--- linux-5.10.64/drivers/firmware/raspberrypi.c	2021-09-29 23:19:57.006485785 +0200
+++ build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-5.10.69/drivers/firmware/raspberrypi.c	2021-09-29 23:26:45.117905773 +0200
@@ -7,6 +7,7 @@
  */

 #include <linux/dma-mapping.h>
+#include <linux/kref.h>
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
@@ -29,6 +30,8 @@
 	struct completion c;
 	u32 enabled;
 	u32 get_throttled;
+
+	struct kref consumers;
 };

 static struct platform_device *g_pdev;
@@ -340,12 +343,31 @@
 						-1, NULL, 0);
 }

+static void rpi_firmware_delete(struct kref *kref)
+{
+	struct rpi_firmware *fw = container_of(kref, struct rpi_firmware,
+					       consumers);
+
+	mbox_free_channel(fw->chan);
+	kfree(fw);
+}
+
+void rpi_firmware_put(struct rpi_firmware *fw)
+{
+	kref_put(&fw->consumers, rpi_firmware_delete);
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_put);
+
 static int rpi_firmware_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rpi_firmware *fw;

-	fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
+	/*
+	 * Memory will be freed by rpi_firmware_delete() once all users have
+	 * released their firmware handles. Don't use devm_kzalloc() here.
+	 */
+	fw = kzalloc(sizeof(*fw), GFP_KERNEL);
 	if (!fw)
 		return -ENOMEM;

@@ -362,6 +384,7 @@
 	}

 	init_completion(&fw->c);
+	kref_init(&fw->consumers);

 	platform_set_drvdata(pdev, fw);
 	g_pdev = pdev;
@@ -392,7 +415,9 @@
 	rpi_hwmon = NULL;
 	platform_device_unregister(rpi_clk);
 	rpi_clk = NULL;
-	mbox_free_channel(fw->chan);
+
+	rpi_firmware_put(fw);
+
 	g_pdev = NULL;

 	return 0;
@@ -402,16 +427,32 @@
  * rpi_firmware_get - Get pointer to rpi_firmware structure.
  * @firmware_node:    Pointer to the firmware Device Tree node.
  *
+ * The reference to rpi_firmware has to be released with rpi_firmware_put().
+ *
  * Returns NULL is the firmware device is not ready.
  */
 struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
 {
 	struct platform_device *pdev = g_pdev;
+	struct rpi_firmware *fw;

 	if (!pdev)
 		return NULL;

-	return platform_get_drvdata(pdev);
+	fw = platform_get_drvdata(pdev);
+	if (!fw)
+		goto err_put_device;
+
+	if (!kref_get_unless_zero(&fw->consumers))
+		goto err_put_device;
+
+	put_device(&pdev->dev);
+
+	return fw;
+
+err_put_device:
+	put_device(&pdev->dev);
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(rpi_firmware_get);