nomadik-mtu-timer.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2019 Stephan Gerhold <stephan@gerhold.net>
*
* Based on arch/arm/cpu/armv7/u8500/timer.c:
* Copyright (C) 2010 Linaro Limited
* John Rigby <john.rigby@linaro.org>
*
* Based on Linux kernel source and internal ST-Ericsson U-Boot source:
* Copyright (C) 2009 Alessandro Rubini
* Copyright (C) 2010 ST-Ericsson
* Copyright (C) 2010 Linus Walleij for ST-Ericsson
*/
#include <common.h>
#include <dm.h>
#include <timer.h>
#include <asm/io.h>
#define MTU_NUM_TIMERS 4
/* The timers */
struct nomadik_mtu_timer_regs {
u32 lr; /* Load register */
u32 cv; /* Current value */
u32 cr; /* Control register */
u32 bglr; /* Background load register */
};
/* The MTU that contains the timers */
struct nomadik_mtu_regs {
u32 imsc; /* Interrupt mask set/clear */
u32 ris; /* Raw interrupt status */
u32 mis; /* Masked interrupt status */
u32 icr; /* Interrupt clear register */
struct nomadik_mtu_timer_regs timers[MTU_NUM_TIMERS];
};
/* Bits for the control register */
#define MTU_CR_ONESHOT BIT(0) /* if 0 = wraps reloading from BGLR */
#define MTU_CR_32BITS BIT(1) /* if 0 = 16-bit counter */
#define MTU_CR_PRESCALE_SHIFT 2
#define MTU_CR_PRESCALE_1 (0 << MTU_CR_PRESCALE_SHIFT)
#define MTU_CR_PRESCALE_16 (1 << MTU_CR_PRESCALE_SHIFT)
#define MTU_CR_PRESCALE_256 (2 << MTU_CR_PRESCALE_SHIFT)
#define MTU_CR_PERIODIC BIT(6) /* if 0 = free-running */
#define MTU_CR_ENABLE BIT(7)
struct nomadik_mtu_priv {
struct nomadik_mtu_timer_regs *timer;
};
static int nomadik_mtu_get_count(struct udevice *dev, u64 *count)
{
struct nomadik_mtu_priv *priv = dev_get_priv(dev);
/* Decrementing counter: invert the value */
*count = timer_conv_64(~readl(&priv->timer->cv));
return 0;
}
static int nomadik_mtu_probe(struct udevice *dev)
{
struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
struct nomadik_mtu_priv *priv = dev_get_priv(dev);
struct nomadik_mtu_regs *mtu;
fdt_addr_t addr;
u32 prescale;
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
mtu = (struct nomadik_mtu_regs *)addr;
priv->timer = mtu->timers; /* Use first timer */
if (!uc_priv->clock_rate)
return -EINVAL;
/* Use divide-by-16 counter if tick rate is more than 32 MHz */
if (uc_priv->clock_rate > 32000000) {
uc_priv->clock_rate /= 16;
prescale = MTU_CR_PRESCALE_16;
} else {
prescale = MTU_CR_PRESCALE_1;
}
/* Configure a free-running, auto-wrap counter with selected prescale */
writel(MTU_CR_ENABLE | prescale | MTU_CR_32BITS, &priv->timer->cr);
return 0;
}
static const struct timer_ops nomadik_mtu_ops = {
.get_count = nomadik_mtu_get_count,
};
static const struct udevice_id nomadik_mtu_ids[] = {
{ .compatible = "st,nomadik-mtu" },
{}
};
U_BOOT_DRIVER(nomadik_mtu) = {
.name = "nomadik_mtu",
.id = UCLASS_TIMER,
.of_match = nomadik_mtu_ids,
.priv_auto_alloc_size = sizeof(struct nomadik_mtu_priv),
.probe = nomadik_mtu_probe,
.ops = &nomadik_mtu_ops,
};