drivers/clocksource/timer-imx-tpm.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 //
   3 // Copyright 2016 Freescale Semiconductor, Inc.
   4 // Copyright 2017 NXP
   5
   6 #include <linux/clk.h>
   7 #include <linux/clockchips.h>
   8 #include <linux/clocksource.h>
   9 #include <linux/delay.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/sched_clock.h>
  12
  13 #include "timer-of.h"
  14
  15 #define TPM_PARAM                       0x4
  16 #define TPM_PARAM_WIDTH_SHIFT           16
  17 #define TPM_PARAM_WIDTH_MASK            (0xff << 16)
  18 #define TPM_SC                          0x10
  19 #define TPM_SC_CMOD_INC_PER_CNT         (0x1 << 3)
  20 #define TPM_SC_CMOD_DIV_DEFAULT         0x3
  21 #define TPM_SC_CMOD_DIV_MAX             0x7
  22 #define TPM_SC_TOF_MASK                 (0x1 << 7)
  23 #define TPM_CNT                         0x14
  24 #define TPM_MOD                         0x18
  25 #define TPM_STATUS                      0x1c
  26 #define TPM_STATUS_CH0F                 BIT(0)
  27 #define TPM_C0SC                        0x20
  28 #define TPM_C0SC_CHIE                   BIT(6)
  29 #define TPM_C0SC_MODE_SHIFT             2
  30 #define TPM_C0SC_MODE_MASK              0x3c
  31 #define TPM_C0SC_MODE_SW_COMPARE        0x4
  32 #define TPM_C0SC_CHF_MASK               (0x1 << 7)
  33 #define TPM_C0V                         0x24
  34
  35 static int counter_width;
  36 static void __iomem *timer_base;
  37
  38 static inline void tpm_timer_disable(void)
  39 {
  40         unsigned int val;
  41
  42         /* channel disable */
  43         val = readl(timer_base + TPM_C0SC);
  44         val &= ~(TPM_C0SC_MODE_MASK | TPM_C0SC_CHIE);
  45         writel(val, timer_base + TPM_C0SC);
  46 }
  47
  48 static inline void tpm_timer_enable(void)
  49 {
  50         unsigned int val;
  51
  52         /* channel enabled in sw compare mode */
  53         val = readl(timer_base + TPM_C0SC);
  54         val |= (TPM_C0SC_MODE_SW_COMPARE << TPM_C0SC_MODE_SHIFT) |
  55                TPM_C0SC_CHIE;
  56         writel(val, timer_base + TPM_C0SC);
  57 }
  58
  59 static inline void tpm_irq_acknowledge(void)
  60 {
  61         writel(TPM_STATUS_CH0F, timer_base + TPM_STATUS);
  62 }
  63
  64 static struct delay_timer tpm_delay_timer;
  65
  66 static inline unsigned long tpm_read_counter(void)
  67 {
  68         return readl(timer_base + TPM_CNT);
  69 }
  70
  71 static unsigned long tpm_read_current_timer(void)
  72 {
  73         return tpm_read_counter();
  74 }
  75
  76 static u64 notrace tpm_read_sched_clock(void)
  77 {
  78         return tpm_read_counter();
  79 }
  80
  81 static int tpm_set_next_event(unsigned long delta,
  82                                 struct clock_event_device *evt)
  83 {
  84         unsigned long next, now;
  85
  86         next = tpm_read_counter();
  87         next += delta;
  88         writel(next, timer_base + TPM_C0V);
  89         now = tpm_read_counter();
  90
  91         /*
  92          * NOTE: We observed in a very small probability, the bus fabric
  93          * contention between GPU and A7 may results a few cycles delay
  94          * of writing CNT registers which may cause the min_delta event got
  95          * missed, so we need add a ETIME check here in case it happened.
