cpufreq: qoriq: optimize the CPU frequency switching time

Each time the CPU switches its frequency, the clock nodes in
DTS are walked through to find proper clock source. This is
very time-consuming. Besides, switching time varies from clock
to clock. To optimize this by buffering all the input clock of CPU.

Since for each CPU each input clock takes 4 bytes memory and
normally there are several input clocks per CPU, that will not
take much memory as well.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
Change-Id: Iff017474e04abc00c4f33cd78153baca88829716
Reviewed-on: http://git.am.freescale.net:8181/28854
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Zhuoyu Zhang <Zhuoyu.Zhang@freescale.com>
Reviewed-by: Zhengxiong Jin <Jason.Jin@freescale.com>

1 files changed, 21 insertions, 11 deletions

diff --git a/drivers/cpufreq/qoriq-cpufreq.c b/drivers/cpufreq/qoriq-cpufreq.c
index 76a8e25..36b2e6e 100644
--- a/drivers/cpufreq/qoriq-cpufreq.c
+++ b/drivers/cpufreq/qoriq-cpufreq.c
@@ -25,12 +25,12 @@
 /**
  * struct cpu_data - per CPU data struct
  * @clk: the clk of CPU
- * @parent: the parent node of cpu clock
+ * @pclk: the parent clock of cpu
  * @table: frequency table
  */
 struct cpu_data {
 	struct clk *clk;
-	struct device_node *parent;
+	struct clk **pclk;
 	struct cpufreq_frequency_table *table;
 };
 
@@ -205,7 +205,7 @@ static void set_affected_cpus(struct cpufreq_policy *policy)
 
 static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
 {
-	struct device_node *np;
+	struct device_node *np, *pnode;
 	int i, count, ret;
 	u32 freq, mask;
 	struct clk *clk;
@@ -230,17 +230,23 @@ static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		goto err_nomem2;
 	}
 
-	data->parent = of_parse_phandle(np, "clocks", 0);
-	if (!data->parent) {
+	pnode = of_parse_phandle(np, "clocks", 0);
+	if (!pnode) {
 		pr_err("%s: could not get clock information\n", __func__);
 		goto err_nomem2;
 	}
 
-	count = of_property_count_strings(data->parent, "clock-names");
+	count = of_property_count_strings(pnode, "clock-names");
+	data->pclk = kcalloc(count, sizeof(struct clk *), GFP_KERNEL);
+	if (!data->pclk) {
+		pr_err("%s: no memory\n", __func__);
+		goto err_node;
+	}
+
 	table = kcalloc(count + 1, sizeof(*table), GFP_KERNEL);
 	if (!table) {
 		pr_err("%s: no memory\n", __func__);
-		goto err_node;
+		goto err_pclk;
 	}
 
 	if (fmask)
@@ -249,7 +255,8 @@ static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		mask = 0x0;
 
 	for (i = 0; i < count; i++) {
-		clk = of_clk_get(data->parent, i);
+		clk = of_clk_get(pnode, i);
+		data->pclk[i] = clk;
 		freq = clk_get_rate(clk);
 		/*
 		 * the clock is valid if its frequency is not masked
@@ -288,13 +295,16 @@ static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	cpufreq_frequency_table_get_attr(table, cpu);
 	of_node_put(np);
+	of_node_put(pnode);
 
 	return 0;
 
 err_nomem1:
 	kfree(table);
+err_pclk:
+	kfree(data->pclk);
 err_node:
-	of_node_put(data->parent);
+	of_node_put(pnode);
 err_nomem2:
 	per_cpu(cpu_data, cpu) = NULL;
 	kfree(data);
@@ -309,7 +319,7 @@ static int __exit qoriq_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 	struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
 
 	cpufreq_frequency_table_put_attr(policy->cpu);
-	of_node_put(data->parent);
+	kfree(data->pclk);
 	kfree(data->table);
 	kfree(data);
 
@@ -417,7 +427,7 @@ static int qoriq_cpufreq_target(struct cpufreq_policy *policy,
 	mutex_lock(&cpufreq_lock);
 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 
-	parent = of_clk_get(data->parent, data->table[new].driver_data);
+	parent = data->pclk[data->table[new].driver_data];
 
 #if (defined(CONFIG_PPC) && defined(CONFIG_HOTPLUG_CPU))
 	if (workaround == 1) {