ABB semaphore protection overhaul The ABB semaphone protection logic that came with TCS211 from TI was broken in several ways: * Some semaphore-protected functions were called from Application_Initialize() context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with NU_INVALID_SUSPEND in this context, but the return value wasn't checked, and NU_Release_Semaphore() would be called unconditionally at the end. The latter call would increment the semaphore count past 1, making the semaphore no longer binary and thus no longer effective for resource protection. The fix is to check the return value from NU_Obtain_Semaphore() and skip the NU_Release_Semaphore() call if the semaphore wasn't properly obtained. * Some SPI hardware manipulation was being done before entering the semaphore- protected critical section. The fix is to reorder the code: first obtain the semaphore, then do everything else. * In the corner case of L1/DSP recovery, l1_abb_power_on() would call some non-semaphore-protected ABB & SPI init functions. The fix is to skip those calls in the case of recovery. * A few additional corner cases existed, all of which are fixed by making ABB semaphore protection 100% consistent for all ABB functions and code paths. There is still one remaining problem of priority inversion: suppose a low- priority task calls an ABB function, and some medium-priority task just happens to preempt right in the middle of that semaphore-protected ABB operation. Then the high-priority SPI task is locked out for a non-deterministic time until that medium-priority task finishes its work and goes back to sleep. This priority inversion problem remains outstanding for now.

/************* Revision Controle System Header *************
 *                  GSM Layer 1 software 
 * L1_VAREX.H
 *
 *        Filename l1_varex.h
 *  Copyright 2003 (C) Texas Instruments  
 *
 ************* Revision Controle System Header *************/

#ifdef L1_ASYNC_C

#if (LONG_JUMP == 3)
  #ifdef __GNUC__
    #define SECTION_ATTR __attribute__ ((section (".l1s_global")))
  #else
    #define SECTION_ATTR
    #pragma DATA_SECTION(l1s,".l1s_global")
    #pragma DATA_SECTION(l1s_dsp_com,".l1s_global")
    #pragma DATA_SECTION(l1a_l1s_com,".l1s_global")
    #pragma DATA_SECTION(l1s_tpu_com,".l1s_global")
    #pragma DATA_SECTION(l1_config,".l1s_global")
  #endif
#else
  #define SECTION_ATTR
#endif

 T_L1S_GLOBAL   l1s SECTION_ATTR;
 T_L1A_GLOBAL   l1a;

 T_L1A_L1S_COM  l1a_l1s_com SECTION_ATTR;
 T_L1S_DSP_COM  l1s_dsp_com SECTION_ATTR;
 T_L1S_TPU_COM  l1s_tpu_com SECTION_ATTR;

#if (L1_DYN_DSP_DWNLD == 1)    // equivalent to an API_HISR flag
 T_L1_API_HISR       l1_apihisr;
 T_L1A_API_HISR_COM l1a_apihisr_com;
#endif

 // variables for L1 configuration
 T_L1_CONFIG    l1_config SECTION_ATTR;

 #undef SECTION_ATTR

#else  // L1_ASYNC_C

 extern T_L1S_GLOBAL   l1s;
 extern T_L1A_GLOBAL   l1a;

 extern T_L1A_L1S_COM  l1a_l1s_com;
 extern T_L1S_DSP_COM  l1s_dsp_com;
 extern T_L1S_TPU_COM  l1s_tpu_com;

 #if (L1_DYN_DSP_DWNLD == 1)    // equivalent to an API_HISR flag
 extern T_L1_API_HISR      l1_apihisr;
 extern T_L1A_API_HISR_COM l1a_apihisr_com;
#endif

 // variables for L1 configuration
 extern T_L1_CONFIG    l1_config;
#endif


extern const UWORD8 ramBootCode[]; // dummy DSP code for boot.