[nrf fromlist] drivers: flash: nrf: Fix ticker stop synchronization

Fix usage fault due to spurious ticker timeout expiry post
enqueuing of ticker stop operation.

Use ticker operation callback to handle completion of ticker
stop operation and then give the semaphore to thread to
notifying the completion of flash operation.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>
(cherry picked from commit d6b567ccffea4d65708896d12ffbcd463cabeb60)
Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: cvinayak

drivers/flash/soc_flash_nrf_ticker.c

@@ -35,20 +35,37 @@ struct ticker_sync_context {
 
 static struct ticker_sync_context _ticker_sync_context;
 
-
 /* semaphore for synchronization of flash operations */
 static struct k_sem sem_sync;
 
-static inline int _ticker_stop(uint8_t inst_idx, uint8_t u_id, uint8_t tic_id)
+static void ticker_stop_work_cb(uint32_t status, void *param)
 {
-	int ret = ticker_stop(inst_idx, u_id, tic_id, NULL, NULL);
+	__ASSERT((status == TICKER_STATUS_SUCCESS ||
+		  status == TICKER_STATUS_FAILURE),
+		 "Failed to stop work ticker, ticker job busy.\n");
 
-	if (ret != TICKER_STATUS_SUCCESS &&
-	    ret != TICKER_STATUS_BUSY) {
-		__ASSERT(0, "Failed to stop ticker.\n");
-	}
+	/* notify thread that data is available */
+	k_sem_give(&sem_sync);
+}
+
+static void ticker_stop_prepare_cb(uint32_t status, void *param)
+{
+	uint8_t instance_index;
+	uint8_t ticker_id;
+	uint32_t ret;
+
+	__ASSERT(status == TICKER_STATUS_SUCCESS,
+		 "Failed to stop prepare ticker.\n");
 
-	return ret;
+	/* Get the ticker instance and ticker id for flash operations */
+	ll_timeslice_ticker_id_get(&instance_index, &ticker_id);
+
+	/* Stop the work ticker, from ULL_LOW context */
+	ret = ticker_stop(instance_index, 2U, (ticker_id + 1U),
+			  ticker_stop_work_cb, NULL);
+	__ASSERT((ret == TICKER_STATUS_SUCCESS ||
+		  ret == TICKER_STATUS_BUSY),
+		 "Failed to request the work ticker to stop.\n");
 }
 
 static void time_slot_callback_work(uint32_t ticks_at_expire,
@@ -58,8 +75,6 @@ static void time_slot_callback_work(uint32_t ticks_at_expire,
 				    void *context)
 {
 	struct flash_op_desc *op_desc;
-	uint8_t instance_index;
-	uint8_t ticker_id;
 	int rc;
 
 	__ASSERT(ll_radio_state_is_idle(),
@@ -68,15 +83,21 @@ static void time_slot_callback_work(uint32_t ticks_at_expire,
 	op_desc = context;
 	rc = op_desc->handler(op_desc->context);
 	if (rc != FLASH_OP_ONGOING) {
+		uint8_t instance_index;
+		uint8_t ticker_id;
+		uint32_t ret;
+
+		/* Get the ticker instance and ticker id for flash operations */
 		ll_timeslice_ticker_id_get(&instance_index, &ticker_id);
 
-		/* Stop the time slot ticker */
-		_ticker_stop(instance_index, 0, ticker_id);
+		/* Stop the prepare ticker, from ULL_HIGH context */
+		ret = ticker_stop(instance_index, 0U, ticker_id,
+				  ticker_stop_prepare_cb, NULL);
+		__ASSERT((ret == TICKER_STATUS_SUCCESS ||
+			  ret == TICKER_STATUS_BUSY),
+			 "Failed to stop ticker.\n");
 
 		_ticker_sync_context.result = (rc == FLASH_OP_DONE) ? 0 : rc;
-
-		/* notify thread that data is available */
-		k_sem_give(&sem_sync);
 	}
 }
 
