[PATCH 2/2] spi: imx: support loopback mode on imx35

From: Martin Kaiser
Date: Thu Sep 01 2016 - 17:31:14 EST


imx35 and compatible chipsets support loopback mode by setting a
loopback control bit in the test register. Make this setting available
for data transfers, similar to what we do for imx51.

Signed-off-by: Martin Kaiser <martin@xxxxxxxxx>
---
drivers/spi/spi-imx.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 5cc72be..53e7a32 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -455,6 +455,9 @@ static void mx51_ecspi_reset(struct spi_imx_data *spi_imx)
#define MX31_CSPISTATUS 0x14
#define MX31_STATUS_RR (1 << 3)

+#define MX31_CSPI_TESTREG 0x1C
+#define MX31_TEST_LBC (1 << 14)
+
/* These functions also work for the i.MX35, but be aware that
* the i.MX35 has a slightly different register layout for bits
* we do not use here.
@@ -510,6 +513,13 @@ static int mx31_config(struct spi_device *spi, struct spi_imx_config *config)

writel(reg, spi_imx->base + MXC_CSPICTRL);

+ reg = readl(spi_imx->base + MX31_CSPI_TESTREG);
+ if (spi->mode & SPI_LOOP)
+ reg |= MX31_TEST_LBC;
+ else
+ reg &= ~MX31_TEST_LBC;
+ writel(reg, spi_imx->base + MX31_CSPI_TESTREG);
+
return 0;
}

@@ -1186,7 +1196,7 @@ static int spi_imx_probe(struct platform_device *pdev)
spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
- if (is_imx51_ecspi(spi_imx))
+ if (is_imx35_cspi(spi_imx) || is_imx51_ecspi(spi_imx))
spi_imx->bitbang.master->mode_bits |= SPI_LOOP;

init_completion(&spi_imx->xfer_done);
--
1.7.10.4