* [PATCH] OMAP2/3 PM: create the OMAP PM interface and add a default no-op layer.
2008-07-17 1:57 [PATCH] OMAP PM interface, version 3 Paul Walmsley
@ 2008-07-17 1:58 ` Paul Walmsley
2008-08-05 14:18 ` [PATCH] OMAP PM interface, version 3 Tony Lindgren
1 sibling, 0 replies; 3+ messages in thread
From: Paul Walmsley @ 2008-07-17 1:58 UTC (permalink / raw)
To: linux-omap; +Cc: jouni.hogander, rnayak
The interface provides device drivers, CPUFreq, and DSP Bridge with a
means of controlling OMAP power management parameters that are not yet
supported by the Linux PM PMQOS interface. Copious documentation and
rationale is in the patch in Documentation/arm/OMAP/omap_pm and the
interface header file, include/asm-arm/arch-omap/omap-pm.h.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
---
Documentation/arm/OMAP/omap_pm | 185 +++++++++++++++++++++
arch/arm/mach-omap2/io.c | 4
arch/arm/plat-omap/Kconfig | 13 +
arch/arm/plat-omap/Makefile | 1
arch/arm/plat-omap/omap-pm-noop.c | 309 +++++++++++++++++++++++++++++++++++
include/asm-arm/arch-omap/omap-pm.h | 300 ++++++++++++++++++++++++++++++++++
6 files changed, 812 insertions(+), 0 deletions(-)
create mode 100644 Documentation/arm/OMAP/omap_pm
create mode 100644 arch/arm/plat-omap/omap-pm-noop.c
create mode 100644 include/asm-arm/arch-omap/omap-pm.h
diff --git a/Documentation/arm/OMAP/omap_pm b/Documentation/arm/OMAP/omap_pm
new file mode 100644
index 0000000..2ec2034
--- /dev/null
+++ b/Documentation/arm/OMAP/omap_pm
@@ -0,0 +1,185 @@
+
+Rationale: the OMAP PM interface
+================================
+
+
+Existing PM interfaces are currently not ideal for OMAP
+-------------------------------------------------------
+
+There are two PM interfaces in use with publicly-distributed OMAP
+Linux code: the TI Shared Resource Framework (SRF) and the Linux PM
+QoS parameters code. Neither interface is ideal for Linux OMAP code.
+
+TI Shared Resource Framework:
+
+The TI CDP 12.14 tree drivers currently use the TI Shared Resource
+Framework (SRF) to control chip power management. Use of the SRF
+allowed TI to get the drivers up and running quickly with considerable
+power savings; and the SRF provided debugging support. However, many
+of the SRF parameters are specified in OMAP-specific terms, such as
+target OPPs, rather than in terms of actual latency or throughput
+requirements. OPPs change depending on OMAP silicon revisions or OMAP
+types, and are meaningless for other architectures, so drivers shared
+between OMAP and other architectures would also have to #ifdef out the
+SRF constraints.
+
+Linux PM QoS parameters:
+
+In February 2008, the mainline Linux kernel added code that is
+somewhat similar to the SRF: the Linux PM QoS parameters code, located
+in kernel/pm_qos_params.c. (This code replaced the latency management
+code that was present in earlier kernels.) Ideally, OMAP drivers
+would be able to use this Linux PM QoS code directly, but the PM QoS
+code has some drawbacks:
+
+- It combines some power management parameters that should be kept
+ separate for maximum power savings on OMAP3. For example, in the PM
+ QoS code, CPU and system DMA wakeup latency are combined into one
+ parameter; but on OMAP3, these are distinct parameters. The Linux
+ PM QoS code also combines all network power management knobs into
+ two non-device-specific parameters. OMAP2/3 systems can have
+ different network devices with different power management
+ requirements - for example, a wired Ethernet interface may have
+ different latency and throughput constraints than a WiFi interface.
+
+- It does not yet cover all of the power management capabilities of
+ the OMAP3 architecture. It does not express latency constraints on
+ a per-device or per-powerdomain basis; it only covers
+ cpu_dma_latency and network throughput and latency, which would not
+ cover most of the OMAP3 devices.
+
+The result is that drivers using the current Linux PM QoS layer
+directly are unlikely to reach the same level of power efficiency as
+driver code using the Shared Resource Framework.
