2 files changed, 89 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 47eff8012a77..0b2bbf144460 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 +1180,13 @@ 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);
+
+        /* Prod the scheduler in case transfer_one() was busy waiting */
+        cond_resched();
 }
 
 /**
@@ -2351,6 +2359,46 @@ 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
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 53be3a4c60cb..ba0dee9d05a3 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -25,6 +25,7 @@
 struct dma_chan;
 struct spi_master;
 struct spi_transfer;
+struct spi_flash_read_message;
 
 /*
  * INTERFACES between SPI master-side drivers and SPI infrastructure.
@@ -361,6 +362,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  * @handle_err: the subsystem calls the driver to handle an error that occurs
  *              in the generic implementation of transfer_one_message().
  * @unprepare_message: undo any work done by prepare_message().
+ * @spi_flash_read: to support spi-controller hardwares that provide
+ *                  accelerated interface to read from flash devices.
  * @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).
@@ -513,6 +516,8 @@ struct spi_master {
                                struct spi_message *message);
         int (*unprepare_message)(struct spi_master *master,
                                  struct spi_message *message);
+        int (*spi_flash_read)(struct  spi_device *spi,
+                              struct spi_flash_read_message *msg);
 
         /*
          * These hooks are for drivers that use a generic implementation
@@ -1019,6 +1024,42 @@ static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd)
         return be16_to_cpu(result);
 }
 
+/**
+ * struct spi_flash_read_message - flash specific information for
+ * spi-masters that provide accelerated flash read interfaces
+ * @buf: buffer to read data
+ * @from: offset within the flash from where data is to be read
+ * @len: length of data to be read
+ * @retlen: actual length of data read
+ * @read_opcode: read_opcode to be used to communicate with flash
+ * @addr_width: number of address bytes
+ * @dummy_bytes: number of dummy bytes
+ * @opcode_nbits: number of lines to send opcode
+ * @addr_nbits: number of lines to send address
+ * @data_nbits: number of lines for data
+ */
+struct spi_flash_read_message {
+        void *buf;
+        loff_t from;
+        size_t len;
+        size_t retlen;
+        u8 read_opcode;
+        u8 addr_width;
+        u8 dummy_bytes;
+        u8 opcode_nbits;
+        u8 addr_nbits;
+        u8 data_nbits;
+};
+
+/* SPI core interface for flash read support */
+static inline bool spi_flash_read_supported(struct spi_device *spi)
+{
+        return spi->master->spi_flash_read ? true : false;
+}
+
+int spi_flash_read(struct spi_device *spi,
+                   struct spi_flash_read_message *msg);
+
 /*---------------------------------------------------------------------------*/
 
 /*