spi: loopback-test: add ability to test zero-length transfer

The spi-loopback-test module currently cannot test the spi_message
including a zero-length transfer.  Because the zero-length transfer is
treated as a special value in several meanings.

1. The number of spi_transfer to execute in one test case is described
by spi_test.transfer_count.  It is normally computed by counting number
of transfers with len > 0 in spi_test.transfers array.

This change stops the detection for the number of spi_transfer.  Each
spi_test.transfer_count needs to be filled by hand now.

2. The spi_test.iterate_len is a list of transfer length to iterate on.
This list is terminated by zero, so zero-length transfer cannot be
included.

This changes the terminal value from 0 to -1.

3. The length for the spi_transfer masked by spi_test.iterate_transfer_mask
is iterated.  Before starting the iteration, the default value which
is statically initialized is applied.  In order to specify the default
value, zero-length is reserved.

Currently, the default values are always '1'.  So this removes this
trick and add '1' to iterate_len list.

By applying all these changes, the spi-loopback-test can execute spi
messages with zero-length transfer.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 9 insertions, 10 deletions

diff --git a/drivers/spi/spi-test.h b/drivers/spi/spi-test.h
index 922c52833239..2dd569138880 100644
--- a/drivers/spi/spi-test.h
+++ b/drivers/spi/spi-test.h
@@ -48,9 +48,8 @@
  *
  * @msg:              a template @spi_message usedfor the default settings
  * @transfers:        array of @spi_transfers that are part of the
- *                    resulting spi_message. The first transfer with len == 0
- *                    signifies the end of the list
- * @transfer_count:   normally computed number of transfers with len > 0
+ *                    resulting spi_message.
+ * @transfer_count:   number of transfers
  *
  * @run_test:         run a specific spi_test - this allows to override
  *                    the default implementation of @spi_test_run_transfer
@@ -62,8 +61,7 @@
  * @expected_return:  the expected return code - in some cases we want to
  *                    test also for error conditions
  *
- * @iterate_len:      list of length to iterate on (in addition to the
- *                    explicitly set @spi_transfer.len)
+ * @iterate_len:      list of length to iterate on
  * @iterate_tx_align: change the alignment of @spi_transfer.tx_buf
  *                    for all values in the below range if set.
  *                    the ranges are:
@@ -89,7 +87,7 @@ struct spi_test {
 	int (*execute_msg)(struct spi_device *spi, struct spi_test *test,
 			   void *tx, void *rx);
 	int expected_return;
-	/* iterate over all the non-zero values */
+	/* iterate over all values, terminated by a -1 */
 	int iterate_len[SPI_TEST_MAX_ITERATE];
 	int iterate_tx_align;
 	int iterate_rx_align;
@@ -126,11 +124,12 @@ int spi_test_execute_msg(struct spi_device *spi,
 int spi_test_run_tests(struct spi_device *spi,
 		       struct spi_test *tests);
 
-/* some of the default @spi_transfer.len to test */
-#define ITERATE_LEN 2, 3, 7, 11, 16, 31, 32, 64, 97, 128, 251, 256, \
+#define ITERATE_LEN_LIST 1, 2, 3, 7, 11, 16, 31, 32, 64, 97, 128, 251, 256, \
 		1021, 1024, 1031, 4093, PAGE_SIZE, 4099, 65536, 65537
-
-#define ITERATE_MAX_LEN ITERATE_LEN, SPI_TEST_MAX_SIZE - 1, SPI_TEST_MAX_SIZE
+/* some of the default @spi_transfer.len to test, terminated by a -1 */
+#define ITERATE_LEN ITERATE_LEN_LIST, -1
+#define ITERATE_MAX_LEN ITERATE_LEN_LIST, (SPI_TEST_MAX_SIZE - 1), \
+		SPI_TEST_MAX_SIZE, -1
 
 /* the default alignment to test */
 #define ITERATE_ALIGN sizeof(int)