+
+To summarize, the SRF provides significant power savings, but
+expresses power constraints in an OMAP- and silicon-revision-specific
+way; and the PM QoS layer expresses PM constraints in a cross-platform
+manner (in terms of fundamental physical units), but does not support
+per-powerdomain constraints and does not cover many of the OMAP power
+management features.
+
+
+A medium-term alternative: the OMAP PM interface
+------------------------------------------------
+
+We need a way for driver code to express PM parameters which:
+
+- supports the range of power management parameters present in the TI SRF;
+
+- separates the drivers from the underlying PM parameter
+ implementation, whether it is the TI SRF or Linux PM QoS or Linux
+ latency framework or something else;
+
+- specifies PM parameters in terms of fundamental units, such as
+ latency and throughput, rather than units which are specific to OMAP
+ or to particular OMAP variants;
+
+- allows drivers which are shared with other architectures (e.g.,
+ DaVinci) to add these constraints in a way which won't affect non-OMAP
+ systems,
+
+- can be implemented immediately with minimal disruption of other
+ architectures.
+
+
+We therefore propose the OMAP PM interface, including the following
+four power management functions for driver code:
+
+1. Set the maximum MPU wakeup latency:
+ (*pdata->set_max_mpu_wakeup_lat)(struct device *dev, unsigned long t)
+
+2. Set the maximum device wakeup latency:
+ (*pdata->set_max_dev_wakeup_lat)(struct device *dev, unsigned long t)
+
+3. Set the maximum system DMA transfer start latency (CORE pwrdm):
+ (*pdata->set_max_sdma_lat)(struct device *dev, long t)
+
+4. Set the minimum bus throughput needed by a device:
+ (*pdata->set_min_bus_tput)(struct device *dev, u8 agent_id, unsigned long r)
+
+
+These functions are extensively documented in the OMAP PM interface header
+file, included in the patch.
+
+
+The OMAP PM layer is intended to be temporary
+---------------------------------------------
+
+The intention is that, in time, the Linux PM QoS layer should support
+the range of power management features present in OMAP3. As this
+happens, existing drivers using the OMAP PM interface can be modified
+to use the Linux PM QoS code; and the OMAP PM interface can disappear.
+
+
+Driver usage of the OMAP PM functions
+-------------------------------------
+
+As the 'pdata' in the above examples indicates, these functions are
+exposed to drivers through function pointers in driver .platform_data
+structures. The function pointers are initialized by the board-*.c
+files to point to the corresponding OMAP PM functions:
+.set_max_dev_wakeup_lat will point to
+omap_pm_set_max_dev_wakeup_lat(), etc. Other architectures which do
+not support these functions should leave these function pointers set
+to NULL. Drivers should use the following idiom:
+
+ if (pdata->set_max_dev_wakeup_lat)
+ (*pdata->set_max_dev_wakeup_lat)(dev, t);
+
+The most common usage of these functions will probably be to specify
+the maximum time from when an interrupt occurs, to when the device
+becomes accessible. To accomplish this, driver writers should use the
+set_max_mpu_wakeup_lat() function to to constrain the MPU wakeup
+latency, and the set_max_dev_wakeup_lat() function to constrain the
+device wakeup latency (from clk_enable() to accessibility). For
+example,
+
+ /* Limit MPU wakeup latency */
+ if (pdata->set_max_mpu_wakeup_lat)
+ (*pdata->set_max_mpu_wakeup_lat)(dev, tc);
+
+ /* Limit device powerdomain wakeup latency */
+ if (pdata->set_max_dev_wakeup_lat)
+ (*pdata->set_max_dev_wakeup_lat)(dev, td);
+
+ /* total wakeup latency in this example: (tc + td) */
+
+
+The PM parameters can be overwritten by calling the function again
+with the new value. The settings can be removed by calling the
+function with a t argument of -1 (except in the case of
+set_max_bus_tput(), which should be called with an r argument of 0).
