QSPI driver: fixes after PR 7783 review

- make QSPI::lock and QSPI::unlock protected
- fix QSPI::_initialize return value
- add assert on QSPI::_initialize failure
- minor comments fixes

Author: maciejbocianski

drivers/QSPI.cpp

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2013 ARM Limited
+ * Copyright (c) 2006-2018 ARM Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,7 +45,8 @@ QSPI::QSPI(PinName io0, PinName io1, PinName io2, PinName io3, PinName sclk, Pin
     _initialized = false;
 
     //Go ahead init the device here with the default config
-    _initialize();
+    bool success = _initialize();
+    MBED_ASSERT(success);
 }
 
 qspi_status_t QSPI::configure_format(qspi_bus_width_t inst_width, qspi_bus_width_t address_width, qspi_address_size_t address_size, qspi_bus_width_t alt_width, qspi_alt_size_t alt_size, qspi_bus_width_t data_width, int dummy_cycles)
@@ -217,8 +218,10 @@ void QSPI::unlock()
 // Note: Private helper function to initialize qspi HAL
 bool QSPI::_initialize() 
 {
-    if (_mode != 0 && _mode != 1)
-        return QSPI_STATUS_INVALID_PARAMETER;
+    if (_mode != 0 && _mode != 1) {
+        _initialized = false;
+        return _initialized;
+    }
 
     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) {

drivers/QSPI.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2015 ARM Limited
+ * Copyright (c) 2006-2018 ARM Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,7 +33,7 @@ namespace mbed {
 
 /** A QSPI Driver, used for communicating with QSPI slave devices
  *
- * The default format is set to Quad-SPI(4-4-4), and a clock frequency of 1MHz
+ * The default format is set to Quad-SPI(1-1-1), and a clock frequency of 1MHz
  * Most QSPI devices will also require Chip Select which is indicated by ssel. 
  *
  * @note Synchronization level: Thread safe
@@ -45,7 +45,7 @@ namespace mbed {
  * #include "mbed.h"
  *
  * // hardware ssel (where applicable)
- * QSPI qspi_device(p5, p6, p7, p8, p9, p10); // io0, io1, io2, io3, sclk, ssel
+ * QSPI qspi_device(QSPI_PIN_IO0, QSPI_PIN_IO1, QSPI_PIN_IO2, QSPI_PIN_IO3, QSPI_PIN_SCK, QSPI_PIN_CSN); // io0, io1, io2, io3, sclk, ssel
  *
  *
  * int main() {
@@ -84,12 +84,12 @@ class QSPI : private NonCopyable<QSPI> {
 
     /** Configure the data transmission format
      *
-     *  @param inst_width Bus width used by instruction phase(Valid values are 1,2,4)
-     *  @param address_width Bus width used by address phase(Valid values are 1,2,4)
-     *  @param address_size Size in bits used by address phase(Valid values are 8,16,24,32)
-     *  @param alt_width Bus width used by alt phase(Valid values are 1,2,4)
-     *  @param alt_size Size in bits used by alt phase(Valid values are 8,16,24,32)
-     *  @param data_width Bus width used by data phase(Valid values are 1,2,4)
+     *  @param inst_width Bus width used by instruction phase(Valid values are QSPI_CFG_BUS_SINGLE, QSPI_CFG_BUS_DUAL, QSPI_CFG_BUS_QUAD)
+     *  @param address_width Bus width used by address phase(Valid values are QSPI_CFG_BUS_SINGLE, QSPI_CFG_BUS_DUAL, QSPI_CFG_BUS_QUAD)
+     *  @param address_size Size in bits used by address phase(Valid values are QSPI_CFG_ADDR_SIZE_8, QSPI_CFG_ADDR_SIZE_16, QSPI_CFG_ADDR_SIZE_24, QSPI_CFG_ADDR_SIZE_32)
+     *  @param alt_width Bus width used by alt phase(Valid values are QSPI_CFG_BUS_SINGLE, QSPI_CFG_BUS_DUAL, QSPI_CFG_BUS_QUAD)
+     *  @param alt_size Size in bits used by alt phase(Valid values are QSPI_CFG_ADDR_SIZE_8, QSPI_CFG_ADDR_SIZE_16, QSPI_CFG_ADDR_SIZE_24, QSPI_CFG_ADDR_SIZE_32)
+     *  @param data_width Bus width used by data phase(Valid values are QSPI_CFG_BUS_SINGLE, QSPI_CFG_BUS_DUAL, QSPI_CFG_BUS_QUAD)
      *  @param dummy_cycles Number of dummy clock cycles to be used after alt phase
      *
      */
@@ -171,6 +171,7 @@ class QSPI : private NonCopyable<QSPI> {
      */
     qspi_status_t command_transfer(unsigned int instruction, int address, const char *tx_buffer, size_t tx_length, const char *rx_buffer, size_t rx_length);
 
+protected:
     /** Acquire exclusive access to this SPI bus
      */
     virtual void lock(void);