linux-kernel - [PATCH 2/2] [v3] acpi: allow building without CONFIG_HAS

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Message-Id: <20241030123701.1538919-2-arnd@kernel.org>
Date: Wed, 30 Oct 2024 12:36:41 +0000
From: Arnd Bergmann <arnd@...nel.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
	Len Brown <lenb@...nel.org>,
	Jarred White <jarredwhite@...ux.microsoft.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] [v3] acpi: allow building without CONFIG_HAS_IOPORT

From: Arnd Bergmann <arnd@...db.de>

CONFIG_HAS_IOPORT will soon become optional and cause a build time
failure when it is disabled but a driver calls inb()/outb(). At the
moment, all architectures that can support ACPI have port I/O, but this
is not necessarily the case in the future on non-x86 architectures.
The result is a set of errors like:

drivers/acpi/osl.c: In function 'acpi_os_read_port':
include/asm-generic/io.h:542:14: error: call to '_inb' declared with attribute error: inb()) requires CONFIG_HAS_IOPORT

Nothing should actually call these functions in this configuration,
and if it does, the result would be undefined behavior today, possibly
a NULL pointer dereference.

Change the low-level functions to return a proper error code when
HAS_IOPORT is disabled.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
v3: fix the returned value and add a comment
---
 drivers/acpi/cppc_acpi.c |  6 ++++--
 drivers/acpi/osl.c       | 12 ++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 1a40f0514eaa..3757424b715f 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1017,7 +1017,8 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 	*val = 0;
 	size = GET_BIT_WIDTH(reg);
 
-	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+	if (IS_ENABLED(CONFIG_HAS_IOPORT) &&
+	    reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 		u32 val_u32;
 		acpi_status status;
 
@@ -1091,7 +1092,8 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 
 	size = GET_BIT_WIDTH(reg);
 
-	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+	if (IS_ENABLED(CONFIG_HAS_IOPORT) &&
+	    reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 		acpi_status status;
 
 		status = acpi_os_write_port((acpi_io_address)reg->address,
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 78a81969d90e..8ab1802c164b 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -642,6 +642,15 @@ acpi_status acpi_os_read_port(acpi_io_address port, u32 *value, u32 width)
 {
 	u32 dummy;
 
+	if (!IS_ENABLED(CONFIG_HAS_IOPORT)) {
+		/*
+		 * set all-1 result as if reading from non-existing
+		 * I/O port
+		 */
+		*value = GENMASK(width, 0);
+		return AE_NOT_IMPLEMENTED;
+	}
+
 	if (value)
 		*value = 0;
 	else
@@ -665,6 +674,9 @@ EXPORT_SYMBOL(acpi_os_read_port);
 
 acpi_status acpi_os_write_port(acpi_io_address port, u32 value, u32 width)
 {
+	if (!IS_ENABLED(CONFIG_HAS_IOPORT))
+		return AE_NOT_IMPLEMENTED;
+
 	if (width <= 8) {
 		outb(value, port);
 	} else if (width <= 16) {
-- 
2.39.5