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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Watchdog timer for PowerPC Book-E systems
*/
#include <div64.h>
#include <dm.h>
#include <wdt.h>
#include <asm/processor.h>
#define WDTP_MASK TCR_WP(0x3f)
/* For the specified period, determine the number of seconds
* corresponding to the reset time. There will be a watchdog
* exception at approximately 3/5 of this time.
*
* The formula to calculate this is given by:
* 2.5 * (2^(63-period+1)) / timebase_freq
*
* In order to simplify things, we assume that period is
* at least 1. This will still result in a very long timeout.
*/
static unsigned long long period_to_sec(unsigned int period)
{
unsigned long long tmp = 1ULL << (64 - period);
unsigned long tmp2 = get_tbclk();
/* tmp may be a very large number and we don't want to overflow,
* so divide the timebase freq instead of multiplying tmp
*/
tmp2 = tmp2 / 5 * 2;
do_div(tmp, tmp2);
return tmp;
}
/*
* This procedure will find the highest period which will give a timeout
* greater than the one required. e.g. for a bus speed of 66666666 and
* and a parameter of 2 secs, then this procedure will return a value of 38.
*/
static unsigned int sec_to_period(unsigned int secs)
{
unsigned int period;
for (period = 63; period > 0; period--) {
if (period_to_sec(period) >= secs)
return period;
}
return 0;
}
static int booke_wdt_reset(struct udevice *dev)
{
mtspr(SPRN_TSR, TSR_ENW | TSR_WIS);
return 0;
}
static int booke_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
{
u32 val;
unsigned int timeout = DIV_ROUND_UP(timeout_ms, 1000);
/* clear status before enabling watchdog */
booke_wdt_reset(dev);
val = mfspr(SPRN_TCR);
val &= ~WDTP_MASK;
val |= (TCR_WIE | TCR_WRC(WRC_CHIP) | TCR_WP(sec_to_period(timeout)));
mtspr(SPRN_TCR, val);
return 0;
}
static int booke_wdt_stop(struct udevice *dev)
{
u32 val;
val = mfspr(SPRN_TCR);
val &= ~(TCR_WIE | WDTP_MASK);
mtspr(SPRN_TCR, val);
/* clear status to make sure nothing is pending */
booke_wdt_reset(dev);
return 0;
}
static const struct wdt_ops booke_wdt_ops = {
.start = booke_wdt_start,
.stop = booke_wdt_stop,
.reset = booke_wdt_reset,
};
static const struct udevice_id booke_wdt_ids[] = {
{ .compatible = "fsl,booke-wdt" },
{}
};
U_BOOT_DRIVER(booke_wdt) = {
.name = "booke_wdt",
.id = UCLASS_WDT,
.of_match = booke_wdt_ids,
.ops = &booke_wdt_ops,
};
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