From ae64ed46c822388bbc90a6b1a42abeb5ccb8db25 Mon Sep 17 00:00:00 2001
From: Jon Hunter <jonathanh@nvidia.com>
Date: Sun, 24 Sep 2023 15:40:41 +0100
Subject: [PATCH] gpu: host1x: Add conftest support

Instead of relying on kernel version to determine if certain functions
or structure are present in the kernel, use the conftest.sh script to
test which functions, structures, etc are present at compile time. This
is beneficial for working with 3rd party Linux kernels that may have
back-ported upstream changes into their kernel and so the kernel version
checks do not work.

Bug 4119327

Change-Id: I56281fa5d95862338bd8a43d6e22225c27590462
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2984422
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
---
 drivers/gpu/host1x-fence/dev.c |  8 +++++---
 drivers/gpu/host1x/cdma.c      |  3 ++-
 scripts/conftest/Makefile      |  1 +
 scripts/conftest/conftest.sh   | 20 ++++++++++++++++++++
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/host1x-fence/dev.c b/drivers/gpu/host1x-fence/dev.c
index c9c2655d..ddbc7713 100644
--- a/drivers/gpu/host1x-fence/dev.c
+++ b/drivers/gpu/host1x-fence/dev.c
@@ -5,6 +5,8 @@
  * Copyright (c) 2022-2023, NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <nvidia/conftest.h>
+
 #include <linux/anon_inodes.h>
 #include <linux/cdev.h>
 #include <linux/file.h>
@@ -415,10 +417,10 @@ static const struct file_operations dev_file_fops = {
 	.compat_ioctl = dev_file_ioctl,
 };
 
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(6, 2, 0))
-static char *host1x_fence_devnode(struct device *dev, umode_t *mode)
-#else
+#if defined(NV_CLASS_STRUCT_DEVNODE_HAS_CONST_DEV_ARG) /* Linux v6.2 */
 static char *host1x_fence_devnode(const struct device *dev, umode_t *mode)
+#else
+static char *host1x_fence_devnode(struct device *dev, umode_t *mode)
 #endif
 {
 	*mode = 0666;
diff --git a/drivers/gpu/host1x/cdma.c b/drivers/gpu/host1x/cdma.c
index 256fc395..59a1e18b 100644
--- a/drivers/gpu/host1x/cdma.c
+++ b/drivers/gpu/host1x/cdma.c
@@ -5,6 +5,7 @@
  * Copyright (c) 2010-2013, NVIDIA Corporation.
  */
 
+#include <nvidia/conftest.h>
 
 #include <asm/cacheflush.h>
 #include <linux/device.h>
@@ -106,7 +107,7 @@ static int host1x_pushbuffer_init(struct push_buffer *pb)
 
 		pb->dma = iova_dma_addr(&host1x->iova, alloc);
 		err = iommu_map(host1x->domain, pb->dma, pb->phys, size,
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 3, 0)
+#if defined(NV_IOMMU_MAP_HAS_GFP_ARG) /* Linux v6.3 */
 				IOMMU_READ, GFP_KERNEL);
 #else
 				IOMMU_READ);
diff --git a/scripts/conftest/Makefile b/scripts/conftest/Makefile
index e77a07ae..28b83344 100644
--- a/scripts/conftest/Makefile
+++ b/scripts/conftest/Makefile
@@ -88,6 +88,7 @@ endef
 # provided by the module-specific Kbuild files.
 #
 
+NV_CONFTEST_FUNCTION_COMPILE_TESTS += class_struct_devnode_has_const_dev_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += devm_thermal_of_zone_register
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += drm_aperture_remove_framebuffers_has_drm_driver_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += drm_driver_struct_has_irq_enabled_arg
diff --git a/scripts/conftest/conftest.sh b/scripts/conftest/conftest.sh
index 74afb507..a61fea28 100755
--- a/scripts/conftest/conftest.sh
+++ b/scripts/conftest/conftest.sh
@@ -6293,6 +6293,26 @@ compile_test() {
             compile_check_conftest "$CODE" "NV_CRYPTO_PRESENT" "" "symbols"
         ;;
 
+        class_struct_devnode_has_const_dev_arg)
+            #
+            # Determine if the 'class' structure devnode function pointer
+            # has const 'struct dev' argument.
+            #
+            # Commit 43a7206b0963 ("driver core: class: make class_register()
+            # take a const *") updated the class_register function to take a
+            # const class structure in Linux v6.2.
+            #
+            CODE="
+            #include <linux/device.h>
+            #include <linux/device/class.h>
+            #include <linux/types.h>
+            void conftest_class_struct_devnode_has_const_dev_arg(struct class *c) {
+                    char *(*fn)(const struct device *dev, umode_t *mode) = c->devnode;
+            }"
+
+            compile_check_conftest "$CODE" "NV_CLASS_STRUCT_DEVNODE_HAS_CONST_DEV_ARG" "" "types"
+        ;;
+
         devm_thermal_of_zone_register)
             #
             # Determine whether devm_thermal_of_zone_register is present.