+
+
+Other specialized interface functions
+-------------------------------------
+
+The four functions listed above are intended to be usable by any
+device driver. However, DSPBridge and CPUFreq have special
+requirements. DSPBridge expresses target DSP performance levels in
+terms of OPP IDs. CPUFreq expresses target MPU performance levels in
+terms of MPU frequency. The OMAP PM interface contains functions for
+these specialized cases to convert that input information (OPPs/MPU
+frequency) into the form that the underlying power management
+implementation needs:
+
+5. (*pdata->omap_pm_dsp_get_opp_table)(void)
+
+6. (*pdata->omap_pm_dsp_set_min_opp)(u8 opp_id)
+
+7. (*pdata->omap_pm_dsp_get_opp)(void)
+
+8. (*pdata->omap_pm_cpu_get_freq_table)(void)
+
+9. (*pdata->omap_pm_cpu_set_freq)(unsigned long f)
+
+10. (*pdata->omap_pm_cpu_get_freq)(void)
+
+
+There are also functions for use by the clockdomain layer to indicate
+that a powerdomain should wake up or be put to sleep:
+
+11. (*pdata->omap_pm_pwrdm_active)(struct powerdomain *pwrdm)
+
+12. (*pdata->omap_pm_pwrdm_inactive)(struct powerdomain *pwrdm)
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index 314994b..645d453 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -38,6 +38,8 @@
#include <asm/arch/clockdomain.h>
#include "clockdomains.h"
+#include <asm/arch/omap-pm.h>
+
/*
* The machine specific code may provide the extra mapping besides the
* default mapping provided here.
@@ -197,9 +199,11 @@ void __init omap2_map_common_io(void)
void __init omap2_init_common_hw(void)
{
omap2_mux_init();
+ omap_pm_if_early_init();
pwrdm_init(powerdomains_omap);
clkdm_init(clockdomains_omap, clkdm_pwrdm_autodeps);
omap2_clk_init();
+ omap_pm_if_init(NULL, NULL);
omap2_init_memory();
gpmc_init();
}
diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
index 960c13f..ca790ac 100644
--- a/arch/arm/plat-omap/Kconfig
+++ b/arch/arm/plat-omap/Kconfig
@@ -247,4 +247,17 @@ config OMAP_SERIAL_WAKE
endmenu
+choice
+ prompt "OMAP PM layer selection"
+ depends on ARCH_OMAP
+ default OMAP_PM_NOOP
+
+config OMAP_PM_NONE
+ bool "No PM layer"
+
+config OMAP_PM_NOOP
+ bool "No-op/debug PM layer"
+
+endchoice
+
endif
diff --git a/arch/arm/plat-omap/Makefile b/arch/arm/plat-omap/Makefile
index 93bbb64..d5453d5 100644
--- a/arch/arm/plat-omap/Makefile
+++ b/arch/arm/plat-omap/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_OMAP_MMU_FWK) += mmu.o
# OMAP mailbox framework
obj-$(CONFIG_OMAP_MBOX_FWK) += mailbox.o
+obj-$(CONFIG_OMAP_PM_NOOP) += omap-pm-noop.o
\ No newline at end of file
diff --git a/arch/arm/plat-omap/omap-pm-noop.c b/arch/arm/plat-omap/omap-pm-noop.c
new file mode 100644
index 0000000..5ff7962
--- /dev/null
+++ b/arch/arm/plat-omap/omap-pm-noop.c
@@ -0,0 +1,309 @@
+/*
+ * omap-pm-noop.c - OMAP power management interface - dummy version
+ *
+ * This code implements the OMAP power management interface to
+ * drivers, CPUIdle, CPUFreq, and DSP Bridge. It is strictly for
+ * debug/demonstration use, as it does nothing but printk() whenever a
+ * function is called (when DEBUG is defined, below)
+ *
+ * Copyright (C) 2008 Texas Instruments, Inc.
