OMAP: Introduce accessory APIs for DVFS

This patch introduces accessory APIs for DVFS.
Data structures added:
1. omap_dev_user_list: This structure maintains list of frequency requests per
   device basis. When a device needs to be scaled to a particular frequency,
   This list is searched to find the maximum request for a given device.
   If noone has placed any request, device frequency is obtained from device
   opp table.
2. omap_vdd_dev_list: This strcucture stores device list per vdd basis.
   Whenever a device is registered with a vdd, it is added to this list.
3. omap_vdd_user_list: User list of devices associated with each voltage domain
   instance. The user list is implemented using plist structure with priority
   node populated with the voltage values.
4. omap_vdd_dvfs_info: This structure is used to abstract DVFS related
   information per VDD basis. It holds pointer to corresponding vdd's
   voltagedomain instance and pointer to user list.

Following APIs have been added to operate on above data structures:
1. omap_dvfs_add_vdd_user - API to add a user into omap_vdd_user_list
2. omap_vdd_user_list - API to remove a user from omap_vdd_user_list
3. omap_dvfs_register_device - API to register a device with vdd
4. omap_dvfs_add_freq_request - API to add a frequency request into
   omap_dev_user_list
5. omap_dvfs_remove_freq_request - API to remove a frequency request from
   omap_dev_user_list
6. omap_dvfs_find_voltage - API to find the opp corresponding to given voltage

DVFS layer is initialized and basic data structures are allocated and
initialized as part of this.

This patch is based on Thara's previous DVFS implementation, but with major
rework.

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

4 files changed, 494 insertions, 2 deletions

diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index 510452e6670..d96bf8f7021 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -79,14 +79,14 @@ endif
 # PRCM
 obj-$(CONFIG_ARCH_OMAP2)		+= prcm.o cm2xxx_3xxx.o prm2xxx_3xxx.o
 obj-$(CONFIG_ARCH_OMAP3)		+= prcm.o cm2xxx_3xxx.o prm2xxx_3xxx.o \
-					   vc3xxx_data.o vp3xxx_data.o
+					   vc3xxx_data.o vp3xxx_data.o dvfs.o
 # XXX The presence of cm2xxx_3xxx.o on the line below is temporary and
 # will be removed once the OMAP4 part of the codebase is converted to
 # use OMAP4-specific PRCM functions.
 obj-$(CONFIG_ARCH_OMAP4)		+= prcm.o cm2xxx_3xxx.o cminst44xx.o \
 					   cm44xx.o prcm_mpu44xx.o \
 					   prminst44xx.o vc44xx_data.o \
-					   vp44xx_data.o
+					   vp44xx_data.o dvfs.o
 
