drivers/clocksource/renesas-ostm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Renesas Timer Support - OSTM
   4  *
   5  * Copyright (C) 2017 Renesas Electronics America, Inc.
   6  * Copyright (C) 2017 Chris Brandt
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/clockchips.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/reset.h>
  14 #include <linux/sched_clock.h>
  15 #include <linux/slab.h>
  16
  17 #include "timer-of.h"
  18
  19 /*
  20  * The OSTM contains independent channels.
  21  * The first OSTM channel probed will be set up as a free running
  22  * clocksource. Additionally we will use this clocksource for the system
  23  * schedule timer sched_clock().
  24  *
  25  * The second (or more) channel probed will be set up as an interrupt
  26  * driven clock event.
  27  */
  28
  29 static void __iomem *system_clock;      /* For sched_clock() */
  30
  31 /* OSTM REGISTERS */
  32 #define OSTM_CMP                0x000   /* RW,32 */
  33 #define OSTM_CNT                0x004   /* R,32 */
  34 #define OSTM_TE                 0x010   /* R,8 */
  35 #define OSTM_TS                 0x014   /* W,8 */
  36 #define OSTM_TT                 0x018   /* W,8 */
  37 #define OSTM_CTL                0x020   /* RW,8 */
  38
  39 #define TE                      0x01
  40 #define TS                      0x01
  41 #define TT                      0x01
  42 #define CTL_PERIODIC            0x00
  43 #define CTL_ONESHOT             0x02
  44 #define CTL_FREERUN             0x02
  45
  46 static void ostm_timer_stop(struct timer_of *to)
  47 {
  48         if (readb(timer_of_base(to) + OSTM_TE) & TE) {
  49                 writeb(TT, timer_of_base(to) + OSTM_TT);
  50
  51                 /*
  52                  * Read back the register simply to confirm the write operation
  53                  * has completed since I/O writes can sometimes get queued by
  54                  * the bus architecture.
  55                  */
  56                 while (readb(timer_of_base(to) + OSTM_TE) & TE)
  57                         ;
  58         }
  59 }
  60
  61 static int __init ostm_init_clksrc(struct timer_of *to)
  62 {
  63         ostm_timer_stop(to);
  64
  65         writel(0, timer_of_base(to) + OSTM_CMP);
  66         writeb(CTL_FREERUN, timer_of_base(to) + OSTM_CTL);
  67         writeb(TS, timer_of_base(to) + OSTM_TS);
  68
  69         return clocksource_mmio_init(timer_of_base(to) + OSTM_CNT,
  70                                      to->np->full_name, timer_of_rate(to), 300,
  71                                      32, clocksource_mmio_readl_up);
  72 }
  73
  74 static u64 notrace ostm_read_sched_clock(void)
  75 {
  76         return readl(system_clock);
  77 }
  78
  79 static void __init ostm_init_sched_clock(struct timer_of *to)
  80 {
  81         system_clock = timer_of_base(to) + OSTM_CNT;
  82         sched_clock_register(ostm_read_sched_clock, 32, timer_of_rate(to));
  83 }
  84
  85 static int ostm_clock_event_next(unsigned long delta,
  86                                  struct clock_event_device *ced)
  87 {
  88         struct timer_of *to = to_timer_of(ced);
  89
  90         ostm_timer_stop(to);
  91
  92         writel(delta, timer_of_base(to) + OSTM_CMP);
  93         writeb(CTL_ONESHOT, timer_of_base(to) + OSTM_CTL);
  94         writeb(TS, timer_of_base(to) + OSTM_TS);
  95
  96         return 0;
  97 }
  98
  99 static int ostm_shutdown(struct clock_event_device *ced)
 100 {
 101         struct timer_of *to = to_timer_of(ced);
 102
 103         ostm_timer_stop(to);
 104
 105         return 0;
 106 }
 107 static int ostm_set_periodic(struct clock_event_device *ced)
 108 {
 109         struct timer_of *to = to_timer_of(ced);
 110
 111         if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
 112                 ostm_timer_stop(to);
 113
 114         writel(timer_of_period(to) - 1, timer_of_base(to) + OSTM_CMP);
 115         writeb(CTL_PERIODIC, timer_of_base(to) + OSTM_CTL);
 116         writeb(TS, timer_of_base(to) + OSTM_TS);
 117
 118         return 0;
 119 }
 120