+ * Copyright (C) 2008 Nokia Corporation
+ * Paul Walmsley
+ *
+ * Interface developed by (in alphabetical order):
+ * Karthik Dasu, Amish Lakhani, Tony Lindgren, Rajendra Nayak, Sakari
+ * Poussa, Veeramanikandan Raju, Igor Stoppa, Paul Walmsley, Richard
+ * Woodruff
+ */
+
+#undef DEBUG
+
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/device.h>
+
+/* Interface documentation is in asm/arch/omap-pm.h */
+#include <asm/arch/omap-pm.h>
+
+#include <asm/arch/powerdomain.h>
+
+static struct omap_opp *dsp_opps;
+static struct omap_opp *mpu_opps;
+
+/*
+ * Device-driver-originated constraints (via board-*.c files)
+ */
+
+void omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t)
+{
+ if (!dev || t < -1) {
+ WARN_ON(1);
+ return;
+ };
+
+ if (t == -1)
+ pr_debug("OMAP PM: remove max MPU wakeup latency constraint: "
+ "dev %s\n", dev_name(dev));
+ else
+ pr_debug("OMAP PM: add max MPU wakeup latency constraint: "
+ "dev %s, t = %ld usec\n", dev_name(dev), t);
+
+ /*
+ * For current Linux, this needs to map the MPU to a
+ * powerdomain, then go through the list of current max lat
+ * constraints on the MPU and find the smallest. If
+ * the latency constraint has changed, the code should
+ * recompute the state to enter for the next powerdomain
+ * state.
+ *
+ * TI CDP code can call constraint_set here.
+ */
+}
+
+void omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r)
+{
+ if (!dev || agent_id != OCP_INITIATOR_AGENT ||
+ agent_id != OCP_TARGET_AGENT) {
+ WARN_ON(1);
+ return;
+ };
+
+ if (r == 0)
+ pr_debug("OMAP PM: remove min bus tput constraint: "
+ "dev %s for agent_id %d\n", dev_name(dev), agent_id);
+ else
+ pr_debug("OMAP PM: add min bus tput constraint: "
+ "dev %s for agent_id %d: rate %ld KiB\n",
+ dev_name(dev), agent_id, r);
+
+ /*
+ * This code should model the interconnect and compute the
+ * required clock frequency, convert that to a VDD2 OPP ID, then
+ * set the VDD2 OPP appropriately.
+ *
+ * TI CDP code can call constraint_set here on the VDD2 OPP.
+ */
+}
+
+void omap_pm_set_max_dev_wakeup_lat(struct device *dev, long t)
+{
+ if (!dev || t < -1) {
+ WARN_ON(1);
+ return;
+ };
+
+ if (t == -1)
+ pr_debug("OMAP PM: remove max device latency constraint: "
+ "dev %s\n", dev_name(dev));
+ else
+ pr_debug("OMAP PM: add max device latency constraint: "
+ "dev %s, t = %ld usec\n", dev_name(dev), t);
+
+ /*
+ * For current Linux, this needs to map the device to a
+ * powerdomain, then go through the list of current max lat
+ * constraints on that powerdomain and find the smallest. If
+ * the latency constraint has changed, the code should
+ * recompute the state to enter for the next powerdomain
+ * state. Conceivably, this code should also determine
+ * whether to actually disable the device clocks or not,
+ * depending on how long it takes to re-enable the clocks.
+ *
+ * TI CDP code can call constraint_set here.
+ */
+}
+
+void omap_pm_set_max_sdma_lat(struct device *dev, long t)
+{
+ if (!dev || t < -1) {
+ WARN_ON(1);
+ return;
+ };
+
+ if (t == -1)
+ pr_debug("OMAP PM: remove max DMA latency constraint: "
+ "dev %s\n", dev_name(dev));
+ else
+ pr_debug("OMAP PM: add max DMA latency constraint: "
+ "dev %s, t = %ld usec\n", dev_name(dev), t);
+
+ /*
+ * For current Linux PM QOS params, this code should scan the
+ * list of maximum CPU and DMA latencies and select the
+ * smallest, then set cpu_dma_latency pm_qos_param
+ * accordingly.
+ *
+ * For future Linux PM QOS params, with separate CPU and DMA
+ * latency params, this code should just set the dma_latency param.
+ *
+ * TI CDP code can call constraint_set here.
+ */
+
+}
+
+
+/*
+ * DSP Bridge-specific constraints
+ */
+
+const struct omap_opp *omap_pm_dsp_get_opp_table(void)
+{
+ pr_debug("OMAP PM: DSP request for OPP table\n");
+
+ /*
+ * Return DSP frequency table here: The final item in the
+ * array should have .rate = .opp_id = 0.
