drivers/clocksource/tegra20_timer.c

   1 /*
   2  * Copyright (C) 2010 Google, Inc.
   3  *
   4  * Author:
   5  *      Colin Cross <ccross@google.com>
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/err.h>
  20 #include <linux/time.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/irq.h>
  23 #include <linux/clockchips.h>
  24 #include <linux/clocksource.h>
  25 #include <linux/clk.h>
  26 #include <linux/io.h>
  27 #include <linux/of_address.h>
  28 #include <linux/of_irq.h>
  29
  30 #include <asm/mach/time.h>
  31 #include <asm/smp_twd.h>
  32 #include <asm/sched_clock.h>
  33
  34 #define RTC_SECONDS            0x08
  35 #define RTC_SHADOW_SECONDS     0x0c
  36 #define RTC_MILLISECONDS       0x10
  37
  38 #define TIMERUS_CNTR_1US 0x10
  39 #define TIMERUS_USEC_CFG 0x14
  40 #define TIMERUS_CNTR_FREEZE 0x4c
  41
  42 #define TIMER1_BASE 0x0
  43 #define TIMER2_BASE 0x8
  44 #define TIMER3_BASE 0x50
  45 #define TIMER4_BASE 0x58
  46
  47 #define TIMER_PTV 0x0
  48 #define TIMER_PCR 0x4
  49
  50 static void __iomem *timer_reg_base;
  51 static void __iomem *rtc_base;
  52
  53 static struct timespec persistent_ts;
  54 static u64 persistent_ms, last_persistent_ms;
  55
  56 #define timer_writel(value, reg) \
  57         __raw_writel(value, timer_reg_base + (reg))
  58 #define timer_readl(reg) \
  59         __raw_readl(timer_reg_base + (reg))
  60
  61 static int tegra_timer_set_next_event(unsigned long cycles,
  62                                          struct clock_event_device *evt)
  63 {
  64         u32 reg;
  65
  66         reg = 0x80000000 | ((cycles > 1) ? (cycles-1) : 0);
  67         timer_writel(reg, TIMER3_BASE + TIMER_PTV);
  68
  69         return 0;
  70 }
  71
  72 static void tegra_timer_set_mode(enum clock_event_mode mode,
  73                                     struct clock_event_device *evt)
  74 {
  75         u32 reg;
  76
  77         timer_writel(0, TIMER3_BASE + TIMER_PTV);
  78
  79         switch (mode) {
  80         case CLOCK_EVT_MODE_PERIODIC:
  81                 reg = 0xC0000000 | ((1000000/HZ)-1);
  82                 timer_writel(reg, TIMER3_BASE + TIMER_PTV);
  83                 break;
  84         case CLOCK_EVT_MODE_ONESHOT:
  85                 break;
  86         case CLOCK_EVT_MODE_UNUSED:
  87         case CLOCK_EVT_MODE_SHUTDOWN:
  88         case CLOCK_EVT_MODE_RESUME:
  89                 break;
  90         }
  91 }
  92
  93 static struct clock_event_device tegra_clockevent = {
  94         .name           = "timer0",
  95         .rating         = 300,
  96         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
  97         .set_next_event = tegra_timer_set_next_event,
  98         .set_mode       = tegra_timer_set_mode,
  99 };
 100
 101 static u32 notrace tegra_read_sched_clock(void)
 102 {
 103         return timer_readl(TIMERUS_CNTR_1US);
 104 }
 105
 106 /*
 107  * tegra_rtc_read - Reads the Tegra RTC registers
 108  * Care must be taken that this funciton is not called while the
 109  * tegra_rtc driver could be executing to avoid race conditions
 110  * on the RTC shadow register
 111  */
 112 static u64 tegra_rtc_read_ms(void)
 113 {
 114         u32 ms = readl(rtc_base + RTC_MILLISECONDS);
 115         u32 s = readl(rtc_base + RTC_SHADOW_SECONDS);
 116         return (u64)s * MSEC_PER_SEC + ms;
 117 }
 118
 119 /*
 120  * tegra_read_persistent_clock -  Return time from a persistent clock.
 121  *
 122  * Reads the time from a source which isn't disabled during PM, the
 123  * 32k sync timer.  Convert the cycles elapsed since last read into
 124  * nsecs and adds to a monotonically increasing timespec.
