dfu: add callback for flush and initiated operation

Add weak callback to allow board specific behavior
- flush
- initiated

This patch prepare usage of DFU back end for communication with
STM32CubeProgrammer on stm32mp1 platform with stm32prog command.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

doc/README.dfu

@@ -143,6 +143,14 @@ Commands:
        mtd <dev>=<alt1>;....;<altN>
        virt <dev>=<alt1>;....;<altN>
 
+Callbacks:
+  The weak callback functions can be implemented to manage specific behavior
+  - dfu_initiated_callback  : called when the DFU transaction is started,
+                              used to initiase the device
+  - dfu_flush_callback      : called at the end of the DFU write after DFU
+                              manifestation, used to manage the device when
+                              DFU transaction is closed
+
 Host tools:
   When U-Boot runs the dfu stack, the DFU host tools can be used
   to send/receive firmwares on each configurated alternate.

drivers/dfu/dfu.c

@@ -22,6 +22,22 @@ static int dfu_alt_num;
 static int alt_num_cnt;
 static struct hash_algo *dfu_hash_algo;
 
+/*
+ * The purpose of the dfu_flush_callback() function is to
+ * provide callback for dfu user
+ */
+__weak void dfu_flush_callback(struct dfu_entity *dfu)
+{
+}
+
+/*
+ * The purpose of the dfu_initiated_callback() function is to
+ * provide callback for dfu user
+ */
+__weak void dfu_initiated_callback(struct dfu_entity *dfu)
+{
+}
+
 /*
  * The purpose of the dfu_usb_get_reset() function is to
  * provide information if after USB_DETACH request
@@ -263,6 +279,7 @@ int dfu_transaction_initiate(struct dfu_entity *dfu, bool read)
 	}
 
 	dfu->inited = 1;
+	dfu_initiated_callback(dfu);
 
 	return 0;
 }
@@ -282,6 +299,8 @@ int dfu_flush(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 		printf("\nDFU complete %s: 0x%08x\n", dfu_hash_algo->name,
 		       dfu->crc);
 
+	dfu_flush_callback(dfu);
+
 	dfu_transaction_cleanup(dfu);
 
 	return ret;

include/dfu.h

@@ -183,6 +183,28 @@ int dfu_read(struct dfu_entity *de, void *buf, int size, int blk_seq_num);
 int dfu_write(struct dfu_entity *de, void *buf, int size, int blk_seq_num);
 int dfu_flush(struct dfu_entity *de, void *buf, int size, int blk_seq_num);
 
+/**
+ * dfu_initiated_callback - weak callback called on DFU transaction start
+ *
+ * It is a callback function called by DFU stack when a DFU transaction is
+ * initiated. This function allows to manage some board specific behavior on
+ * DFU targets.
+ *
+ * @param dfu - pointer to the dfu_entity, which should be initialized
+ *
+ */
+void dfu_initiated_callback(struct dfu_entity *dfu);
+/**
+ * dfu_flush_callback - weak callback called at the end of the DFU write
+ *
+ * It is a callback function called by DFU stack after DFU manifestation.
+ * This function allows to manage some board specific behavior on DFU targets
+ *
+ * @param dfu - pointer to the dfu_entity, which should be flushed
+ *
+ */
+void dfu_flush_callback(struct dfu_entity *dfu);
+
 /*
  * dfu_defer_flush - pointer to store dfu_entity for deferred flashing.
  *		     It should be NULL when not used.