 121 static int ostm_set_oneshot(struct clock_event_device *ced)
 122 {
 123         struct timer_of *to = to_timer_of(ced);
 124
 125         ostm_timer_stop(to);
 126
 127         return 0;
 128 }
 129
 130 static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
 131 {
 132         struct clock_event_device *ced = dev_id;
 133
 134         if (clockevent_state_oneshot(ced))
 135                 ostm_timer_stop(to_timer_of(ced));
 136
 137         /* notify clockevent layer */
 138         if (ced->event_handler)
 139                 ced->event_handler(ced);
 140
 141         return IRQ_HANDLED;
 142 }
 143
 144 static int __init ostm_init_clkevt(struct timer_of *to)
 145 {
 146         struct clock_event_device *ced = &to->clkevt;
 147
 148         ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC;
 149         ced->set_state_shutdown = ostm_shutdown;
 150         ced->set_state_periodic = ostm_set_periodic;
 151         ced->set_state_oneshot = ostm_set_oneshot;
 152         ced->set_next_event = ostm_clock_event_next;
 153         ced->shift = 32;
 154         ced->rating = 300;
 155         ced->cpumask = cpumask_of(0);
 156         clockevents_config_and_register(ced, timer_of_rate(to), 0xf,
 157                                         0xffffffff);
 158
 159         return 0;
 160 }
 161
 162 static int __init ostm_init(struct device_node *np)
 163 {
 164         struct reset_control *rstc;
 165         struct timer_of *to;
 166         int ret;
 167
 168         to = kzalloc(sizeof(*to), GFP_KERNEL);
 169         if (!to)
 170                 return -ENOMEM;
 171
 172         rstc = of_reset_control_get_optional_exclusive(np, NULL);
 173         if (IS_ERR(rstc)) {
 174                 ret = PTR_ERR(rstc);
 175                 goto err_free;
 176         }
 177
 178         reset_control_deassert(rstc);
 179
 180         to->flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
 181         if (system_clock) {
 182                 /*
 183                  * clock sources don't use interrupts, clock events do
 184                  */
 185                 to->flags |= TIMER_OF_IRQ;
 186                 to->of_irq.flags = IRQF_TIMER | IRQF_IRQPOLL;
 187                 to->of_irq.handler = ostm_timer_interrupt;
 188         }
 189
 190         ret = timer_of_init(np, to);
 191         if (ret)
 192                 goto err_reset;
 193
 194         /*
 195          * First probed device will be used as system clocksource. Any
 196          * additional devices will be used as clock events.
 197          */
 198         if (!system_clock) {
 199                 ret = ostm_init_clksrc(to);
 200                 if (ret)
 201                         goto err_cleanup;
 202
 203                 ostm_init_sched_clock(to);
 204                 pr_info("%pOF: used for clocksource\n", np);
 205         } else {
 206                 ret = ostm_init_clkevt(to);
 207                 if (ret)
 208                         goto err_cleanup;
 209
 210                 pr_info("%pOF: used for clock events\n", np);
 211         }
 212
 213         return 0;
 214
 215 err_cleanup:
 216         timer_of_cleanup(to);
 217 err_reset:
 218         reset_control_assert(rstc);
 219         reset_control_put(rstc);
 220 err_free:
 221         kfree(to);
 222         return ret;
 223 }
 224
 225 TIMER_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
 226
 227 #ifdef CONFIG_ARCH_RZG2L
 228 static int __init ostm_probe(struct platform_device *pdev)
 229 {
 230         struct device *dev = &pdev->dev;
 231
 232         return ostm_init(dev->of_node);
 233 }
 234
 235 static const struct of_device_id ostm_of_table[] = {
 236         { .compatible = "renesas,ostm", },
 237         { /* sentinel */ }
 238 };
 239
 240 static struct platform_driver ostm_device_driver = {
 241         .driver = {
 242                 .name = "renesas_ostm",
 243                 .of_match_table = of_match_ptr(ostm_of_table),
 244                 .suppress_bind_attrs = true,
 245         },
 246 };
 247 builtin_platform_driver_probe(ostm_device_driver, ostm_probe);
 248 #endif