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android13/device/google/contexthub/firmware/os/platform/stm32/rtc.c

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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <cpu/barrier.h>
#include <cpu/cpuMath.h>
#include <plat/rtc.h>
#include <plat/pwr.h>
#include <timer.h>
#include <platform.h>
#include <plat/exti.h>
#include <plat/cmsis.h>
#include <variant/variant.h>
#ifndef NS_PER_S
#define NS_PER_S UINT64_C(1000000000)
#endif
struct StmRtc
{
volatile uint32_t TR; /* 0x00 */
volatile uint32_t DR; /* 0x04 */
volatile uint32_t CR; /* 0x08 */
volatile uint32_t ISR; /* 0x0C */
volatile uint32_t PRER; /* 0x10 */
volatile uint32_t WUTR; /* 0x14 */
volatile uint32_t CALIBR; /* 0x18 */
volatile uint32_t ALRMAR; /* 0x1C */
volatile uint32_t ALRMBR; /* 0x20 */
volatile uint32_t WPR; /* 0x24 */
volatile uint32_t SSR; /* 0x28 */
volatile uint32_t SHIFTR; /* 0x2C */
volatile uint32_t TSTR; /* 0x30 */
volatile uint32_t TSDR; /* 0x34 */
volatile uint32_t TSSSR; /* 0x38 */
volatile uint32_t CALR; /* 0x3C */
volatile uint32_t TAFCR; /* 0x40 */
volatile uint32_t ALRMASSR; /* 0x44 */
volatile uint32_t ALRMBSSR; /* 0x48 */
uint8_t unused0[4]; /* 0x4C */
volatile uint32_t BKPR[20]; /* 0x50 - 0x9C */
};
#define RTC ((struct StmRtc*)RTC_BASE)
/* RTC bit defintions */
#define RTC_CR_WUCKSEL_MASK 0x00000007UL
#define RTC_CR_WUCKSEL_16DIV 0x00000000UL
#define RTC_CR_WUCKSEL_8DIV 0x00000001UL
#define RTC_CR_WUCKSEL_4DIV 0x00000002UL
#define RTC_CR_WUCKSEL_2DIV 0x00000003UL
#define RTC_CR_WUCKSEL_CK_SPRE 0x00000004UL
#define RTC_CR_WUCKSEL_CK_SPRE_2 0x00000006UL
#define RTC_CR_BYPSHAD 0x00000020UL
#define RTC_CR_FMT 0x00000040UL
#define RTC_CR_ALRAE 0x00000100UL
#define RTC_CR_WUTE 0x00000400UL
#define RTC_CR_ALRAIE 0x00001000UL
#define RTC_CR_WUTIE 0x00004000UL
#define RTC_ISR_ALRAWF 0x00000001UL
#define RTC_ISR_WUTWF 0x00000004UL
#define RTC_ISR_RSF 0x00000020UL
#define RTC_ISR_INITF 0x00000040UL
#define RTC_ISR_INIT 0x00000080UL
#define RTC_ISR_WUTF 0x00000400UL
/* RTC internal values */
#define RTC_FREQ_HZ 32768UL
#define RTC_WKUP_DOWNCOUNT_MAX 0x10000UL
/* TODO: Reset to crystal PPM once known */
#define RTC_PPM 50UL
/* Default prescalars of P[async] = 127 and P[sync] = 255 are appropriate
* produce a 1 Hz clock when using a 32.768kHZ clock source */
#ifndef RTC_PREDIV_A
#define RTC_PREDIV_A 31UL
#endif
#ifndef RTC_PREDIV_S
#define RTC_PREDIV_S 1023UL
#endif
#ifndef RTC_CALM
#define RTC_CALM 0
#endif
#ifndef RTC_CALP
#define RTC_CALP 0
#endif
/* Jitter = max wakeup timer resolution (61.035 us)
