drm/mali-dp: Add core_id file to the sysfs interface

Add a core_id file in the driver's sysfs directory,
exposing the hardware CORE ID. This is useful to allow
userspace to discover the hardware version used.
Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

drivers/gpu/drm/arm/malidp_drv.c

@@ -371,6 +371,32 @@ static bool malidp_has_sufficient_address_space(const struct resource *res,
 	return true;
 }
 
+static ssize_t core_id_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+	struct malidp_drm *malidp = drm->dev_private;
+
+	return snprintf(buf, PAGE_SIZE, "%08x\n", malidp->core_id);
+}
+
+DEVICE_ATTR_RO(core_id);
+
+static int malidp_init_sysfs(struct device *dev)
+{
+	int ret = device_create_file(dev, &dev_attr_core_id);
+
+	if (ret)
+		DRM_ERROR("failed to create device file for core_id\n");
+
+	return ret;
+}
+
+static void malidp_fini_sysfs(struct device *dev)
+{
+	device_remove_file(dev, &dev_attr_core_id);
+}
+
 #define MAX_OUTPUT_CHANNELS	3
 
 static int malidp_runtime_pm_suspend(struct device *dev)
@@ -503,6 +529,8 @@ static int malidp_bind(struct device *dev)
 	DRM_INFO("found ARM Mali-DP%3x version r%dp%d\n", version >> 16,
 		 (version >> 12) & 0xf, (version >> 8) & 0xf);
 
+	malidp->core_id = version;
+
 	/* set the number of lines used for output of RGB data */
 	ret = of_property_read_u8_array(dev->of_node,
 					"arm,malidp-output-port-lines",
@@ -521,6 +549,10 @@ static int malidp_bind(struct device *dev)
 	if (ret < 0)
 		goto query_hw_fail;
 
+	ret = malidp_init_sysfs(dev);
+	if (ret)
+		goto init_fail;
+
 	/* Set the CRTC's port so that the encoder component can find it */
 	malidp->crtc.port = of_graph_get_port_by_id(dev->of_node, 0);
 
@@ -580,6 +612,8 @@ static int malidp_bind(struct device *dev)
 bind_fail:
 	of_node_put(malidp->crtc.port);
 	malidp->crtc.port = NULL;
+init_fail:
+	malidp_fini_sysfs(dev);
 	malidp_fini(drm);
 query_hw_fail:
 	pm_runtime_put(dev);
@@ -614,6 +648,7 @@ static void malidp_unbind(struct device *dev)
 	component_unbind_all(dev, drm);
 	of_node_put(malidp->crtc.port);
 	malidp->crtc.port = NULL;
+	malidp_fini_sysfs(dev);
 	malidp_fini(drm);
 	pm_runtime_put(dev);
 	if (pm_runtime_enabled(dev))

drivers/gpu/drm/arm/malidp_drv.h

@@ -25,6 +25,7 @@ struct malidp_drm {
 	wait_queue_head_t wq;
 	atomic_t config_valid;
 	struct drm_atomic_state *pm_state;
+	u32 core_id;
 };
 
 #define crtc_to_malidp_device(x) container_of(x, struct malidp_drm, crtc)