@@ -85,15 +106,16 @@ static void time_slot_delay(uint32_t ticks_at_expire, uint32_t ticks_delay,
 {
 	uint8_t instance_index;
 	uint8_t ticker_id;
-	int err;
+	uint32_t ret;
 
+	/* Get the ticker instance and ticker id for flash operations */
 	ll_timeslice_ticker_id_get(&instance_index, &ticker_id);
 
-	/* start a secondary one-shot ticker after ticks_delay,
+	/* Start a secondary one-shot ticker after ticks_delay,
 	 * this will let any radio role to gracefully abort and release the
 	 * Radio h/w.
 	 */
-	err = ticker_start(instance_index, /* Radio instance ticker */
+	ret = ticker_start(instance_index, /* Radio instance ticker */
 			   1, /* user id for link layer ULL_HIGH */
 			      /* (MAYFLY_CALL_ID_WORKER) */
 			   (ticker_id + 1), /* ticker_id */
@@ -109,14 +131,16 @@ static void time_slot_delay(uint32_t ticks_at_expire, uint32_t ticks_delay,
 			   NULL, /* no op callback */
 			   NULL);
 
-	if (err != TICKER_STATUS_SUCCESS && err != TICKER_STATUS_BUSY) {
+	if (ret != TICKER_STATUS_SUCCESS && ret != TICKER_STATUS_BUSY) {
+		/* Failed to enqueue the ticker start operation request */
 		_ticker_sync_context.result = 0;
 
-		/* abort flash timeslots */
-		_ticker_stop(instance_index, 0, ticker_id);
-
-		/* notify thread that data is available */
-		k_sem_give(&sem_sync);
+		/* Abort flash prepare ticker, from ULL_HIGH context */
+		ret = ticker_stop(instance_index, 0U, ticker_id,
+				  ticker_stop_prepare_cb, NULL);
+		__ASSERT((ret == TICKER_STATUS_SUCCESS ||
+			  ret == TICKER_STATUS_BUSY),
+			 "Failed to stop ticker.\n");
 	}
 }
 
@@ -159,7 +183,6 @@ int nrf_flash_sync_init(void)
 
 void nrf_flash_sync_set_context(uint32_t duration)
 {
-
 	/* FLASH_SYNC_SWITCHING_TIME is delay which is always added by
 	 * the slot calling mechanism
 	 */
@@ -171,12 +194,14 @@ int nrf_flash_sync_exe(struct flash_op_desc *op_desc)
 {
 	uint8_t instance_index;
 	uint8_t ticker_id;
+	uint32_t ret;
 	int result;
-	uint32_t err;
 
+	/* Get the ticker instance and ticker id for flash operations */
 	ll_timeslice_ticker_id_get(&instance_index, &ticker_id);
 
-	err = ticker_start(instance_index,
+	/* Start periodic flash operation prepare time slots */
+	ret = ticker_start(instance_index,
 			   3, /* user id for thread mode */
 			      /* (MAYFLY_CALL_ID_PROGRAM) */
 			   ticker_id, /* flash ticker id */
@@ -194,11 +219,15 @@ int nrf_flash_sync_exe(struct flash_op_desc *op_desc)
 			   NULL, /* no op callback */
 			   NULL);
 
-	if (err != TICKER_STATUS_SUCCESS && err != TICKER_STATUS_BUSY) {
+	if (ret != TICKER_STATUS_SUCCESS && ret != TICKER_STATUS_BUSY) {
+		/* Failed to enqueue the ticker start operation request */
 		result = -ECANCELED;
 	} else if (k_sem_take(&sem_sync, K_MSEC(FLASH_TIMEOUT_MS)) != 0) {
-		/* Stop any scheduled jobs */
-		_ticker_stop(instance_index, 3, ticker_id);
+		/* Stop any scheduled jobs, from thread context */
+		ret = ticker_stop(instance_index, 3U, ticker_id, NULL, NULL);
+		__ASSERT((ret == TICKER_STATUS_SUCCESS ||
+			  ret == TICKER_STATUS_BUSY),
+			 "Failed to stop ticker.\n");
 
 		/* wait for operation's complete overrun*/
 		result = -ETIMEDOUT;