drivers/clocksource/nomadik-mtu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2008 STMicroelectronics
   4  * Copyright (C) 2010 Alessandro Rubini
   5  * Copyright (C) 2010 Linus Walleij for ST-Ericsson
   6  */
   7 #include <linux/init.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/irq.h>
  10 #include <linux/io.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/clocksource.h>
  13 #include <linux/of_address.h>
  14 #include <linux/of_irq.h>
  15 #include <linux/of_platform.h>
  16 #include <linux/clk.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/delay.h>
  19 #include <linux/err.h>
  20 #include <linux/sched_clock.h>
  21 #include <asm/mach/time.h>
  22
  23 /*
  24  * The MTU device hosts four different counters, with 4 set of
  25  * registers. These are register names.
  26  */
  27
  28 #define MTU_IMSC        0x00    /* Interrupt mask set/clear */
  29 #define MTU_RIS         0x04    /* Raw interrupt status */
  30 #define MTU_MIS         0x08    /* Masked interrupt status */
  31 #define MTU_ICR         0x0C    /* Interrupt clear register */
  32
  33 /* per-timer registers take 0..3 as argument */
  34 #define MTU_LR(x)       (0x10 + 0x10 * (x) + 0x00)      /* Load value */
  35 #define MTU_VAL(x)      (0x10 + 0x10 * (x) + 0x04)      /* Current value */
  36 #define MTU_CR(x)       (0x10 + 0x10 * (x) + 0x08)      /* Control reg */
  37 #define MTU_BGLR(x)     (0x10 + 0x10 * (x) + 0x0c)      /* At next overflow */
  38
  39 /* bits for the control register */
  40 #define MTU_CRn_ENA             0x80
  41 #define MTU_CRn_PERIODIC        0x40    /* if 0 = free-running */
  42 #define MTU_CRn_PRESCALE_MASK   0x0c
  43 #define MTU_CRn_PRESCALE_1              0x00
  44 #define MTU_CRn_PRESCALE_16             0x04
  45 #define MTU_CRn_PRESCALE_256            0x08
  46 #define MTU_CRn_32BITS          0x02
  47 #define MTU_CRn_ONESHOT         0x01    /* if 0 = wraps reloading from BGLR*/
  48
  49 /* Other registers are usual amba/primecell registers, currently not used */
  50 #define MTU_ITCR        0xff0
  51 #define MTU_ITOP        0xff4
  52
  53 #define MTU_PERIPH_ID0  0xfe0
  54 #define MTU_PERIPH_ID1  0xfe4
  55 #define MTU_PERIPH_ID2  0xfe8
  56 #define MTU_PERIPH_ID3  0xfeC
  57
  58 #define MTU_PCELL0      0xff0
  59 #define MTU_PCELL1      0xff4
  60 #define MTU_PCELL2      0xff8
  61 #define MTU_PCELL3      0xffC
  62
  63 static void __iomem *mtu_base;
  64 static bool clkevt_periodic;
  65 static u32 clk_prescale;
  66 static u32 nmdk_cycle;          /* write-once */
  67 static struct delay_timer mtu_delay_timer;
  68
  69 /*
  70  * Override the global weak sched_clock symbol with this
  71  * local implementation which uses the clocksource to get some
  72  * better resolution when scheduling the kernel.
  73  */
  74 static u64 notrace nomadik_read_sched_clock(void)
  75 {
  76         if (unlikely(!mtu_base))
  77                 return 0;
  78
  79         return -readl(mtu_base + MTU_VAL(0));
  80 }
  81
  82 static unsigned long nmdk_timer_read_current_timer(void)
  83 {
  84         return ~readl_relaxed(mtu_base + MTU_VAL(0));
  85 }
  86
  87 /* Clockevent device: use one-shot mode */
  88 static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
  89 {
  90         writel(1 << 1, mtu_base + MTU_IMSC);
  91         writel(evt, mtu_base + MTU_LR(1));
  92         /* Load highest value, enable device, enable interrupts */
  93         writel(MTU_CRn_ONESHOT | clk_prescale |
  94                MTU_CRn_32BITS | MTU_CRn_ENA,
  95                mtu_base + MTU_CR(1));
  96
  97         return 0;
  98 }
  99
 100 static void nmdk_clkevt_reset(void)
 101 {
 102         if (clkevt_periodic) {
 103                 /* Timer: configure load and background-load, and fire it up */
 104                 writel(nmdk_cycle, mtu_base + MTU_LR(1));
 105                 writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
 106
 107                 writel(MTU_CRn_PERIODIC | clk_prescale |
 108                        MTU_CRn_32BITS | MTU_CRn_ENA,
 109                        mtu_base + MTU_CR(1));
 110                 writel(1 << 1, mtu_base + MTU_IMSC);
 111         } else {
 112                 /* Generate an interrupt to start the clockevent again */
 113                 (void) nmdk_clkevt_next(nmdk_cycle, NULL);
 114         }
 115 }
 116
 117 static int nmdk_clkevt_shutdown(struct clock_event_device *evt)
 118 {
 119         writel(0, mtu_base + MTU_IMSC);
 120         /* disable timer */
 121         writel(0, mtu_base + MTU_CR(1));
 122         /* load some high default value */
 123         writel(0xffffffff, mtu_base + MTU_LR(1));
 124         return 0;
 125 }
 126
 127 static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt)
 128 {
 129         clkevt_periodic = false;
 130         return 0;
 131 }
 132
 133 static int nmdk_clkevt_set_periodic(struct clock_event_device *evt)
 134 {
 135         clkevt_periodic = true;
 136         nmdk_clkevt_reset();
 137         return 0;
 138 }
 139
 140 static void nmdk_clksrc_reset(void)
 141 {
 142         /* Disable */
 143         writel(0, mtu_base + MTU_CR(0));
 144
 145         /* ClockSource: configure load and background-load, and fire it up */
 146         writel(nmdk_cycle, mtu_base + MTU_LR(0));
 147         writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
 148
 149         writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
 150                mtu_base + MTU_CR(0));
 151 }
 152
 153 static void nmdk_clkevt_resume(struct clock_event_device *cedev)
 154 {
 155         nmdk_clkevt_reset();
 156         nmdk_clksrc_reset();
 157 }
 158
 159 static struct clock_event_device nmdk_clkevt = {
 160         .name                   = "mtu_1",
 161         .features               = CLOCK_EVT_FEAT_ONESHOT |
 162                                   CLOCK_EVT_FEAT_PERIODIC |
 163                                   CLOCK_EVT_FEAT_DYNIRQ,
 164         .rating                 = 200,
 165         .set_state_shutdown     = nmdk_clkevt_shutdown,
 166         .set_state_periodic     = nmdk_clkevt_set_periodic,
 167         .set_state_oneshot      = nmdk_clkevt_set_oneshot,
 168         .set_next_event         = nmdk_clkevt_next,
 169         .resume                 = nmdk_clkevt_resume,
 170 };
 171
 172 /*
 173  * IRQ Handler for timer 1 of the MTU block.
