QSPI HAL addition

Adding new QSPI HAL header file. This should help to use memory-maped devices
as memories, graphical displays.

The API consist of few functions, most important are read/write/write_command functions.

The command format is:

```
----------------------------------------------
| Instruction | Address | Alt | Dummy | Data |
----------------------------------------------
```

We define only synch API at the moment.

hal/qspi_api.h

@@ -0,0 +1,186 @@
+
+/** \addtogroup hal */
+/** @{*/
+/* mbed Microcontroller Library
+ * Copyright (c) 2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MBED_QSPI_API_H
+#define MBED_QSPI_API_H
+
+#include "device.h"
+
+#if DEVICE_QSPI
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \defgroup hal_qspi QSPI HAL
+ * @{
+ */
+
+/** QSPI HAL object declaration
+ */
+typedef struct qspi_s qspi_t;
+
+/** QSPI Bus width
+ * 
+ * Some parts of commands provide variable bus width 
+ */
+typedef enum qspi_bus_width {
+    QSPI_CFG_BUS_SINGLE,
+    QSPI_CFG_BUS_DUAL,
+    QSPI_CFG_BUS_QUAD,
+} qspi_bus_width_t;
+
+/** Address size
+ */
+typedef enum qspi_address_size {
+    QSPI_CFG_ADDR_SIZE_8,
+    QSPI_CFG_ADDR_SIZE_16,
+    QSPI_CFG_ADDR_SIZE_24,
+    QSPI_CFG_ADDR_SIZE_32,
+} qspi_address_size_t;
+
+/** Alternative size
+ */
+typedef enum qspi_alt_size {
+    QSPI_CFG_ALT_SIZE_8,
+    QSPI_CFG_ALT_SIZE_16,
+    QSPI_CFG_ALT_SIZE_24,
+    QSPI_CFG_ALT_SIZE_32,
+} qspi_alt_size_t;
+
+/** QSPI command declaration
+ *
+ * Defines a frame format
+ */
+typedef struct qspi_command {
+    struct instruction {
+        qspi_bus_width_t bus_width; /**< Bus width for the instruction >*/
+        uint8_t value;  /**< Instruction, 0 - disabled, non-zero defined value used >*/
+    };
+    struct address {
+        qspi_bus_width_t bus_width; /**< Bus width for the address >*/
+        qspi_address_size_t size; /**< Address size >*/
+        uint32_t value; /**< Address, 0 - disabled, non-zero defined value used >*/
+    };
+    struct alt {
+        qspi_bus_width_t bus_width; /**< Bus width for alternative  >*/
+        qspi_alt_size_t size; /**< Alternative size >*/
+        uint32_t value; /**< Alternative, 0 - disabled, non-zero defined value used >*/
+    };
+    uint8_t dummy_count; /**< Dummy cycles count >*/
+    struct data {
+        qspi_bus_width_t bus_width; /**< Bus width for data >*/
+    };
+} qspi_command_t;
+
+/** QSPI return status
+ */
+typedef enum qspi_status {
+    QSPI_STATUS_ERROR = -1, /**< Generic error >*/
+    QSPI_STATUS_INVALID_PARAMETER = -2, /**< The parameter is invalid >*/
+    QSPI_STATUS_OK    =  0, /**< Function executed sucessfully  >*/
+} qspi_status_t;
+
+/** Initialize QSPI peripheral. 
+ *
+ * It should initialize QSPI pins (io0-io3, sclk and ssel), set frequency and SPI mode. The clock for the peripheral should be enabled
+ * 
+ * @param obj QSPI object
+ * @param io0 Data pin 0
+ * @param io1 Data pin 1
+ * @param io2 Data pin 2
+ * @param io3 Data pin 3
+ * @param sclk The clock pin
+ * @param ssel The chip select pin
+ * @param hz The bus frequency
+ * @param mode SPI mode
+ * @return QSPI_STATUS_OK if initialisation successfully executed
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_init(qspi_t *obj, PinName io0, PinName io1, PinName io2, PinName io3, PinName sclk, PinName ssel, uint32_t hz, uint8_t mode);
+
+/** Deinitilize QSPI peripheral
+ *
+ * It should release pins that are associated with the QSPI object, and disable clocks for QSPI peripheral module that was associated with the object
+ *
+ * @param obj QSPI object
+ * @return QSPI_STATUS_OK if deinitialisation successfully executed
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_free(qspi_t *obj);
+
+/** Set the QSPI baud rate
+ *
+ * Actual frequency may differ from the desired frequency due to available dividers and the bus clock
+ * Configures the QSPI peripheral's baud rate
+ * @param obj The SPI object to configure
+ * @param hz  The baud rate in Hz
+ * @return QSPI_STATUS_OK if frequency was set
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_frequency(qspi_t *obj, int hz);
+
+/** Send only QSPI command
+ *
+ * @param obj QSPI object
+ * @param command QSPI command
+ * @return QSPI_STATUS_OK if command was sent without any error
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_write_command(qspi_t *obj, const qspi_command_t *command);
+
+/** Send a command and block of data
+ *
+ * @param obj QSPI object
+ * @param command QSPI command
+ * @param data TX buffer
+ * @param length TX buffer length in bytes
+ * @return QSPI_STATUS_OK if the data has been succesfully sent
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_write(qspi_t *obj, const qspi_command_t *command, const void *data, size_t length);
+
+/** Receive a command and block of data
+ *
+ * @param obj QSPI object
+ * @param command QSPI command
+ * @param data RX buffer
+ * @param length RX buffer length in bytes
+ * @return QSPI_STATUS_OK if data has been succesfully received
+           QSPI_STATUS_INVALID_PARAMETER if invalid parameter found
+           QSPI_STATUS_ERROR otherwise
+ */
+qspi_status_t qspi_read(qspi_t *obj, const qspi_command_t *command, void *data, size_t length);
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+#endif
+
+/** @}*/