Remove ownership in QSPI driver

drivers/include/drivers/QSPI.h

@@ -223,8 +223,6 @@ protected:
 
     qspi_t _qspi;
 
-    bool acquire(void);
-    static QSPI *_owner;
     static SingletonPtr<PlatformMutex> _mutex;
     qspi_bus_width_t _inst_width; //Bus width for Instruction phase
     qspi_bus_width_t _address_width; //Bus width for Address phase
@@ -242,10 +240,6 @@ protected:
     bool (QSPI::* _init_func)(void);
 
 private:
-    /* Private acquire function without locking/unlocking
-     * Implemented in order to avoid duplicate locking and boost performance
-     */
-    bool _acquire(void);
     bool _initialize();
     bool _initialize_direct();
 

drivers/source/QSPI.cpp

@@ -23,7 +23,6 @@
 
 namespace mbed {
 
-QSPI *QSPI::_owner = NULL;
 SingletonPtr<PlatformMutex> QSPI::_mutex;
 
 uint8_t convert_bus_width_to_line_count(qspi_bus_width_t width)
@@ -124,15 +123,9 @@ qspi_status_t QSPI::set_frequency(int hz)
     if (_initialized) {
         lock();
         _hz = hz;
-        //If the same owner, just change freq.
-        //Otherwise we may have to change mode as well, so call _acquire
-        if (_owner == this) {
         if (QSPI_STATUS_OK != qspi_frequency(&_qspi, _hz)) {
             ret_status = QSPI_STATUS_ERROR;
         }
-        } else {
-            _acquire();
-        }
         unlock();
     } else {
         ret_status = QSPI_STATUS_ERROR;
@@ -149,12 +142,10 @@ qspi_status_t QSPI::read(int address, char *rx_buffer, size_t *rx_length)
         if ((rx_length != NULL) && (rx_buffer != NULL)) {
             if (*rx_length != 0) {
                 lock();
-                if (true == _acquire()) {
                 _build_qspi_command(QSPI_NO_INST, address, -1);
                 if (QSPI_STATUS_OK == qspi_read(&_qspi, &_qspi_command, rx_buffer, rx_length)) {
                     ret_status = QSPI_STATUS_OK;
                 }
-                }
                 unlock();
             }
         } else {
@@ -173,12 +164,10 @@ qspi_status_t QSPI::write(int address, const char *tx_buffer, size_t *tx_length)
         if ((tx_length != NULL) && (tx_buffer != NULL)) {
             if (*tx_length != 0) {
                 lock();
-                if (true == _acquire()) {
                 _build_qspi_command(QSPI_NO_INST, address, -1);
                 if (QSPI_STATUS_OK == qspi_write(&_qspi, &_qspi_command, tx_buffer, tx_length)) {
                     ret_status = QSPI_STATUS_OK;
                 }
-                }
                 unlock();
             }
         } else {
@@ -197,12 +186,10 @@ qspi_status_t QSPI::read(qspi_inst_t instruction, int alt, int address, char *rx
         if ((rx_length != NULL) && (rx_buffer != NULL)) {
             if (*rx_length != 0) {
                 lock();
-                if (true == _acquire()) {
                 _build_qspi_command(instruction, address, alt);
                 if (QSPI_STATUS_OK == qspi_read(&_qspi, &_qspi_command, rx_buffer, rx_length)) {
                     ret_status = QSPI_STATUS_OK;
                 }
-                }
                 unlock();
             }
         } else {
@@ -221,12 +208,10 @@ qspi_status_t QSPI::write(qspi_inst_t instruction, int alt, int address, const c
         if ((tx_length != NULL) && (tx_buffer != NULL)) {
             if (*tx_length != 0) {
                 lock();
-                if (true == _acquire()) {
                 _build_qspi_command(instruction, address, alt);
                 if (QSPI_STATUS_OK == qspi_write(&_qspi, &_qspi_command, tx_buffer, tx_length)) {
                     ret_status = QSPI_STATUS_OK;
                 }
-                }
                 unlock();
             }
         } else {
@@ -243,12 +228,10 @@ qspi_status_t QSPI::command_transfer(qspi_inst_t instruction, int address, const
 
     if (_initialized) {
         lock();
-        if (true == _acquire()) {
         _build_qspi_command(instruction, address, -1); //We just need the command
         if (QSPI_STATUS_OK == qspi_command_transfer(&_qspi, &_qspi_command, (const void *)tx_buffer, tx_length, (void *)rx_buffer, rx_length)) {
             ret_status = QSPI_STATUS_OK;
         }
-        }
         unlock();
     }
 
@@ -276,7 +259,6 @@ bool QSPI::_initialize()
     qspi_status_t ret = qspi_init(&_qspi, _qspi_io0, _qspi_io1, _qspi_io2, _qspi_io3, _qspi_clk, _qspi_cs, _hz, _mode);
     if (QSPI_STATUS_OK == ret) {
         _initialized = true;
-        _owner = this;
     } else {
         _initialized = false;
     }
@@ -295,7 +277,6 @@ bool QSPI::_initialize_direct()
     qspi_status_t ret = qspi_init_direct(&_qspi, _static_pinmap, _hz, _mode);
     if (QSPI_STATUS_OK == ret) {
         _initialized = true;
-        _owner = this;
     } else {
         _initialized = false;
     }
@@ -303,18 +284,6 @@ bool QSPI::_initialize_direct()
     return _initialized;
 }
 
-// Note: Private function with no locking
-bool QSPI::_acquire()
-{
-    if (_owner != this) {
-        //This will set freq as well
-        (this->*_init_func)();
-        _owner = this;
-    }
-
-    return _initialized;
-}
-
 void QSPI::_build_qspi_command(qspi_inst_t instruction, int address, int alt)
 {
     memset(&_qspi_command, 0,  sizeof(qspi_command_t));