* + 2 RTC cycles for synchronization (61.035 us) */
#define RTC_DIV2_PERIOD_NS UINT64_C(61035)
#define RTC_DIV4_PERIOD_NS UINT64_C(122070)
#define RTC_DIV8_PERIOD_NS UINT64_C(244141)
#define RTC_DIV16_PERIOD_NS UINT64_C(488281)
#define RTC_VALID_DELAY_FOR_PERIOD(delay, period) \
(delay < (period * (RTC_WKUP_DOWNCOUNT_MAX + 1)))
static void rtcSetDefaultDateTimeAndPrescalar(void)
{
/* Enable writability of RTC registers */
RTC->WPR = 0xCA;
RTC->WPR = 0x53;
/* Enter RTC init mode */
RTC->ISR |= RTC_ISR_INIT;
mem_reorder_barrier();
/* Wait for initialization mode to be entered. */
while ((RTC->ISR & RTC_ISR_INITF) == 0);
/* Set prescalar rtc register. Two writes required. */
RTC->PRER = RTC_PREDIV_S;
RTC->PRER |= (RTC_PREDIV_A << 16);
RTC->CALR = (RTC_CALP << 15) | (RTC_CALM & 0x1FF);
/* 24 hour format */
RTC->CR &= ~RTC_CR_FMT;
/* disable shadow registers */
RTC->CR |= RTC_CR_BYPSHAD;
/* Set time and date registers to defaults */
/* Midnight */
RTC->TR = 0x0;
RTC->SSR = 0x0;
/* Sat Jan 1st, 2000 BCD */
RTC->DR = 0b1100000100000001;
/* Exit init mode for RTC */
RTC->ISR &= ~RTC_ISR_INIT;
/* Re-enable register write protection. RTC counting doesn't start for
* 4 RTC cycles after set - must poll RSF before read DR or TR */
RTC->WPR = 0xFF;
extiEnableIntLine(EXTI_LINE_RTC_WKUP, EXTI_TRIGGER_RISING);
NVIC_EnableIRQ(RTC_WKUP_IRQn);
}
void rtcInit(void)
{
pwrEnableAndClockRtc(RTC_CLK);
rtcSetDefaultDateTimeAndPrescalar();
}
/* Set calendar alarm to go off after delay has expired. uint64_t delay must
* be in valid uint64_t format */
int rtcSetWakeupTimer(uint64_t delay)
{
uint64_t intState;
uint64_t periodNsRecip;
uint32_t wakeupClock;
uint32_t periodNs;
/* Minimum wakeup interrupt period is 122 us, max is 36.4 hours */
if (delay < (RTC_DIV2_PERIOD_NS * 2)) {
return RTC_ERR_TOO_SMALL;
} else if (delay > (NS_PER_S * 2 * RTC_WKUP_DOWNCOUNT_MAX)) {
delay = NS_PER_S * 2 * RTC_WKUP_DOWNCOUNT_MAX;
}
/* Get appropriate clock period for delay size. Wakeup clock = RTC/x. */
if (RTC_VALID_DELAY_FOR_PERIOD(delay, RTC_DIV2_PERIOD_NS)) {
wakeupClock = RTC_CR_WUCKSEL_2DIV;
periodNs = RTC_DIV2_PERIOD_NS;
periodNsRecip = U64_RECIPROCAL_CALCULATE(RTC_DIV2_PERIOD_NS);
}
else if (RTC_VALID_DELAY_FOR_PERIOD(delay, RTC_DIV4_PERIOD_NS)) {
wakeupClock = RTC_CR_WUCKSEL_4DIV;
periodNs = RTC_DIV4_PERIOD_NS;
periodNsRecip = U64_RECIPROCAL_CALCULATE(RTC_DIV4_PERIOD_NS);
}
else if (RTC_VALID_DELAY_FOR_PERIOD(delay, RTC_DIV8_PERIOD_NS)) {
wakeupClock = RTC_CR_WUCKSEL_8DIV;
periodNs = RTC_DIV8_PERIOD_NS;
periodNsRecip = U64_RECIPROCAL_CALCULATE(RTC_DIV8_PERIOD_NS);
