spi: spidev: Warn loudly if instantiated from DT as "spidev"

Since spidev is a detail of how Linux controls a device rather than a
description of the hardware in the system we should never have a node
described as "spidev" in DT, any SPI device could be a spidev so this
is just not a useful description.

In order to help prevent users from writing such device trees generate a
warning if spidev is instantiated as a DT node without an ID in the match
table.

Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 19 insertions, 7 deletions

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 23ad97807797..92c909eed6b5 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -703,6 +703,14 @@ static const struct file_operations spidev_fops = {
 
 static struct class *spidev_class;
 
+#ifdef CONFIG_OF
+static const struct of_device_id spidev_dt_ids[] = {
+        { .compatible = "rohm,dh2228fv" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, spidev_dt_ids);
+#endif
+
 /*-------------------------------------------------------------------------*/
 
 static int spidev_probe(struct spi_device *spi)
@@ -711,6 +719,17 @@ static int spidev_probe(struct spi_device *spi)
         int                     status;
         unsigned long           minor;
 
+        /*
+         * spidev should never be referenced in DT without a specific
+         * compatbile string, it is a Linux implementation thing
+         * rather than a description of the hardware.
+         */
+        if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
+                dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
+                WARN_ON(spi->dev.of_node &&
+                        !of_match_device(spidev_dt_ids, &spi->dev));
+        }
+
         /* Allocate driver data */
         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
         if (!spidev)
@@ -777,13 +796,6 @@ static int spidev_remove(struct spi_device *spi)
         return 0;
 }
 
-static const struct of_device_id spidev_dt_ids[] = {
-        { .compatible = "rohm,dh2228fv" },
-        {},
-};
-
-MODULE_DEVICE_TABLE(of, spidev_dt_ids);
-
 static struct spi_driver spidev_spi_driver = {
         .driver = {
                 .name =         "spidev",