amdgpu/pm: Implement new API function "emit" that accepts buffer base and write offset

   (v3)
     Rewrote patchset to order patches as (API, hw impl, usecase)

     - added API for new power management function emit_clk_levels
       This function should duplicate the functionality of print_clk_levels,
       but this solution passes the buffer base and write offset down the stack.
     - new powerplay function emit_clock_levels, implemented by smu_emit_ppclk_levels()
       This function parallels the implementation of smu_print_ppclk_levels and
       calls emit_clk_levels, and allows the returns of errors
     - new helper function smu_convert_to_smuclk called by smu_print_ppclk_levels and
       smu_emit_ppclk_levels
Signed-off-by: Darren Powell <darren.powell@amd.com>
Reviewed-By: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/include/kgd_pp_interface.h

@@ -321,6 +321,7 @@ struct amd_pm_funcs {
 	int (*get_fan_speed_pwm)(void *handle, u32 *speed);
 	int (*force_clock_level)(void *handle, enum pp_clock_type type, uint32_t mask);
 	int (*print_clock_levels)(void *handle, enum pp_clock_type type, char *buf);
+	int (*emit_clock_levels)(void *handle, enum pp_clock_type type, char *buf, int *offset);
 	int (*force_performance_level)(void *handle, enum amd_dpm_forced_level level);
 	int (*get_sclk_od)(void *handle);
 	int (*set_sclk_od)(void *handle, uint32_t value);

drivers/gpu/drm/amd/pm/amdgpu_dpm.c

@@ -890,6 +890,27 @@ int amdgpu_dpm_print_clock_levels(struct amdgpu_device *adev,
 	return ret;
 }
 
+int amdgpu_dpm_emit_clock_levels(struct amdgpu_device *adev,
+				  enum pp_clock_type type,
+				  char *buf,
+				  int *offset)
+{
+	const struct amd_pm_funcs *pp_funcs = adev->powerplay.pp_funcs;
+	int ret = 0;
+
+	if (!pp_funcs->emit_clock_levels)
+		return -ENOENT;
+
+	mutex_lock(&adev->pm.mutex);
+	ret = pp_funcs->emit_clock_levels(adev->powerplay.pp_handle,
+					   type,
+					   buf,
+					   offset);
+	mutex_unlock(&adev->pm.mutex);
+
+	return ret;
+}
+
 int amdgpu_dpm_set_ppfeature_status(struct amdgpu_device *adev,
 				    uint64_t ppfeature_masks)
 {

drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h

@@ -441,6 +441,10 @@ int amdgpu_dpm_odn_edit_dpm_table(struct amdgpu_device *adev,
 int amdgpu_dpm_print_clock_levels(struct amdgpu_device *adev,
 				  enum pp_clock_type type,
 				  char *buf);
+int amdgpu_dpm_emit_clock_levels(struct amdgpu_device *adev,
+				  enum pp_clock_type type,
+				  char *buf,
+				  int *offset);
 int amdgpu_dpm_set_ppfeature_status(struct amdgpu_device *adev,
 				    uint64_t ppfeature_masks);
 int amdgpu_dpm_get_ppfeature_status(struct amdgpu_device *adev, char *buf);

drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c

@@ -2216,11 +2216,8 @@ static int smu_print_smuclk_levels(struct smu_context *smu, enum smu_clk_type cl
 	return ret;
 }
 
-static int smu_print_ppclk_levels(void *handle,
-				  enum pp_clock_type type,
-				  char *buf)
+static enum smu_clk_type smu_convert_to_smuclk(enum pp_clock_type type)
 {
-	struct smu_context *smu = handle;
 	enum smu_clk_type clk_type;
 
 	switch (type) {
@@ -2253,12 +2250,46 @@ static int smu_print_ppclk_levels(void *handle,
 	case OD_CCLK:
 		clk_type = SMU_OD_CCLK; break;
 	default:
-		return -EINVAL;
+		clk_type = SMU_CLK_COUNT; break;
 	}
 
+	return clk_type;
+}
+
+static int smu_print_ppclk_levels(void *handle,
+				  enum pp_clock_type type,
+				  char *buf)
+{
+	struct smu_context *smu = handle;
+	enum smu_clk_type clk_type;
+
+	clk_type = smu_convert_to_smuclk(type);
+	if (clk_type == SMU_CLK_COUNT)
+		return -EINVAL;
+
 	return smu_print_smuclk_levels(smu, clk_type, buf);
 }
 
+static int smu_emit_ppclk_levels(void *handle, enum pp_clock_type type, char *buf, int *offset)
+{
+	struct smu_context *smu = handle;
+	enum smu_clk_type clk_type;
+	int ret = 0;
+
+	clk_type = smu_convert_to_smuclk(type);
+	if (clk_type == SMU_CLK_COUNT)
+		return -EINVAL;
+
+	if (!smu->pm_enabled || !smu->adev->pm.dpm_enabled)
+		return -EOPNOTSUPP;
+
+	if (!smu->ppt_funcs->emit_clk_levels)
+		ret = -ENOENT;
+
+	return smu->ppt_funcs->emit_clk_levels(smu, clk_type, buf, offset);
+
+}
+
 static int smu_od_edit_dpm_table(void *handle,
 				 enum PP_OD_DPM_TABLE_COMMAND type,
 				 long *input, uint32_t size)
@@ -2824,6 +2855,7 @@ static const struct amd_pm_funcs swsmu_pm_funcs = {
 	.get_fan_speed_pwm   = smu_get_fan_speed_pwm,
 	.force_clock_level       = smu_force_ppclk_levels,
 	.print_clock_levels      = smu_print_ppclk_levels,
+	.emit_clock_levels       = smu_emit_ppclk_levels,
 	.force_performance_level = smu_force_performance_level,
 	.read_sensor             = smu_read_sensor,
 	.get_performance_level   = smu_get_performance_level,

drivers/gpu/drm/amd/pm/swsmu/inc/amdgpu_smu.h

@@ -605,9 +605,23 @@ struct pptable_funcs {
 	 *                    to buffer. Star current level.
 	 *
 	 * Used for sysfs interfaces.
+	 * Return: Number of characters written to the buffer
 	 */
 	int (*print_clk_levels)(struct smu_context *smu, enum smu_clk_type clk_type, char *buf);
 
+	/**
+	 * @emit_clk_levels: Print DPM clock levels for a clock domain
+	 *                    to buffer using sysfs_emit_at. Star current level.
+	 *
+	 * Used for sysfs interfaces.
+	 * &buf: sysfs buffer
+	 * &offset: offset within buffer to start printing, which is updated by the
+	 * function.
+	 *
+	 * Return: 0 on Success or Negative to indicate an error occurred.
+	 */
+	int (*emit_clk_levels)(struct smu_context *smu, enum smu_clk_type clk_type, char *buf, int *offset);
+
 	/**
 	 * @force_clk_levels: Set a range of allowed DPM levels for a clock
 	 *                    domain.