1 /***************************************************************************//**
2  * @file
3  * @brief CMSIS Cortex-M4 System Layer for EFM32 devices.
4  *******************************************************************************
5  * # License
6  * <b>Copyright 2020 Silicon Laboratories Inc. www.silabs.com</b>
7  *******************************************************************************
8  *
9  * SPDX-License-Identifier: Zlib
10  *
11  * The licensor of this software is Silicon Laboratories Inc.
12  *
13  * This software is provided 'as-is', without any express or implied
14  * warranty. In no event will the authors be held liable for any damages
15  * arising from the use of this software.
16  *
17  * Permission is granted to anyone to use this software for any purpose,
18  * including commercial applications, and to alter it and redistribute it
19  * freely, subject to the following restrictions:
20  *
21  * 1. The origin of this software must not be misrepresented; you must not
22  *    claim that you wrote the original software. If you use this software
23  *    in a product, an acknowledgment in the product documentation would be
24  *    appreciated but is not required.
25  * 2. Altered source versions must be plainly marked as such, and must not be
26  *    misrepresented as being the original software.
27  * 3. This notice may not be removed or altered from any source distribution.
28  *
29  ******************************************************************************/
30 
31 #include <stdint.h>
32 #include "em_device.h"
33 
34 /*******************************************************************************
35  ******************************   DEFINES   ************************************
36  ******************************************************************************/
37 
38 /** LFRCO frequency, tuned to below frequency during manufacturing. */
39 #define EFM32_LFRCO_FREQ  (32768UL)
40 /** ULFRCO frequency */
41 #define EFM32_ULFRCO_FREQ (1000UL)
42 
43 /*******************************************************************************
44  **************************   LOCAL VARIABLES   ********************************
45  ******************************************************************************/
46 
47 /* System oscillator frequencies. These frequencies are normally constant */
48 /* for a target, but they are made configurable in order to allow run-time */
49 /* handling of different boards. The crystal oscillator clocks can be set */
50 /* compile time to a non-default value by defining respective EFM32_nFXO_FREQ */
51 /* values according to board design. By defining the EFM32_nFXO_FREQ to 0, */
52 /* one indicates that the oscillator is not present, in order to save some */
53 /* SW footprint. */
54 
55 #ifndef EFM32_HFRCO_MAX_FREQ
56 /** Maximum HFRCO frequency */
57 #define EFM32_HFRCO_MAX_FREQ            (72000000UL)
58 #endif
59 
60 #ifndef EFM32_HFXO_FREQ
61 /** HFXO frequency */
62 #define EFM32_HFXO_FREQ                 (50000000UL)
63 #endif
64 
65 #ifndef EFM32_HFRCO_STARTUP_FREQ
66 /** HFRCO startup frequency */
67 #define EFM32_HFRCO_STARTUP_FREQ        (19000000UL)
68 #endif
69 
70 /* Do not define variable if HF crystal oscillator not present */
71 #if (EFM32_HFXO_FREQ > 0U)
72 /** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */
73 /** System HFXO clock. */
74 static uint32_t SystemHFXOClock = EFM32_HFXO_FREQ;
75 /** @endcond (DO_NOT_INCLUDE_WITH_DOXYGEN) */
76 #endif
77 
78 #ifndef EFM32_LFXO_FREQ
79 /** LFXO frequency */
80 #define EFM32_LFXO_FREQ (EFM32_LFRCO_FREQ)
81 #endif
82 /* Do not define variable if LF crystal oscillator not present */
83 #if (EFM32_LFXO_FREQ > 0U)
84 /** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */
85 /** System LFXO clock. */
86 static uint32_t SystemLFXOClock = EFM32_LFXO_FREQ;
87 /** @endcond (DO_NOT_INCLUDE_WITH_DOXYGEN) */
88 #endif
89 
90 /*******************************************************************************
91  **************************   GLOBAL VARIABLES   *******************************
92  ******************************************************************************/
93 
94 /**
95  * @brief
96  *   System System Clock Frequency (Core Clock).
97  *
98  * @details
99  *   Required CMSIS global variable that must be kept up-to-date.
100  */
101 uint32_t SystemCoreClock = EFM32_HFRCO_STARTUP_FREQ;
102 
103 /**
104  * @brief
105  *   System HFRCO frequency
106  *
107  * @note
108  *   This is an EFM32 proprietary variable, not part of the CMSIS definition.
109  *
110  * @details
111  *   Frequency of the system HFRCO oscillator
112  */
113 uint32_t SystemHfrcoFreq = EFM32_HFRCO_STARTUP_FREQ;
114 
115 /*******************************************************************************
116  **************************   GLOBAL FUNCTIONS   *******************************
117  ******************************************************************************/
118 
119 /***************************************************************************//**
120  * @brief
121  *   Get the current core clock frequency.