 # OMAP voltage domains
 ifeq ($(CONFIG_PM),y)
diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach-omap2/dvfs.c
new file mode 100755
index 00000000000..c788b7b8ed4
--- /dev/null
+++ b/arch/arm/mach-omap2/dvfs.c
@@ -0,0 +1,455 @@
+/*
+ * OMAP3/OMAP4 DVFS Management Routines
+ *
+ * Author: Vishwanath BS	<vishwanath.bs@ti.com>
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ * Vishwanath BS <vishwanath.bs@ti.com>
+ *
+ * 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.
+ */
+
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/plist.h>
+#include <linux/slab.h>
+#include <linux/opp.h>
+#include <plat/common.h>
+#include <plat/omap_device.h>
+#include <plat/voltage.h>
+/**
+ * struct omap_dev_user_list - Structure maitain userlist per devide
+ *
+ * @dev:       The device requesting for a particular frequency
+ * @node:      The list head entry
+ * @freq:      frequency being requested
+ *
+ * Using this structure, user list (requesting dev * and frequency) for
+ * each device is maintained. This is how we can have different devices
+ * at different frequencies (to support frequency locking and throttling).
+ * Even if one of the devices in a given vdd has locked it's frequency,
+ * other's can still scale their frequency using this list.
+ * If no one has placed a frequency request for a device, then device is
+ * set to the frequency from it's opp table.
+ */
+struct omap_dev_user_list {
+		struct device *dev;
+		struct plist_node node;
+		u32 freq;
+};
+
+/**
+ * struct omap_vdd_dev_list - Device list per vdd
+ *
+ * @dev:	The device belonging to a particular vdd
+ * @node:	The list head entry
+ */
+struct omap_vdd_dev_list {
+	struct device *dev;
+	struct list_head node;
+	struct plist_head user_list;
+	spinlock_t user_lock; /* spinlock for plist */
+};
+
+/**
+ * struct omap_vdd_user_list - The per vdd user list
+ *
+ * @dev:	The device asking for the vdd to be set at a particular
+ *			voltage
+ * @node:	The list head entry
+ * @volt:	The voltage requested by the device <dev>
+ */
+struct omap_vdd_user_list {
+	struct device *dev;
+	struct plist_node node;
+	u32 volt;
+};
+
+/**
+ * struct omap_vdd_dvfs_info - The per vdd dvfs info
+ *
+ * @user_lock:	spinlock for plist operations
+ * @user_list:	The vdd user list
+ * @scaling_mutex:	Mutex for protecting dvfs data structures for a vdd
+ * @voltdm: Voltage domains for which dvfs info stored
+ *
+ * This is a fundamental structure used to store all the required
+ * DVFS related information for a vdd.
+ */
+struct omap_vdd_dvfs_info {
+	spinlock_t user_lock; /* spin lock */
+	struct plist_head user_list;
+	struct mutex scaling_mutex; /* dvfs mutex */
+	struct voltagedomain *voltdm;
+	struct list_head dev_list;
+};
+
+static struct omap_vdd_dvfs_info *omap_dvfs_info_list;
+static int omap_nr_vdd;
+
+static struct voltagedomain omap3_vdd[] = {
+	{
+	.name = "mpu",
+	},
+	{
+	.name = "core",
+	},
+};
+
+static int __init omap_dvfs_init(void);
+
+static struct omap_vdd_dvfs_info *get_dvfs_info(struct voltagedomain *voltdm)
+{
+	int i;
+	if (!voltdm || !omap_dvfs_info_list)
+		return NULL;
+
+	for (i = 0; i < omap_nr_vdd; i++)
+		if (omap_dvfs_info_list[i].voltdm == voltdm)
+			return &omap_dvfs_info_list[i];
+
+	pr_warning("%s: unable find dvfs info for vdd %s\n",
+			__func__, voltdm->name);
+	return NULL;
+}
+
+/**
+ * omap_dvfs_find_voltage() - search for given voltage
+ * @dev:	device pointer associated with the opp type
+ * @volt:	voltage to search for
+ *
+ * Searches for exact match in the opp list and returns handle to the matching
