LXR uboot/drivers/timer/nomadik-mtu-timer.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright (C) 2019 Stephan Gerhold <stephan@gerhold.net>
   4 *
   5 * Based on arch/arm/cpu/armv7/u8500/timer.c:
   6 * Copyright (C) 2010 Linaro Limited
   7 * John Rigby <john.rigby@linaro.org>
   8 *
   9 * Based on Linux kernel source and internal ST-Ericsson U-Boot source:
  10 * Copyright (C) 2009 Alessandro Rubini
  11 * Copyright (C) 2010 ST-Ericsson
  12 * Copyright (C) 2010 Linus Walleij for ST-Ericsson
  13 */
  14
  15#include <common.h>
  16#include <dm.h>
  17#include <timer.h>
  18#include <asm/io.h>
  19#include <linux/bitops.h>
  20
  21#define MTU_NUM_TIMERS          4
  22
  23/* The timers */
  24struct nomadik_mtu_timer_regs {
  25        u32 lr;         /* Load register */
  26        u32 cv;         /* Current value */
  27        u32 cr;         /* Control register */
  28        u32 bglr;       /* Background load register */
  29};
  30
  31/* The MTU that contains the timers */
  32struct nomadik_mtu_regs {
  33        u32 imsc;       /* Interrupt mask set/clear */
  34        u32 ris;        /* Raw interrupt status */
  35        u32 mis;        /* Masked interrupt status */
  36        u32 icr;        /* Interrupt clear register */
  37
  38        struct nomadik_mtu_timer_regs timers[MTU_NUM_TIMERS];
  39};
  40
  41/* Bits for the control register */
  42#define MTU_CR_ONESHOT          BIT(0)  /* if 0 = wraps reloading from BGLR */
  43#define MTU_CR_32BITS           BIT(1)  /* if 0 = 16-bit counter */
  44
  45#define MTU_CR_PRESCALE_SHIFT   2
  46#define MTU_CR_PRESCALE_1       (0 << MTU_CR_PRESCALE_SHIFT)
  47#define MTU_CR_PRESCALE_16      (1 << MTU_CR_PRESCALE_SHIFT)
  48#define MTU_CR_PRESCALE_256     (2 << MTU_CR_PRESCALE_SHIFT)
  49
  50#define MTU_CR_PERIODIC         BIT(6)  /* if 0 = free-running */
  51#define MTU_CR_ENABLE           BIT(7)
  52
  53struct nomadik_mtu_priv {
  54        struct nomadik_mtu_timer_regs *timer;
  55};
  56
  57static u64 nomadik_mtu_get_count(struct udevice *dev)
  58{
  59        struct nomadik_mtu_priv *priv = dev_get_priv(dev);
  60
  61        /* Decrementing counter: invert the value */
  62        return timer_conv_64(~readl(&priv->timer->cv));
  63}
  64
  65static int nomadik_mtu_probe(struct udevice *dev)
  66{
  67        struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
  68        struct nomadik_mtu_priv *priv = dev_get_priv(dev);
  69        struct nomadik_mtu_regs *mtu;
  70        fdt_addr_t addr;
  71        u32 prescale;
  72
  73        addr = dev_read_addr(dev);
  74        if (addr == FDT_ADDR_T_NONE)
  75                return -EINVAL;
  76
  77        mtu = (struct nomadik_mtu_regs *)addr;
  78        priv->timer = mtu->timers; /* Use first timer */
  79
  80        if (!uc_priv->clock_rate)
  81                return -EINVAL;
  82
  83        /* Use divide-by-16 counter if tick rate is more than 32 MHz */
  84        if (uc_priv->clock_rate > 32000000) {
  85                uc_priv->clock_rate /= 16;
  86                prescale = MTU_CR_PRESCALE_16;
  87        } else {
  88                prescale = MTU_CR_PRESCALE_1;
  89        }
  90
  91        /* Configure a free-running, auto-wrap counter with selected prescale */
  92        writel(MTU_CR_ENABLE | prescale | MTU_CR_32BITS, &priv->timer->cr);
  93
  94        return 0;
  95}
  96
  97static const struct timer_ops nomadik_mtu_ops = {
  98        .get_count = nomadik_mtu_get_count,
  99};
 100
 101static const struct udevice_id nomadik_mtu_ids[] = {
 102        { .compatible = "st,nomadik-mtu" },
 103        {}
 104};
 105
 106U_BOOT_DRIVER(nomadik_mtu) = {
 107        .name = "nomadik_mtu",
 108        .id = UCLASS_TIMER,
 109        .of_match = nomadik_mtu_ids,
 110        .priv_auto_alloc_size = sizeof(struct nomadik_mtu_priv),
 111        .probe = nomadik_mtu_probe,
 112        .ops = &nomadik_mtu_ops,
 113};
 114