 125  * Care must be taken that this funciton is not called while the
 126  * tegra_rtc driver could be executing to avoid race conditions
 127  * on the RTC shadow register
 128  */
 129 static void tegra_read_persistent_clock(struct timespec *ts)
 130 {
 131         u64 delta;
 132         struct timespec *tsp = &persistent_ts;
 133
 134         last_persistent_ms = persistent_ms;
 135         persistent_ms = tegra_rtc_read_ms();
 136         delta = persistent_ms - last_persistent_ms;
 137
 138         timespec_add_ns(tsp, delta * NSEC_PER_MSEC);
 139         *ts = *tsp;
 140 }
 141
 142 static irqreturn_t tegra_timer_interrupt(int irq, void *dev_id)
 143 {
 144         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 145         timer_writel(1<<30, TIMER3_BASE + TIMER_PCR);
 146         evt->event_handler(evt);
 147         return IRQ_HANDLED;
 148 }
 149
 150 static struct irqaction tegra_timer_irq = {
 151         .name           = "timer0",
 152         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_TRIGGER_HIGH,
 153         .handler        = tegra_timer_interrupt,
 154         .dev_id         = &tegra_clockevent,
 155 };
 156
 157 static const struct of_device_id timer_match[] __initconst = {
 158         { .compatible = "nvidia,tegra20-timer" },
 159         {}
 160 };
 161
 162 static const struct of_device_id rtc_match[] __initconst = {
 163         { .compatible = "nvidia,tegra20-rtc" },
 164         {}
 165 };
 166
 167 static void __init tegra20_init_timer(void)
 168 {
 169         struct device_node *np;
 170         struct clk *clk;
 171         unsigned long rate;
 172         int ret;
 173
 174         np = of_find_matching_node(NULL, timer_match);
 175         if (!np) {
 176                 pr_err("Failed to find timer DT node\n");
 177                 BUG();
 178         }
 179
 180         timer_reg_base = of_iomap(np, 0);
 181         if (!timer_reg_base) {
 182                 pr_err("Can't map timer registers\n");
 183                 BUG();
 184         }
 185
 186         tegra_timer_irq.irq = irq_of_parse_and_map(np, 2);
 187         if (tegra_timer_irq.irq <= 0) {
 188                 pr_err("Failed to map timer IRQ\n");
 189                 BUG();
 190         }
 191
 192         clk = clk_get_sys("timer", NULL);
 193         if (IS_ERR(clk)) {
 194                 pr_warn("Unable to get timer clock. Assuming 12Mhz input clock.\n");
 195                 rate = 12000000;
 196         } else {
 197                 clk_prepare_enable(clk);
 198                 rate = clk_get_rate(clk);
 199         }
 200
 201         of_node_put(np);
 202
 203         np = of_find_matching_node(NULL, rtc_match);
 204         if (!np) {
 205                 pr_err("Failed to find RTC DT node\n");
 206                 BUG();
 207         }
 208
 209         rtc_base = of_iomap(np, 0);
 210         if (!rtc_base) {
 211                 pr_err("Can't map RTC registers");
 212                 BUG();
 213         }
 214
 215         /*
 216          * rtc registers are used by read_persistent_clock, keep the rtc clock
 217          * enabled
 218          */
 219         clk = clk_get_sys("rtc-tegra", NULL);
 220         if (IS_ERR(clk))
 221                 pr_warn("Unable to get rtc-tegra clock\n");
 222         else
 223                 clk_prepare_enable(clk);
 224
 225         of_node_put(np);
 226
 227         switch (rate) {
 228         case 12000000:
 229                 timer_writel(0x000b, TIMERUS_USEC_CFG);
 230                 break;
 231         case 13000000:
 232                 timer_writel(0x000c, TIMERUS_USEC_CFG);
 233                 break;
 234         case 19200000:
 235                 timer_writel(0x045f, TIMERUS_USEC_CFG);
 236                 break;
 237         case 26000000:
 238                 timer_writel(0x0019, TIMERUS_USEC_CFG);
 239                 break;
 240         default:
 241                 WARN(1, "Unknown clock rate");
 242         }
 243
 244         setup_sched_clock(tegra_read_sched_clock, 32, 1000000);
 245
 246         if (clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
 247                 "timer_us", 1000000, 300, 32, clocksource_mmio_readl_up)) {
 248                 pr_err("Failed to register clocksource\n");
 249                 BUG();
 250         }
 251
 252         ret = setup_irq(tegra_timer_irq.irq, &tegra_timer_irq);
 253         if (ret) {
 254                 pr_err("Failed to register timer IRQ: %d\n", ret);
 255                 BUG();
 256         }
 257
 258         tegra_clockevent.cpumask = cpu_all_mask;
 259         tegra_clockevent.irq = tegra_timer_irq.irq;
 260         clockevents_config_and_register(&tegra_clockevent, 1000000,
 261                                         0x1, 0x1fffffff);
 262 #ifdef CONFIG_HAVE_ARM_TWD
 263         twd_local_timer_of_register();
 264 #endif
 265         register_persistent_clock(NULL, tegra_read_persistent_clock);
 266 }
 267 CLOCKSOURCE_OF_DECLARE(tegra20, "nvidia,tegra20-timer", tegra20_init_timer);
 268
 269 #ifdef CONFIG_PM
 270 static u32 usec_config;
 271
 272 void tegra_timer_suspend(void)
 273 {
 274         usec_config = timer_readl(TIMERUS_USEC_CFG);
 275 }
 276
 277 void tegra_timer_resume(void)
 278 {
 279         timer_writel(usec_config, TIMERUS_USEC_CFG);
 280 }
 281 #endif