cpufreq: arm_big_little: Add generic driver to read frequency table from DT

Some platforms might read frequency table from cluster nodes in DT, as they
might not have specific hardware for that. For them, this patch adds a generic
big LITTLE cpufreq driver.

Freqs passed from DT must be in KHz and DT node should be like:

    cluster0: cluster@0 {
            reg = <0>;
            freqs = <500000 600000 700000 800000>;
    }

    cluster1: cluster@1 {
            reg = <1>;
            freqs = <900000 1000000 1100000 1200000>;
    }
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

3 files changed, 113 insertions, 0 deletions

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 55c53bd742e..84d08cabbac 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -118,6 +118,15 @@ config ARM_BIG_LITTLE_CPUFREQ
 	tristate
 	depends on ARM_CPU_TOPOLOGY
 
+config ARM_DT_BL_CPUFREQ
+	tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"
+	select ARM_BIG_LITTLE_CPUFREQ
+	depends on OF
+	default y
+	help
+	  This enables the Generic CPUfreq driver for ARM big.LITTLE platform.
+	  This gets frequency tables from DT.
+
 config ARM_VEXPRESS_BL_CPUFREQ
 	tristate "ARM Vexpress big LITTLE CPUfreq driver"
 	select ARM_BIG_LITTLE_CPUFREQ
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index f26fd28849e..6148eac24fc 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -59,6 +59,9 @@ obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ)	+= highbank-cpufreq.o
 obj-$(CONFIG_ARM_IMX6Q_CPUFREQ)		+= imx6q-cpufreq.o
 obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ)	+= arm_big_little.o
 obj-$(CONFIG_ARM_VEXPRESS_BL_CPUFREQ)	+= vexpress_big_little.o
+#Keep DT_BL_CPUFREQ as the last entry in all big LITTLE drivers, so that it is
+#probed last.
+obj-$(CONFIG_ARM_DT_BL_CPUFREQ)	+= arm_dt_big_little.o
 
 ##################################################################################
 # PowerPC platform drivers
diff --git a/drivers/cpufreq/arm_dt_big_little.c b/drivers/cpufreq/arm_dt_big_little.c
new file mode 100644
index 00000000000..2a41854bd4c
--- /dev/null
+++ b/drivers/cpufreq/arm_dt_big_little.c
@@ -0,0 +1,101 @@
+/*
+ * Generic big.LITTLE CPUFreq Interface driver
+ *
+ * It provides necessary ops to arm_big_little cpufreq driver and gets
+ * Frequency information from Device Tree. Freq table in DT must be in KHz.
+ *
+ * Copyright (C) 2012 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include "arm_big_little.h"
+
+static struct cpufreq_frequency_table *generic_get_freq_tbl(u32 cluster,
+		int *count)
+{
+	struct device_node *np = NULL;
+	const struct property *pp;
+	unsigned int *table = NULL;
+	int cluster_id;
+	struct cpufreq_frequency_table *cpufreq_table;
+
+	while ((np = of_find_node_by_name(np, "cluster"))) {
+		if (of_property_read_u32(np, "reg", &cluster_id))
+			continue;
+
+		if (cluster_id != cluster)
+			continue;
+
+		pp = of_find_property(np, "freqs", NULL);
+		if (!pp)
+			continue;
+
+		*count = pp->length / sizeof(u32);
+		if (!*count)
+			continue;
+
+		table = kmalloc(sizeof(*table) * (*count), GFP_KERNEL);
+		if (!table) {
+			pr_err("%s: Failed to allocate memory for table\n",
+					__func__);
+			return NULL;
+		}
+
+		of_property_read_u32_array(np, "freqs", table, *count);
+		break;
+	}
+
+	if (!table) {
+		pr_err("%s: Unable to retrieve Freq table from Device Tree",
+				__func__);
+		return NULL;
+	}
+
+	cpufreq_table = arm_bl_copy_table_from_array(table, *count);
+	kfree(table);
+
+	return cpufreq_table;
+}
+
+static void generic_put_freq_tbl(u32 cluster)
+{
+	arm_bl_free_freq_table(cluster);
+}
+
+static struct cpufreq_arm_bl_ops generic_bl_ops = {
+	.name	= "generic-bl",
+	.get_freq_tbl = generic_get_freq_tbl,
+	.put_freq_tbl = generic_put_freq_tbl,
+};
+
+static int generic_bl_init(void)
+{
+	return bl_cpufreq_register(&generic_bl_ops);
+}
+module_init(generic_bl_init);
+
+static void generic_bl_exit(void)
+{
+	return bl_cpufreq_unregister(&generic_bl_ops);
+}
+module_exit(generic_bl_exit);
+
+MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver");
+MODULE_LICENSE("GPL");