122  *
123  * @details
124  *   Calculate and get the current core clock frequency based on the current
125  *   configuration. Assuming that the SystemCoreClock global variable is
126  *   maintained, the core clock frequency is stored in that variable as well.
127  *   This function will however calculate the core clock based on actual HW
128  *   configuration. It will also update the SystemCoreClock global variable.
129  *
130  * @note
131  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
132  *
133  * @return
134  *   The current core clock frequency in Hz.
135  ******************************************************************************/
SystemCoreClockGet(void)136 uint32_t SystemCoreClockGet(void)
137 {
138   uint32_t ret;
139   uint32_t presc;
140 
141   ret   = SystemHFClockGet();
142   presc = (CMU->HFCOREPRESC & _CMU_HFCOREPRESC_PRESC_MASK)
143           >> _CMU_HFCOREPRESC_PRESC_SHIFT;
144   ret  /= presc + 1U;
145 
146   /* Keep CMSIS system clock variable up-to-date */
147   SystemCoreClock = ret;
148 
149   return ret;
150 }
151 
152 /***************************************************************************//**
153  * @brief
154  *   Get the maximum core clock frequency.
155  *
156  * @note
157  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
158  *
159  * @return
160  *   The maximum core clock frequency in Hz.
161  ******************************************************************************/
SystemMaxCoreClockGet(void)162 uint32_t SystemMaxCoreClockGet(void)
163 {
164 #if (EFM32_HFRCO_MAX_FREQ > EFM32_HFXO_FREQ)
165   return EFM32_HFRCO_MAX_FREQ;
166 #else
167   return EFM32_HFXO_FREQ;
168 #endif
169 }
170 
171 /***************************************************************************//**
172  * @brief
173  *   Get the current HFCLK frequency.
174  *
175  * @note
176  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
177  *
178  * @return
179  *   The current HFCLK frequency in Hz.
180  ******************************************************************************/
SystemHFClockGet(void)181 uint32_t SystemHFClockGet(void)
182 {
183   uint32_t ret;
184 
185   switch (CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK) {
186     case CMU_HFCLKSTATUS_SELECTED_LFXO:
187 #if (EFM32_LFXO_FREQ > 0U)
188       ret = SystemLFXOClock;
189 #else
190       /* We should not get here, since core should not be clocked. May */
191       /* be caused by a misconfiguration though. */
192       ret = 0U;
193 #endif
194       break;
195 
196     case CMU_HFCLKSTATUS_SELECTED_LFRCO:
197       ret = EFM32_LFRCO_FREQ;
198       break;
199 
200     case CMU_HFCLKSTATUS_SELECTED_HFXO:
201 #if (EFM32_HFXO_FREQ > 0U)
202       ret = SystemHFXOClock;
203 #else
204       /* We should not get here, since core should not be clocked. May */
205       /* be caused by a misconfiguration though. */
206       ret = 0U;
207 #endif
208       break;
209 
210     case CMU_HFCLKSTATUS_SELECTED_USHFRCO:
211       switch ((CMU->USHFRCOCTRL & _CMU_USHFRCOCTRL_FREQRANGE_MASK)
212               >> _CMU_USHFRCOCTRL_FREQRANGE_SHIFT) {
213         case 7:
214           ret = 16000000U;
215           break;
216         case 11:
217           ret = 32000000U;
218           break;
219         case 13:
220           ret = 48000000U;
221           break;
222         case 14:
223           ret = 50000000U;
224           break;
225         default:
226           ret = 0U;
227           break;
228       }
229       break;
230 
231     case CMU_HFCLKSTATUS_SELECTED_HFRCODIV2:
232       ret = SystemHfrcoFreq / 2;
233       break;
234 
235     default: /* CMU_HFCLKSTATUS_SELECTED_HFRCO */
236       ret = SystemHfrcoFreq;
237       break;
238   }
239 
240   return ret / (1U + ((CMU->HFPRESC & _CMU_HFPRESC_PRESC_MASK)
241                       >> _CMU_HFPRESC_PRESC_SHIFT));
242 }
243 
244 /***************************************************************************//**
245  * @brief
246  *   Get high frequency crystal oscillator clock frequency for target system.
247  *
248  * @note
249  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
250  *
251  * @return
252  *   HFXO frequency in Hz.
253  ******************************************************************************/
SystemHFXOClockGet(void)254 uint32_t SystemHFXOClockGet(void)
255 {
256   /* External crystal oscillator present? */
257 #if (EFM32_HFXO_FREQ > 0U)
258   return SystemHFXOClock;
259 #else
260   return 0U;
261 #endif
262 }
263 
264 /***************************************************************************//**
265  * @brief
266  *   Set high frequency crystal oscillator clock frequency for target system.
