diff --git a/drivers/gpu/nvgpu/include/nvgpu/soc.h b/drivers/gpu/nvgpu/include/nvgpu/soc.h
index 9abe93fe6..fd03d01df 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/soc.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/soc.h
@@ -31,6 +31,10 @@ struct gk20a;
  *
  * @param g[in]		GPU super structure.
  *
+ * - Extract out platform info by calling NvTegraSysGetPlatform().
+ * - If info is NULL return false.
+ * - If info is not "silicon" then return false. Otherwise return true.
+ *
  * @return Returns true if it's silicon else return false.
  */
 bool nvgpu_platform_is_silicon(struct gk20a *g);
@@ -40,6 +44,14 @@ bool nvgpu_platform_is_silicon(struct gk20a *g);
  *
  * @param g[in]		GPU super structure.
  *
+ * - Read CPU type by calling NvTegraSysGetCpuType().
+ * - Read platform info by calling NvTegraSysGetPlatform().
+ * - If any of above two or both are NULL return false.
+ * - True if any/all of the below condition is true.
+ *   - CPU type is "vdk" or
+ *   - CPU type is "dsim" or
+ *   - CPU type is "asim" or
+ *   - platform info is "quickturn".
  * @return Returns true if it's simulation else returns false.
  */
 bool nvgpu_platform_is_simulation(struct gk20a *g);
@@ -49,6 +61,11 @@ bool nvgpu_platform_is_simulation(struct gk20a *g);
  *
  * @param g[in]		GPU super structure.
  *
+ * - Get tegra Platform info using NvTegraSysGetPlatform().
+ * - Return false if return info is NULL.
+ * - Return true if any/all of the below condition is true.
+ *   - Info is  "system_fpga" or
+ *   - Info is  "unit_fpga".
  * @return Returns true if it's fpga else returns false.
  */
 bool nvgpu_platform_is_fpga(struct gk20a *g);
@@ -58,6 +75,8 @@ bool nvgpu_platform_is_fpga(struct gk20a *g);
  *
  * @param g[in]		GPU super structure.
  *
+ * - Return true if NvHvCheckOsNative() is successful.
+ *
  * @return Returns true if it's virtualized environment else returns false.
  */
 bool nvgpu_is_hypervisor_mode(struct gk20a *g);
@@ -76,6 +95,8 @@ bool nvgpu_is_bpmp_running(struct gk20a *g);
  *
  * @param g[in]		GPU super structure.
  *
+ * - Return true only if NvTegraSysGetChipId() is equal to TEGRA_CHIPID_TEGRA19
+ *   and NvTegraSysGetChipRevision() is equal to TEGRA_REVISION_A01.
  * @return Returns true if soc is t194-a01 else returns false.
  */
 bool nvgpu_is_soc_t194_a01(struct gk20a *g);
@@ -85,6 +106,10 @@ bool nvgpu_is_soc_t194_a01(struct gk20a *g);
  *
  * @param g[in]		GPU super structure.
  *
+ * - Set VMID_UNINITIALIZED to r->gid.
+ * - Check if nvgpu_is_hypervisor_mode is enabled if yes then
+ *   - If module is not virtual then set nvgpu_hv_ipa_pa to desc->phys_addr.
+ *
  * @return Returns 0 on success or in case of failure, a suitable error code.
  */
 int nvgpu_init_soc_vars(struct gk20a *g);
@@ -94,9 +119,23 @@ int nvgpu_init_soc_vars(struct gk20a *g);
  *
  * @param usecs[in]		Delay in microseconds.
  *
+ * - Wait using nanospin_ns until usecs expires. Log error if API returns non
+ *   zero value once wait time expires.
+ *
  * @return None.
  */
 void nvgpu_delay_usecs(unsigned int usecs);
+
+#ifdef CONFIG_NVGPU_NON_FUSA
 u64 nvgpu_us_counter(void);
+#endif
+
+/**
+ * @brief Get GPU cycles.
+ *
+ * @param None.
+ *
+ * @return 64 bit number which has GPU cycles.
+ */
 u64 nvgpu_get_cycles(void);
 #endif /* NVGPU_SOC_H */
diff --git a/drivers/gpu/nvgpu/os/posix/soc.c b/drivers/gpu/nvgpu/os/posix/soc.c
index bb40d38bc..2746790eb 100644
--- a/drivers/gpu/nvgpu/os/posix/soc.c
+++ b/drivers/gpu/nvgpu/os/posix/soc.c
@@ -57,10 +57,12 @@ void nvgpu_delay_usecs(unsigned int usecs)
 {
 }
 
+#ifdef CONFIG_NVGPU_NON_FUSA
 u64 nvgpu_us_counter(void)
 {
 	return (u64)nvgpu_current_time_us();
 }
+#endif
 
 u64 nvgpu_get_cycles(void)
 {