tty: Use conftest to find if tty_operations::write() has argument u8 ptr

Use conftest to find if the function write() of tty_operations
struct has the argument as U8 pointer data type. This datatype
is changed from Linux 6.5 with commit 69851e4ab8feeb ("tty:
propagate u8 data to tty_operations::write()")

Bug 4346767

Change-Id: I49f9ef844da0dee8e209e597989f1d179a2a804b
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3028632
(cherry picked from commit a757343f2e)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3053702
Reviewed-by: Jonathan Hunter <jonathanh@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
Tested-by: Jonathan Hunter <jonathanh@nvidia.com>

Makefile

@@ -27,9 +27,6 @@ ifeq ($(shell test $(LINUX_VERSION) -ge $(LINUX_VERSION_6_6); echo $$?),0)
 # probe_new is removed from i2c driver structure
 subdir-ccflags-y += -DNV_I2C_LEGACY_PROBE_NEW_REMOVED
 
-# API changes to replace u8 with unsigned char
-subdir-ccflags-y += -DNV_TTY_SERIAL_TYPE_U8_CHANGE
-
 # v4l2_async_subdev is renamed to v4l2_async_connection.
 subdir-ccflags-y += -DNV_V4L2_ASYNC_SUBDEV_RENAME
 

drivers/tty/serial/wch_35x/wch_serial.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2023, NVIDIA CORPORATION & AFFILIATES.  All rights reserved.
+ * Copyright (c) 2021-2024, NVIDIA CORPORATION & AFFILIATES.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -54,7 +54,7 @@ static void ser_tasklet_action(unsigned long);
 static int ser_startup(struct ser_state *, int);
 static void ser_shutdown(struct ser_state *);
 static _INLINE_ void _ser_put_char(struct ser_port *, struct circ_buf *, unsigned char);
-#if defined(NV_TTY_SERIAL_TYPE_U8_CHANGE)
+#if defined(NV_TTY_OPERATIONS_STRUCT_WRITE_HAS_U8_PTR_ARG) /* Linux 6.5 */
 static int ser_put_char(struct tty_struct *, u8);
 #else
 static int ser_put_char(struct tty_struct *, unsigned char);
@@ -68,7 +68,7 @@ static void ser_unthrottle(struct tty_struct *);
 static int ser_get_info(struct ser_state *, struct serial_struct *);
 static int ser_set_info(struct ser_state *, struct serial_struct *);
 static unsigned int ser_write_room(struct tty_struct *tty);
-#if defined(NV_TTY_SERIAL_TYPE_U8_CHANGE)
+#if defined(NV_TTY_OPERATIONS_STRUCT_WRITE_HAS_U8_PTR_ARG) /* Linux 6.5 */
 static ssize_t ser_write(struct tty_struct *, const u8 *, size_t);
 #else
 static int ser_write(struct tty_struct *, const unsigned char *, int);
@@ -622,7 +622,7 @@ static _INLINE_ void _ser_put_char(struct ser_port *port, struct circ_buf *circ,
     spin_unlock_irqrestore(&port->lock, flags);
 }
 
-#if defined(NV_TTY_SERIAL_TYPE_U8_CHANGE)
+#if defined(NV_TTY_OPERATIONS_STRUCT_WRITE_HAS_U8_PTR_ARG) /* Linux 6.5 */
 static int ser_put_char(struct tty_struct *tty, u8 ch)
 #else
 static int ser_put_char(struct tty_struct *tty, unsigned char ch)
@@ -921,7 +921,7 @@ static unsigned int ser_write_room(struct tty_struct *tty)
     return status;
 }
 
-#if defined(NV_TTY_SERIAL_TYPE_U8_CHANGE)
+#if defined(NV_TTY_OPERATIONS_STRUCT_WRITE_HAS_U8_PTR_ARG) /* Linux 6.5 */
 static ssize_t ser_write(struct tty_struct *tty, const u8 *buf, size_t count)
 #else
 static int ser_write(struct tty_struct *tty, const unsigned char *buf, int count)

scripts/conftest/Makefile

@@ -145,6 +145,7 @@ NV_CONFTEST_FUNCTION_COMPILE_TESTS += spi_get_chipselect
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += tc_taprio_qopt_offload_struct_has_cmd
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += tegra_dev_iommu_get_stream_id
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += tegra_ivc_struct_has_iosys_map
+NV_CONFTEST_FUNCTION_COMPILE_TESTS += tty_operations_struct_write_has_u8_ptr_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += vm_area_struct_has_const_vm_flags
 NV_CONFTEST_GENERIC_COMPILE_TESTS += is_export_symbol_present_drm_gem_prime_fd_to_handle
 NV_CONFTEST_GENERIC_COMPILE_TESTS += is_export_symbol_present_drm_gem_prime_handle_to_fd

scripts/conftest/conftest.sh

@@ -7385,6 +7385,27 @@ compile_test() {
             compile_check_conftest "$CODE" "NV_TEGRA_DEV_IOMMU_GET_STREAM_ID_PRESENT" "" "functions"
         ;;
 
+        tty_operations_struct_write_has_u8_ptr_arg)
+            #
+            # Determine if the function write() of tty_operations has u8 type pointer argument.
+            #
+            # The data type of function write() of struct tty_operation has changed
+            # to u8 data type from Linux 6.5 with change
+            # commit 69851e4ab8feeb3 ("tty: propagate u8 data to tty_operations::write()")
+            #
+            CODE="
+            #include <linux/tty.h>
+            #include <linux/tty_driver.h>
+            static inline int ser_write(struct tty_struct *ttys, const unsigned char *buf, int l) {
+                 return l;
+            }
+            static struct tty_operations tty_ops = {
+                  .write = ser_write,
+            };"
+
+            compile_check_conftest "$CODE" "NV_TTY_OPERATIONS_STRUCT_WRITE_HAS_U8_PTR_ARG" "" "functions"
+        ;;
+
         # When adding a new conftest entry, please use the correct format for
         # specifying the relevant upstream Linux kernel commit.
         #