[PATCH 1/2] spi: Provide per-message prepare and unprepare operations

[PATCH 1/2] spi: Provide per-message prepare and unprepare operations

[Mark Brown]

From: Mark Brown <broonie@linaro.org>

Many SPI drivers perform setup and tear down on every message, usually
doing things like DMA mapping the message. Provide hooks for them to use
to provide such operations.

This is of limited value for drivers that implement transfer_one_message()
but will be of much greater utility with future factoring out of standard
implementations of that function.

Signed-off-by: Mark Brown <broonie@linaro.org>
---
 drivers/spi/spi.c       | 22 ++++++++++++++++++++++
 include/linux/spi/spi.h | 11 +++++++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b86ba60..253ea3b 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -606,6 +606,18 @@ static void spi_pump_messages(struct kthread_work *work)
 
 	trace_spi_message_start(master->cur_msg);
 
+	if (master->prepare_message) {
+		ret = master->prepare_message(master, master->cur_msg);
+		if (ret) {
+			dev_err(&master->dev,
+				"failed to prepare message: %d\n", ret);
+			master->cur_msg->status = ret;
+			spi_finalize_current_message(master);
+			return;
+		}
+		master->cur_msg_prepared = true;
+	}
+
 	ret = master->transfer_one_message(master, master->cur_msg);
 	if (ret) {
 		dev_err(&master->dev,
@@ -687,6 +699,7 @@ void spi_finalize_current_message(struct spi_master *master)
 {
 	struct spi_message *mesg;
 	unsigned long flags;
+	int ret;
 
 	spin_lock_irqsave(&master->queue_lock, flags);
 	mesg = master->cur_msg;
@@ -695,6 +708,15 @@ void spi_finalize_current_message(struct spi_master *master)
 	queue_kthread_work(&master->kworker, &master->pump_messages);
 	spin_unlock_irqrestore(&master->queue_lock, flags);
 
+	if (master->cur_msg_prepared && master->unprepare_message) {
+		ret = master->unprepare_message(master, mesg);
+		if (ret) {
+			dev_err(&master->dev,
+				"failed to unprepare message: %d\n", ret);
+		}
+	}
+	master->cur_msg_prepared = false;
+
 	mesg->state = NULL;
 	if (mesg->complete)
 		mesg->complete(mesg->context);
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index b329192..98620486 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -257,6 +257,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  * @queue_lock: spinlock to syncronise access to message queue
  * @queue: message queue
  * @cur_msg: the currently in-flight message
+ * @cur_msg_prepared: spi_prepare_message was called for the currently
+ *                    in-flight message
  * @busy: message pump is busy
  * @running: message pump is running
  * @rt: whether this queue is set to run as a realtime task
@@ -274,6 +276,10 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  * @unprepare_transfer_hardware: there are currently no more messages on the
  *	queue so the subsystem notifies the driver that it may relax the
  *	hardware by issuing this call
+ * @prepare_message: set up the controller to transfer a single message,
+ *                   for example doing DMA mapping.  Called from threaded
+ *                   context.
+ * @unprepare_message: undo any work done by prepare_message().
  * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
  *	number. Any individual value may be -ENOENT for CS lines that
  *	are not GPIOs (driven by the SPI controller itself).
@@ -388,11 +394,16 @@ struct spi_master {
 	bool				running;
 	bool				rt;
 	bool				auto_runtime_pm;
+	bool                            cur_msg_prepared;
 
 	int (*prepare_transfer_hardware)(struct spi_master *master);
 	int (*transfer_one_message)(struct spi_master *master,
 				    struct spi_message *mesg);
 	int (*unprepare_transfer_hardware)(struct spi_master *master);
+	int (*prepare_message)(struct spi_master *master,
+			       struct spi_message *message);
+	int (*unprepare_message)(struct spi_master *master,
+				 struct spi_message *message);
 
 	/* gpio chip select */
 	int			*cs_gpios;
-- 
1.8.4.rc3

[PATCH 2/2] spi/s3c64xx: Use prepare_message() and unprepare_message()

[Mark Brown]

From: Mark Brown <broonie@linaro.org>

This is of very little value in itself but will be useful once the loop
iterating over the transfers is also factored out into the core.

Signed-off-by: Mark Brown <broonie@linaro.org>
---
 drivers/spi/spi-s3c64xx.c | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 8e732a1..c7b36c0 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -849,16 +849,12 @@ static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
 	}
 }
 
-static int s3c64xx_spi_transfer_one_message(struct spi_master *master,
-					    struct spi_message *msg)
+static int s3c64xx_spi_prepare_message(struct spi_master *master,
+				       struct spi_message *msg)
 {
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
 	struct spi_device *spi = msg->spi;
 	struct s3c64xx_spi_csinfo *cs = spi->controller_data;
-	struct spi_transfer *xfer;
-	int status = 0, cs_toggle = 0;
-	u32 speed;
-	u8 bpw;
 
 	/* If Master's(controller) state differs from that needed by Slave */
 	if (sdd->cur_speed != spi->max_speed_hz
@@ -874,13 +870,25 @@ static int s3c64xx_spi_transfer_one_message(struct spi_master *master,
 	if (s3c64xx_spi_map_mssg(sdd, msg)) {
 		dev_err(&spi->dev,
 			"Xfer: Unable to map message buffers!\n");
-		status = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 
 	/* Configure feedback delay */
 	writel(cs->fb_delay & 0x3, sdd->regs + S3C64XX_SPI_FB_CLK);
 
+	return 0;
+}
+
+static int s3c64xx_spi_transfer_one_message(struct spi_master *master,
+					    struct spi_message *msg)
+{
+	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
+	struct spi_device *spi = msg->spi;
+	struct spi_transfer *xfer;
+	int status = 0, cs_toggle = 0;
+	u32 speed;
+	u8 bpw;
+
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 
 		unsigned long flags;
@@ -988,6 +996,16 @@ out:
 	return 0;
 }
 
+static int s3c64xx_spi_unprepare_message(struct spi_master *master,
+					    struct spi_message *msg)
+{
+	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
+
+	s3c64xx_spi_unmap_mssg(sdd, msg);
+
+	return 0;
+}
+
 static struct s3c64xx_spi_csinfo *s3c64xx_get_slave_ctrldata(
 				struct spi_device *spi)
 {
@@ -1360,7 +1378,9 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
 	master->setup = s3c64xx_spi_setup;
 	master->cleanup = s3c64xx_spi_cleanup;
 	master->prepare_transfer_hardware = s3c64xx_spi_prepare_transfer;
+	master->prepare_message = s3c64xx_spi_prepare_message;
 	master->transfer_one_message = s3c64xx_spi_transfer_one_message;
+	master->unprepare_message = s3c64xx_spi_unprepare_message;
 	master->unprepare_transfer_hardware = s3c64xx_spi_unprepare_transfer;
 	master->num_chipselect = sci->num_cs;
 	master->dma_alignment = 8;
-- 
1.8.4.rc3