnt, S3C2410_TCNTB(2));
  71                 __raw_writel(tcnt, S3C2410_TCMPB(2));
  72                 __raw_writel(tcon, S3C2410_TCON);
  73
  74                 break;
  75         case 4:
  76                 tcon &= ~(7<<20);
  77                 tcon |= S3C2410_TCON_T4MANUALUPD;
  78
  79                 __raw_writel(tcnt, S3C2410_TCNTB(4));
  80                 __raw_writel(tcnt, S3C2410_TCMPB(4));
  81                 __raw_writel(tcon, S3C2410_TCON);
  82
  83                 break;
  84         default:
  85                 break;
  86         }
  87 }
  88
  89 static inline void exynos4_pwm_start(unsigned int pwm_id, bool periodic)
  90 {
  91         unsigned long tcon;
  92
  93         tcon  = __raw_readl(S3C2410_TCON);
  94
  95         switch (pwm_id) {
  96         case 2:
  97                 tcon |= S3C2410_TCON_T2START;
  98                 tcon &= ~S3C2410_TCON_T2MANUALUPD;
  99
 100                 if (periodic)
 101                         tcon |= S3C2410_TCON_T2RELOAD;
 102                 else
 103                         tcon &= ~S3C2410_TCON_T2RELOAD;
 104                 break;
 105         case 4:
 106                 tcon |= S3C2410_TCON_T4START;
 107                 tcon &= ~S3C2410_TCON_T4MANUALUPD;
 108
 109                 if (periodic)
 110                         tcon |= S3C2410_TCON_T4RELOAD;
 111                 else
 112                         tcon &= ~S3C2410_TCON_T4RELOAD;
 113                 break;
 114         default:
 115                 break;
 116         }
 117         __raw_writel(tcon, S3C2410_TCON);
 118 }
 119
 120 static int exynos4_pwm_set_next_event(unsigned long cycles,
 121                                         struct clock_event_device *evt)
 122 {
 123         exynos4_pwm_init(2, cycles);
 124         exynos4_pwm_start(2, 0);
 125         return 0;
 126 }
 127
 128 static void exynos4_pwm_set_mode(enum clock_event_mode mode,
 129                                 struct clock_event_device *evt)
 130 {
 131         exynos4_pwm_stop(2);
 132
 133         switch (mode) {
 134         case CLOCK_EVT_MODE_PERIODIC:
 135                 exynos4_pwm_init(2, clock_count_per_tick);
 136                 exynos4_pwm_start(2, 1);
 137                 break;
 138         case CLOCK_EVT_MODE_ONESHOT:
 139                 break;
 140         case CLOCK_EVT_MODE_UNUSED:
 141         case CLOCK_EVT_MODE_SHUTDOWN:
 142         case CLOCK_EVT_MODE_RESUME:
 143                 break;
 144         }
 145 }
 146
 147 static struct clock_event_device pwm_event_device = {
 148         .name           = "pwm_timer2",
 149         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 150         .rating         = 200,
 151         .shift          = 32,
 152         .set_next_event = exynos4_pwm_set_next_event,
 153         .set_mode       = exynos4_pwm_set_mode,
 154 };
 155
 156 irqreturn_t exynos4_clock_event_isr(int irq, void *dev_id)
 157 {
 158         struct clock_event_device *evt = &pwm_event_device;
 159
 160         evt->event_handler(evt);
 161
 162         return IRQ_HANDLED;
 163 }
 164
 165 static struct irqaction exynos4_clock_event_irq = {
 166         .name           = "pwm_timer2_irq",
 167         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 168         .handler        = exynos4_clock_event_isr,
 169 };
 170
 171 static void __init exynos4_clockevent_init(void)
 172 {
 173         unsigned long pclk;
 174         unsigned long clock_rate;
 175         struct clk *tscaler;
 176
 177         pclk = clk_get_rate(timerclk);
 178
 179         /* configure clock tick */
 180
 181         tscaler = clk_get_parent(tdiv2);
 182
 183         clk_set_rate(tscaler, pclk / 2);
 184         clk_set_rate(tdiv2, pclk / 2);
