linux-kernel - [RFC v2 08/39] drm: handle HAS

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Message-Id: <20220429135108.2781579-16-schnelle@linux.ibm.com>
Date:   Fri, 29 Apr 2022 15:50:13 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-pci@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        Dave Airlie <airlied@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        virtualization@...ts.linux-foundation.org (open list:DRM DRIVER FOR QXL
        VIRTUAL GPU),
        spice-devel@...ts.freedesktop.org (open list:DRM DRIVER FOR QXL VIRTUAL
        GPU), dri-devel@...ts.freedesktop.org (open list:DRM DRIVERS)
Subject: [RFC v2 08/39] drm: handle HAS_IOPORT dependencies

In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
not being declared. 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 <arnd@...nel.org>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
 drivers/gpu/drm/qxl/Kconfig   |  1 +
 drivers/gpu/drm/tiny/bochs.c  | 19 +++++++++++++++++++
 drivers/gpu/drm/tiny/cirrus.c |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
index ca3f51c2a8fe..d0e0d440c8d9 100644
--- a/drivers/gpu/drm/qxl/Kconfig
+++ b/drivers/gpu/drm/qxl/Kconfig
@@ -2,6 +2,7 @@
 config DRM_QXL
 	tristate "QXL virtual GPU"
 	depends on DRM && PCI && MMU
+	depends on HAS_IOPORT
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	select DRM_TTM_HELPER
diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index ed971c8bb446..9acc726d99ec 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <asm/bug.h>
 #include <linux/pci.h>
 
 #include <drm/drm_aperture.h>
@@ -102,7 +103,11 @@ static void bochs_vga_writeb(struct bochs_device *bochs, u16 ioport, u8 val)
 
 		writeb(val, bochs->mmio + offset);
 	} else {
+#ifdef HAS_IOPORT
 		outb(val, ioport);
+#else
+		WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
+#endif
 	}
 }
 
@@ -116,7 +121,12 @@ static u8 bochs_vga_readb(struct bochs_device *bochs, u16 ioport)
 
 		return readb(bochs->mmio + offset);
 	} else {
+#ifdef HAS_IOPORT
 		return inb(ioport);
+#else
+		WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
+		return 0xff;
+#endif
 	}
 }
 
@@ -129,8 +139,13 @@ static u16 bochs_dispi_read(struct bochs_device *bochs, u16 reg)
 
 		ret = readw(bochs->mmio + offset);
 	} else {
+#ifdef HAS_IOPORT
 		outw(reg, VBE_DISPI_IOPORT_INDEX);
 		ret = inw(VBE_DISPI_IOPORT_DATA);
+#else
+		WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
+		ret = 0xffff;
+#endif
 	}
 	return ret;
 }
@@ -142,8 +157,12 @@ static void bochs_dispi_write(struct bochs_device *bochs, u16 reg, u16 val)
 
 		writew(val, bochs->mmio + offset);
 	} else {
+#ifdef HAS_IOPORT
 		outw(reg, VBE_DISPI_IOPORT_INDEX);
 		outw(val, VBE_DISPI_IOPORT_DATA);
+#else
+		WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
+#endif
 	}
 }
 
diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index c8e791840862..0dc4788c5399 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -306,8 +306,10 @@ static int cirrus_mode_set(struct cirrus_device *cirrus,
 
 	cirrus_set_start_address(cirrus, 0);
 
+#ifdef CONFIG_HAS_IOPORT
 	/* Unblank (needed on S3 resume, vgabios doesn't do it then) */
 	outb(0x20, 0x3c0);
+#endif
 
 	drm_dev_exit(idx);
 	return 0;
-- 
2.32.0