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      1 /*
      2  * Copyright (C) 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <plat/inc/pwr.h>
     18 #include <plat/inc/wdt.h>
     19 #include <plat/inc/cmsis.h>
     20 
     21 struct StmWwdg {
     22     volatile uint16_t CR;
     23     uint8_t unused0[2];
     24     volatile uint16_t CFR;
     25     uint8_t unused1[2];
     26     volatile uint16_t SR;
     27     uint8_t unused2[2];
     28 };
     29 
     30 #define WWDG ((struct StmWwdg*)WWDG_BASE)
     31 
     32 /* WWDG bit definitions */
     33 #define WWDG_CR_ENABLE 0x80
     34 
     35 #define WWDG_TCNT_HIGH 0x40
     36 #define WWDG_TCNT_MASK 0x3F
     37 
     38 #define WWDG_CFR_DIV2 0x0080
     39 #define WWDG_CFR_DIV4 0x0100
     40 #define WWDG_CFR_DIV8 0x0180
     41 #define WWDG_CFR_EWI  0x0200
     42 
     43 /* WWDG parameters */
     44 #define WWDG_WINDOW_SIZE 0x3F // 0 < x <= 0x3F
     45 
     46 void WWDG_IRQHandler(void);
     47 void __attribute__((naked)) WWDG_IRQHandler(void)
     48 {
     49     asm volatile(
     50         "mov    r0, #2                    \n"
     51         "b      cpuCommonFaultCode        \n"
     52     );
     53 }
     54 
     55 void wdtEnableClk()
     56 {
     57     pwrUnitClock(PERIPH_BUS_APB1, PERIPH_APB1_WWDG, true);
     58 }
     59 
     60 void wdtEnableIrq()
     61 {
     62     NVIC_EnableIRQ(WWDG_IRQn);
     63 }
     64 
     65 void wdtDisableClk()
     66 {
     67     pwrUnitClock(PERIPH_BUS_APB1, PERIPH_APB1_WWDG, false);
     68 }
     69 
     70 void wdtDisableIrq()
     71 {
     72     NVIC_DisableIRQ(WWDG_IRQn);
     73 }
     74 
     75 void wdtInit()
     76 {
     77     wdtEnableClk();
     78     WWDG->CFR = WWDG_CFR_EWI | WWDG_CFR_DIV8 | WWDG_TCNT_HIGH | (WWDG_WINDOW_SIZE & WWDG_TCNT_MASK);
     79     WWDG->CR  = WWDG_CR_ENABLE | WWDG_TCNT_HIGH | (WWDG_WINDOW_SIZE & WWDG_TCNT_MASK);
     80     // with 16Mhz APB1 clock, this is 256*DIV = 2,048 uS per WWDG tick with DIV=8, max 131,072 uS WWDG window
     81     wdtEnableIrq();
     82 }
     83 
     84 void wdtPing()
     85 {
     86     WWDG->CR = (WWDG->CR & ~WWDG_TCNT_MASK) | WWDG_TCNT_HIGH | (WWDG_WINDOW_SIZE & WWDG_TCNT_MASK);
     87 }
     88