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/of_address.h>
  12 #include <linux/of_irq.h>
  13 #include <linux/sched_clock.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 int rating;
  37 static void __iomem *timer_base;
  38 static struct clock_event_device clockevent_tpm;
  39
  40 static inline void tpm_timer_disable(void)
  41 {
  42         unsigned int val;
  43
  44         /* channel disable */
  45         val = readl(timer_base + TPM_C0SC);
  46         val &= ~(TPM_C0SC_MODE_MASK | TPM_C0SC_CHIE);
  47         writel(val, timer_base + TPM_C0SC);
  48 }
  49
  50 static inline void tpm_timer_enable(void)
  51 {
  52         unsigned int val;
  53
  54         /* channel enabled in sw compare mode */
  55         val = readl(timer_base + TPM_C0SC);
  56         val |= (TPM_C0SC_MODE_SW_COMPARE << TPM_C0SC_MODE_SHIFT) |
  57                TPM_C0SC_CHIE;
  58         writel(val, timer_base + TPM_C0SC);
  59 }
  60
  61 static inline void tpm_irq_acknowledge(void)
  62 {
  63         writel(TPM_STATUS_CH0F, timer_base + TPM_STATUS);
  64 }
  65
  66 static struct delay_timer tpm_delay_timer;
  67
  68 static inline unsigned long tpm_read_counter(void)
  69 {
  70         return readl(timer_base + TPM_CNT);
  71 }
  72
  73 static unsigned long tpm_read_current_timer(void)
  74 {
  75         return tpm_read_counter();
  76 }
  77
  78 static u64 notrace tpm_read_sched_clock(void)
  79 {
  80         return tpm_read_counter();
  81 }
  82
  83 static int __init tpm_clocksource_init(unsigned long rate)
  84 {
  85         tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
  86         tpm_delay_timer.freq = rate;
  87         register_current_timer_delay(&tpm_delay_timer);
  88
  89         sched_clock_register(tpm_read_sched_clock, counter_width, rate);
  90
  91         return clocksource_mmio_init(timer_base + TPM_CNT, "imx-tpm",
  92                                      rate, rating, counter_width,
  93                                      clocksource_mmio_readl_up);
  94 }
  95
  96 static int tpm_set_next_event(unsigned long delta,
  97                                 struct clock_event_device *evt)
  98 {
  99         unsigned long next, now;
 100
 101         next = tpm_read_counter();
 102         next += delta;
 103         writel(next, timer_base + TPM_C0V);
 104         now = tpm_read_counter();
 105
 106         /*
 107          * NOTE: We observed in a very small probability, the bus fabric
 108          * contention between GPU and A7 may results a few cycles delay
 109          * of writing CNT registers which may cause the min_delta event got
 110          * missed, so we need add a ETIME check here in case it happened.
 111          */
 112         return (int)(next - now) <= 0 ? -ETIME : 0;
 113 }
 114
 115 static int tpm_set_state_oneshot(struct clock_event_device *evt)
 116 {
 117         tpm_timer_enable();
 118
 119         return 0;
 120 }
 121
 122 static int tpm_set_state_shutdown(struct clock_event_device *evt)
 123 {
 124         tpm_timer_disable();
 125
 126         return 0;
 127 }
 128
 129 static irqreturn_t tpm_timer_interrupt(int irq, void *dev_id)
 130 {
 131         struct clock_event_device *evt = dev_id;
 132
 133         tpm_irq_acknowledge();
 134
 135         evt->event_handler(evt);
 136
 137         return IRQ_HANDLED;
 138 }
 139
 140 static struct clock_event_device clockevent_tpm = {
 141         .name                   = "i.MX7ULP TPM Timer",
 142         .features               = CLOCK_EVT_FEAT_ONESHOT,
 143         .set_state_oneshot      = tpm_set_state_oneshot,
 144         .set_next_event         = tpm_set_next_event,
 145         .set_state_shutdown     = tpm_set_state_shutdown,
 146 };
 147
 148 static int __init tpm_clockevent_init(unsigned long rate, int irq)
 149 {
 150         int ret;
 151
