This patch series introduces support for support of Dynamic Voltage and Frequency Scaling (DVFS) for OMAP devices. DVFS is a technique that uses the optimal operating frequency and voltage to allow a task to be performed in the required amount of time. OMAP processors have voltage domains whose voltage can be scaled to various levels depending on which the operating frequencies of certain devices belonging to the domain will also need to be scaled. This voltage frequency tuple is known as Operating Performance Point (OPP). A device can have multiple OPP's. Also a voltage domain could be shared between multiple devices. Also there could be dependencies between various voltage domains for maintaining system performance like VDD<X> should be at voltage v1 when VDD<Y> is at voltage v2. The design of this framework take into account all the above mentioned points. To summarize the basic design of DVFS framework:- 1. Have device opp tables for each device whose operating frequency can be scaled. This is easy now due to the existance of hwmod layer which allow storing of device specific info. The device opp tables contain the opp pairs (frequency voltage tuples), the voltage domain pointer to which the device belongs to, the device specific set_rate and get_rate API's which will do the actual scaling of the device frequency and retrieve the current device frequency. 2. Introduce use counting on a per VDD basis. This is to take care multiple requests to scale a VDD. The VDD will be scaled to the maximum of the voltages requested. 3. Keep track of all scalable devices belonging to a particular voltage domain the voltage layer. 4. Generic API in the omap device layer which can be called by anybody to scale a device opp. This API will take in the device pointer and frequency to which the device needs to be scaled to. This API will then internally find out the voltage domain to which the device belongs to and the voltage to which the voltage domain needs to be put to for the device to be scaled to the new frequency from the device opp table. Then this API will call into the newly introduced API in voltage layer (as mentioned in 2) to see if there are other requests for the associated voltage domain to be at a voltage higher than the current chosen one. If not this API will go ahead and scale the voltage domain to the new voltage, run through the list of all scalable devices belonging to this voltage domain and scale them to the appropriate frequencies using the set_rate pointer in the device opp tables. 5. Handle inter VDD dependecies. Work pending - 2. Add OMAP4 support. Contributors to conceptualization of the design include Benoit Cousson <b-cousson@xxxxxx>, Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>, Paul Wamsley <paul@xxxxxxxxx>, Vishwanath Sripathy <vishwanath.bs@xxxxxx> Parthasarathy Basak <p-basak2@xxxxxx> Anand Sawant <sawant@xxxxxx> This patch series is primarily based of lo-master and is dependent on the cpufreq patches in Kevin's PM tree and the Voltage layer and Smartreflex sereis posted by me to the list. These patches can be viewed at http://dev.omapzoom.org/?p=thara/omap-dvfs.git;a=summary head - pm-dvfs This series has been tested on OMAP3430 SDP for mpu, iva and core DVFS through cpu freq framework. Thara Gopinath (14): OMAP: Introduce a user list for each voltage domain instance in the voltage driver. OMAP: Introduce API in the OPP layer to find the opp entry corresponding to a voltage. OMAP: Introduce voltage domain information in the hwmod structures OMAP: Introduce API to register a device with a voltagedomain OMAP: Introduce device specific set rate and get rate in omap_device structure OMAP: Voltage layer changes to support DVFS. OMAP: Introduce dependent voltage domain support. OMAP: Introduce device scale OMAP: Disable smartreflex across DVFS OMAP3: Introduce custom set rate and get rate APIs for scalable devices OMAP3: Update cpufreq driver to use the new set_rate API OMAP3: Introduce voltage domain info in the hwmod structures. OMAP3: Add voltage dependency table for VDD1. OMAP2PLUS: Enable various options in defconfig arch/arm/configs/omap2plus_defconfig | 4 + arch/arm/mach-omap2/omap_hwmod_3xxx_data.c | 3 + arch/arm/mach-omap2/pm.c | 110 ++++++++ arch/arm/mach-omap2/voltage.c | 366 ++++++++++++++++++++++++- arch/arm/plat-omap/cpu-omap.c | 3 +- arch/arm/plat-omap/include/plat/omap_device.h | 12 +- arch/arm/plat-omap/include/plat/omap_hwmod.h | 5 + arch/arm/plat-omap/include/plat/voltage.h | 21 ++ arch/arm/plat-omap/omap_device.c | 139 ++++++++++ drivers/base/power/opp.c | 28 ++ include/linux/opp.h | 8 + 11 files changed, 696 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
