[PATCH 5/8] platform/chrome: cros_ec_chardev: Introduce chardev_data

[Tzung-Bi Shih]

Introduce struct chardev_pdata to hold platform driver data.

The platform driver data is allocated by kzalloc() instead of devm
variant, allowing for managed cleanup that can eventually extend beyond
device removal if files are still open.

Signed-off-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
---
 drivers/platform/chrome/cros_ec_chardev.c | 51 +++++++++++++++++------
 1 file changed, 39 insertions(+), 12 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
index 002be3352100..e7012e44a006 100644
--- a/drivers/platform/chrome/cros_ec_chardev.c
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/fs.h>
+#include <linux/kref.h>
 #include <linux/miscdevice.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
@@ -31,6 +32,21 @@
 /* Arbitrary bounded size for the event queue */
 #define CROS_MAX_EVENT_LEN	PAGE_SIZE
 
+/*
+ * Platform device driver data.
+ */
+struct chardev_pdata {
+	struct miscdevice misc;
+	struct kref kref;
+};
+
+static void chardev_pdata_release(struct kref *kref)
+{
+	struct chardev_pdata *pdata = container_of(kref, typeof(*pdata), kref);
+
+	kfree(pdata);
+}
+
 struct chardev_priv {
 	struct cros_ec_device *ec_dev;
 	struct notifier_block notifier;
@@ -374,28 +390,39 @@ static int cros_ec_chardev_probe(struct platform_device *pdev)
 {
 	struct cros_ec_dev *ec = dev_get_drvdata(pdev->dev.parent);
 	struct cros_ec_platform *ec_platform = dev_get_platdata(ec->dev);
-	struct miscdevice *misc;
+	struct chardev_pdata *pdata;
+	int ret;
 
-	/* Create a char device: we want to create it anew */
-	misc = devm_kzalloc(&pdev->dev, sizeof(*misc), GFP_KERNEL);
-	if (!misc)
+	pdata = kzalloc_obj(*pdata);
+	if (!pdata)
 		return -ENOMEM;
 
-	misc->minor = MISC_DYNAMIC_MINOR;
-	misc->fops = &chardev_fops;
-	misc->name = ec_platform->ec_name;
-	misc->parent = pdev->dev.parent;
+	platform_set_drvdata(pdev, pdata);
+	kref_init(&pdata->kref);
 
-	dev_set_drvdata(&pdev->dev, misc);
+	pdata->misc.minor = MISC_DYNAMIC_MINOR;
+	pdata->misc.fops = &chardev_fops;
+	pdata->misc.name = ec_platform->ec_name;
+	pdata->misc.parent = pdev->dev.parent;
 
-	return misc_register(misc);
+	ret = misc_register(&pdata->misc);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register misc device\n");
+		goto err_put_pdata;
+	}
+
+	return 0;
+err_put_pdata:
+	kref_put(&pdata->kref, chardev_pdata_release);
+	return ret;
 }
 
 static void cros_ec_chardev_remove(struct platform_device *pdev)
 {
-	struct miscdevice *misc = dev_get_drvdata(&pdev->dev);
+	struct chardev_pdata *pdata = platform_get_drvdata(pdev);
 
-	misc_deregister(misc);
+	misc_deregister(&pdata->misc);
+	kref_put(&pdata->kref, chardev_pdata_release);
 }
 
 static const struct platform_device_id cros_ec_chardev_id[] = {
-- 
2.51.0