fbdev/metronomefb: Use struct fb_info.screen_buffer

Use info->screen_buffer when reading and writing framebuffers in
system memory. It's the correct pointer for this address space.

The struct fb_info has a union to store the framebuffer memory. This can
either be info->screen_base if the framebuffer is stored in I/O memory,
or info->screen_buffer if the framebuffer is stored in system memory.

As the driver operates on the latter address space, it is wrong to use
.screen_base and .screen_buffer must be used instead. This also gets
rid of casting needed due to not using the correct data type.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230428122452.4856-9-tzimmermann@suse.de

drivers/video/fbdev/metronomefb.c

@@ -438,7 +438,7 @@ static void metronomefb_dpy_update(struct metronomefb_par *par)
 {
 	int fbsize;
 	u16 cksum;
-	unsigned char *buf = (unsigned char __force *)par->info->screen_base;
+	unsigned char *buf = par->info->screen_buffer;
 
 	fbsize = par->info->fix.smem_len;
 	/* copy from vm to metromem */
@@ -453,7 +453,7 @@ static u16 metronomefb_dpy_update_page(struct metronomefb_par *par, int index)
 {
 	int i;
 	u16 csum = 0;
-	u16 *buf = (u16 __force *)(par->info->screen_base + index);
+	u16 *buf = (u16 *)(par->info->screen_buffer + index);
 	u16 *img = (u16 *)(par->metromem_img + index);
 
 	/* swizzle from vm to metromem and recalc cksum at the same time*/
@@ -543,7 +543,7 @@ static ssize_t metronomefb_write(struct fb_info *info, const char __user *buf,
 		count = total_size - p;
 	}
 
-	dst = (void __force *)(info->screen_base + p);
+	dst = info->screen_buffer + p;
 
 	if (copy_from_user(dst, buf, count))
 		err = -EFAULT;
@@ -599,7 +599,7 @@ static int metronomefb_probe(struct platform_device *dev)
 		goto err;
 
 	/* we have two blocks of memory.
-	info->screen_base which is vm, and is the fb used by apps.
+	info->screen_buffer which is vm, and is the fb used by apps.
 	par->metromem which is physically contiguous memory and
 	contains the display controller commands, waveform,
 	processed image data and padding. this is the data pulled
@@ -634,7 +634,7 @@ static int metronomefb_probe(struct platform_device *dev)
 	if (!videomemory)
 		goto err_fb_rel;
 
-	info->screen_base = (char __force __iomem *)videomemory;
+	info->screen_buffer = videomemory;
 	info->fbops = &metronomefb_ops;
 
 	metronomefb_fix.line_length = fw;
@@ -756,7 +756,7 @@ static int metronomefb_remove(struct platform_device *dev)
 		fb_dealloc_cmap(&info->cmap);
 		par->board->cleanup(par);
 		vfree(par->csum_table);
-		vfree((void __force *)info->screen_base);
+		vfree(info->screen_buffer);
 		module_put(par->board->owner);
 		dev_dbg(&dev->dev, "calling release\n");
 		framebuffer_release(info);