[PATCH 6/7] spi: fsi: Check mux status before transfers

Eddie James
2020-08-20T17:03:42Z

The SPI controllers are not accessible if the mux isn't set. Therefore,
check the mux status before starting a transfer and fail out if it isn't
set.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
drivers/spi/spi-fsi.c | 40 +++++++++++++++++++++++++++-------------
1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index 53cfa201e187..9c0a4413ec3d 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -12,6 +12,7 @@

#define FSI_ENGID_SPI 0x23
#define FSI_MBOX_ROOT_CTRL_8 0x2860
+#define FSI_MBOX_ROOT_CTRL_8_SPI_MUX 0xf0000000

#define FSI2SPI_DATA0 0x00
#define FSI2SPI_DATA1 0x04
@@ -84,6 +85,26 @@ struct fsi_spi_sequence {
u64 data;
};

+static int fsi_spi_check_mux(struct fsi_device *fsi, struct device *dev)
+{
+ int rc;
+ u32 root_ctrl_8;
+ __be32 root_ctrl_8_be;
+
+ rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8_be,
+ sizeof(root_ctrl_8_be));
+ if (rc)
+ return rc;
+
+ root_ctrl_8 = be32_to_cpu(root_ctrl_8_be);
+ dev_dbg(dev, "Root control register 8: %08x\n", root_ctrl_8);
+ if ((root_ctrl_8 & FSI_MBOX_ROOT_CTRL_8_SPI_MUX) ==
+ FSI_MBOX_ROOT_CTRL_8_SPI_MUX)
+ return 0;
+
+ return -ENOLINK;
+}
+
static int fsi_spi_check_status(struct fsi_spi *ctx)
{
int rc;
@@ -449,11 +470,15 @@ static int fsi_spi_transfer_init(struct fsi_spi *ctx)
static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
struct spi_message *mesg)
{
- int rc = 0;
+ int rc;
u8 seq_slave = SPI_FSI_SEQUENCE_SEL_SLAVE(mesg->spi->chip_select + 1);
struct spi_transfer *transfer;
struct fsi_spi *ctx = spi_controller_get_devdata(ctlr);

+ rc = fsi_spi_check_mux(ctx->fsi, ctx->dev);
+ if (rc)
+ return rc;
+
list_for_each_entry(transfer, &mesg->transfers, transfer_list) {
struct fsi_spi_sequence seq;
struct spi_transfer *next = NULL;
@@ -537,24 +562,13 @@ static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
static int fsi_spi_probe(struct device *dev)
{
int rc;
- u32 root_ctrl_8;
struct device_node *np;
int num_controllers_registered = 0;
struct fsi_device *fsi = to_fsi_dev(dev);

- /*
- * Check the SPI mux before attempting to probe. If the mux isn't set
- * then the SPI controllers can't access their slave devices.
- */
- rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8,
- sizeof(root_ctrl_8));
+ rc = fsi_spi_check_mux(fsi, dev);
if (rc)
- return rc;
-
- if (!root_ctrl_8) {
- dev_dbg(dev, "SPI mux not set, aborting probe.\n");
return -ENODEV;
- }

for_each_available_child_of_node(dev->of_node, np) {
u32 base;
--
2.26.2