[PATCH v2 08/24] serdev: Provide modalias attribute for modalias devices

[Ricardo Ribalda Delgado]

Create modalias sysfs attribute for modalias devices.
This is required by modprobe/udev to autoload the serdev driver.

Eg:
root@qt5022:~# cat /sys/bus/serial/devices/serial1-0/modalias
serdev:ttydev

Cc: Rob Herring <r...@kernel.org>
Cc: Johan Hovold <jo...@kernel.org>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Jiri Slaby <jsl...@suse.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
---
 drivers/tty/serdev/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index 5df01d8cf307..b9bb0c0ee319 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -23,12 +23,17 @@ static ssize_t modalias_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
 {
        int len;
+       struct serdev_device *serdev = to_serdev_device(dev);
 
        len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
        if (len != -ENODEV)
                return len;
 
-       return of_device_modalias(dev, buf, PAGE_SIZE);
+       len = of_device_modalias(dev, buf, PAGE_SIZE);
+       if (len != -ENODEV)
+               return len;
+
+       return sprintf(buf, "%s%s\n", SERDEV_MODULE_PREFIX, serdev->modalias);
 }
 static DEVICE_ATTR_RO(modalias);
 
-- 
2.17.1