drm/tilcdc: request and mapp iomem with devres

tilcdc currently just ioremaps its iomem, without doing the (a bit more
robust) request on the memory first. The devm_ functions provide a handy
way to both request and ioremap the memory with automatic cleanup.

Replace the manual ioremap with the devm_ version.
Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: Jyri Sarha <jyri.sarha@iki.fi>
Tested-by: Jyri Sarha <jyri.sarha@iki.fi>
Signed-off-by: Jyri Sarha <jyri.sarha@iki.fi>
Link: https://patchwork.freedesktop.org/patch/msgid/20231222115216.19218-2-pstanner@redhat.com

drivers/gpu/drm/tilcdc/tilcdc_drv.c

@@ -182,9 +182,6 @@ static void tilcdc_fini(struct drm_device *dev)
 	if (priv->clk)
 		clk_put(priv->clk);
 
-	if (priv->mmio)
-		iounmap(priv->mmio);
-
 	if (priv->wq)
 		destroy_workqueue(priv->wq);
 
@@ -201,7 +198,6 @@ static int tilcdc_init(const struct drm_driver *ddrv, struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct device_node *node = dev->of_node;
 	struct tilcdc_drm_private *priv;
-	struct resource *res;
 	u32 bpp = 0;
 	int ret;
 
@@ -226,17 +222,10 @@ static int tilcdc_init(const struct drm_driver *ddrv, struct device *dev)
 		goto init_failed;
 	}
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res) {
-		dev_err(dev, "failed to get memory resource\n");
-		ret = -EINVAL;
-		goto init_failed;
-	}
-
-	priv->mmio = ioremap(res->start, resource_size(res));
-	if (!priv->mmio) {
-		dev_err(dev, "failed to ioremap\n");
-		ret = -ENOMEM;
+	priv->mmio = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->mmio)) {
+		dev_err(dev, "failed to request / ioremap\n");
+		ret = PTR_ERR(priv->mmio);
 		goto init_failed;
 	}