linux-kernel - [PATCH RESEND] firmware: qemu_fw_cfg: Do not hard depend on CONFIG_HAS_IOPORT

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Message-ID: <20250616161408.26748-1-tiwai@suse.de>
Date: Mon, 16 Jun 2025 18:14:06 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Gabriel Somlo <somlo@....edu>,
	"Michael S . Tsirkin" <mst@...hat.com>
Cc: Fabian Vogt <fvogt@...e.de>,
	linux-kernel@...r.kernel.org,
	qemu-devel@...gnu.org
Subject: [PATCH RESEND] firmware: qemu_fw_cfg: Do not hard depend on CONFIG_HAS_IOPORT_MAP

From: Fabian Vogt <fvogt@...e.de>

Some platforms require CONFIG_NO_IOPORT_MAP=y but would also support
qemu_fw_cfg over MMIO. Currently the qemu_fw_cfg module can't be built for
those as it needs HAS_IOPORT_MAP=y for ioport remapping.

This patch allows to build the qemu_fw_cfg in those cases. If
CONFIG_HAS_IOPORT_MAP=n, qemu_fw_cfg is built without support for ioport
based access.

Signed-off-by: Fabian Vogt <fvogt@...e.de>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---

Resent, as the original submission seems overlooked:
 https://lore.kernel.org/2294036.ElGaqSPkdT@linux-e202.suse.de/
The patch has been on openSUSE / SUSE kernels already for years.

 drivers/firmware/Kconfig       | 1 -
 drivers/firmware/qemu_fw_cfg.c | 5 +++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index bbd2155d8483..91442f85f0f0 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -122,7 +122,6 @@ config RASPBERRYPI_FIRMWARE
 config FW_CFG_SYSFS
 	tristate "QEMU fw_cfg device support in sysfs"
 	depends on SYSFS && (ARM || ARM64 || PARISC || PPC_PMAC || RISCV || SPARC || X86)
-	depends on HAS_IOPORT_MAP
 	default n
 	help
 	  Say Y or M here to enable the exporting of the QEMU firmware
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 2615fb780e3c..e15116f84a70 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -258,6 +258,7 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 			return -EFAULT;
 		}
 	} else {
+#ifdef CONFIG_HAS_IOPORT_MAP
 		if (!request_region(fw_cfg_p_base,
 				    fw_cfg_p_size, "fw_cfg_io"))
 			return -EBUSY;
@@ -266,6 +267,10 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 			release_region(fw_cfg_p_base, fw_cfg_p_size);
 			return -EFAULT;
 		}
+#else
+		dev_err(&pdev->dev, "IO region given but CONFIG_HAS_IOPORT_MAP=n");
+		return -EINVAL;
+#endif
 	}
 
 	/* were custom register offsets provided (e.g. on the command line)? */
-- 
2.49.0