From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Add modlias support to serdev so that the serdev client driver can be
autoloaded by udev when the serdev client device gets created.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/tty/serdev/core.c       | 15 +++++++++++----
 include/linux/mod_devicetable.h |  1 +
 scripts/mod/file2alias.c        |  8 ++++++++
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index f90095cb778f..8c2a40a537d9 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -34,7 +34,11 @@ static ssize_t modalias_show(struct device *dev,
 	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 sysfs_emit(buf, SERDEV_DEVICE_MODALIAS_FMT "\n", dev_name(dev));
 }
 static DEVICE_ATTR_RO(modalias);
 
@@ -48,13 +52,16 @@ static int serdev_device_uevent(const struct device *dev, struct kobj_uevent_env
 {
 	int rc;
 
-	/* TODO: platform modalias */
-
 	rc = acpi_device_uevent_modalias(dev, env);
 	if (rc != -ENODEV)
 		return rc;
 
-	return of_device_uevent_modalias(dev, env);
+	rc = of_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
+
+	return add_uevent_var(env, "MODALIAS=" SERDEV_DEVICE_MODALIAS_FMT,
+					dev_name(dev));
 }
 
 static void serdev_device_release(struct device *dev)
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 70c54c4bedba..dad9637cf285 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -976,6 +976,7 @@ struct coreboot_device_id {
 	kernel_ulong_t driver_data;
 };
 
+#define SERDEV_DEVICE_MODALIAS_FMT "serdev:%s"
 #define SERDEV_NAME_SIZE 32
 
 struct serdev_device_id {
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index b3333560b95e..27e9f7c718c4 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1371,6 +1371,13 @@ static void do_coreboot_entry(struct module *mod, void *symval)
 	module_alias_printf(mod, false, "coreboot:t%08X", tag);
 }
 
+/* Looks like: serdev:S */
+static void do_serdev_entry(struct module *mod, void *symval)
+{
+	DEF_FIELD_ADDR(symval, serdev_device_id, name);
+	module_alias_printf(mod, false, SERDEV_DEVICE_MODALIAS_FMT, *name);
+}
+
 /* Does namelen bytes of name exactly match the symbol? */
 static bool sym_is(const char *name, unsigned namelen, const char *symbol)
 {
@@ -1467,6 +1474,7 @@ static const struct devtable devtable[] = {
 	{"usb", SIZE_usb_device_id, do_usb_entry_multi},
 	{"pnp", SIZE_pnp_device_id, do_pnp_device_entry},
 	{"pnp_card", SIZE_pnp_card_device_id, do_pnp_card_entry},
+	{"serdev", SIZE_serdev_device_id, do_serdev_entry},
 };
 
 /* Create MODULE_ALIAS() statements.

-- 
2.48.1