+ */
+
+ return NULL;
+}
+
+void omap_pm_dsp_set_min_opp(u8 opp_id)
+{
+ if (opp_id == 0) {
+ WARN_ON(1);
+ return;
+ }
+
+ pr_debug("OMAP PM: DSP requests minimum VDD1 OPP to be %d\n", opp_id);
+
+ /*
+ *
+ * For l-o dev tree, our VDD1 clk is keyed on OPP ID, so we
+ * can just test to see which is higher, the CPU's desired OPP
+ * ID or the DSP's desired OPP ID, and use whichever is
+ * highest.
+ *
+ * In CDP12.14+, the VDD1 OPP custom clock that controls the DSP
+ * rate is keyed on MPU speed, not the OPP ID. So we need to
+ * map the OPP ID to the MPU speed for use with clk_set_rate()
+ * if it is higher than the current OPP clock rate.
+ *
+ */
+}
+
+
+u8 omap_pm_dsp_get_opp(void)
+{
+ pr_debug("OMAP PM: DSP requests current DSP OPP ID\n");
+
+ /*
+ * For l-o dev tree, call clk_get_rate() on VDD1 OPP clock
+ *
+ * CDP12.14+:
+ * Call clk_get_rate() on the OPP custom clock, map that to an
+ * OPP ID using the tables defined in board-*.c/chip-*.c files.
+ */
+
+ return 0;
+}
+
+/*
+ * CPUFreq-originated constraint
+ *
+ * In the future, this should be handled by custom OPP clocktype
+ * functions.
+ */
+
+struct cpufreq_frequency_table **omap_pm_cpu_get_freq_table(void)
+{
+ pr_debug("OMAP PM: CPUFreq request for frequency table\n");
+
+ /*
+ * Return CPUFreq frequency table here: loop over
+ * all VDD1 clkrates, pull out the mpu_ck frequencies, build
+ * table
+ */
+
+ return NULL;
+}
+
+void omap_pm_cpu_set_freq(unsigned long f)
+{
+ if (f == 0) {
+ WARN_ON(1);
+ return;
+ }
+
+ pr_debug("OMAP PM: CPUFreq requests CPU frequency to be set to %lu\n",
+ f);
+
+ /*
+ * For l-o dev tree, determine whether MPU freq or DSP OPP id
+ * freq is higher. Find the OPP ID corresponding to the
+ * higher frequency. Call clk_round_rate() and clk_set_rate()
+ * on the OPP custom clock.
+ *
+ * CDP should just be able to set the VDD1 OPP clock rate here.
+ */
+}
+
+unsigned long omap_pm_cpu_get_freq(void)
+{
+ pr_debug("OMAP PM: CPUFreq requests current CPU frequency\n");
+
+ /*
+ * Call clk_get_rate() on the mpu_ck.
+ */
+
+ return 0;
+}
+
+/*
+ * Powerdomain usecounting hooks
+ */
+
+void omap_pm_pwrdm_active(struct powerdomain *pwrdm)
+{
+ if (!pwrdm) {
+ WARN_ON(1);
+ return;
+ };
+
+ pr_debug("OMAP PM: powerdomain %s is becoming active\n", pwrdm->name);
+
+ /*
+ * CDP code apparently will need these for the enable_power_domain()
+ * and disable_power_domain() functions.
+ */
+}
+
+void omap_pm_pwrdm_inactive(struct powerdomain *pwrdm)
+{
+ if (!pwrdm) {
+ WARN_ON(1);
+ return;
+ };
+
+ pr_debug("OMAP PM: powerdomain %s is becoming inactive\n",
+ pwrdm->name);
+
+ /*
+ * CDP code apparently will need these for the enable_power_domain()
+ * and disable_power_domain() functions.
