Use minor number for device node

Allocate a range of minor numbers and use the minor number as index
when creating the /dev/ethosu<nr> device node.

Change-Id: I76c2a3995ff5087e42a4e95945eb884a4bfb58f6

3 files changed, 41 insertions, 21 deletions

diff --git a/kernel/ethosu_device.c b/kernel/ethosu_device.c
index 40b214c..13c30f6 100644
--- a/kernel/ethosu_device.c
+++ b/kernel/ethosu_device.c
@@ -44,8 +44,6 @@
  * Defines
  ****************************************************************************/
 
-#define MINOR_VERSION  0 /* Minor version starts at 0 */
-#define MINOR_COUNT    1 /* Allocate 1 minor version */
 #define DMA_ADDR_BITS 32 /* Number of address bits */
 
 #define CAPABILITIES_RESP_TIMEOUT_MS 100
@@ -397,6 +395,7 @@ static void ethosu_mbox_rx(void *user_arg)
 int ethosu_dev_init(struct ethosu_device *edev,
 		    struct device *dev,
 		    struct class *class,
+		    dev_t devt,
 		    struct resource *in_queue,
 		    struct resource *out_queue)
 {
@@ -413,6 +412,7 @@ int ethosu_dev_init(struct ethosu_device *edev,
 
 	edev->dev = dev;
 	edev->class = class;
+	edev->devt = devt;
 	mutex_init(&edev->mutex);
 	INIT_LIST_HEAD(&edev->capabilities_list);
 	INIT_LIST_HEAD(&edev->inference_list);
@@ -428,24 +428,17 @@ int ethosu_dev_init(struct ethosu_device *edev,
 	if (ret)
 		goto release_reserved_mem;
 
-	ret = alloc_chrdev_region(&edev->devt, MINOR_VERSION, MINOR_COUNT,
-				  "ethosu");
-	if (ret) {
-		dev_err(edev->dev, "Failed to allocate chrdev region.\n");
-		goto deinit_mailbox;
-	}
-
 	cdev_init(&edev->cdev, &fops);
 	edev->cdev.owner = THIS_MODULE;
 
-	ret = cdev_add(&edev->cdev, edev->devt, MINOR_COUNT);
+	ret = cdev_add(&edev->cdev, edev->devt, 1);
 	if (ret) {
 		dev_err(edev->dev, "Failed to add character device.\n");
-		goto region_unregister;
+		goto deinit_mailbox;
 	}
 
 	sysdev = device_create(edev->class, NULL, edev->devt, edev,
-			       "ethosu%d", MAJOR(edev->devt));
+			       "ethosu%d", MINOR(edev->devt));
 	if (IS_ERR(sysdev)) {
 		dev_err(edev->dev, "Failed to create device.\n");
 		ret = PTR_ERR(sysdev);
@@ -461,9 +454,6 @@ int ethosu_dev_init(struct ethosu_device *edev,
 del_cdev:
 	cdev_del(&edev->cdev);
 
-region_unregister:
-	unregister_chrdev_region(edev->devt, 1);
-
 deinit_mailbox:
 	ethosu_mailbox_deinit(&edev->mailbox);
 
@@ -478,7 +468,6 @@ void ethosu_dev_deinit(struct ethosu_device *edev)
 	ethosu_mailbox_deinit(&edev->mailbox);
 	device_destroy(edev->class, edev->cdev.dev);
 	cdev_del(&edev->cdev);
-	unregister_chrdev_region(edev->devt, MINOR_COUNT);
 	of_reserved_mem_device_release(edev->dev);
 
 	dev_info(edev->dev, "%s\n", __FUNCTION__);
diff --git a/kernel/ethosu_device.h b/kernel/ethosu_device.h
index 0722814..3afdda8 100644
--- a/kernel/ethosu_device.h
+++ b/kernel/ethosu_device.h
@@ -76,6 +76,7 @@ struct ethosu_capabilities {
 int ethosu_dev_init(struct ethosu_device *edev,
 		    struct device *dev,
 		    struct class *class,
+		    dev_t devt,
 		    struct resource *in_queue,
 		    struct resource *out_queue);
 
diff --git a/kernel/ethosu_driver.c b/kernel/ethosu_driver.c
index 3fc752b..9d02431 100644
--- a/kernel/ethosu_driver.c
+++ b/kernel/ethosu_driver.c
@@ -18,6 +18,8 @@
  * SPDX-License-Identifier: GPL-2.0-only
  */
 