267  *
268  * @note
269  *   This function is mainly provided for being able to handle target systems
270  *   with different HF crystal oscillator frequencies run-time. If used, it
271  *   should probably only be used once during system startup.
272  *
273  * @note
274  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
275  *
276  * @param[in] freq
277  *   HFXO frequency in Hz used for target.
278  ******************************************************************************/
SystemHFXOClockSet(uint32_t freq)279 void SystemHFXOClockSet(uint32_t freq)
280 {
281   /* External crystal oscillator present? */
282 #if (EFM32_HFXO_FREQ > 0U)
283   SystemHFXOClock = freq;
284 
285   /* Update core clock frequency if HFXO is used to clock core */
286   if ((CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK)
287       == CMU_HFCLKSTATUS_SELECTED_HFXO) {
288     /* The function will update the global variable */
289     (void)SystemCoreClockGet();
290   }
291 #else
292   (void)freq; /* Unused parameter */
293 #endif
294 }
295 
296 /***************************************************************************//**
297  * @brief
298  *   Initialize the system.
299  *
300  * @details
301  *   Do required generic HW system init.
302  *
303  * @note
304  *   This function is invoked during system init, before the main() routine
305  *   and any data has been initialized. For this reason, it cannot do any
306  *   initialization of variables etc.
307  ******************************************************************************/
SystemInit(void)308 void SystemInit(void)
309 {
310 #if defined(__VTOR_PRESENT) && (__VTOR_PRESENT == 1U)
311   SCB->VTOR = (uint32_t)&__Vectors;
312 #endif
313 
314 #if (__FPU_PRESENT == 1U) && (__FPU_USED == 1U)
315   /* Set floating point coprosessor access mode. */
316   SCB->CPACR |= ((3UL << 10 * 2)                    /* set CP10 Full Access */
317                  | (3UL << 11 * 2));                /* set CP11 Full Access */
318 #endif
319 
320 #if defined(UNALIGNED_SUPPORT_DISABLE)
321   SCB->CCR |= SCB_CCR_UNALIGN_TRP_Msk;
322 #endif
323 }
324 
325 /***************************************************************************//**
326  * @brief
327  *   Get low frequency RC oscillator clock frequency for target system.
328  *
329  * @note
330  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
331  *
332  * @return
333  *   LFRCO frequency in Hz.
334  ******************************************************************************/
SystemLFRCOClockGet(void)335 uint32_t SystemLFRCOClockGet(void)
336 {
337   /* Currently we assume that this frequency is properly tuned during */
338   /* manufacturing and is not changed after reset. If future requirements */
339   /* for re-tuning by user, we can add support for that. */
340   return EFM32_LFRCO_FREQ;
341 }
342 
343 /***************************************************************************//**
344  * @brief
345  *   Get ultra low frequency RC oscillator clock frequency for target system.
346  *
347  * @note
348  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
349  *
350  * @return
351  *   ULFRCO frequency in Hz.
352  ******************************************************************************/
SystemULFRCOClockGet(void)353 uint32_t SystemULFRCOClockGet(void)
354 {
355   /* The ULFRCO frequency is not tuned, and can be very inaccurate */
356   return EFM32_ULFRCO_FREQ;
357 }
358 
359 /***************************************************************************//**
360  * @brief
361  *   Get low frequency crystal oscillator clock frequency for target system.
362  *
363  * @note
364  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
365  *
366  * @return
367  *   LFXO frequency in Hz.
368  ******************************************************************************/
SystemLFXOClockGet(void)369 uint32_t SystemLFXOClockGet(void)
370 {
371   /* External crystal oscillator present? */
372 #if (EFM32_LFXO_FREQ > 0U)
373   return SystemLFXOClock;
374 #else
375   return 0U;
376 #endif
377 }
378 
379 /***************************************************************************//**
380  * @brief
381  *   Set low frequency crystal oscillator clock frequency for target system.
382  *
383  * @note
384  *   This function is mainly provided for being able to handle target systems
385  *   with different HF crystal oscillator frequencies run-time. If used, it
386  *   should probably only be used once during system startup.
387  *
388  * @note
389  *   This is an EFM32 proprietary function, not part of the CMSIS definition.
390  *
391  * @param[in] freq
392  *   LFXO frequency in Hz used for target.
393  ******************************************************************************/
SystemLFXOClockSet(uint32_t freq)394 void SystemLFXOClockSet(uint32_t freq)
395 {
396   /* External crystal oscillator present? */
397 #if (EFM32_LFXO_FREQ > 0U)
398   SystemLFXOClock = freq;
399 
400   /* Update core clock frequency if LFXO is used to clock core */
401   if ((CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK)
402       == CMU_HFCLKSTATUS_SELECTED_LFXO) {
403     /* The function will update the global variable */
404     (void)SystemCoreClockGet();
405   }
406 #else
407   (void)freq; /* Unused parameter */
408 #endif
409 }
410