}
else if (RTC_VALID_DELAY_FOR_PERIOD(delay, RTC_DIV16_PERIOD_NS)) {
wakeupClock = RTC_CR_WUCKSEL_16DIV;
periodNs = RTC_DIV16_PERIOD_NS;
periodNsRecip = U64_RECIPROCAL_CALCULATE(RTC_DIV16_PERIOD_NS);
}
else {
if (RTC_VALID_DELAY_FOR_PERIOD(delay, NS_PER_S))
wakeupClock = RTC_CR_WUCKSEL_CK_SPRE;
else
wakeupClock = RTC_CR_WUCKSEL_CK_SPRE_2;
periodNs = NS_PER_S;
periodNsRecip = U64_RECIPROCAL_CALCULATE(NS_PER_S);
}
intState = cpuIntsOff();
/* Enable RTC register write */
RTC->WPR = 0xCA;
RTC->WPR = 0x53;
/* Disable wakeup timer */
RTC->CR &= ~RTC_CR_WUTE;
/* Wait for access enabled for wakeup timer registers */
while ((RTC->ISR & RTC_ISR_WUTWF) == 0);
/* Clear wakeup clock source */
RTC->CR &= ~RTC_CR_WUCKSEL_MASK;
RTC->CR |= wakeupClock;
/* Downcounter value for wakeup clock. Wakeup flag is set every
* RTC->WUTR[15:0] + 1 cycles of the WUT clock. */
RTC->WUTR = cpuMathRecipAssistedUdiv64by32(delay, periodNs, periodNsRecip) - 1;
/* Enable wakeup interrupts */
RTC->CR |= RTC_CR_WUTIE;
extiClearPendingLine(EXTI_LINE_RTC_WKUP);
/* Enable wakeup timer */
RTC->CR |= RTC_CR_WUTE;
/* Clear overflow flag */
RTC->ISR &= ~RTC_ISR_WUTF;
/* Write-protect RTC registers */
RTC->WPR = 0xFF;
cpuIntsRestore(intState);
return 0;
}
uint64_t rtcGetTime(void)
{
int32_t time_s;
uint32_t dr, tr, ssr;
// cumulative adjustments from 32 day months (year 2000)
// 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
// 1, 3, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1
// 0 1, 4, 5, 7, 8, 10, 11, 12, 14, 15, 17
static const uint8_t adjust[] = { 0, 1, 4, 5, 7, 8, 10, 11, 12, 14, 15, 17 };
uint8_t month;
// need to loop incase an interrupt occurs in the middle or ssr
// decrements (which can propagate changes to tr and dr)
do {
ssr = RTC->SSR;
tr = RTC->TR;
dr = RTC->DR;
} while (ssr != RTC->SSR);
month = (((dr >> 12) & 0x1) * 10) + ((dr >> 8) & 0xf) - 1;
time_s = (((((dr >> 4) & 0x3) * 10) + (dr & 0xF) - 1) + (month << 5) - adjust[month]) * 86400ULL;
time_s += ((((tr >> 22) & 0x1) * 43200ULL) +
(((tr >> 20) & 0x3) * 36000ULL) +
(((tr >> 16) & 0xF) * 3600ULL) +
(((tr >> 12) & 0x7) * 600ULL) +
(((tr >> 8) & 0xF) * 60ULL) +
(((tr >> 4) & 0x7) * 10ULL) +
(((tr) & 0xF)));
return (time_s * NS_PER_S) + U64_DIV_BY_CONST_U16(((RTC_PREDIV_S - ssr) * NS_PER_S), (RTC_PREDIV_S + 1));
}
void EXTI22_RTC_WKUP_IRQHandler(void);
void EXTI22_RTC_WKUP_IRQHandler(void)
{
extiClearPendingLine(EXTI_LINE_RTC_WKUP);
timIntHandler();
}
uint32_t* rtcGetBackupStorage(void)
{
return (uint32_t*)RTC->BKPR;
}
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