video: fbdev: vesafb: use arch_phys_wc_add()

This driver uses the same area for MTRR as for the ioremap_wc(), if
anything it just uses a smaller size in case MTRR reservation fails.
ioremap_wc() API is already used to take advantage of architecture
write-combining when available.

Convert the driver from using the x86 specific MTRR code to
the architecture agnostic arch_phys_wc_add(). arch_phys_wc_add()
will avoid MTRR if write-combining is available.

There are a few motivations for this:

a) Take advantage of PAT when available

b) Help bury MTRR code away, MTRR is architecture specific and on
x86 its replaced by PAT

c) Help with the goal of eventually using _PAGE_CACHE_UC over
_PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (see commit
de33c442e titled "x86 PAT: fix performance drop for glx,
use UC minus for ioremap(), ioremap_nocache() and
pci_mmap_page_range()")

The conversion done is expressed by the following Coccinelle
SmPL patch, it additionally required manual intervention to
address all the #ifdery and removal of redundant things which
arch_phys_wc_add() already addresses such as verbose message
about when MTRR fails and doing nothing when we didn't get
an MTRR.

@ mtrr_found @
expression index, base, size;
@@

-index = mtrr_add(base, size, MTRR_TYPE_WRCOMB, 1);
+index = arch_phys_wc_add(base, size);

@ mtrr_rm depends on mtrr_found @
expression mtrr_found.index, mtrr_found.base, mtrr_found.size;
@@

-mtrr_del(index, base, size);
+arch_phys_wc_del(index);

@ mtrr_rm_zero_arg depends on mtrr_found @
expression mtrr_found.index;
@@

-mtrr_del(index, 0, 0);
+arch_phys_wc_del(index);

@ mtrr_rm_fb_info depends on mtrr_found @
struct fb_info *info;
expression mtrr_found.index;
@@

-mtrr_del(index, info->fix.smem_start, info->fix.smem_len);
+arch_phys_wc_del(index);

@ ioremap_replace_nocache depends on mtrr_found @
struct fb_info *info;
expression base, size;
@@

-info->screen_base = ioremap_nocache(base, size);
+info->screen_base = ioremap_wc(base, size);

@ ioremap_replace_default depends on mtrr_found @
struct fb_info *info;
expression base, size;
@@

-info->screen_base = ioremap(base, size);
+info->screen_base = ioremap_wc(base, size);

Generated-by: Coccinelle SmPL
Cc: Toshi Kani <[e-mail]>
Cc: Suresh Siddha <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Juergen Gross <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: Jean-Christophe Plagniol-Villard <[e-mail]>
Cc: Rob Clark <[e-mail]>
Cc: Jingoo Han <[e-mail]>
Cc: Wolfram Sang <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Luis R. Rodriguez <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/video/fbdev/vesafb.c

···
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
+#include <linux/io.h>
 
 #include <video/vga.h>
-#include <asm/io.h>
-#include <asm/mtrr.h>
 
 #define dac_reg	(0x3c8)
 #define dac_val	(0x3c9)
···
 
 static void vesafb_destroy(struct fb_info *info)
 {
-#ifdef CONFIG_MTRR
 	struct vesafb_par *par = info->par;
-#endif
 
 	fb_dealloc_cmap(&info->cmap);
-
-#ifdef CONFIG_MTRR
-	if (par->wc_cookie >= 0)
-		mtrr_del(par->wc_cookie, 0, 0);
-#endif
+	arch_phys_wc_del(par->wc_cookie);
 	if (info->screen_base)
 		iounmap(info->screen_base);
 	release_mem_region(info->apertures->ranges[0].base, info->apertures->ranges[0].size);
···
 	request_region(0x3c0, 32, "vesafb");
 
 	if (mtrr == 3) {
-#ifdef CONFIG_MTRR
 		unsigned int temp_size = size_total;
 
 		/* Find the largest power-of-two */
···
 
 		/* Try and find a power of two to add */
 		do {
-			par->wc_cookie = mtrr_add(vesafb_fix.smem_start,
-						  temp_size,
-						  MTRR_TYPE_WRCOMB, 1);
+			par->wc_cookie =
+				arch_phys_wc_add(vesafb_fix.smem_start,
+						 temp_size);
 			temp_size >>= 1;
-		} while (temp_size >= PAGE_SIZE && par->wc_cookie == -EINVAL);
-#endif
+		} while (temp_size >= PAGE_SIZE && par->wc_cookie < 0);
+
 		info->screen_base = ioremap_wc(vesafb_fix.smem_start, vesafb_fix.smem_len);
 	} else {
-#ifdef CONFIG_MTRR
 		if (mtrr && mtrr != 3)
 			WARN_ONCE(1, "Only MTRR_TYPE_WRCOMB (3) make sense\n");
-#endif
 		info->screen_base = ioremap(vesafb_fix.smem_start, vesafb_fix.smem_len);
 	}
 
···
 	fb_info(info, "%s frame buffer device\n", info->fix.id);
 	return 0;
 err:
-#ifdef CONFIG_MTRR
-	if (par->wc_cookie >= 0)
-		mtrr_del(par->wc_cookie, 0, 0);
-#endif
+	arch_phys_wc_del(par->wc_cookie);
 	if (info->screen_base)
 		iounmap(info->screen_base);
 	framebuffer_release(info);