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| 1 | +/* |
| 2 | +* Copyright (c) 2011 Renesas Electronics Corporation and/or its affiliates |
| 3 | +* |
| 4 | +* SPDX-License-Identifier: BSD-3-Clause |
| 5 | +*/ |
| 6 | +/*********************************************************************************************************************** |
| 7 | +* File Name : r_bsp_locking.c |
| 8 | +* Description : This implements a locking mechanism that can be used by all code. The locking is done atomically so |
| 9 | +* common resources can be accessed safely. |
| 10 | +***********************************************************************************************************************/ |
| 11 | +/********************************************************************************************************************** |
| 12 | +* History : DD.MM.YYYY Version Description |
| 13 | +* : 28.02.2019 2.00 Merged processing of all devices. |
| 14 | +* Added support for GNUC and ICCRX. |
| 15 | +* Fixed coding style. |
| 16 | +* : 26.07.2019 2.01 Modified comment of API function to Doxygen style. |
| 17 | +* : 10.12.2019 2.02 Modified comment. |
| 18 | +* : 31.05.2024 2.03 Fixed coding style. |
| 19 | +* : 26.02.2025 2.04 Changed the disclaimer. |
| 20 | +***********************************************************************************************************************/ |
| 21 | + |
| 22 | +/*********************************************************************************************************************** |
| 23 | +Includes <System Includes> , "Project Includes" |
| 24 | +***********************************************************************************************************************/ |
| 25 | +/* Platform configuration. */ |
| 26 | +#include "platform.h" |
| 27 | + |
| 28 | +/*********************************************************************************************************************** |
| 29 | +Macro definitions |
| 30 | +***********************************************************************************************************************/ |
| 31 | + |
| 32 | +/*********************************************************************************************************************** |
| 33 | +Typedef definitions |
| 34 | +***********************************************************************************************************************/ |
| 35 | + |
| 36 | +/*********************************************************************************************************************** |
| 37 | +Exported global variables (to be accessed by other files) |
| 38 | +***********************************************************************************************************************/ |
| 39 | + |
| 40 | +/*********************************************************************************************************************** |
| 41 | +Private global variables and functions |
| 42 | +***********************************************************************************************************************/ |
| 43 | + |
| 44 | +/********************************************************************************************************************** |
| 45 | + * Function Name: R_BSP_SoftwareLock |
| 46 | + ******************************************************************************************************************//** |
| 47 | + * @brief Attempts to reserve a lock. |
| 48 | + * @param[out] plock Pointer to lock structure with lock to try and acquire. |
| 49 | + * @retval true Successful, lock was available and acquired. |
| 50 | + * @retval false Failure, lock was already acquired and is not available. |
| 51 | + * @details This function implements an atomic locking mechanism. Locks can be used in numerous ways. Two common uses |
| 52 | + * of locks are to protect critical sections of code and to protect against duplicate resource allocation. |
| 53 | + * For protecting critical sections of code the user would require that the code first obtain the critical section's |
| 54 | + * lock before executing. An example of protecting against duplicate resource allocation would be if the user had two |
| 55 | + * FIT modules that used the same peripheral. For example, the user may have one FIT module that uses the SCI |
| 56 | + * peripheral in UART mode and another FIT module that uses the SCI peripheral in I2C mode. To make sure that both |
| 57 | + * modules cannot use the same SCI channel, locks can be used. |
| 58 | + * Care should be taken when using locks as they do not provide advanced features one might expect from an RTOS |
| 59 | + * semaphore or mutex. If used improperly locks can lead to deadlock in the user's system. |
| 60 | + * Users can override the default locking mechanisms. |
| 61 | + */ |
| 62 | +bool R_BSP_SoftwareLock(BSP_CFG_USER_LOCKING_TYPE * const plock) |
| 63 | +{ |
| 64 | +#if BSP_CFG_USER_LOCKING_ENABLED == 0 |
| 65 | + bool ret = false; |
| 66 | + |
| 67 | + /* Variable used in trying to acquire lock. Using the xchg instruction makes this atomic */ |
| 68 | + int32_t is_locked = true; |
| 69 | + |
| 70 | + /* This example uses the RX MCU's atomic xchg() instruction. plock->lock is the lock we are trying to reserve. |
| 71 | + The way this works is that 'is_locked' gets the value of the plock->lock and plock->lock gets the value of |
| 72 | + 'is_locked' which we just set to 'true'. Basically this is an atomic 'swap' command. If the lock had not yet been |
| 73 | + reserved then its value would be 'false' and after the xchg() instruction finished 'is_locked' would have |
| 74 | + 'false'. If it had already been reserved then 'is_locked' would have 'true' after the xchg() instruction. Since |
| 75 | + plock->lock was already 'true' and we just set it back to 'true' everything is ok. To see if we reserved the lock |
| 76 | + we just need to check the value of 'is_locked' after this instruction finishes. */ |
| 77 | + |
| 78 | + /* Try to acquire semaphore to obtain lock */ |
