linux-kernel - [PATCH v2 12/13] comedi: amplc_dio200_common: Conditionally remove I/O port support

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Message-Id: <20230913164013.107520-13-abbotti@mev.co.uk>
Date:   Wed, 13 Sep 2023 17:40:12 +0100
From:   Ian Abbott <abbotti@....co.uk>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ian Abbott <abbotti@....co.uk>,
        H Hartley Sweeten <hsweeten@...ionengravers.com>,
        Arnd Bergmann <arnd@...nel.org>,
        Niklas Schnelle <schnelle@...ux.ibm.com>
Subject: [PATCH v2 12/13] comedi: amplc_dio200_common: Conditionally remove I/O port support

In a future patch, the port I/O functions (`inb()`, `outb()`, and
friends will only be declared in the `HAS_IOPORT` configuration option
is enabled.

The amplc_dio200_common module is used by the amplc_dio200 module (for
ISA cards) and the amplc_dio200_pci module (for PCI and PCI Express
cards).  It supports both port I/O and memory-mapped I/O.

Port I/O and memory-mapped I/O is confined to the `dio200___read8()`,
`dio200___read32()`, `dio200___write8()` and `dio200___write32()`
functions.  Conditionally compile two versions of those functions.  If
the `CONFIG_HAS_IOPORT` macro is defined, call either the port I/O or
memory mapped I/O functions depending on the `mmio` member of the
`struct comedi_device`.  If the `CONFIG_HAS_IOPORT` macro is undefined
only call the memory-mapped I/O functions.

Add a run-time check to `amplc_dio200_common_attach()` to return an
error if the device wants to use port I/O when the `CONFIG_HAS_IOPORT`
macro is undefined.

The changes allow the module to be built even if the port I/O functions
have not been declared.

Cc: Arnd Bergmann <arnd@...nel.org>
Cc: Niklas Schnelle <schnelle@...ux.ibm.com>
Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
v2: Correct `CONFIG_HAS_PORTIO` to `CONFIG_HAS_IOPORT` in commit
description.
---
 drivers/comedi/drivers/amplc_dio200_common.c | 36 ++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/comedi/drivers/amplc_dio200_common.c b/drivers/comedi/drivers/amplc_dio200_common.c
index e6d63e89e7bf..b1a9b4c4a185 100644
--- a/drivers/comedi/drivers/amplc_dio200_common.c
+++ b/drivers/comedi/drivers/amplc_dio200_common.c
@@ -86,6 +86,8 @@ struct dio200_subdev_intr {
 	unsigned int active:1;
 };
 
+#ifdef CONFIG_HAS_IOPORT
+
 static unsigned char dio200___read8(struct comedi_device *dev,
 				    unsigned int offset)
 {
@@ -120,6 +122,34 @@ static void dio200___write32(struct comedi_device *dev,
 		outl(val, dev->iobase + offset);
 }
 
+#else /* CONFIG_HAS_IOPORT */
+
+static unsigned char dio200___read8(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	return readb(dev->mmio + offset);
+}
+
+static void dio200___write8(struct comedi_device *dev,
+			    unsigned int offset, unsigned char val)
+{
+	writeb(val, dev->mmio + offset);
+}
+
+static unsigned int dio200___read32(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	return readl(dev->mmio + offset);
+}
+
+static void dio200___write32(struct comedi_device *dev,
+			     unsigned int offset, unsigned int val)
+{
+	writel(val, dev->mmio + offset);
+}
+
+#endif /* CONFIG_HAS_IOPORT */
+
 static unsigned char dio200_read8(struct comedi_device *dev,
 				  unsigned int offset)
 {
@@ -803,6 +833,12 @@ int amplc_dio200_common_attach(struct comedi_device *dev, unsigned int irq,
 	unsigned int n;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_HAS_IOPORT) && !dev->mmio) {
+		dev_err(dev->class_dev,
+			"error! need I/O port support\n");
+		return -ENXIO;
+	}
+
 	ret = comedi_alloc_subdevices(dev, board->n_subdevs);
 	if (ret)
 		return ret;
-- 
2.40.1