OMAP: Implement Basic DVFS

This patch introduces an API to perform DVFS for a given voltage domain.
It takes omap_vdd_dvfs_info pointer as input parameter, computes the highest
requested voltage for that vdd and scales all the devices in that vdd to the
requested frequency along with voltage scaling.

Based on original patch from Thara.

Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Cc: Thara Gopinath <thara@ti.com>

1 files changed, 86 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach-omap2/dvfs.c
index 8832e4a4bdd..cefc2be3681 100644
--- a/arch/arm/mach-omap2/dvfs.c
+++ b/arch/arm/mach-omap2/dvfs.c
@@ -21,7 +21,7 @@
 #include <plat/omap_device.h>
 
 /**
- * struct omap_dev_user_list - Structure maitain userlist per devide
+ * struct omap_dev_user_list - Structure maitain userlist per device
  *
  * @dev:       The device requesting for a particular frequency
  * @node:      The list head entry
@@ -413,6 +413,91 @@ static int omap_dvfs_remove_freq_request(struct omap_vdd_dvfs_info *dvfs_info,
 }
 
 /**
+ * omap_dvfs_voltage_scale() : API to scale the devices associated with a
+ *						voltage domain vdd voltage.
+ *
+ * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
+ *
+ * This API runs through the list of devices associated with the
+ * voltage domain and scales the device rates to the one requested
+ * by the user or those corresponding to the new voltage of the
+ * voltage domain. Target voltage is the highest voltage in the vdd_user_list.
+ *
+ * Returns 0 on success
+ * else the error value.
+ */
+static int omap_dvfs_voltage_scale(struct omap_vdd_dvfs_info *dvfs_info)
+{
+	unsigned long curr_volt;
+	int is_volt_scaled = 0;
+	struct omap_vdd_dev_list *temp_dev;
+	struct plist_node *node;
+	int ret = 0;
+	struct voltagedomain *voltdm;
+	unsigned long volt;
+
+	if (!dvfs_info || IS_ERR(dvfs_info)) {
+		pr_warning("%s: VDD specified does not exist!\n", __func__);
+		return -EINVAL;
+	}
+
+	voltdm = dvfs_info->voltdm;
+
+	mutex_lock(&dvfs_info->scaling_mutex);
+
+	/* Find the highest voltage being requested */
+	node = plist_last(&dvfs_info->user_list);
+	volt = node->prio;
+
+	curr_volt = omap_voltage_get_nom_volt(voltdm);
+
+	if (curr_volt == volt) {
+		is_volt_scaled = 1;
+	} else if (curr_volt < volt) {
+		ret = omap_voltage_scale_vdd(voltdm, volt);
+		if (ret) {
+			pr_warning("%s: Unable to scale the %s to %ld volt\n",
+						__func__, voltdm->name, volt);
+			mutex_unlock(&dvfs_info->scaling_mutex);
+			return ret;
+		}
+		is_volt_scaled = 1;
+	}
+
+	list_for_each_entry(temp_dev, &dvfs_info->dev_list, node) {
+		struct device *dev;
+		struct opp *opp;
+		unsigned long freq;
+
+		dev = temp_dev->dev;
+		if (!plist_head_empty(&temp_dev->user_list)) {
+			node = plist_last(&temp_dev->user_list);
+			freq = node->prio;
+		} else {
+			opp = omap_dvfs_find_voltage(dev, volt);
+			if (IS_ERR(opp))
+				continue;
+			freq = opp_get_freq(opp);
+		}
+
+		if (freq == omap_device_get_rate(dev)) {
+			dev_dbg(dev, "%s: Already at the requested"
+				"rate %ld\n", __func__, freq);
+			continue;
+		}
+
+		ret |= omap_device_set_rate(dev, freq);
+	}
+
+	if (!is_volt_scaled && !ret)
+		omap_voltage_scale_vdd(voltdm, volt);
+
+	mutex_unlock(&dvfs_info->scaling_mutex);
+
+	return 0;
+}
+
+/**
  * omap_dvfs_init() - Initialize omap dvfs layer
  *
  * Initalizes omap dvfs layer. It basically allocates memory for