+ * opp if found, else returns ERR_PTR in case of error and should be handled
+ * using IS_ERR. If there are multiple opps with same voltage, it will return
+ * the first available entry.
+ */
+static struct opp *omap_dvfs_find_voltage(struct device *dev,
+		unsigned long volt)
+{
+	struct opp *opp = ERR_PTR(-ENODEV);
+	unsigned long f = 0;
+
+	do {
+		opp = opp_find_freq_ceil(dev, &f);
+		if (IS_ERR(opp))
+			break;
+		if (opp_get_voltage(opp) >= volt)
+			break;
+		f++;
+	} while (1);
+
+	return opp;
+}
+
+/**
+ * omap_dvfs_add_vdd_user() - Add a voltage request
+ * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
+ * @dev: device making the request
+ * @volt: requesting voltage in uV
+ *
+ * Adds the given devices' voltage request into corresponding
+ * vdd's omap_vdd_dvfs_info user list (plist). This list is used
+ * to find the maximum voltage request for a given vdd.
+ *
+ * Returns 0 on success.
+ */
+static int omap_dvfs_add_vdd_user(struct omap_vdd_dvfs_info *dvfs_info,
+		struct device *dev, unsigned long volt)
+{
+	struct omap_vdd_user_list *user = NULL, *temp_user;
+	struct plist_node *node;
+
+	if (!dvfs_info || IS_ERR(dvfs_info)) {
+		dev_warn(dev, "%s: VDD specified does not exist!\n", __func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&dvfs_info->scaling_mutex);
+
+	plist_for_each_entry(temp_user, &dvfs_info->user_list, node) {
+		if (temp_user->dev == dev) {
+			user = temp_user;
+			break;
+		}
+	}
+
+	if (!user) {
+		user = kzalloc(sizeof(struct omap_vdd_user_list), GFP_KERNEL);
+		if (!user) {
+			dev_err(dev, "%s: Unable to creat a new user for vdd_%s\n",
+				__func__, dvfs_info->voltdm->name);
+			mutex_unlock(&dvfs_info->scaling_mutex);
+			return -ENOMEM;
+		}
+		user->dev = dev;
+	} else {
+		plist_del(&user->node, &dvfs_info->user_list);
+	}
+
+	plist_node_init(&user->node, volt);
+	plist_add(&user->node, &dvfs_info->user_list);
+	node = plist_last(&dvfs_info->user_list);
+	user->volt = node->prio;
+
+	mutex_unlock(&dvfs_info->scaling_mutex);
+
+	return 0;
+}
+
+/**
+ * omap_dvfs_remove_vdd_user() - Remove a voltage request
+ * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
+ * @dev: device making the request
+ *
+ * Removes the given devices' voltage request from corresponding
+ * vdd's omap_vdd_dvfs_info user list (plist).
+ *
+ * Returns 0 on success.
+ */
+static int omap_dvfs_remove_vdd_user(struct omap_vdd_dvfs_info *dvfs_info,
+		struct device *dev)
+{
+	struct omap_vdd_user_list *user = NULL, *temp_user;
+	int ret = 0;
+
+	if (!dvfs_info || IS_ERR(dvfs_info)) {
+		dev_err(dev, "%s: VDD specified does not exist!\n", __func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&dvfs_info->scaling_mutex);
+
+	plist_for_each_entry(temp_user, &dvfs_info->user_list, node) {
+		if (temp_user->dev == dev) {
+			user = temp_user;
+			break;
+		}
+	}
+
+	if (user)
+		plist_del(&user->node, &dvfs_info->user_list);
+	else {
+		dev_err(dev, "%s: Unable to find the user for vdd_%s\n",
+					__func__, dvfs_info->voltdm->name);
+		ret = -ENOMEM;
+	}
+	mutex_unlock(&dvfs_info->scaling_mutex);
+
+	return ret;
+}
+
+/**
+ * omap_dvfs_register_device - Add a device into voltage domain
+ * @voltdm:	voltage domain to which the device is to be added
+ * @dev:	Device to be added
+ *
+ * This API will add a given device into user_list of corresponding
+ * vdd's omap_vdd_dvfs_info strucure. This list is traversed to scale
+ * frequencies of all the devices on a given vdd. This api is called
+ * while hwmod db is built for an omap_device.
+ *
+ * Returns 0 on success.
+ */
+int omap_dvfs_register_device(struct voltagedomain *voltdm, struct device *dev)