 152         ret = request_irq(irq, tpm_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
 153                           "i.MX7ULP TPM Timer", &clockevent_tpm);
 154
 155         clockevent_tpm.rating = rating;
 156         clockevent_tpm.cpumask = cpumask_of(0);
 157         clockevent_tpm.irq = irq;
 158         clockevents_config_and_register(&clockevent_tpm, rate, 300,
 159                                         GENMASK(counter_width - 1, 1));
 160
 161         return ret;
 162 }
 163
 164 static int __init tpm_timer_init(struct device_node *np)
 165 {
 166         struct clk *ipg, *per;
 167         int irq, ret;
 168         u32 rate;
 169
 170         timer_base = of_iomap(np, 0);
 171         if (!timer_base) {
 172                 pr_err("tpm: failed to get base address\n");
 173                 return -ENXIO;
 174         }
 175
 176         irq = irq_of_parse_and_map(np, 0);
 177         if (!irq) {
 178                 pr_err("tpm: failed to get irq\n");
 179                 ret = -ENOENT;
 180                 goto err_iomap;
 181         }
 182
 183         ipg = of_clk_get_by_name(np, "ipg");
 184         per = of_clk_get_by_name(np, "per");
 185         if (IS_ERR(ipg) || IS_ERR(per)) {
 186                 pr_err("tpm: failed to get ipg or per clk\n");
 187                 ret = -ENODEV;
 188                 goto err_clk_get;
 189         }
 190
 191         /* enable clk before accessing registers */
 192         ret = clk_prepare_enable(ipg);
 193         if (ret) {
 194                 pr_err("tpm: ipg clock enable failed (%d)\n", ret);
 195                 goto err_clk_get;
 196         }
 197
 198         ret = clk_prepare_enable(per);
 199         if (ret) {
 200                 pr_err("tpm: per clock enable failed (%d)\n", ret);
 201                 goto err_per_clk_enable;
 202         }
 203
 204         counter_width = (readl(timer_base + TPM_PARAM) & TPM_PARAM_WIDTH_MASK)
 205                 >> TPM_PARAM_WIDTH_SHIFT;
 206         /* use rating 200 for 32-bit counter and 150 for 16-bit counter */
 207         rating = counter_width == 0x20 ? 200 : 150;
 208
 209         /*
 210          * Initialize tpm module to a known state
 211          * 1) Counter disabled
 212          * 2) TPM counter operates in up counting mode
 213          * 3) Timer Overflow Interrupt disabled
 214          * 4) Channel0 disabled
 215          * 5) DMA transfers disabled
 216          */
 217         /* make sure counter is disabled */
 218         writel(0, timer_base + TPM_SC);
 219         /* TOF is W1C */
 220         writel(TPM_SC_TOF_MASK, timer_base + TPM_SC);
 221         writel(0, timer_base + TPM_CNT);
 222         /* CHF is W1C */
 223         writel(TPM_C0SC_CHF_MASK, timer_base + TPM_C0SC);
 224
 225         /*
 226          * increase per cnt,
 227          * div 8 for 32-bit counter and div 128 for 16-bit counter
 228          */
 229         writel(TPM_SC_CMOD_INC_PER_CNT |
 230                 (counter_width == 0x20 ?
 231                 TPM_SC_CMOD_DIV_DEFAULT : TPM_SC_CMOD_DIV_MAX),
 232                      timer_base + TPM_SC);
 233
 234         /* set MOD register to maximum for free running mode */
 235         writel(GENMASK(counter_width - 1, 0), timer_base + TPM_MOD);
 236
 237         rate = clk_get_rate(per) >> 3;
 238         ret = tpm_clocksource_init(rate);
 239         if (ret)
 240                 goto err_per_clk_enable;
 241
 242         ret = tpm_clockevent_init(rate, irq);
 243         if (ret)
 244                 goto err_per_clk_enable;
 245
 246         return 0;
 247
 248 err_per_clk_enable:
 249         clk_disable_unprepare(ipg);
 250 err_clk_get:
 251         clk_put(per);
 252         clk_put(ipg);
 253 err_iomap:
 254         iounmap(timer_base);
 255         return ret;
 256 }
 257 TIMER_OF_DECLARE(imx7ulp, "fsl,imx7ulp-tpm", tpm_timer_init);