drivers/clocksource/timer-msc313e.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * MStar timer driver
   4  *
   5  * Copyright (C) 2021 Daniel Palmer
   6  * Copyright (C) 2021 Romain Perier
   7  *
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14 #include <linux/irqreturn.h>
  15 #include <linux/sched_clock.h>
  16 #include <linux/of.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_irq.h>
  19
  20 #ifdef CONFIG_ARM
  21 #include <linux/delay.h>
  22 #endif
  23
  24 #include "timer-of.h"
  25
  26 #define TIMER_NAME "msc313e_timer"
  27
  28 #define MSC313E_REG_CTRL                0x00
  29 #define MSC313E_REG_CTRL_TIMER_EN       BIT(0)
  30 #define MSC313E_REG_CTRL_TIMER_TRIG     BIT(1)
  31 #define MSC313E_REG_CTRL_TIMER_INT_EN   BIT(8)
  32 #define MSC313E_REG_TIMER_MAX_LOW       0x08
  33 #define MSC313E_REG_TIMER_MAX_HIGH      0x0c
  34 #define MSC313E_REG_COUNTER_LOW         0x10
  35 #define MSC313E_REG_COUNTER_HIGH        0x14
  36 #define MSC313E_REG_TIMER_DIVIDE        0x18
  37
  38 #define MSC313E_CLK_DIVIDER             9
  39 #define TIMER_SYNC_TICKS                3
  40
  41 #ifdef CONFIG_ARM
  42 struct msc313e_delay {
  43         void __iomem *base;
  44         struct delay_timer delay;
  45 };
  46 static struct msc313e_delay msc313e_delay;
  47 #endif
  48
  49 static void __iomem *msc313e_clksrc;
  50
  51 static void msc313e_timer_stop(void __iomem *base)
  52 {
  53         writew(0, base + MSC313E_REG_CTRL);
  54 }
  55
  56 static void msc313e_timer_start(void __iomem *base, bool periodic)
  57 {
  58         u16 reg;
  59
  60         reg = readw(base + MSC313E_REG_CTRL);
  61         if (periodic)
  62                 reg |= MSC313E_REG_CTRL_TIMER_EN;
  63         else
  64                 reg |= MSC313E_REG_CTRL_TIMER_TRIG;
  65         writew(reg | MSC313E_REG_CTRL_TIMER_INT_EN, base + MSC313E_REG_CTRL);
  66 }
  67
  68 static void msc313e_timer_setup(void __iomem *base, unsigned long delay)
  69 {
  70         unsigned long flags;
  71
  72         local_irq_save(flags);
  73         writew(delay >> 16, base + MSC313E_REG_TIMER_MAX_HIGH);
  74         writew(delay & 0xffff, base + MSC313E_REG_TIMER_MAX_LOW);
  75         local_irq_restore(flags);
  76 }
  77
  78 static unsigned long msc313e_timer_current_value(void __iomem *base)
  79 {
  80         unsigned long flags;
  81         u16 l, h;
  82
  83         local_irq_save(flags);
  84         l = readw(base + MSC313E_REG_COUNTER_LOW);
  85         h = readw(base + MSC313E_REG_COUNTER_HIGH);
  86         local_irq_restore(flags);
  87
  88         return (((u32)h) << 16 | l);
  89 }
  90
  91 static int msc313e_timer_clkevt_shutdown(struct clock_event_device *evt)
  92 {
  93         struct timer_of *timer = to_timer_of(evt);
  94
  95         msc313e_timer_stop(timer_of_base(timer));
  96
  97         return 0;
  98 }
  99
 100 static int msc313e_timer_clkevt_set_oneshot(struct clock_event_device *evt)
 101 {
 102         struct timer_of *timer = to_timer_of(evt);
 103
 104         msc313e_timer_stop(timer_of_base(timer));
 105         msc313e_timer_start(timer_of_base(timer), false);
 106
 107         return 0;
 108 }
 109
 110 static int msc313e_timer_clkevt_set_periodic(struct clock_event_device *evt)
 111 {
 112         struct timer_of *timer = to_timer_of(evt);
 113
 114         msc313e_timer_stop(timer_of_base(timer));
 115         msc313e_timer_setup(timer_of_base(timer), timer_of_period(timer));
 116         msc313e_timer_start(timer_of_base(timer), true);
 117
 118         return 0;
 119 }
 120
 121 static int msc313e_timer_clkevt_next_event(unsigned long evt, struct clock_event_device *clkevt)
 122 {
 123         struct timer_of *timer = to_timer_of(clkevt);
 124
 125         msc313e_timer_stop(timer_of_base(timer));
 126         msc313e_timer_setup(timer_of_base(timer), evt);
 127         msc313e_timer_start(timer_of_base(timer), false);
 128
 129         return 0;
 130 }
 131
 132 static irqreturn_t msc313e_timer_clkevt_irq(int irq, void *dev_id)
 133 {
 134         struct clock_event_device *evt = dev_id;
 135
 136         evt->event_handler(evt);