+{
+	struct omap_vdd_dev_list *temp_dev;
+	struct omap_vdd_dvfs_info *dvfs_info = get_dvfs_info(voltdm);
+
+	if (!voltdm || IS_ERR(voltdm) || !dvfs_info) {
+		dev_warn(dev, "%s: VDD specified does not exist!\n", __func__);
+		return -EINVAL;
+	}
+
+	list_for_each_entry(temp_dev, &dvfs_info->dev_list, node) {
+		if (temp_dev->dev == dev) {
+			dev_warn(dev, "%s: Device already added to vdee_%s\n",
+				__func__, dvfs_info->voltdm->name);
+			return -EINVAL;
+		}
+	}
+
+	temp_dev = kzalloc(sizeof(struct omap_vdd_dev_list), GFP_KERNEL);
+	if (!temp_dev) {
+		dev_err(dev, "%s: Unable to creat a new device for vdd_%s\n",
+			__func__, dvfs_info->voltdm->name);
+		return -ENOMEM;
+	}
+
+	/* Initialize priority ordered list */
+	spin_lock_init(&temp_dev->user_lock);
+	plist_head_init(&temp_dev->user_list, &temp_dev->user_lock);
+
+	temp_dev->dev = dev;
+	list_add(&temp_dev->node, &dvfs_info->dev_list);
+
+	return 0;
+}
+
+/**
+ * omap_dvfs_add_freq_request() - add a requested device frequency
+ *
+ *
+ * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
+ * @req_dev: device making the request
+ * @target_dev: target device for which frequency request is being made
+ * @freq:	target device frequency
+ *
+ * This API adds a requested frequency into target's device frequency list.
+ *
+ * Returns 0 on success.
+ */
+static int omap_dvfs_add_freq_request(struct omap_vdd_dvfs_info *dvfs_info,
+	struct device *req_dev, struct device *target_dev, unsigned long freq)
+{
+	struct omap_dev_user_list *dev_user = NULL, *tmp_user;
+	struct omap_vdd_dev_list *temp_dev;
+
+	if (!dvfs_info || IS_ERR(dvfs_info)) {
+		dev_warn(target_dev, "%s: VDD specified does not exist!\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&dvfs_info->scaling_mutex);
+
+	list_for_each_entry(temp_dev, &dvfs_info->dev_list, node) {
+		if (temp_dev->dev == target_dev)
+			break;
+	}
+
+	if (temp_dev->dev != target_dev) {
+		dev_warn(target_dev, "%s: target_dev does not exist!\n",
+			__func__);
+		mutex_unlock(&dvfs_info->scaling_mutex);
+		return -EINVAL;
+	}
+
+	plist_for_each_entry(tmp_user, &temp_dev->user_list, node) {
+		if (tmp_user->dev == req_dev) {
+			dev_user = tmp_user;
+			break;
+		}
+	}
+
+	if (!dev_user) {
+		dev_user = kzalloc(sizeof(struct omap_dev_user_list),
+					GFP_KERNEL);
+		if (!dev_user) {
+			dev_err(target_dev, "%s: Unable to creat a new user for vdd_%s\n",
+				__func__, dvfs_info->voltdm->name);
+			mutex_unlock(&dvfs_info->scaling_mutex);
+			return -ENOMEM;
+		}
+		dev_user->dev = req_dev;
+	} else {
+		plist_del(&dev_user->node, &temp_dev->user_list);
+	}
+
+	plist_node_init(&dev_user->node, freq);
+	plist_add(&dev_user->node, &temp_dev->user_list);
+
+	mutex_unlock(&dvfs_info->scaling_mutex);
+	return 0;
+}
+
+/**
+ * omap_dvfs_remove_freq_request() - Remove the requested device frequency
+ *
+ * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
+ * @req_dev: device removing the request
+ * @target_dev: target device from which frequency request is being removed
+ *
+ * This API removes a requested frequency from target's device frequency list.
+ *
+ * Returns 0 on success.
+ */
+
+static int omap_dvfs_remove_freq_request(struct omap_vdd_dvfs_info *dvfs_info,
+	struct device *req_dev, struct device *target_dev)
+{
+	struct omap_dev_user_list *dev_user = NULL, *tmp_user;
+	int ret = 0;
+	struct omap_vdd_dev_list *temp_dev;
+
+	if (!dvfs_info || IS_ERR(dvfs_info)) {
+		dev_warn(target_dev, "%s: VDD specified does not exist!\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&dvfs_info->scaling_mutex);
+
