drivers/clocksource/mxs_timer.c

   1 /*
   2  *  Copyright (C) 2000-2001 Deep Blue Solutions
   3  *  Copyright (C) 2002 Shane Nay (shane@minirl.com)
   4  *  Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
   5  *  Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de)
   6  *  Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (at your option) any later version.
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  20  * MA 02110-1301, USA.
  21  */
  22
  23 #include <linux/err.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/irq.h>
  26 #include <linux/clockchips.h>
  27 #include <linux/clk.h>
  28 #include <linux/of.h>
  29 #include <linux/of_address.h>
  30 #include <linux/of_irq.h>
  31 #include <linux/stmp_device.h>
  32 #include <linux/sched_clock.h>
  33
  34 #include <asm/mach/time.h>
  35
  36 /*
  37  * There are 2 versions of the timrot on Freescale MXS-based SoCs.
  38  * The v1 on MX23 only gets 16 bits counter, while v2 on MX28
  39  * extends the counter to 32 bits.
  40  *
  41  * The implementation uses two timers, one for clock_event and
  42  * another for clocksource. MX28 uses timrot 0 and 1, while MX23
  43  * uses 0 and 2.
  44  */
  45
  46 #define MX23_TIMROT_VERSION_OFFSET      0x0a0
  47 #define MX28_TIMROT_VERSION_OFFSET      0x120
  48 #define BP_TIMROT_MAJOR_VERSION         24
  49 #define BV_TIMROT_VERSION_1             0x01
  50 #define BV_TIMROT_VERSION_2             0x02
  51 #define timrot_is_v1()  (timrot_major_version == BV_TIMROT_VERSION_1)
  52
  53 /*
  54  * There are 4 registers for each timrotv2 instance, and 2 registers
  55  * for each timrotv1. So address step 0x40 in macros below strides
  56  * one instance of timrotv2 while two instances of timrotv1.
  57  *
  58  * As the result, HW_TIMROT_XXXn(1) defines the address of timrot1
  59  * on MX28 while timrot2 on MX23.
  60  */
  61 /* common between v1 and v2 */
  62 #define HW_TIMROT_ROTCTRL               0x00
  63 #define HW_TIMROT_TIMCTRLn(n)           (0x20 + (n) * 0x40)
  64 /* v1 only */
  65 #define HW_TIMROT_TIMCOUNTn(n)          (0x30 + (n) * 0x40)
  66 /* v2 only */
  67 #define HW_TIMROT_RUNNING_COUNTn(n)     (0x30 + (n) * 0x40)
  68 #define HW_TIMROT_FIXED_COUNTn(n)       (0x40 + (n) * 0x40)
  69
  70 #define BM_TIMROT_TIMCTRLn_RELOAD       (1 << 6)
  71 #define BM_TIMROT_TIMCTRLn_UPDATE       (1 << 7)
  72 #define BM_TIMROT_TIMCTRLn_IRQ_EN       (1 << 14)
  73 #define BM_TIMROT_TIMCTRLn_IRQ          (1 << 15)
  74 #define BP_TIMROT_TIMCTRLn_SELECT       0
  75 #define BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL         0x8
  76 #define BV_TIMROTv2_TIMCTRLn_SELECT__32KHZ_XTAL         0xb
  77 #define BV_TIMROTv2_TIMCTRLn_SELECT__TICK_ALWAYS        0xf
  78
  79 static struct clock_event_device mxs_clockevent_device;
  80 static enum clock_event_mode mxs_clockevent_mode = CLOCK_EVT_MODE_UNUSED;
  81
  82 static void __iomem *mxs_timrot_base;
  83 static u32 timrot_major_version;
  84
  85 static inline void timrot_irq_disable(void)
  86 {
  87         __raw_writel(BM_TIMROT_TIMCTRLn_IRQ_EN, mxs_timrot_base +
  88                      HW_TIMROT_TIMCTRLn(0) + STMP_OFFSET_REG_CLR);
  89 }
  90
  91 static inline void timrot_irq_enable(void)
  92 {
  93         __raw_writel(BM_TIMROT_TIMCTRLn_IRQ_EN, mxs_timrot_base +
  94                      HW_TIMROT_TIMCTRLn(0) + STMP_OFFSET_REG_SET);
  95 }
  96
  97 static void timrot_irq_acknowledge(void)
  98 {
  99         __raw_writel(BM_TIMROT_TIMCTRLn_IRQ, mxs_timrot_base +
 100                      HW_TIMROT_TIMCTRLn(0) + STMP_OFFSET_REG_CLR);
 101 }
 102
 103 static cycle_t timrotv1_get_cycles(struct clocksource *cs)
 104 {
 105         return ~((__raw_readl(mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1))
 106                         & 0xffff0000) >> 16);
 107 }
 108
 109 static int timrotv1_set_next_event(unsigned long evt,
