arc_timer.c
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/*
* Copyright (C) 2016 Synopsys, Inc. All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <timer.h>
#include <asm/arcregs.h>
#include <asm/io.h>
DECLARE_GLOBAL_DATA_PTR;
#define NH_MODE (1 << 1)
/*
* ARC timer control registers are mapped to auxiliary address space.
* There are special ARC asm command to access that addresses.
* Therefore we use built-in functions to read from and write to timer
* control register.
*/
/* Driver private data. Contains timer id. Could be either 0 or 1. */
struct arc_timer_priv {
uint timer_id;
};
static int arc_timer_get_count(struct udevice *dev, u64 *count)
{
u32 val = 0;
struct arc_timer_priv *priv = dev_get_priv(dev);
switch (priv->timer_id) {
case 0:
val = read_aux_reg(ARC_AUX_TIMER0_CNT);
break;
case 1:
val = read_aux_reg(ARC_AUX_TIMER1_CNT);
break;
}
*count = timer_conv_64(val);
return 0;
}
static int arc_timer_probe(struct udevice *dev)
{
int id;
struct arc_timer_priv *priv = dev_get_priv(dev);
/* Get registers offset and size */
id = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev), "reg", -1);
if (id < 0)
return -EINVAL;
if (id > 1)
return -ENXIO;
priv->timer_id = (uint)id;
/*
* In ARC core there're special registers (Auxiliary or AUX) in its
* separate memory space that are used for accessing some hardware
* features of the core. They are not mapped in normal memory space
* and also always have the same location regardless core configuration.
* Thus to simplify understanding of the programming model we chose to
* access AUX regs of Timer0 and Timer1 separately instead of using
* offsets from some base address.
*/
switch (priv->timer_id) {
case 0:
/* Disable timer if CPU is halted */
write_aux_reg(ARC_AUX_TIMER0_CTRL, NH_MODE);
/* Set max value for counter/timer */
write_aux_reg(ARC_AUX_TIMER0_LIMIT, 0xffffffff);
/* Set initial count value and restart counter/timer */
write_aux_reg(ARC_AUX_TIMER0_CNT, 0);
break;
case 1:
/* Disable timer if CPU is halted */
write_aux_reg(ARC_AUX_TIMER1_CTRL, NH_MODE);
/* Set max value for counter/timer */
write_aux_reg(ARC_AUX_TIMER1_LIMIT, 0xffffffff);
/* Set initial count value and restart counter/timer */
write_aux_reg(ARC_AUX_TIMER1_CNT, 0);
break;
}
return 0;
}
static const struct timer_ops arc_timer_ops = {
.get_count = arc_timer_get_count,
};
static const struct udevice_id arc_timer_ids[] = {
{ .compatible = "snps,arc-timer" },
{}
};
U_BOOT_DRIVER(arc_timer) = {
.name = "arc_timer",
.id = UCLASS_TIMER,
.of_match = arc_timer_ids,
.probe = arc_timer_probe,
.ops = &arc_timer_ops,
.flags = DM_FLAG_PRE_RELOC,
.priv_auto_alloc_size = sizeof(struct arc_timer_priv),
};