FreeBSD: support charp module_params like hw.amdgpu.virtual_display, f…

…ixes freebsd#134

Depends on: https://reviews.freebsd.org/D34252

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -462,7 +462,6 @@ module_param_named(pg_mask, amdgpu_pg_mask, uint, 0444);
 MODULE_PARM_DESC(sdma_phase_quantum, "SDMA context switch phase quantum (x 1K GPU clock cycles, 0 = no change (default 32))");
 module_param_named(sdma_phase_quantum, amdgpu_sdma_phase_quantum, uint, 0444);
 
-#ifdef __linux__
 /**
  * DOC: disable_cu (charp)
  * Set to disable CUs (It's set like se.sh.cu,...). The default is NULL.
@@ -480,7 +479,6 @@ module_param_named(disable_cu, amdgpu_disable_cu, charp, 0444);
 MODULE_PARM_DESC(virtual_display,
 		 "Enable virtual display feature (the virtual_display will be set like xxxx:xx:xx.x,x;xxxx:xx:xx.x,x)");
 module_param_named(virtual_display, amdgpu_virtual_display, charp, 0444);
-#endif
 
 /**
  * DOC: job_hang_limit (int)

linuxkpi/bsd/include/linux/moduleparam.h

@@ -37,6 +37,8 @@
 
 #include <linux/types.h>
 
+extern int lkpi_sysctl_handle_charp(SYSCTL_HANDLER_ARGS);
+
 #ifndef LINUXKPI_PARAM_PARENT
 #define	LINUXKPI_PARAM_PARENT	_compat_linuxkpi
 #endif
@@ -136,6 +138,15 @@ SYSCTL_DECL(_dev_drm);
 	name, LINUXKPI_PARAM_PERM(perm), &(var), 0,\
 	LINUXKPI_PARAM_DESC(name)))
 
+#define	LINUXKPI_PARAM_charp(name, var, perm)				\
+	extern const char LINUXKPI_PARAM_DESC(name)[];			\
+	LINUXKPI_PARAM_PASS(SYSCTL_PROC(LINUXKPI_PARAM_PARENT, OID_AUTO, \
+	LINUXKPI_PARAM_NAME(name), LINUXKPI_PARAM_PERM(perm) | CTLTYPE_STRING | CTLFLAG_MPSAFE, \
+	&(var), 0, lkpi_sysctl_handle_charp, "A", LINUXKPI_PARAM_DESC(name))); \
+	LINUXKPI_PARAM_PASS(SYSCTL_PROC(DRM_PARAM_NAME, OID_AUTO,	\
+	name, LINUXKPI_PARAM_PERM(perm) | CTLTYPE_STRING | CTLFLAG_MPSAFE, \
+	&(var), 0, lkpi_sysctl_handle_charp, "A", LINUXKPI_PARAM_DESC(name)))
+
 #define	module_param_string(name, str, len, perm)			\
 	extern const char LINUXKPI_PARAM_DESC(name)[];			\
 	LINUXKPI_PARAM_PASS(SYSCTL_STRING(LINUXKPI_PARAM_PARENT, OID_AUTO,\