 110                                         struct clock_event_device *dev)
 111 {
 112         /* timrot decrements the count */
 113         __raw_writel(evt, mxs_timrot_base + HW_TIMROT_TIMCOUNTn(0));
 114
 115         return 0;
 116 }
 117
 118 static int timrotv2_set_next_event(unsigned long evt,
 119                                         struct clock_event_device *dev)
 120 {
 121         /* timrot decrements the count */
 122         __raw_writel(evt, mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(0));
 123
 124         return 0;
 125 }
 126
 127 static irqreturn_t mxs_timer_interrupt(int irq, void *dev_id)
 128 {
 129         struct clock_event_device *evt = dev_id;
 130
 131         timrot_irq_acknowledge();
 132         evt->event_handler(evt);
 133
 134         return IRQ_HANDLED;
 135 }
 136
 137 static struct irqaction mxs_timer_irq = {
 138         .name           = "MXS Timer Tick",
 139         .dev_id         = &mxs_clockevent_device,
 140         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 141         .handler        = mxs_timer_interrupt,
 142 };
 143
 144 #ifdef DEBUG
 145 static const char *clock_event_mode_label[] const = {
 146         [CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
 147         [CLOCK_EVT_MODE_ONESHOT]  = "CLOCK_EVT_MODE_ONESHOT",
 148         [CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
 149         [CLOCK_EVT_MODE_UNUSED]   = "CLOCK_EVT_MODE_UNUSED"
 150 };
 151 #endif /* DEBUG */
 152
 153 static void mxs_set_mode(enum clock_event_mode mode,
 154                                 struct clock_event_device *evt)
 155 {
 156         /* Disable interrupt in timer module */
 157         timrot_irq_disable();
 158
 159         if (mode != mxs_clockevent_mode) {
 160                 /* Set event time into the furthest future */
 161                 if (timrot_is_v1())
 162                         __raw_writel(0xffff,
 163                                 mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1));
 164                 else
 165                         __raw_writel(0xffffffff,
 166                                 mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(1));
 167
 168                 /* Clear pending interrupt */
 169                 timrot_irq_acknowledge();
 170         }
 171
 172 #ifdef DEBUG
 173         pr_info("%s: changing mode from %s to %s\n", __func__,
 174                 clock_event_mode_label[mxs_clockevent_mode],
 175                 clock_event_mode_label[mode]);
 176 #endif /* DEBUG */
 177
 178         /* Remember timer mode */
 179         mxs_clockevent_mode = mode;
 180
 181         switch (mode) {
 182         case CLOCK_EVT_MODE_PERIODIC:
 183                 pr_err("%s: Periodic mode is not implemented\n", __func__);
 184                 break;
 185         case CLOCK_EVT_MODE_ONESHOT:
 186                 timrot_irq_enable();
 187                 break;
 188         case CLOCK_EVT_MODE_SHUTDOWN:
 189         case CLOCK_EVT_MODE_UNUSED:
 190         case CLOCK_EVT_MODE_RESUME:
 191                 /* Left event sources disabled, no more interrupts appear */
 192                 break;
 193         }
 194 }
 195
 196 static struct clock_event_device mxs_clockevent_device = {
 197         .name           = "mxs_timrot",
 198         .features       = CLOCK_EVT_FEAT_ONESHOT,
 199         .set_mode       = mxs_set_mode,
 200         .set_next_event = timrotv2_set_next_event,
 201         .rating         = 200,
 202 };
 203
 204 static int __init mxs_clockevent_init(struct clk *timer_clk)
 205 {
 206         if (timrot_is_v1())
 207                 mxs_clockevent_device.set_next_event = timrotv1_set_next_event;
 208         mxs_clockevent_device.cpumask = cpumask_of(0);
 209         clockevents_config_and_register(&mxs_clockevent_device,
 210                                         clk_get_rate(timer_clk),