+	list_for_each_entry(temp_dev, &dvfs_info->dev_list, node) {
+		if (temp_dev->dev == target_dev)
+			break;
+	}
+
+	if (temp_dev->dev != target_dev) {
+		dev_warn(target_dev, "%s: target_dev does not exist!\n",
+			__func__);
+		mutex_unlock(&dvfs_info->scaling_mutex);
+		return -EINVAL;
+	}
+
+	plist_for_each_entry(tmp_user, &temp_dev->user_list, node) {
+		if (tmp_user->dev == req_dev) {
+			dev_user = tmp_user;
+			break;
+		}
+	}
+
+	if (dev_user)
+		plist_del(&dev_user->node, &temp_dev->user_list);
+	else {
+		dev_err(target_dev, "%s: Unable to remove the user for vdd_%s\n",
+				__func__, dvfs_info->voltdm->name);
+			ret = -EINVAL;
+		}
+
+	return ret;
+}
+
+/**
+ * omap_dvfs_init() - Initialize omap dvfs layer
+ *
+ * Initalizes omap dvfs layer. It basically allocates memory for
+ * omap_dvfs_info_list and  populates voltdm pointer inside
+ * omap_vdd_dvfs_info structure for all the VDDs.
+ *
+ * Returns 0 on success.
+ */
+static int __init omap_dvfs_init()
+{
+	int i;
+	struct voltagedomain *vdd_list;
+	if (cpu_is_omap34xx()) {
+		omap_nr_vdd = 2;
+		vdd_list = omap3_vdd;
+	}
+
+	omap_dvfs_info_list = kzalloc(omap_nr_vdd *
+			sizeof(struct omap_vdd_dvfs_info), GFP_KERNEL);
+	if (!omap_dvfs_info_list) {
+		pr_warning("%s: Unable to allocate memory for vdd_list",
+			__func__);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < omap_nr_vdd; i++) {
+		omap_dvfs_info_list[i].voltdm =
+			omap_voltage_domain_lookup(vdd_list[i].name);
+		/* Init the plist */
+		spin_lock_init(&omap_dvfs_info_list[i].user_lock);
+		plist_head_init(&omap_dvfs_info_list[i].user_list,
+					&omap_dvfs_info_list[i].user_lock);
+		/* Init the DVFS mutex */
+		mutex_init(&omap_dvfs_info_list[i].scaling_mutex);
+		/* Init the device list */
+		INIT_LIST_HEAD(&omap_dvfs_info_list[i].dev_list);
+	}
+
+	return 0;
+}
+core_initcall(omap_dvfs_init);
diff --git a/arch/arm/plat-omap/include/plat/dvfs.h b/arch/arm/plat-omap/include/plat/dvfs.h
new file mode 100755
index 00000000000..1302990c27d
--- /dev/null
+++ b/arch/arm/plat-omap/include/plat/dvfs.h
@@ -0,0 +1,27 @@
+/*
+ * OMAP3/OMAP4 DVFS Management Routines
+ *
+ * Author: Vishwanath BS	<vishwanath.bs@ti.com>
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ * Vishwanath BS <vishwanath.bs@ti.com>
+ *
+ * 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.
+ */
+
+#ifndef __ARCH_ARM_MACH_OMAP2_DVFS_H
+#define __ARCH_ARM_MACH_OMAP2_DVFS_H
+#include <plat/voltage.h>
+
+#ifdef CONFIG_PM
+int omap_dvfs_register_device(struct voltagedomain *voltdm, struct device *dev);
+#else
+static inline int omap_dvfs_register_device(struct voltagedomain *voltdm,
+		struct device *dev)
+{
+	return -EINVAL;
+}
+#endif
+#endif
diff --git a/arch/arm/plat-omap/omap_device.c b/arch/arm/plat-omap/omap_device.c
index 9bbda9acb73..744ced06d98 100644
--- a/arch/arm/plat-omap/omap_device.c
+++ b/arch/arm/plat-omap/omap_device.c
@@ -88,6 +88,7 @@
 #include <plat/omap_device.h>
 #include <plat/omap_hwmod.h>
 #include <plat/clock.h>
+#include <plat/dvfs.h>
 
 /* These parameters are passed to _omap_device_{de,}activate() */
 #define USE_WAKEUP_LAT			0
@@ -497,6 +498,15 @@ struct omap_device *omap_device_build_ss(const char *pdev_name, int pdev_id,
 	for (i = 0; i < oh_cnt; i++) {
 		hwmods[i]->od = od;
 		_add_optional_clock_clkdev(od, hwmods[i]);
+		if (!is_early_device && hwmods[i]->vdd_name) {
+			struct omap_hwmod *oh = hwmods[i];
+			struct voltagedomain *voltdm;
+
+			voltdm = omap_voltage_domain_lookup(oh->vdd_name);
+			if (!omap_dvfs_register_device(voltdm, &od->pdev.dev))
+				oh->voltdm = voltdm;
+		}
+		
 	}
 
 	if (ret)