| 79 | + R_BSP_EXCHANGE(&is_locked, &plock->lock); |
| 80 | + |
| 81 | + /* Check to see if semaphore was successfully taken */ |
| 82 | + if (false == is_locked) |
| 83 | + { |
| 84 | + /* Lock obtained, return success. */ |
| 85 | + ret = true; |
| 86 | + } |
| 87 | + else |
| 88 | + { |
| 89 | + /* Lock was not obtained, another task already has it. */ |
| 90 | + R_BSP_NOP(); |
| 91 | + } |
| 92 | + |
| 93 | + return ret; |
| 94 | +#else |
| 95 | + /* User is going to handle the locking themselves. */ |
| 96 | + return BSP_CFG_USER_LOCKING_SW_LOCK_FUNCTION(plock); |
| 97 | +#endif /* BSP_CFG_USER_LOCKING_ENABLED == 0 */ |
| 98 | +} /* End of function R_BSP_SoftwareLock() */ |
| 99 | + |
| 100 | +/********************************************************************************************************************** |
| 101 | + * Function Name: R_BSP_SoftwareUnlock |
| 102 | + ******************************************************************************************************************//** |
| 103 | + * @brief Releases a lock. |
| 104 | + * @param[out] plock Pointer to lock structure with lock to release. |
| 105 | + * @retval true Successful, lock was released. Or the lock has been already released. |
| 106 | + * @retval false Failure, lock could not be released. |
| 107 | + * @details This function releases a lock that was previously acquired using the R_BSP_SoftwareLock() function. |
| 108 | + */ |
| 109 | +bool R_BSP_SoftwareUnlock(BSP_CFG_USER_LOCKING_TYPE * const plock) |
| 110 | +{ |
| 111 | +#if BSP_CFG_USER_LOCKING_ENABLED == 0 |
| 112 | + /* Set lock back to unlocked. */ |
| 113 | + plock->lock = false; |
| 114 | + |
| 115 | + return true; |
| 116 | +#else |
| 117 | + /* User is going to handle the locking themselves. */ |
| 118 | + return BSP_CFG_USER_LOCKING_SW_UNLOCK_FUNCTION(plock); |
| 119 | +#endif |
| 120 | +} /* End of function R_BSP_SoftwareUnlock() */ |
| 121 | + |
| 122 | + |
| 123 | +/********************************************************************************************************************** |
| 124 | + * Function Name: R_BSP_HardwareLock |
| 125 | + ******************************************************************************************************************//** |
| 126 | + * @brief Attempts to reserve a hardware peripheral lock. |
| 127 | + * @param[in] hw_index Index of lock to acquire from the hardware lock array. |
| 128 | + * @retval true Successful, lock was available and acquired. |
| 129 | + * @retval false Failure, lock was already acquired and is not available. |
| 130 | + * @details This function attempts to acquire the lock for a hardware resource of the MCU. Instead of sending in a |
| 131 | + * pointer to a lock as with the R_BSP_SoftwareLock() function, the user sends in an index to an array that holds 1 |
| 132 | + * lock per MCU hardware resource. This array is shared amongst all FIT modules and user code therefore allowing |
| 133 | + * multiple FIT modules (and user code) to use the same locks. The user can see the available hardware resources by |
| 134 | + * looking at the mcu_lock_t enum in mcu_locks.h. These enum values are also the index into the hardware lock array. |
| 135 | + * The same atomic locking mechanisms from the R_BSP_SoftwareLock() function are used with this function as well. |
| 136 | + * @note Each entry in the mcu_lock_t enum in mcu_locks.h will be allocated a lock. On RX MCUs, each lock is required |
| 137 | + * to be 4-bytes. If RAM space is an issue then the user can remove the entries from the mcu_lock_t enum they are not |
| 138 | + * using. For example, if the user is not using the CRC peripheral then they could delete the BSP_LOCK_CRC entry. The |
| 139 | + * user will save 4-bytes per deleted entry. |
| 140 | + */ |
| 141 | +bool R_BSP_HardwareLock(mcu_lock_t const hw_index) |
| 142 | +{ |
| 143 | +#if BSP_CFG_USER_LOCKING_ENABLED == 0 |
| 144 | + /* Pass actual lock to software lock function. */ |
| 145 | + return R_BSP_SoftwareLock(&g_bsp_Locks[hw_index]); |
| 146 | +#else |
| 147 | + /* User is going to handle the locking themselves. */ |
| 148 | + return BSP_CFG_USER_LOCKING_HW_LOCK_FUNCTION(hw_index); |
| 149 | +#endif |
| 150 | +} /* End of function R_BSP_HardwareLock() */ |
| 151 | + |
| 152 | +/********************************************************************************************************************** |
| 153 | + * Function Name: R_BSP_HardwareUnlock |
| 154 | + ******************************************************************************************************************//** |
| 155 | + * @brief Releases a hardware peripheral lock. |
| 156 | + * @param[in] hw_index Index of lock to release from the hardware lock array. |
| 157 | + * @retval true Successful, lock was released. |
| 158 | + * @retval false Failure, lock could not be released. |
| 159 | + * @details This function attempts to release the lock for a hardware resource of the MCU that was previously acquired |
| 160 | + * using the R_BSP_HardwareLock() function. |
| 161 | + * @note Each entry in the mcu_lock_t enum in mcu_locks.h will be allocated a lock. On RX MCUs, each lock is required |
| 162 | + * to be 4-bytes. If RAM space is an issue then the user can remove the entries from the mcu_lock_t enum that they are |
| 163 | + * not using. For example, if the user is not using the CRC peripheral then they could delete the BSP_LOCK_CRC entry. |
| 164 | + * The user will save 4-bytes per deleted entry. |
| 165 | + */ |
| 166 | +bool R_BSP_HardwareUnlock(mcu_lock_t const hw_index) |
| 167 | +{ |
| 168 | +#if BSP_CFG_USER_LOCKING_ENABLED == 0 |
| 169 | + /* Pass actual lock to software unlock function. */ |
| 170 | + return R_BSP_SoftwareUnlock(&g_bsp_Locks[hw_index]); |
| 171 | +#else |
| 172 | + /* User is going to handle the locking themselves. */ |
| 173 | + return BSP_CFG_USER_LOCKING_HW_UNLOCK_FUNCTION(hw_index); |
| 174 | +#endif |
| 175 | +} /* End of function R_BSP_HardwareUnlock() */ |
| 176 | + |
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