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path: root/drivers/spi/spi.c
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Diffstat (limited to 'drivers/spi/spi.c')
-rw-r--r--drivers/spi/spi.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 8a30c6b66a64..85c18d8a86b3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -526,6 +526,95 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n)
/*-------------------------------------------------------------------------*/
+static void spi_set_cs(struct spi_device *spi, bool enable)
+{
+ if (spi->mode & SPI_CS_HIGH)
+ enable = !enable;
+
+ if (spi->cs_gpio >= 0)
+ gpio_set_value(spi->cs_gpio, !enable);
+ else if (spi->master->set_cs)
+ spi->master->set_cs(spi, !enable);
+}
+
+/*
+ * spi_transfer_one_message - Default implementation of transfer_one_message()
+ *
+ * This is a standard implementation of transfer_one_message() for
+ * drivers which impelment a transfer_one() operation. It provides
+ * standard handling of delays and chip select management.
+ */
+static int spi_transfer_one_message(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct spi_transfer *xfer;
+ bool cur_cs = true;
+ bool keep_cs = false;
+ int ret = 0;
+
+ spi_set_cs(msg->spi, true);
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ trace_spi_transfer_start(msg, xfer);
+
+ INIT_COMPLETION(master->xfer_completion);
+
+ ret = master->transfer_one(master, msg->spi, xfer);
+ if (ret < 0) {
+ dev_err(&msg->spi->dev,
+ "SPI transfer failed: %d\n", ret);
+ goto out;
+ }
+
+ if (ret > 0)
+ wait_for_completion(&master->xfer_completion);
+
+ trace_spi_transfer_stop(msg, xfer);
+
+ if (msg->status != -EINPROGRESS)
+ goto out;
+
+ if (xfer->delay_usecs)
+ udelay(xfer->delay_usecs);
+
+ if (xfer->cs_change) {
+ if (list_is_last(&xfer->transfer_list,
+ &msg->transfers)) {
+ keep_cs = true;
+ } else {
+ cur_cs = !cur_cs;
+ spi_set_cs(msg->spi, cur_cs);
+ }
+ }
+
+ msg->actual_length += xfer->len;
+ }
+
+out:
+ if (ret != 0 || !keep_cs)
+ spi_set_cs(msg->spi, false);
+
+ if (msg->status == -EINPROGRESS)
+ msg->status = ret;
+
+ spi_finalize_current_message(master);
+
+ return ret;
+}
+
+/**
+ * spi_finalize_current_transfer - report completion of a transfer
+ *
+ * Called by SPI drivers using the core transfer_one_message()
+ * implementation to notify it that the current interrupt driven
+ * transfer has finised and the next one may be scheduled.
+ */
+void spi_finalize_current_transfer(struct spi_master *master)
+{
+ complete(&master->xfer_completion);
+}
+EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
+
/**
* spi_pump_messages - kthread work function which processes spi message queue
* @work: pointer to kthread work struct contained in the master struct
@@ -836,6 +925,8 @@ static int spi_master_initialize_queue(struct spi_master *master)
master->queued = true;
master->transfer = spi_queued_transfer;
+ if (!master->transfer_one_message)
+ master->transfer_one_message = spi_transfer_one_message;
/* Initialize and start queue */
ret = spi_init_queue(master);
@@ -1242,6 +1333,7 @@ int spi_register_master(struct spi_master *master)
spin_lock_init(&master->bus_lock_spinlock);
mutex_init(&master->bus_lock_mutex);
master->bus_lock_flag = 0;
+ init_completion(&master->xfer_completion);
/* register the device, then userspace will see it.
* registration fails if the bus ID is in use.