drm/i915/debugfs: New debugfs for display clock frequencies

Instead of mixing display & non-display stuff together, move
display specific clock info to new debugfs. This patch will
create a new debugfs "i915_cdclk_info" to expose Current & Max
cdclk and Max pixel clock frequency info.

Example:
$ cat /sys/kernel/debug/dri/0/i915_cdclk_info
Current CD clock frequency: 163200 kHz
Max CD clock frequency: 652800 kHz
Max pixel clock frequency: 1305600 kHz

V2: - s/i915_display_clock_info/i915_cdclk_info/ (Jani)
    - Move the logic to intel_cdclk.c (Jani)
    - Don't remove info from i915_frequency_info (Jani)
V3: - Drop locking (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230413114502.1105288-1-bhanuprakash.modem@intel.com

drivers/gpu/drm/i915/display/intel_cdclk.c

@@ -3235,6 +3235,27 @@ u32 intel_read_rawclk(struct drm_i915_private *dev_priv)
 	return freq;
 }
 
+static int i915_cdclk_info_show(struct seq_file *m, void *unused)
+{
+	struct drm_i915_private *i915 = m->private;
+
+	seq_printf(m, "Current CD clock frequency: %d kHz\n", i915->display.cdclk.hw.cdclk);
+	seq_printf(m, "Max CD clock frequency: %d kHz\n", i915->display.cdclk.max_cdclk_freq);
+	seq_printf(m, "Max pixel clock frequency: %d kHz\n", i915->max_dotclk_freq);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(i915_cdclk_info);
+
+void intel_cdclk_debugfs_register(struct drm_i915_private *i915)
+{
+	struct drm_minor *minor = i915->drm.primary;
+
+	debugfs_create_file("i915_cdclk_info", 0444, minor->debugfs_root,
+			    i915, &i915_cdclk_info_fops);
+}
+
 static const struct intel_cdclk_funcs mtl_cdclk_funcs = {
 	.get_cdclk = bxt_get_cdclk,
 	.set_cdclk = bxt_set_cdclk,

drivers/gpu/drm/i915/display/intel_cdclk.h

@@ -82,5 +82,6 @@ intel_atomic_get_cdclk_state(struct intel_atomic_state *state);
 	to_intel_cdclk_state(intel_atomic_get_new_global_obj_state(state, &to_i915(state->base.dev)->display.cdclk.obj))
 
 int intel_cdclk_init(struct drm_i915_private *dev_priv);
+void intel_cdclk_debugfs_register(struct drm_i915_private *i915);
 
 #endif /* __INTEL_CDCLK_H__ */

drivers/gpu/drm/i915/display/intel_display_debugfs.c

@@ -1094,6 +1094,7 @@ void intel_display_debugfs_register(struct drm_i915_private *i915)
 				 ARRAY_SIZE(intel_display_debugfs_list),
 				 minor->debugfs_root, minor);
 
+	intel_cdclk_debugfs_register(i915);
 	intel_dmc_debugfs_register(i915);
 	intel_fbc_debugfs_register(i915);
 	intel_hpd_debugfs_register(i915);