diff options
Diffstat (limited to 'arch/arm/plat-omap/include/plat/omap-pm.h')
| -rw-r--r-- | arch/arm/plat-omap/include/plat/omap-pm.h | 130 |
1 files changed, 100 insertions, 30 deletions
diff --git a/arch/arm/plat-omap/include/plat/omap-pm.h b/arch/arm/plat-omap/include/plat/omap-pm.h index 3ee41d71149..728fbb9dd54 100644 --- a/arch/arm/plat-omap/include/plat/omap-pm.h +++ b/arch/arm/plat-omap/include/plat/omap-pm.h @@ -1,8 +1,8 @@ /* * omap-pm.h - OMAP power management interface * - * Copyright (C) 2008-2009 Texas Instruments, Inc. - * Copyright (C) 2008-2009 Nokia Corporation + * Copyright (C) 2008-2010 Texas Instruments, Inc. + * Copyright (C) 2008-2010 Nokia Corporation * Paul Walmsley * * Interface developed by (in alphabetical order): Karthik Dasu, Jouni @@ -16,6 +16,7 @@ #include <linux/device.h> #include <linux/cpufreq.h> +#include <linux/clk.h> #include "powerdomain.h" @@ -89,7 +90,7 @@ void omap_pm_if_exit(void); * @t: maximum MPU wakeup latency in microseconds * * Request that the maximum interrupt latency for the MPU to be no - * greater than 't' microseconds. "Interrupt latency" in this case is + * greater than @t microseconds. "Interrupt latency" in this case is * defined as the elapsed time from the occurrence of a hardware or * timer interrupt to the time when the device driver's interrupt * service routine has been entered by the MPU. @@ -105,15 +106,19 @@ void omap_pm_if_exit(void); * elapsed from when a device driver enables a hardware device with * clk_enable(), to when the device is ready for register access or * other use. To control this device wakeup latency, use - * set_max_dev_wakeup_lat() + * omap_pm_set_max_dev_wakeup_lat() * - * Multiple calls to set_max_mpu_wakeup_lat() will replace the + * Multiple calls to omap_pm_set_max_mpu_wakeup_lat() will replace the * previous t value. To remove the latency target for the MPU, call * with t = -1. * - * No return value. + * XXX This constraint will be deprecated soon in favor of the more + * general omap_pm_set_max_dev_wakeup_lat() + * + * Returns -EINVAL for an invalid argument, -ERANGE if the constraint + * is not satisfiable, or 0 upon success. */ -void omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t); +int omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t); /** @@ -123,8 +128,8 @@ void omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t); * @r: minimum throughput (in KiB/s) * * Request that the minimum data throughput on the OCP interconnect - * attached to device 'dev' interconnect agent 'tbus_id' be no less - * than 'r' KiB/s. + * attached to device @dev interconnect agent @tbus_id be no less + * than @r KiB/s. * * It is expected that the OMAP PM or bus code will use this * information to set the interconnect clock to run at the lowest @@ -138,40 +143,44 @@ void omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t); * code will also need to add an minimum L3 interconnect speed * constraint, * - * Multiple calls to set_min_bus_tput() will replace the previous rate - * value for this device. To remove the interconnect throughput - * restriction for this device, call with r = 0. + * Multiple calls to omap_pm_set_min_bus_tput() will replace the + * previous rate value for this device. To remove the interconnect + * throughput restriction for this device, call with r = 0. * - * No return value. + * Returns -EINVAL for an invalid argument, -ERANGE if the constraint + * is not satisfiable, or 0 upon success. */ -void omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r); +int omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r); /** * omap_pm_set_max_dev_wakeup_lat - set the maximum device enable latency - * @dev: struct device * + * @req_dev: struct device * requesting the constraint, or NULL if none + * @dev: struct device * to set the constraint one * @t: maximum device wakeup latency in microseconds * - * Request that the maximum amount of time necessary for a device to - * become accessible after its clocks are enabled should be no greater - * than 't' microseconds. Specifically, this represents the time from - * when a device driver enables device clocks with clk_enable(), to - * when the register reads and writes on the device will succeed. - * This function should be called before clk_disable() is called, - * since the power state transition decision may be made during - * clk_disable(). + * Request that the maximum amount of time necessary for a device @dev + * to become accessible after its clocks are enabled should be no + * greater than @t microseconds. Specifically, this represents the + * time from when a device driver enables device clocks with + * clk_enable(), to when the register