 185         clk_set_parent(tin2, tdiv2);
 186
 187         clock_rate = clk_get_rate(tin2);
 188
 189         clock_count_per_tick = clock_rate / HZ;
 190
 191         pwm_event_device.mult =
 192                 div_sc(clock_rate, NSEC_PER_SEC, pwm_event_device.shift);
 193         pwm_event_device.max_delta_ns =
 194                 clockevent_delta2ns(-1, &pwm_event_device);
 195         pwm_event_device.min_delta_ns =
 196                 clockevent_delta2ns(1, &pwm_event_device);
 197
 198         pwm_event_device.cpumask = cpumask_of(0);
 199         clockevents_register_device(&pwm_event_device);
 200
 201         setup_irq(IRQ_TIMER2, &exynos4_clock_event_irq);
 202 }
 203
 204 static cycle_t exynos4_pwm4_read(struct clocksource *cs)
 205 {
 206         return (cycle_t) ~__raw_readl(S3C_TIMERREG(0x40));
 207 }
 208
 209 #ifdef CONFIG_PM
 210 static void exynos4_pwm4_resume(struct clocksource *cs)
 211 {
 212         unsigned long pclk;
 213
 214         pclk = clk_get_rate(timerclk);
 215
 216         clk_set_rate(tdiv4, pclk / 2);
 217         clk_set_parent(tin4, tdiv4);
 218
 219         exynos4_pwm_init(4, ~0);
 220         exynos4_pwm_start(4, 1);
 221 }
 222 #endif
 223
 224 struct clocksource pwm_clocksource = {
 225         .name           = "pwm_timer4",
 226         .rating         = 250,
 227         .read           = exynos4_pwm4_read,
 228         .mask           = CLOCKSOURCE_MASK(32),
 229         .flags          = CLOCK_SOURCE_IS_CONTINUOUS ,
 230 #ifdef CONFIG_PM
 231         .resume         = exynos4_pwm4_resume,
 232 #endif
 233 };
 234
 235 static void __init exynos4_clocksource_init(void)
 236 {
 237         unsigned long pclk;
 238         unsigned long clock_rate;
 239
 240         pclk = clk_get_rate(timerclk);
 241
 242         clk_set_rate(tdiv4, pclk / 2);
 243         clk_set_parent(tin4, tdiv4);
 244
 245         clock_rate = clk_get_rate(tin4);
 246
 247         exynos4_pwm_init(4, ~0);
 248         exynos4_pwm_start(4, 1);
 249
 250         if (clocksource_register_hz(&pwm_clocksource, clock_rate))
 251                 panic("%s: can't register clocksource\n", pwm_clocksource.name);
 252 }
 253
 254 static void __init exynos4_timer_resources(void)
 255 {
 256         struct platform_device tmpdev;
 257
 258         tmpdev.dev.bus = &platform_bus_type;
 259
 260         timerclk = clk_get(NULL, "timers");
 261         if (IS_ERR(timerclk))
 262                 panic("failed to get timers clock for system timer");
 263
 264         clk_enable(timerclk);
 265
 266         tmpdev.id = 2;
 267         tin2 = clk_get(&tmpdev.dev, "pwm-tin");
 268         if (IS_ERR(tin2))
 269                 panic("failed to get pwm-tin2 clock for system timer");
 270
 271         tdiv2 = clk_get(&tmpdev.dev, "pwm-tdiv");
 272         if (IS_ERR(tdiv2))
 273                 panic("failed to get pwm-tdiv2 clock for system timer");
 274         clk_enable(tin2);
 275
 276         tmpdev.id = 4;
 277         tin4 = clk_get(&tmpdev.dev, "pwm-tin");
 278         if (IS_ERR(tin4))
 279                 panic("failed to get pwm-tin4 clock for system timer");
 280
 281         tdiv4 = clk_get(&tmpdev.dev, "pwm-tdiv");
 282         if (IS_ERR(tdiv4))
 283                 panic("failed to get pwm-tdiv4 clock for system timer");
 284
 285         clk_enable(tin4);
 286 }
 287
 288 static void __init exynos4_timer_init(void)
 289 {
 290 #ifdef CONFIG_LOCAL_TIMERS
 291         twd_base = S5P_VA_TWD;
 292 #endif
 293
 294         exynos4_timer_resources();
 295         exynos4_clockevent_init();
 296         exynos4_clocksource_init();
 297 }
 298
 299 struct sys_timer exynos4_timer = {
 300         .init           = exynos4_timer_init,
 301 };