clk: sunxi-ng: common: Support minimum and maximum rate

The Allwinner SoC's typically have an upper and lower limit for their
clocks' rates. Up until now, support for that has been implemented
separately for each clock type.

Implement that functionality in the sunxi-ng's common part making use of
the CCF rate liming capabilities, so that it is available for all clock
types.
Suggested-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
Cc: stable@vger.kernel.org
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20240310-pinephone-pll-fixes-v4-1-46fc80c83637@oltmanns.devSigned-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

drivers/clk/sunxi-ng/ccu_common.c

@@ -44,6 +44,16 @@ bool ccu_is_better_rate(struct ccu_common *common,
 			unsigned long current_rate,
 			unsigned long best_rate)
 {
+	unsigned long min_rate, max_rate;
+
+	clk_hw_get_rate_range(&common->hw, &min_rate, &max_rate);
+
+	if (current_rate > max_rate)
+		return false;
+
+	if (current_rate < min_rate)
+		return false;
+
 	if (common->features & CCU_FEATURE_CLOSEST_RATE)
 		return abs(current_rate - target_rate) < abs(best_rate - target_rate);
 
@@ -122,6 +132,7 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
 
 	for (i = 0; i < desc->hw_clks->num ; i++) {
 		struct clk_hw *hw = desc->hw_clks->hws[i];
+		struct ccu_common *common = hw_to_ccu_common(hw);
 		const char *name;
 
 		if (!hw)
@@ -136,6 +147,14 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
 			pr_err("Couldn't register clock %d - %s\n", i, name);
 			goto err_clk_unreg;
 		}
+
+		if (common->max_rate)
+			clk_hw_set_rate_range(hw, common->min_rate,
+					      common->max_rate);
+		else
+			WARN(common->min_rate,
+			     "No max_rate, ignoring min_rate of clock %d - %s\n",
+			     i, name);
 	}
 
 	ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,

drivers/clk/sunxi-ng/ccu_common.h

@@ -31,6 +31,9 @@ struct ccu_common {
 	u16		lock_reg;
 	u32		prediv;
 
+	unsigned long	min_rate;
+	unsigned long	max_rate;
+
 	unsigned long	features;
 	spinlock_t	*lock;
 	struct clk_hw	hw;