Doc: Added info about backward incompatibilities in CMSIS-Core

Author: vovamarch

CMSIS/Documentation/Doxygen/Core/src/history.md

@@ -14,7 +14,8 @@ The table below provides information about the changes delivered with specific v
       <td>
         <ul>
           <li>Core(M) and Core(A) joined into single Core component</li>
-          <li>Core header files reworked, aligned with TRMs</li>
+          <li>Core header files reworked, aligned with Cortex-M Technical Reference Manuals (TRMs).
+              <br/>See \ref core6_changes "Breaking changes in CMSIS-Core v6 header files" for details, and [GitHub issue #122](https://github.com/ARM-software/CMSIS_6/issues/122).</li>
           <li>Previously deprecated features removed</li>
           <li>Dropped support for Arm Compiler 5</li>
         </ul>
@@ -366,3 +367,105 @@ The table below provides information about the changes delivered with specific v
      </td>
     </tr>
 </table>
+
+
+\anchor core6_changes
+<h1>Breaking changes in CMSIS-Core v6 header files</h1>
+
+\ref cmsis_standard_files in CMSIS-Core v6.0.0 have received a number of changes that are incompatible with CMSIS-Core v5.6.0.
+
+In summary, following types of incompatible changes are present:
+ - struct member is renamed in an existing structure (e.g. NVIC->PR -> NVIC->IPR)
+ - struct name is changed (e.g. CoreDebug_Type -> DCB_Type)
+ - define name is changed (e.g. CoreDebug_DEMCR_TRCENA_Msk -> DCB_DEMCR_TRCENA_Msk)
+
+[GitHub issue #122](https://github.com/ARM-software/CMSIS_6/issues/122) discusses how to resolve such incompatibilities.
+
+Below is detailed information about the changes relevant for each Cortex-M core.
+
+**Cortex-M0, Cortex-M0+, Cortex-M1:**
+ - struct NVIC_Type
+   - member IP renamed to IPR
+ - struct SCB_Type
+   - member SHP renamed to SHPR
+
+
+**Cortex-M3, Cortex-M4:**
+ - struct NVIC_Type
+   - member IP renamed to IPR
+ - struct SCB_Type
+   - member SHP renamed to SHPR
+   - member PFR renamed to ID_PFR
+   - member PFR renamed to ID_PFR
+   - member DFR renamed to ID_PFR
+   - member ADR renamed to ID_AFR
+   - member MMFR renamed to ID_MMFR
+   - member ISAR renamed to ID_ISAR
+   - member STIR added
+ - struct ITM_Type:
+   - members PIDx and CIDx removed
+ - define names for ITM_TCR_* changed
+ - define names for ITM_LSR_* changed
+ - struct TPI_Type renamed to TPIU_Type
+ - define names for TPI_* renamed to TPIU_*
+ - define names for FPU_MVFR0/1_* changed (Cortex-M4)
+ - struct CoreDebug_Type renamed to DCB_Type
+ - defines for CoreDebug_* renamed to DCB_*
+
+
+**Cortex-M7:**
+ - struct NVIC_Type
+   - member IP renamed to IPR
+ - struct SCB_Type
+   - member ID_MFR renamed to ID_MMFR
+ - struct ITM_Type:
+   - members PIDx and CIDx removed
+ - define names for ITM_TCR_* changed
+ - define names for ITM_LSR_* changed
+ - struct TPI_Type renamed to TPIU_Type
+ - define names for TPI_* renamed to TPIU_*
+ - define names for FPU_MVFR0/1_* changed
+ - struct CoreDebug_Type renamed to DCB_Type
+ - defines for CoreDebug_* renamed to DCB_*
+
+
+**Cortex-M23:**
+ - struct DWT_Type
+   - member RESERVED0[6] replaced by CYCCNT, CPICNT, EXCCNT, SLEEPCNT, LSUCNT, FOLDCNT
+   - other RESERVED members mainly removed
+ - struct TPI_Type renamed to TPIU_Type
+ - define names for TPI_* renamed to TPIU_*
+ - struct CoreDebug_Type removed (struct DCB_Type already existed)
+ - defines CoreDebug_ removed (defines DCB_ already existed)
+
+
+**Cortex-M33:**
+ - struct ITM_Type:
+   - members LAR, LSR removed
+   - members PIDx and CIDx removed
+ - struct TPI_Type renamed to TPIU_Type
+ - define names for TPI_* renamed to TPIU_*
+ - define names for FPU_MVFR0/1_* changed
+ - struct CoreDebug_Type removed (struct DCB_Type already existed)
+ - defines CoreDebug_ removed (defines DCB_ already existed)
+
+
+**Cortex-M55, Cortex-M85:**
+ - struct ITM_Type:
+   - members LAR, LSR removed
+   - members PIDx and CIDx removed
+ - struct DWT_Type:
+   - members PIDx and CIDx removed
+ - struct EWIC_Type
+   - all members renamed
+ - define names EWIC_* changed
+ - struct TPI_Type renamed to TPIU_Type
+   - members LAR, LSR replaced
+ - define names for TPI_* renamed to TPIU_*
+ - struct PMU_Type
+   - members PIDx and CIDx removed
+ - struct CoreDebug_Type removed (struct DCB_Type already existed)
+ - defines CoreDebug_ removed (defines DCB_ already existed)
+ - struct DIB_Type
+   - members DLAR, DLSR removed (replaced by RESERVED0[2])
+ - defines for DIB_DLAR_* and DIB_DLSR_* removed