reads and writes on the device + * will succeed. This function should be called before clk_disable() + * is called, since the power state transition decision may be made + * during clk_disable(). * * It is intended that underlying PM code will use this information to * determine what power state to put the powerdomain enclosing this * device into. * - * Multiple calls to set_max_dev_wakeup_lat() will replace the - * previous wakeup latency values for this device. To remove the wakeup - * latency restriction for this device, call with t = -1. + * Multiple calls to omap_pm_set_max_dev_wakeup_lat() will replace the + * previous wakeup latency values for this device. To remove the + * wakeup latency restriction for this device, call with t = -1. * - * No return value. + * Returns -EINVAL for an invalid argument, -ERANGE if the constraint + * is not satisfiable, or 0 upon success. */ -void omap_pm_set_max_dev_wakeup_lat(struct device *dev, long t); +int omap_pm_set_max_dev_wakeup_lat(struct device *req_dev, struct device *dev, + long t); /** @@ -198,10 +207,71 @@ void omap_pm_set_max_dev_wakeup_lat(struct device *dev, long t); * value for this device. To remove the maximum DMA latency for this * device, call with t = -1. * - * No return value. + * Returns -EINVAL for an invalid argument, -ERANGE if the constraint + * is not satisfiable, or 0 upon success. */ -void omap_pm_set_max_sdma_lat(struct device *dev, long t); +int omap_pm_set_max_sdma_lat(struct device *dev, long t); + +/** + * omap_pm_set_min_clk_rate - set minimum clock rate requested by @dev + * @dev: struct device * requesting the constraint + * @clk: struct clk * to set the minimum rate constraint on + * @r: minimum rate in Hz + * + * Request that the minimum clock rate on the device @dev's clk @clk + * be no less than @r Hz. + * + * It is expected that the OMAP PM code will use this information to + * find an OPP or clock setting that will satisfy this clock rate + * constraint, along with any other applicable system constraints on + * the clock rate or corresponding voltage, etc. + * + * omap_pm_set_min_clk_rate() differs from the clock code's + * clk_set_rate() in that it considers other constraints before taking + * any hardware action, and may change a system OPP rather than just a + * clock rate. clk_set_rate() is intended to be a low-level + * interface. + * + * omap_pm_set_min_clk_rate() is easily open to abuse. A better API + * would be something like "omap_pm_set_min_dev_performance()"; + * however, there is no easily-generalizable concept of performance + * that applies to all devices. Only a device (and possibly the + * device subsystem) has both the subsystem-specific knowledge, and + * the hardware IP block-specific knowledge, to translate a constraint + * on "touchscreen sampling accuracy" or "number of pixels or polygons + * rendered per second" to a clock rate. This translation can be + * dependent on the hardware IP block's revision, or firmware version, + * and the driver is the only code on the system that has this + * information and can know how to translate that into a clock rate. + * + * The intended use-case for this function is for userspace or other + * kernel code to communicate a particular performance requirement to + * a subsystem; then for the subsystem to communicate that requirement + * to something that is meaningful to the device driver; then for the + * device driver to convert that requirement to a clock rate, and to + * then call omap_pm_set_min_clk_rate(). + * + * Users of this function (such as device drivers) should not simply + * call this function with some high clock rate to ensure "high + * performance." Rather, the device driver should take a performance + * constraint from its subsystem, such as "render at least X polygons + * per second," and use some formula or table to convert that into a + * clock rate constraint given the hardware type and hardware + * revision. Device drivers or subsystems should not assume that they + * know how to make a power/performance tradeoff - some device use + * cases may tolerate a lower-fidelity device function for lower power + * consumption; others may demand a higher-fidelity device function, + * no matter what the power consumption. + * + * Multiple calls to omap_pm_set_min_clk_rate() will replace the + * previous rate value for the device @dev. To remove the minimum clock + * rate constraint for the device, call with r = 0. + * + * Returns -EINVAL for an invalid argument, -ERANGE if the constraint + * is not satisfiable, or 0 upon success. + */ +int omap_pm_set_min_clk_rate(struct device *dev, struct clk *c, long r); /* * DSP Bridge-specific constraints |