1 files changed, 94 insertions, 2 deletions

diff --git a/drivers/sh/clk/core.c b/drivers/sh/clk/core.c
index fd0d1b98901c..cb12a8e1466b 100644
--- a/drivers/sh/clk/core.c
+++ b/drivers/sh/clk/core.c
@@ -90,8 +90,8 @@ struct clk_rate_round_data {
 static long clk_rate_round_helper(struct clk_rate_round_data *rounder)
 {
 	unsigned long rate_error, rate_error_prev = ~0UL;
-	unsigned long rate_best_fit = rounder->rate;
 	unsigned long highest, lowest, freq;
+	long rate_best_fit = -ENOENT;
 	int i;
 
 	highest = 0;
@@ -146,7 +146,7 @@ long clk_rate_table_round(struct clk *clk,
 	};
 
 	if (clk->nr_freqs < 1)
-		return 0;
+		return -ENOSYS;
 
 	return clk_rate_round_helper(&table_round);
 }
@@ -541,6 +541,98 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 }
 EXPORT_SYMBOL_GPL(clk_round_rate);
 
+long clk_round_parent(struct clk *clk, unsigned long target,
+		      unsigned long *best_freq, unsigned long *parent_freq,
+		      unsigned int div_min, unsigned int div_max)
+{
+	struct cpufreq_frequency_table *freq, *best = NULL;
+	unsigned long error = ULONG_MAX, freq_high, freq_low, div;
+	struct clk *parent = clk_get_parent(clk);
+
+	if (!parent) {
+		*parent_freq = 0;
+		*best_freq = clk_round_rate(clk, target);
+		return abs(target - *best_freq);
+	}
+
+	for (freq = parent->freq_table; freq->frequency != CPUFREQ_TABLE_END;
+	     freq++) {
+		if (freq->frequency == CPUFREQ_ENTRY_INVALID)
+			continue;
+
+		if (unlikely(freq->frequency / target <= div_min - 1)) {
+			unsigned long freq_max;
+
+			freq_max = (freq->frequency + div_min / 2) / div_min;
+			if (error > target - freq_max) {
+				error = target - freq_max;
+				best = freq;
+				if (best_freq)
+					*best_freq = freq_max;
+			}
+
+			pr_debug("too low freq %u, error %lu\n", freq->frequency,
+				 target - freq_max);
+
+			if (!error)
+				break;
+
+			continue;
+		}
+
+		if (unlikely(freq->frequency / target >= div_max)) {
+			unsigned long freq_min;
+
+			freq_min = (freq->frequency + div_max / 2) / div_max;
+			if (error > freq_min - target) {
+				error = freq_min - target;
+				best = freq;
+				if (best_freq)
+					*best_freq = freq_min;
+			}
+
+			pr_debug("too high freq %u, error %lu\n", freq->frequency,
+				 freq_min - target);
+
+			if (!error)
+				break;
+
+			continue;
+		}
+
+		div = freq->frequency / target;
+		freq_high = freq->frequency / div;
+		freq_low = freq->frequency / (div + 1);
+
+		if (freq_high - target < error) {
+			error = freq_high - target;
+			best = freq;
+			if (best_freq)
+				*best_freq = freq_high;
+		}
+
+		if (target - freq_low < error) {
+			error = target - freq_low;
+			best = freq;
+			if (best_freq)
+				*best_freq = freq_low;
+		}
+
+		pr_debug("%u / %lu = %lu, / %lu = %lu, best %lu, parent %u\n",
+			 freq->frequency, div, freq_high, div + 1, freq_low,
+			 *best_freq, best->frequency);
+
+		if (!error)
+			break;
+	}
+
+	if (parent_freq)
+		*parent_freq = best->frequency;
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(clk_round_parent);
+
 #ifdef CONFIG_PM
 static int clks_sysdev_suspend(struct sys_device *dev, pm_message_t state)
 {