drm: handle HAS_IOPORT dependencies

In a future patch HAS_IOPORT=n will disable inb()/outb() and friends at
compile time. We thus need to add HAS_IOPORT as dependency for those
drivers using them. In the bochs driver there is optional MMIO support
detected at runtime, warn if this isn't taken when HAS_IOPORT is not
defined.

There is also a direct and hard coded use in cirrus.c which according to
the comment is only necessary during resume. Let's just skip this as
for example s390 which doesn't have I/O port support also doesen't
support suspend/resume.

Co-developed-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Acked-by: Lucas De Marchi <[e-mail]> # xe
Signed-off-by: Niklas Schnelle <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>

drivers/gpu/drm/gma500/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
 config DRM_GMA500
 	tristate "Intel GMA500/600/3600/3650 KMS Framebuffer"
-	depends on DRM && PCI && X86 && MMU
+	depends on DRM && PCI && X86 && MMU && HAS_IOPORT
 	select DRM_KMS_HELPER
 	select FB_IOMEM_HELPERS if DRM_FBDEV_EMULATION
 	select I2C

drivers/gpu/drm/qxl/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
 config DRM_QXL
 	tristate "QXL virtual GPU"
-	depends on DRM && PCI && MMU
+	depends on DRM && PCI && MMU && HAS_IOPORT
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	select DRM_TTM_HELPER

drivers/gpu/drm/tiny/bochs.c

···
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <linux/bug.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 
···
 
 /* ---------------------------------------------------------------------- */
 
+static __always_inline bool bochs_uses_mmio(struct bochs_device *bochs)
+{
+	return !IS_ENABLED(CONFIG_HAS_IOPORT) || bochs->mmio;
+}
+
 static void bochs_vga_writeb(struct bochs_device *bochs, u16 ioport, u8 val)
 {
 	if (WARN_ON(ioport < 0x3c0 || ioport > 0x3df))
 		return;
 
-	if (bochs->mmio) {
+	if (bochs_uses_mmio(bochs)) {
 		int offset = ioport - 0x3c0 + 0x400;
 
 		writeb(val, bochs->mmio + offset);
···
 	if (WARN_ON(ioport < 0x3c0 || ioport > 0x3df))
 		return 0xff;
 
-	if (bochs->mmio) {
+	if (bochs_uses_mmio(bochs)) {
 		int offset = ioport - 0x3c0 + 0x400;
 
 		return readb(bochs->mmio + offset);
···
 {
 	u16 ret = 0;
 
-	if (bochs->mmio) {
+	if (bochs_uses_mmio(bochs)) {
 		int offset = 0x500 + (reg << 1);
 
 		ret = readw(bochs->mmio + offset);
···
 
 static void bochs_dispi_write(struct bochs_device *bochs, u16 reg, u16 val)
 {
-	if (bochs->mmio) {
+	if (bochs_uses_mmio(bochs)) {
 		int offset = 0x500 + (reg << 1);
 
 		writew(val, bochs->mmio + offset);
···
 			DRM_ERROR("Cannot map mmio region\n");
 			return -ENOMEM;
 		}
-	} else {
+	} else if (IS_ENABLED(CONFIG_HAS_IOPORT)) {
 		ioaddr = VBE_DISPI_IOPORT_INDEX;
 		iosize = 2;
 		if (!request_region(ioaddr, iosize, "bochs-drm")) {
···
 			return -EBUSY;
 		}
 		bochs->ioports = 1;
+	} else {
+		dev_err(dev->dev, "I/O ports are not supported\n");
+		return -EIO;
 	}
 
 	id = bochs_dispi_read(bochs, VBE_DISPI_INDEX_ID);

drivers/gpu/drm/tiny/cirrus.c

···
 
 	cirrus_mode_set(cirrus, &crtc_state->mode);
 
+#ifdef CONFIG_HAS_IOPORT
 	/* Unblank (needed on S3 resume, vgabios doesn't do it then) */
 	outb(VGA_AR_ENABLE_DISPLAY, VGA_ATT_W);
+#endif
 
 	drm_dev_exit(idx);
 }

drivers/gpu/drm/xe/Kconfig

···
 
 config DRM_XE_DISPLAY
 	bool "Enable display support"
-	depends on DRM_XE && DRM_XE=m
+	depends on DRM_XE && DRM_XE=m && HAS_IOPORT
 	select FB_IOMEM_HELPERS
 	select I2C
 	select I2C_ALGOBIT