1 /**
2 ******************************************************************************
3 * @file system_stm32u5xx_ns.c
4 * @author MCD Application Team
5 * @brief CMSIS Cortex-M33 Device Peripheral Access Layer System Source File
6 * to be used in non-secure application when the system implements
7 * the TrustZone-M security.
8 *
9 * This file provides two functions and one global variable to be called from
10 * user application:
11 * - SystemInit(): This function is called at non-secure startup before
12 * branch to non-secure main program.
13 * This call is made inside the "startup_stm32u5xx.s" file.
14 *
15 * - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
16 * by the user application to setup the SysTick
17 * timer or configure other parameters.
18 *
19 * - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
20 * be called whenever the core clock is changed
21 * during program execution.
22 *
23 * After each device reset the MSI (4 MHz) is used as system clock source.
24 * Then SystemInit() function is called, in "startup_stm32u5xx.s" file, to
25 * configure the system clock before to branch to main secure program.
26 * Later, when non-secure SystemInit() function is called, in "startup_stm32u5xx.s"
27 * file, the system clock may have been updated from reset value by the main
28 * secure program.
29 *
30 ******************************************************************************
31 * @attention
32 *
33 * Copyright (c) 2021 STMicroelectronics.
34 * All rights reserved.
35 *
36 * This software is licensed under terms that can be found in the LICENSE file
37 * in the root directory of this software component.
38 * If no LICENSE file comes with this software, it is provided AS-IS.
39 *
40 ******************************************************************************
41 */
42
43 /** @addtogroup CMSIS
44 * @{
45 */
46
47 /** @addtogroup STM32U5xx_system
48 * @{
49 */
50
51 /** @addtogroup STM32U5xx_System_Private_Includes
52 * @{
53 */
54
55 #include "stm32u5xx.h"
56
57
58 /**
59 * @}
60 */
61
62 /** @addtogroup STM32U5xx_System_Private_TypesDefinitions
63 * @{
64 */
65
66 /**
67 * @}
68 */
69
70 /** @addtogroup STM32U5xx_System_Private_Defines
71 * @{
72 */
73
74 #if !defined (HSE_VALUE)
75 #define HSE_VALUE 16000000U /*!< Value of the External oscillator in Hz */
76 #endif /* HSE_VALUE */
77
78 #if !defined (MSI_VALUE)
79 #define MSI_VALUE 4000000U /*!< Value of the Internal oscillator in Hz*/
80 #endif /* MSI_VALUE */
81
82 #if !defined (HSI_VALUE)
83 #define HSI_VALUE 16000000U /*!< Value of the Internal oscillator in Hz*/
84 #endif /* HSI_VALUE */
85
86 /**
87 * @}
88 */
89
90 /** @addtogroup STM32U5xx_System_Private_Macros
91 * @{
92 */
93
94 /**
95 * @}
96 */
97
98 /** @addtogroup STM32U5xx_System_Private_Variables
99 * @{
100 */
101 /* The SystemCoreClock variable is updated in three ways:
102 1) by calling CMSIS function SystemCoreClockUpdate()
103 2) by calling HAL API function HAL_RCC_GetHCLKFreq()
104 3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency
105 Note: If you use this function to configure the system clock; then there
106 is no need to call the 2 first functions listed above, since SystemCoreClock
107 variable is updated automatically.
108 */
109 uint32_t SystemCoreClock = 4000000U;
110
111 const uint8_t AHBPrescTable[16] = {0U, 0U, 0U, 0U, 0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U, 6U, 7U, 8U, 9U};
112 const uint8_t APBPrescTable[8] = {0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U};
113 const uint32_t MSIRangeTable[16] = {48000000U,24000000U,16000000U,12000000U, 4000000U, 2000000U, 1330000U,\
114 1000000U, 3072000U, 1536000U,1024000U, 768000U, 400000U, 200000U, 133000U, 100000U};
115 /**
116 * @}
117 */
118
119 /** @addtogroup STM32U5xx_System_Private_FunctionPrototypes
120 * @{
121 */
122
123 /**
124 * @}
125 */
126
127 /** @addtogroup STM32U5xx_System_Private_Functions
128 * @{
129 */
130
131 /**
132 * @brief Setup the microcontroller system.
133 * @retval None
134 */
135
SystemInit(void)136 void SystemInit(void)
137 {
138 /* Nothing done in non-secure */
139
140 /* Non-secure main application shall call SystemCoreClockUpdate() to update */
141 /* the SystemCoreClock variable to insure non-secure application relies on */
142 /* the initial clock reference set by secure application. */
143 }
144
145 /**
146 * @brief Update SystemCoreClock variable according to Clock Register Values.
147 * The SystemCoreClock variable contains the core clock (HCLK), it can
148 * be used by the user application to setup the SysTick timer or configure
149 * other parameters.
150 *
151 * @note From the non-secure application, the SystemCoreClock value is
152 * retrieved from the secure domain via a Non-Secure Callable function
153 * since the RCC peripheral may be protected with security attributes
154 * that prevent to compute the SystemCoreClock variable from the RCC
155 * peripheral registers.
156 *
157 * @note Each time the core clock (HCLK) changes, this function must be called
158 * to update SystemCoreClock variable value. Otherwise, any configuration
159 * based on this variable will be incorrect.
160 *
161 * @note - The system frequency computed by this function is not the real
162 * frequency in the chip. It is calculated based on the predefined
163 * constant and the selected clock source:
164 *
165 * - If SYSCLK source is MSI, SystemCoreClock will contain the MSI_VALUE(*)
166 *
167 * - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(**)
168 *
169 * - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(***)
170 *
171 * - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(***)
172 * or HSI_VALUE(*) or MSI_VALUE(*) multiplied/divided by the PLL factors.
173 *
174 * (*) MSI_VALUE is a constant defined in stm32u5xx_hal.h file (default value
175 * 4 MHz) but the real value may vary depending on the variations
176 * in voltage and temperature.
177 *
178 * (**) HSI_VALUE is a constant defined in stm32u5xx_hal.h file (default value
179 * 16 MHz) but the real value may vary depending on the variations
180 * in voltage and temperature.
181 *
182 * (***) HSE_VALUE is a constant defined in stm32u5xx_hal.h file (default value
183 * 8 MHz), user has to ensure that HSE_VALUE is same as the real
184 * frequency of the crystal used. Otherwise, this function may
185 * have wrong result.
186 *
187 * - The result of this function could be not correct when using fractional
188 * value for HSE crystal.
189 *
190 * @retval None
191 */
SystemCoreClockUpdate(void)192 void SystemCoreClockUpdate(void)
193 {
194 /* Get the SystemCoreClock value from the secure domain */
195 SystemCoreClock = SECURE_SystemCoreClockUpdate();
196 }
197
198
199 /**
200 * @}
201 */
202
203 /**
204 * @}
205 */
206
207 /**
208 * @}
209 */
210
211
