Merge pull request #676 from maciejbocianski/update_qspi_docs

Update QSPI porting guide

Author: Amanda Butler

docs/reference/contributing/target/QuadSPI.md

@@ -4,8 +4,6 @@ Implementing QSPI enables Mbed OS to communicate with external memories much fas
 
 The most common use case is an external memory to use as additional data storage.
 
-<span class="warnings">**Warning:** We are changing the QSPI HAL API in an upcoming release of Mbed OS. This page documents code that exists on a feature branch of Mbed OS. You can find details on how it may affect you in the [Implementing the QSPI API](#implementing-quadspi) section.</span>
-
 ### Assumptions
 
 #### Defined behavior
@@ -29,6 +27,29 @@ To make sure your platform is ready for the upcoming changes, you need to implem
 
 The target needs to define the `qspi_s` structure - target specific QSPI object.
 
+The target needs to define the QSPI interface pin names:
+
+- `QSPI_FLASHn_XXX` for pins connected to onboard flash memory.
+- `QSPIn_XXX` for pins routed out to external connector.
+
+`n` is the interface index, typically `1` if single QSPI interface available.
+
+```
+QSPIn_IO0
+QSPIn_IO1
+QSPIn_IO2
+QSPIn_IO3
+QSPIn_SCK
+QSPIn_CSN
+
+QSPI_FLASHn_IO0
+QSPI_FLASHn_IO1
+QSPI_FLASHn_IO2
+QSPI_FLASHn_IO3
+QSPI_FLASHn_SCK
+QSPI_FLASHn_CSN
+```
+
 Functions to implement:
 
 ```
@@ -41,7 +62,7 @@ qspi_status_t qspi_read(qspi_t *obj, const qspi_command_t *command, void *data,
 
 ```
 
-Use `qspi_write` and `qspi_read` for data transfers. For communicating with a device, use `qspi_command_transfer`.
+Use `qspi_write` and `qspi_read` for data transfers. To communicate with a device, use `qspi_command_transfer`.
 
 To enable the QSPI HAL, define `QSPI` in the targets.json file inside `device_has`:
 
@@ -53,4 +74,12 @@ To enable the QSPI HAL, define `QSPI` in the targets.json file inside `device_ha
 
 ### Testing
 
-To be implemented
+The Mbed OS HAL provides a set of conformance tests for the QSPI interface.
+
+<span class="notes">**Note:** QSPI HAL tests require QSPI Flash pins to be defined.</span>
+
+You can use these tests to validate the correctness of your implementation. To run the QSPI HAL tests, use the following command:
+
+```
+mbed test -t <toolchain> -m <target> -n tests-mbed_hal-qspi
+```