From 87699e7f2357b9448ad9d7f0b777a110babd3f05 Mon Sep 17 00:00:00 2001
From: Paul Cercueil <paul@crapouillou.net>
Date: Mon, 8 Nov 2021 13:54:49 +0000
Subject: [PATCH] Add option to disable MMAP API

Since the high-speed MMAP API is specific to Analog Devices' Linux
kernel, add an option to disable it.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 CMakeLists.txt       |  2 ++
 iio-config.h.cmakein |  1 +
 local.c              | 12 +++++++-----
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3b583a4a9..30576c045 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -247,6 +247,7 @@ if(WITH_LOCAL_BACKEND)
 		list(APPEND LIBIIO_CFILES ./libini/libini.c)
 	endif()
 
+	option(WITH_LOCAL_MMAP_API "Use the mmap API provided in Analog Devices' kernel (not upstream)" ON)
 	option(WITH_HWMON "Add compatibility with the hardware monitoring (hwmon) subsystem" OFF)
 endif()
 
@@ -621,6 +622,7 @@ list(APPEND IIO_FEATURES_${HAVE_BONJOUR} bonjour)
 list(APPEND IIO_FEATURES_${ENABLE_IPV6} ipv6)
 list(APPEND IIO_FEATURES_${WITH_SERIAL_BACKEND} serial)
 list(APPEND IIO_FEATURES_${WITH_LOCAL_BACKEND} local)
+list(APPEND IIO_FEATURES_${WITH_LOCAL_MMAP_API} local-mmap)
 list(APPEND IIO_FEATURES_${WITH_HWMON} hwmon)
 list(APPEND IIO_FEATURES_${WITH_USB_BACKEND} usb)
 list(APPEND IIO_FEATURES_${WITH_TESTS} utils)
diff --git a/iio-config.h.cmakein b/iio-config.h.cmakein
index a6cc0160c..ab2687dc2 100644
--- a/iio-config.h.cmakein
+++ b/iio-config.h.cmakein
@@ -18,6 +18,7 @@
 #cmakedefine01 WITH_IIOD_USBD
 #cmakedefine01 WITH_IIOD_SERIAL
 #cmakedefine01 WITH_LOCAL_CONFIG
+#cmakedefine01 WITH_LOCAL_MMAP_API
 #cmakedefine01 WITH_HWMON
 #cmakedefine01 WITH_AIO
 #cmakedefine01 HAVE_DNS_SD
diff --git a/local.c b/local.c
index daa39dc90..10a4a993d 100644
--- a/local.c
+++ b/local.c
@@ -439,7 +439,7 @@ static ssize_t local_get_buffer(const struct iio_device *dev,
 	int f = pdata->fd;
 	ssize_t ret;
 
-	if (!pdata->is_high_speed)
+	if (!WITH_LOCAL_MMAP_API || !pdata->is_high_speed)
 		return -ENOSYS;
 	if (f == -1)
 		return -EBADF;
@@ -957,11 +957,13 @@ static int local_open(const struct iio_device *dev,
 	pdata->cyclic_buffer_enqueued = false;
 	pdata->samples_count = samples_count;
 
-	ret = enable_high_speed(dev);
-	if (ret < 0 && ret != -ENOSYS)
-		goto err_close;
+	if (WITH_LOCAL_MMAP_API) {
+		ret = enable_high_speed(dev);
+		if (ret < 0 && ret != -ENOSYS)
+			goto err_close;
 
-	pdata->is_high_speed = !ret;
+		pdata->is_high_speed = !ret;
+	}
 
 	if (!pdata->is_high_speed) {
 		unsigned long size = samples_count * pdata->max_nb_blocks;