+ */
+}
+
+/*
+ * Should be called before clk framework since clk fw will call
+ * omap_pm_pwrdm_{in,}active()
+ */
+int __init omap_pm_if_early_init(void)
+{
+ return 0;
+}
+
+/* Must be called after clock framework is initialized */
+int __init omap_pm_if_init(struct omap_opp *mpu_opp_table,
+ struct omap_opp *dsp_opp_table)
+{
+ mpu_opps = mpu_opp_table;
+ dsp_opps = dsp_opp_table;
+ return 0;
+}
+
+void omap_pm_if_exit(void)
+{
+ /* Deallocate CPUFreq frequency table here */
+}
+
diff --git a/include/asm-arm/arch-omap/omap-pm.h b/include/asm-arm/arch-omap/omap-pm.h
new file mode 100644
index 0000000..d272dba
--- /dev/null
+++ b/include/asm-arm/arch-omap/omap-pm.h
@@ -0,0 +1,300 @@
+/*
+ * omap-pm.h - OMAP power management interface
+ *
+ * Copyright (C) 2008 Texas Instruments, Inc.
+ * Copyright (C) 2008 Nokia Corporation
+ * Paul Walmsley
+ *
+ * Interface developed by (in alphabetical order): Karthik Dasu, Jouni
+ * Högander, Tony Lindgren, Rajendra Nayak, Sakari Poussa,
+ * Veeramanikandan Raju, Anand Sawant, Igor Stoppa, Paul Walmsley,
+ * Richard Woodruff
+ */
+
+#ifndef ASM_ARM_ARCH_OMAP_OMAP_PM_H
+#define ASM_ARM_ARCH_OMAP_OMAP_PM_H
+
+#include <linux/device.h>
+#include <linux/cpufreq.h>
+
+#include "powerdomain.h"
+
+/**
+ * struct omap_opp - clock frequency-to-OPP ID table for DSP, MPU
+ * @rate: target clock rate
+ * @opp_id: OPP ID
+ * @min_vdd: minimum VDD1 voltage (in millivolts) for this OPP
+ *
+ * Operating performance point data. Can vary by OMAP chip and board.
+ */
+struct omap_opp {
+ unsigned long rate;
+ u8 opp_id;
+ u16 min_vdd;
+};
+
+/*
+ * agent_id values for use with omap_pm_set_min_bus_tput():
+ *
+ * OCP_INITIATOR_AGENT is only valid for devices that can act as
+ * initiators -- it represents the device's L3 interconnect
+ * connection. OCP_TARGET_AGENT represents the device's L4
+ * interconnect connection.
+ */
+#define OCP_TARGET_AGENT 1
+#define OCP_INITIATOR_AGENT 2
+
+/**
+ * omap_pm_if_early_init - OMAP PM init code called before clock fw init
+ *
+ * Initialize anything that must be configured before the clock
+ * framework starts. The "_if_" is to avoid name collisions with the
+ * PM idle-loop code.
+ */
+int __init omap_pm_if_early_init(void);
+
+/**
+ * omap_pm_if_init - OMAP PM init code called after clock fw init
+ * @mpu_opp_table: array ptr to struct omap_opp for MPU
+ * @dsp_opp_table: array ptr to struct omap_opp for DSP
+ *
+ * The main initialization code. OPP tables are passed in here. The
+ * "_if_" is to avoid name collisions with the PM idle-loop code.
+ */
+int __init omap_pm_if_init(struct omap_opp *mpu_opp_table,
+ struct omap_opp *dsp_opp_table);
+
+/**
+ * omap_pm_if_exit - OMAP PM exit code
+ *
+ * Exit code; currently unused. The "_if_" is to avoid name
+ * collisions with the PM idle-loop code.
+ */
+void omap_pm_if_exit(void);
+
+/*
+ * Device-driver-originated constraints (via board-*.c files, platform_data)
+ */
+
+
+/**
+ * omap_pm_set_max_mpu_wakeup_lat - set the maximum MPU wakeup latency
+ * @dev: struct device * requesting the constraint
+ * @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
+ * 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.
+ *
+ * It is intended that underlying PM code will use this information to
+ * determine what power state to put the MPU powerdomain into, and
+ * possibly the CORE powerdomain as well, since interrupt handling
+ * code currently runs from SDRAM. Advanced PM or board*.c code may
+ * also configure interrupt controller priorities, OCP bus priorities,
+ * CPU speed(s), etc.
+ *
+ * This function will not affect device wakeup latency, e.g., time
+ * 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()
+ *
+ * Multiple calls to 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.
+ */
+void omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t);
+
+
+/**
+ * omap_pm_set_min_bus_tput - set minimum bus throughput needed by device
+ * @dev: struct device * requesting the constraint
+ * @tbus_id: interconnect to operate on (OCP_{INITIATOR,TARGET}_AGENT)
+ * @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.