 211                                         timrot_is_v1() ? 0xf : 0x2,
 212                                         timrot_is_v1() ? 0xfffe : 0xfffffffe);
 213
 214         return 0;
 215 }
 216
 217 static struct clocksource clocksource_mxs = {
 218         .name           = "mxs_timer",
 219         .rating         = 200,
 220         .read           = timrotv1_get_cycles,
 221         .mask           = CLOCKSOURCE_MASK(16),
 222         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 223 };
 224
 225 static u32 notrace mxs_read_sched_clock_v2(void)
 226 {
 227         return ~readl_relaxed(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1));
 228 }
 229
 230 static int __init mxs_clocksource_init(struct clk *timer_clk)
 231 {
 232         unsigned int c = clk_get_rate(timer_clk);
 233
 234         if (timrot_is_v1())
 235                 clocksource_register_hz(&clocksource_mxs, c);
 236         else {
 237                 clocksource_mmio_init(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1),
 238                         "mxs_timer", c, 200, 32, clocksource_mmio_readl_down);
 239                 setup_sched_clock(mxs_read_sched_clock_v2, 32, c);
 240         }
 241
 242         return 0;
 243 }
 244
 245 static void __init mxs_timer_init(struct device_node *np)
 246 {
 247         struct clk *timer_clk;
 248         int irq;
 249
 250         mxs_timrot_base = of_iomap(np, 0);
 251         WARN_ON(!mxs_timrot_base);
 252
 253         timer_clk = of_clk_get(np, 0);
 254         if (IS_ERR(timer_clk)) {
 255                 pr_err("%s: failed to get clk\n", __func__);
 256                 return;
 257         }
 258
 259         clk_prepare_enable(timer_clk);
 260
 261         /*
 262          * Initialize timers to a known state
 263          */
 264         stmp_reset_block(mxs_timrot_base + HW_TIMROT_ROTCTRL);
 265
 266         /* get timrot version */
 267         timrot_major_version = __raw_readl(mxs_timrot_base +
 268                         (of_device_is_compatible(np, "fsl,imx23-timrot") ?
 269                                                 MX23_TIMROT_VERSION_OFFSET :
 270                                                 MX28_TIMROT_VERSION_OFFSET));
 271         timrot_major_version >>= BP_TIMROT_MAJOR_VERSION;
 272
 273         /* one for clock_event */
 274         __raw_writel((timrot_is_v1() ?
 275                         BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL :
 276                         BV_TIMROTv2_TIMCTRLn_SELECT__TICK_ALWAYS) |
 277                         BM_TIMROT_TIMCTRLn_UPDATE |
 278                         BM_TIMROT_TIMCTRLn_IRQ_EN,
 279                         mxs_timrot_base + HW_TIMROT_TIMCTRLn(0));
 280
 281         /* another for clocksource */
 282         __raw_writel((timrot_is_v1() ?
 283                         BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL :
 284                         BV_TIMROTv2_TIMCTRLn_SELECT__TICK_ALWAYS) |
 285                         BM_TIMROT_TIMCTRLn_RELOAD,
 286                         mxs_timrot_base + HW_TIMROT_TIMCTRLn(1));
 287
 288         /* set clocksource timer fixed count to the maximum */
 289         if (timrot_is_v1())
 290                 __raw_writel(0xffff,
 291                         mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1));
 292         else
 293                 __raw_writel(0xffffffff,
 294                         mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(1));
 295
 296         /* init and register the timer to the framework */
 297         mxs_clocksource_init(timer_clk);
 298         mxs_clockevent_init(timer_clk);
 299
 300         /* Make irqs happen */
 301         irq = irq_of_parse_and_map(np, 0);
 302         setup_irq(irq, &mxs_timer_irq);
 303 }
 304 CLOCKSOURCE_OF_DECLARE(mxs, "fsl,timrot", mxs_timer_init);