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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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