 137
 138         return IRQ_HANDLED;
 139 }
 140
 141 static u64 msc313e_timer_clksrc_read(struct clocksource *cs)
 142 {
 143         return msc313e_timer_current_value(msc313e_clksrc) & cs->mask;
 144 }
 145
 146 #ifdef CONFIG_ARM
 147 static unsigned long msc313e_read_delay_timer_read(void)
 148 {
 149         return msc313e_timer_current_value(msc313e_delay.base);
 150 }
 151 #endif
 152
 153 static u64 msc313e_timer_sched_clock_read(void)
 154 {
 155         return msc313e_timer_current_value(msc313e_clksrc);
 156 }
 157
 158 static struct clock_event_device msc313e_clkevt = {
 159         .name = TIMER_NAME,
 160         .rating = 300,
 161         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 162         .set_state_shutdown = msc313e_timer_clkevt_shutdown,
 163         .set_state_periodic = msc313e_timer_clkevt_set_periodic,
 164         .set_state_oneshot = msc313e_timer_clkevt_set_oneshot,
 165         .tick_resume = msc313e_timer_clkevt_shutdown,
 166         .set_next_event = msc313e_timer_clkevt_next_event,
 167 };
 168
 169 static int __init msc313e_clkevt_init(struct device_node *np)
 170 {
 171         int ret;
 172         struct timer_of *to;
 173
 174         to = kzalloc(sizeof(*to), GFP_KERNEL);
 175         if (!to)
 176                 return -ENOMEM;
 177
 178         to->flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE;
 179         to->of_irq.handler = msc313e_timer_clkevt_irq;
 180         ret = timer_of_init(np, to);
 181         if (ret)
 182                 return ret;
 183
 184         if (of_device_is_compatible(np, "sstar,ssd20xd-timer")) {
 185                 to->of_clk.rate = clk_get_rate(to->of_clk.clk) / MSC313E_CLK_DIVIDER;
 186                 to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ);
 187                 writew(MSC313E_CLK_DIVIDER - 1, timer_of_base(to) + MSC313E_REG_TIMER_DIVIDE);
 188         }
 189
 190         msc313e_clkevt.cpumask = cpu_possible_mask;
 191         msc313e_clkevt.irq = to->of_irq.irq;
 192         to->clkevt = msc313e_clkevt;
 193
 194         clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
 195                                         TIMER_SYNC_TICKS, 0xffffffff);
 196         return 0;
 197 }
 198
 199 static int __init msc313e_clksrc_init(struct device_node *np)
 200 {
 201         struct timer_of to = { 0 };
 202         int ret;
 203         u16 reg;
 204
 205         to.flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
 206         ret = timer_of_init(np, &to);
 207         if (ret)
 208                 return ret;
 209
 210         msc313e_clksrc = timer_of_base(&to);
 211         reg = readw(msc313e_clksrc + MSC313E_REG_CTRL);
 212         reg |= MSC313E_REG_CTRL_TIMER_EN;
 213         writew(reg, msc313e_clksrc + MSC313E_REG_CTRL);
 214
 215 #ifdef CONFIG_ARM
 216         msc313e_delay.base = timer_of_base(&to);
 217         msc313e_delay.delay.read_current_timer = msc313e_read_delay_timer_read;
 218         msc313e_delay.delay.freq = timer_of_rate(&to);
 219
 220         register_current_timer_delay(&msc313e_delay.delay);
 221 #endif
 222
 223         sched_clock_register(msc313e_timer_sched_clock_read, 32, timer_of_rate(&to));
 224         return clocksource_mmio_init(timer_of_base(&to), TIMER_NAME, timer_of_rate(&to), 300, 32,
 225                                      msc313e_timer_clksrc_read);
 226 }
 227
 228 static int __init msc313e_timer_init(struct device_node *np)
 229 {
 230         int ret = 0;
 231         static int num_called;
 232
 233         switch (num_called) {
 234         case 0:
 235                 ret = msc313e_clksrc_init(np);
 236                 if (ret)
 237                         return ret;
 238                 break;
 239
 240         default:
 241                 ret = msc313e_clkevt_init(np);
 242                 if (ret)
 243                         return ret;
 244                 break;
 245         }
 246
 247         num_called++;
 248
 249         return 0;
 250 }
 251
 252 TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init);
 253 TIMER_OF_DECLARE(ssd20xd, "sstar,ssd20xd-timer", msc313e_timer_init);