  96          */
  97         return (int)(next - now) <= 0 ? -ETIME : 0;
  98 }
  99
 100 static int tpm_set_state_oneshot(struct clock_event_device *evt)
 101 {
 102         tpm_timer_enable();
 103
 104         return 0;
 105 }
 106
 107 static int tpm_set_state_shutdown(struct clock_event_device *evt)
 108 {
 109         tpm_timer_disable();
 110
 111         return 0;
 112 }
 113
 114 static irqreturn_t tpm_timer_interrupt(int irq, void *dev_id)
 115 {
 116         struct clock_event_device *evt = dev_id;
 117
 118         tpm_irq_acknowledge();
 119
 120         evt->event_handler(evt);
 121
 122         return IRQ_HANDLED;
 123 }
 124
 125 static struct timer_of to_tpm = {
 126         .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
 127         .clkevt = {
 128                 .name                   = "i.MX7ULP TPM Timer",
 129                 .rating                 = 200,
 130                 .features               = CLOCK_EVT_FEAT_ONESHOT,
 131                 .set_state_shutdown     = tpm_set_state_shutdown,
 132                 .set_state_oneshot      = tpm_set_state_oneshot,
 133                 .set_next_event         = tpm_set_next_event,
 134                 .cpumask                = cpu_possible_mask,
 135         },
 136         .of_irq = {
 137                 .handler                = tpm_timer_interrupt,
 138                 .flags                  = IRQF_TIMER | IRQF_IRQPOLL,
 139         },
 140         .of_clk = {
 141                 .name = "per",
 142         },
 143 };
 144
 145 static int __init tpm_clocksource_init(void)
 146 {
 147         tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
 148         tpm_delay_timer.freq = timer_of_rate(&to_tpm) >> 3;
 149         register_current_timer_delay(&tpm_delay_timer);
 150
 151         sched_clock_register(tpm_read_sched_clock, counter_width,
 152                              timer_of_rate(&to_tpm) >> 3);
 153
 154         return clocksource_mmio_init(timer_base + TPM_CNT,
 155                                      "imx-tpm",
 156                                      timer_of_rate(&to_tpm) >> 3,
 157                                      to_tpm.clkevt.rating,
 158                                      counter_width,
 159                                      clocksource_mmio_readl_up);
 160 }
 161
 162 static void __init tpm_clockevent_init(void)
 163 {
 164         clockevents_config_and_register(&to_tpm.clkevt,
 165                                         timer_of_rate(&to_tpm) >> 3,
 166                                         300,
 167                                         GENMASK(counter_width - 1,
 168                                         1));
 169 }
 170
 171 static int __init tpm_timer_init(struct device_node *np)
 172 {
 173         struct clk *ipg;
 174         int ret;
 175
 176         ipg = of_clk_get_by_name(np, "ipg");
 177         if (IS_ERR(ipg)) {
 178                 pr_err("tpm: failed to get ipg clk\n");
 179                 return -ENODEV;
 180         }
 181         /* enable clk before accessing registers */
 182         ret = clk_prepare_enable(ipg);
 183         if (ret) {
 184                 pr_err("tpm: ipg clock enable failed (%d)\n", ret);
 185                 clk_put(ipg);
 186                 return ret;
 187         }
 188
 189         ret = timer_of_init(np, &to_tpm);
 190         if (ret)
 191                 return ret;
 192
 193         timer_base = timer_of_base(&to_tpm);
 194
 195         counter_width = (readl(timer_base + TPM_PARAM)
 196                 & TPM_PARAM_WIDTH_MASK) >> TPM_PARAM_WIDTH_SHIFT;
 197         /* use rating 200 for 32-bit counter and 150 for 16-bit counter */
 198         to_tpm.clkevt.rating = counter_width == 0x20 ? 200 : 150;
 199
 200         /*
 201          * Initialize tpm module to a known state
 202          * 1) Counter disabled
 203          * 2) TPM counter operates in up counting mode
 204          * 3) Timer Overflow Interrupt disabled
 205          * 4) Channel0 disabled
 206          * 5) DMA transfers disabled
 207          */
 208         /* make sure counter is disabled */
 209         writel(0, timer_base + TPM_SC);
 210         /* TOF is W1C */
 211         writel(TPM_SC_TOF_MASK, timer_base + TPM_SC);
 212         writel(0, timer_base + TPM_CNT);
 213         /* CHF is W1C */
 214         writel(TPM_C0SC_CHF_MASK, timer_base + TPM_C0SC);
 215
 216         /*
 217          * increase per cnt,
 218          * div 8 for 32-bit counter and div 128 for 16-bit counter
 219          */
 220         writel(TPM_SC_CMOD_INC_PER_CNT |
 221                 (counter_width == 0x20 ?
 222                 TPM_SC_CMOD_DIV_DEFAULT : TPM_SC_CMOD_DIV_MAX),
 223                 timer_base + TPM_SC);
 224
 225         /* set MOD register to maximum for free running mode */
 226         writel(GENMASK(counter_width - 1, 0), timer_base + TPM_MOD);
 227
 228         tpm_clockevent_init();
 229
 230         return tpm_clocksource_init();
 231 }
 232 TIMER_OF_DECLARE(imx7ulp, "fsl,imx7ulp-tpm", tpm_timer_init);