 174  */
 175 static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
 176 {
 177         struct clock_event_device *evdev = dev_id;
 178
 179         writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
 180         evdev->event_handler(evdev);
 181         return IRQ_HANDLED;
 182 }
 183
 184 static int __init nmdk_timer_init(void __iomem *base, int irq,
 185                                    struct clk *pclk, struct clk *clk)
 186 {
 187         unsigned long rate;
 188         int ret;
 189         int min_ticks;
 190
 191         mtu_base = base;
 192
 193         BUG_ON(clk_prepare_enable(pclk));
 194         BUG_ON(clk_prepare_enable(clk));
 195
 196         /*
 197          * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
 198          * for ux500, and in one specific Ux500 case 32768 Hz.
 199          *
 200          * Use a divide-by-16 counter if the tick rate is more than 32MHz.
 201          * At 32 MHz, the timer (with 32 bit counter) can be programmed
 202          * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
 203          * with 16 gives too low timer resolution.
 204          */
 205         rate = clk_get_rate(clk);
 206         if (rate > 32000000) {
 207                 rate /= 16;
 208                 clk_prescale = MTU_CRn_PRESCALE_16;
 209         } else {
 210                 clk_prescale = MTU_CRn_PRESCALE_1;
 211         }
 212
 213         /* Cycles for periodic mode */
 214         nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
 215
 216
 217         /* Timer 0 is the free running clocksource */
 218         nmdk_clksrc_reset();
 219
 220         ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
 221                                     rate, 200, 32, clocksource_mmio_readl_down);
 222         if (ret) {
 223                 pr_err("timer: failed to initialize clock source %s\n", "mtu_0");
 224                 return ret;
 225         }
 226
 227         sched_clock_register(nomadik_read_sched_clock, 32, rate);
 228
 229         /* Timer 1 is used for events, register irq and clockevents */
 230         if (request_irq(irq, nmdk_timer_interrupt, IRQF_TIMER,
 231                         "Nomadik Timer Tick", &nmdk_clkevt))
 232                 pr_err("%s: request_irq() failed\n", "Nomadik Timer Tick");
 233         nmdk_clkevt.cpumask = cpumask_of(0);
 234         nmdk_clkevt.irq = irq;
 235         if (rate < 100000)
 236                 min_ticks = 5;
 237         else
 238                 min_ticks = 2;
 239         clockevents_config_and_register(&nmdk_clkevt, rate, min_ticks,
 240                                         0xffffffffU);
 241
 242         mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
 243         mtu_delay_timer.freq = rate;
 244         register_current_timer_delay(&mtu_delay_timer);
 245
 246         return 0;
 247 }
 248
 249 static int __init nmdk_timer_of_init(struct device_node *node)
 250 {
 251         struct clk *pclk;
 252         struct clk *clk;
 253         void __iomem *base;
 254         int irq;
 255
 256         base = of_iomap(node, 0);
 257         if (!base) {
 258                 pr_err("Can't remap registers\n");
 259                 return -ENXIO;
 260         }
 261
 262         pclk = of_clk_get_by_name(node, "apb_pclk");
 263         if (IS_ERR(pclk)) {
 264                 pr_err("could not get apb_pclk\n");
 265                 return PTR_ERR(pclk);
 266         }
 267
 268         clk = of_clk_get_by_name(node, "timclk");
 269         if (IS_ERR(clk)) {
 270                 pr_err("could not get timclk\n");
 271                 return PTR_ERR(clk);
 272         }
 273
 274         irq = irq_of_parse_and_map(node, 0);
 275         if (irq <= 0) {
 276                 pr_err("Can't parse IRQ\n");
 277                 return -EINVAL;
 278         }
 279
 280         return nmdk_timer_init(base, irq, pclk, clk);
 281 }
 282 TIMER_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
 283                        nmdk_timer_of_init);