spi: introduce accelerated read support for spi flash devices

In addition to providing direct access to SPI bus, some spi controller
hardwares (like ti-qspi) provide special port (like memory mapped port)
that are optimized to improve SPI flash read performance.
This means the controller can automatically send the SPI signals
required to read data from the SPI flash device.
For this, SPI controller needs to know flash specific information like
read command to use, dummy bytes and address width.

Introduce spi_flash_read() interface to support accelerated read
over SPI flash devices. SPI master drivers can implement this callback to
support interfaces such as memory mapped read etc. m25p80 flash driver
and other flash drivers can call this make use of such interfaces. The
interface should only be used with SPI flashes and cannot be used with
other SPI devices.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 47eff8012a77..dcc6f6e92668 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1152,6 +1152,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
 		}
 	}
 
+	mutex_lock(&master->bus_lock_mutex);
 	trace_spi_message_start(master->cur_msg);
 
 	if (master->prepare_message) {
@@ -1161,6 +1162,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
 				"failed to prepare message: %d\n", ret);
 			master->cur_msg->status = ret;
 			spi_finalize_current_message(master);
+			mutex_unlock(&master->bus_lock_mutex);
 			return;
 		}
 		master->cur_msg_prepared = true;
@@ -1170,6 +1172,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
 	if (ret) {
 		master->cur_msg->status = ret;
 		spi_finalize_current_message(master);
+		mutex_unlock(&master->bus_lock_mutex);
 		return;
 	}
 
@@ -1177,8 +1180,10 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
 	if (ret) {
 		dev_err(&master->dev,
 			"failed to transfer one message from queue\n");
+		mutex_unlock(&master->bus_lock_mutex);
 		return;
 	}
+	mutex_unlock(&master->bus_lock_mutex);
 }
 
 /**
@@ -2351,6 +2356,46 @@ int spi_async_locked(struct spi_device *spi, struct spi_message *message)
 EXPORT_SYMBOL_GPL(spi_async_locked);
 
 
+int spi_flash_read(struct spi_device *spi,
+		   struct spi_flash_read_message *msg)
+
+{
+	struct spi_master *master = spi->master;
+	int ret;
+
+	if ((msg->opcode_nbits == SPI_NBITS_DUAL ||
+	     msg->addr_nbits == SPI_NBITS_DUAL) &&
+	    !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
+		return -EINVAL;
+	if ((msg->opcode_nbits == SPI_NBITS_QUAD ||
+	     msg->addr_nbits == SPI_NBITS_QUAD) &&
+	    !(spi->mode & SPI_TX_QUAD))
+		return -EINVAL;
+	if (msg->data_nbits == SPI_NBITS_DUAL &&
+	    !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
+		return -EINVAL;
+	if (msg->data_nbits == SPI_NBITS_QUAD &&
+	    !(spi->mode &  SPI_RX_QUAD))
+		return -EINVAL;
+
+	if (master->auto_runtime_pm) {
+		ret = pm_runtime_get_sync(master->dev.parent);
+		if (ret < 0) {
+			dev_err(&master->dev, "Failed to power device: %d\n",
+				ret);
+			return ret;
+		}
+	}
+	mutex_lock(&master->bus_lock_mutex);
+	ret = master->spi_flash_read(spi, msg);
+	mutex_unlock(&master->bus_lock_mutex);
+	if (master->auto_runtime_pm)
+		pm_runtime_put(master->dev.parent);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_flash_read);
+
 /*-------------------------------------------------------------------------*/
 
 /* Utility methods for SPI master protocol drivers, layered on