+#include <linux/bitmap.h>
+#include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/of.h>
@@ -33,11 +35,18 @@
 #define ETHOSU_DRIVER_VERSION "1.0"
 #define ETHOSU_DRIVER_NAME    "ethosu"
 
+#define MINOR_BASE      0 /* Minor version starts at 0 */
+#define MINOR_COUNT    64 /* Allocate minor versions */
+
 /****************************************************************************
  * Variables
  ****************************************************************************/
 
-struct class *ethosu_class;
+static struct class *ethosu_class;
+
+static dev_t devt;
+
+static DECLARE_BITMAP(minors, MINOR_COUNT);
 
 /****************************************************************************
  * Arm Ethos-U
@@ -48,10 +57,18 @@ static int ethosu_pdev_probe(struct platform_device *pdev)
 	struct ethosu_device *edev;
 	struct resource *in_queue_res;
 	struct resource *out_queue_res;
+	int minor;
 	int ret;
 
 	dev_info(&pdev->dev, "Probe\n");
 
+	minor = find_first_zero_bit(minors, MINOR_COUNT);
+	if (minor >= MINOR_COUNT) {
+		dev_err(&pdev->dev, "No more minor numbers.\n");
+
+		return -ENOMEM;
+	}
+
 	/* Get path to TCM memory */
 	in_queue_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 						    "in_queue");
@@ -77,11 +94,14 @@ static int ethosu_pdev_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, edev);
 
 	/* Initialize device */
-	ret = ethosu_dev_init(edev, &pdev->dev, ethosu_class, in_queue_res,
+	ret = ethosu_dev_init(edev, &pdev->dev, ethosu_class,
+			      MKDEV(MAJOR(devt), minor), in_queue_res,
 			      out_queue_res);
 	if (ret)
 		goto free_dev;
 
+	set_bit(minor, minors);
+
 	return 0;
 
 free_dev:
@@ -94,8 +114,7 @@ static int ethosu_pdev_remove(struct platform_device *pdev)
 {
 	struct ethosu_device *edev = platform_get_drvdata(pdev);
 
-	dev_info(&pdev->dev, "Remove\n");
-
+	clear_bit(MINOR(edev->devt), minors);
 	ethosu_dev_deinit(edev);
 
 	return 0;
@@ -133,14 +152,24 @@ static int __init ethosu_init(void)
 		return PTR_ERR(ethosu_class);
 	}
 
+	ret = alloc_chrdev_region(&devt, MINOR_BASE, MINOR_COUNT,
+				  ETHOSU_DRIVER_NAME);
+	if (ret) {
+		printk("Failed to allocate chrdev region.\n");
+		goto destroy_class;
+	}
+
 	ret = platform_driver_register(&ethosu_pdev_driver);
 	if (ret) {
 		printk("Failed to register Arm Ethos-U platform driver.\n");
-		goto destroy_class;
+		goto region_unregister;
 	}
 
 	return 0;
 
+region_unregister:
+	unregister_chrdev_region(devt, MINOR_COUNT);
+
 destroy_class:
 	class_destroy(ethosu_class);
 
@@ -150,6 +179,7 @@ destroy_class:
 static void __exit ethosu_exit(void)
 {
 	platform_driver_unregister(&ethosu_pdev_driver);
+	unregister_chrdev_region(devt, MINOR_COUNT);
 	class_destroy(ethosu_class);
 }