linux-kernel - [PATCH v3 12/14] intel_gna: add a 'misc' device

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Date:   Thu, 13 May 2021 13:00:38 +0200
From:   Maciej Kwapulinski <maciej.kwapulinski@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Maciej Kwapulinski <maciej.kwapulinski@...ux.intel.com>,
        Savo Novakovic <savox.novakovic@...el.com>
Subject: [PATCH v3 12/14] intel_gna: add a 'misc' device

The new 'misc' device is the node for applications in user space to
interact with the driver.

Signed-off-by: Maciej Kwapulinski <maciej.kwapulinski@...ux.intel.com>
Tested-by: Savo Novakovic <savox.novakovic@...el.com>
---
 drivers/misc/intel/gna/device.c | 52 +++++++++++++++++++++++++++++++--
 drivers/misc/intel/gna/device.h | 11 +++----
 2 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/intel/gna/device.c b/drivers/misc/intel/gna/device.c
index 0e31b8c6bb70..1e6345a8325b 100644
--- a/drivers/misc/intel/gna/device.c
+++ b/drivers/misc/intel/gna/device.c
@@ -20,6 +20,18 @@ module_param(recovery_timeout, int, 0644);
 MODULE_PARM_DESC(recovery_timeout, "Recovery timeout in seconds");
 #endif
 
+struct file;
+
+static int gna_open(struct inode *inode, struct file *f)
+{
+	return -EPERM;
+}
+
+static const struct file_operations gna_file_ops = {
+	.owner		=	THIS_MODULE,
+	.open		=	gna_open,
+};
+
 static void gna_devm_idr_destroy(void *data)
 {
 	struct idr *idr = data;
@@ -27,6 +39,36 @@ static void gna_devm_idr_destroy(void *data)
 	idr_destroy(idr);
 }
 
+static void gna_devm_deregister_misc_dev(void *data)
+{
+	struct miscdevice *misc = data;
+
+	misc_deregister(misc);
+}
+
+static int gna_devm_register_misc_dev(struct device *parent, struct miscdevice *misc)
+{
+	int ret;
+
+	ret = misc_register(misc);
+	if (ret) {
+		dev_err(parent, "misc device %s registering failed. errcode: %d\n",
+			misc->name, ret);
+		gna_devm_deregister_misc_dev(misc);
+	} else {
+		dev_dbg(parent, "device: %s registered\n",
+			misc->name);
+	}
+
+	ret = devm_add_action(parent, gna_devm_deregister_misc_dev, misc);
+	if (ret) {
+		dev_err(parent, "could not add devm action for %s misc deregister\n", misc->name);
+		gna_devm_deregister_misc_dev(misc);
+	}
+
+	return ret;
+}
+
 static irqreturn_t gna_interrupt(int irq, void *priv)
 {
 	struct gna_private *gna_priv;
@@ -81,13 +123,13 @@ int gna_probe(struct device *parent, struct gna_dev_info *dev_info, void __iomem
 	gna_priv->recovery_timeout_jiffies = msecs_to_jiffies(recovery_timeout * 1000);
 	gna_priv->iobase = iobase;
 	gna_priv->info = *dev_info;
-	gna_priv->parent = parent;
+	gna_priv->misc.parent = parent;
 
 	dev_misc_name = devm_kasprintf(parent, GFP_KERNEL, "%s%d", GNA_DV_NAME, gna_priv->index);
 	if (!dev_misc_name)
 		return -ENOMEM;
 
-	gna_priv->name = dev_misc_name;
+	gna_priv->misc.name = dev_misc_name;
 
 	if (!(sizeof(dma_addr_t) > 4) ||
 		dma_set_mask(parent, DMA_BIT_MASK(64))) {
@@ -145,7 +187,11 @@ int gna_probe(struct device *parent, struct gna_dev_info *dev_info, void __iomem
 		return ret;
 	}
 
-	return 0;
+	gna_priv->misc.minor = MISC_DYNAMIC_MINOR;
+	gna_priv->misc.fops = &gna_file_ops;
+	gna_priv->misc.mode = 0666;
+
+	return gna_devm_register_misc_dev(parent, &gna_priv->misc);
 }
 
 static u32 gna_device_type_by_hwid(u32 hwid)
diff --git a/drivers/misc/intel/gna/device.h b/drivers/misc/intel/gna/device.h
index 75784882f57c..ea3caf679c77 100644
--- a/drivers/misc/intel/gna/device.h
+++ b/drivers/misc/intel/gna/device.h
@@ -8,6 +8,7 @@
 #include <linux/idr.h>
 #include <linux/io.h>
 #include <linux/list.h>
+#include <linux/miscdevice.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
 
@@ -41,8 +42,8 @@ struct gna_private {
 
 	int recovery_timeout_jiffies;
 
-	const char *name;
-	struct device *parent;
+	/* gna misc-device */
+	struct miscdevice misc;
 
 	/* hardware status set by interrupt handler */
 	u32 hw_status;
@@ -86,17 +87,17 @@ static inline void gna_reg_write(struct gna_private *gna_priv, u32 reg, u32 val)
 
 static inline struct device *gna_parent(struct gna_private *gna_priv)
 {
-	return gna_priv->parent;
+	return gna_priv->misc.parent;
 }
 
 static inline const char *gna_name(struct gna_private *gna_priv)
 {
-	return gna_priv->name;
+	return gna_priv->misc.name;
 }
 
 static inline struct device *gna_dev(struct gna_private *gna_priv)
 {
-	return gna_priv->parent;
+	return gna_priv->misc.this_device;
 }
 
 #endif /* __GNA_DEVICE_H__ */
-- 
2.28.0