This adds an option to create spidev nodes for any chip selects not
bound to a driver via DT/ACPI.  It probably doesn't play nicely with
modules.

Signed-off-by: Mans Rullgard <[email protected]>
---
 drivers/spi/Kconfig |  4 ++++
 drivers/spi/spi.c   | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 8b9c2a38d1cc..4977fc2fbb30 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -689,6 +689,10 @@ config SPI_SPIDEV
          Note that this application programming interface is EXPERIMENTAL
          and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes.
 
+config SPI_SPIDEV_AUTO
+       bool "Create spidev nodes for unclaimed chip selects"
+       depends on SPI_SPIDEV
+
 config SPI_TLE62X0
        tristate "Infineon TLE62X0 (for power switching)"
        depends on SYSFS
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index dee1cb87d24f..8c0294387e6d 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1654,6 +1654,34 @@ static void acpi_register_spi_devices(struct spi_master 
*master)
 static inline void acpi_register_spi_devices(struct spi_master *master) {}
 #endif /* CONFIG_ACPI */
 
+#ifdef CONFIG_SPI_SPIDEV_AUTO
+static void spidev_register_spi_devices(struct spi_master *master)
+{
+       struct spi_device *spi;
+       int err;
+       int i;
+
+       for (i = 0; i < master->num_chipselect; i++) {
+               spi = spi_alloc_device(master);
+               if (!spi)
+                       return;
+
+               strlcpy(spi->modalias, "spidev", sizeof(spi->modalias));
+               spi->chip_select = i;
+
+               err = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
+
+               if (!err)
+                       err = spi_add_device(spi);
+
+               if (err)
+                       spi_dev_put(spi);
+       }
+}
+#else
+static void spidev_register_spi_devices(struct spi_master *master) { }
+#endif
+
 static void spi_master_release(struct device *dev)
 {
        struct spi_master *master;
@@ -1849,6 +1877,7 @@ int spi_register_master(struct spi_master *master)
        /* Register devices from the device tree and ACPI */
        of_register_spi_devices(master);
        acpi_register_spi_devices(master);
+       spidev_register_spi_devices(master);
 done:
        return status;
 }
-- 
2.7.0

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