drm/radeon/dpm: fetch the max clk from voltage dep tables helper

This patch adds a helper function to fetch the max clock
from the voltage clock dependecy tables.  Clocks above that
level tend to be unstable and will require additional driver
tweaks in order to work properly.

This patch implemented the helper function to fetch the max clocks
from the dependency tables.  The following patches implement the
per-asic clock filtering.

See bug:
https://bugs.freedesktop.org/show_bug.cgi?id=68235

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/btc_dpm.c

@@ -1168,6 +1168,23 @@ static const struct radeon_blacklist_clocks btc_blacklist_clocks[] =
         { 25000, 30000, RADEON_SCLK_UP }
 };
 
+void btc_get_max_clock_from_voltage_dependency_table(struct radeon_clock_voltage_dependency_table *table,
+						     u32 *max_clock)
+{
+	u32 i, clock = 0;
+
+	if ((table == NULL) || (table->count == 0)) {
+		*max_clock = clock;
+		return;
+	}
+
+	for (i = 0; i < table->count; i++) {
+		if (clock < table->entries[i].clk)
+			clock = table->entries[i].clk;
+	}
+	*max_clock = clock;
+}
+
 void btc_apply_voltage_dependency_rules(struct radeon_clock_voltage_dependency_table *table,
 					u32 clock, u16 max_voltage, u16 *voltage)
 {