+ *
+ * It is expected that the OMAP PM or bus code will use this
+ * information to set the interconnect clock to run at the lowest
+ * possible speed that satisfies all current system users. The PM or
+ * bus code will adjust the estimate based on its model of the bus, so
+ * device driver authors should attempt to specify an accurate
+ * quantity for their device use case, and let the PM or bus code
+ * overestimate the numbers as necessary to handle request/response
+ * latency, other competing users on the system, etc. On OMAP2/3, if
+ * a driver requests a minimum L4 interconnect speed constraint, the
+ * 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.
+ *
+ * No return value.
+ */
+void 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 *
+ * @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().
+ *
+ * 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.
+ *
+ * No return value.
+ */
+void omap_pm_set_max_dev_wakeup_lat(struct device *dev, long t);
+
+
+/**
+ * omap_pm_set_max_sdma_lat - set the maximum system DMA transfer start latency
+ * @dev: struct device *
+ * @t: maximum DMA transfer start latency in microseconds
+ *
+ * Request that the maximum system DMA transfer start latency for this
+ * device 'dev' should be no greater than 't' microseconds. "DMA
+ * transfer start latency" here is defined as the elapsed time from
+ * when a device (e.g., McBSP) requests that a system DMA transfer
+ * start or continue, to the time at which data starts to flow into
+ * that device from the system DMA controller.
+ *
+ * It is intended that underlying PM code will use this information to
+ * determine what power state to put the CORE powerdomain into.
+ *
+ * Since system DMA transfers may not involve the MPU, this function
+ * will not affect MPU wakeup latency. Use set_max_cpu_lat() to do
+ * so. Similarly, this function will not affect device wakeup latency
+ * -- use set_max_dev_wakeup_lat() to affect that.
+ *
+ * Multiple calls to set_max_sdma_lat() will replace the previous t
+ * value for this device. To remove the maximum DMA latency for this
+ * device, call with t = -1.
+ *
+ * No return value.
+ */
+void omap_pm_set_max_sdma_lat(struct device *dev, long t);
+
+
+/*
+ * DSP Bridge-specific constraints
+ */
+
+/**
+ * omap_pm_dsp_get_opp_table - get OPP->DSP clock frequency table
+ *
+ * Intended for use by DSPBridge. Returns an array of OPP->DSP clock
+ * frequency entries. The final item in the array should have .rate =
+ * .opp_id = 0.
+ */
+const struct omap_opp *omap_pm_dsp_get_opp_table(void);
+
+/**
+ * omap_pm_dsp_set_min_opp - receive desired OPP target ID from DSP Bridge
+ * @opp_id: target DSP OPP ID
+ *
+ * Set a minimum OPP ID for the DSP. This is intended to be called
+ * only from the DSP Bridge MPU-side driver. Unfortunately, the only
+ * information that code receives from the DSP/BIOS load estimator is the
+ * target OPP ID; hence, this interface. No return value.
+ */
+void omap_pm_dsp_set_min_opp(u8 opp_id);
+
+/**
+ * omap_pm_dsp_get_opp - report the current DSP OPP ID
+ *
+ * Report the current OPP for the DSP. Since on OMAP3, the DSP and
+ * MPU share a single voltage domain, the OPP ID returned back may
+ * represent a higher DSP speed than the OPP requested via
+ * omap_pm_dsp_set_min_opp().
+ *
+ * Returns the current VDD1 OPP ID, or 0 upon error.
+ */
+u8 omap_pm_dsp_get_opp(void);
+
+
+/*
+ * CPUFreq-originated constraint
+ *
+ * In the future, this should be handled by custom OPP clocktype
+ * functions.
+ */
+
+/**
+ * omap_pm_cpu_get_freq_table - return a cpufreq_frequency_table array ptr
+ *
+ * Provide a frequency table usable by CPUFreq for the current chip/board.
+ * Returns a pointer to a struct cpufreq_frequency_table array or NULL
+ * upon error.
+ */
+struct cpufreq_frequency_table **omap_pm_cpu_get_freq_table(void);
+
+/**
+ * omap_pm_cpu_set_freq - set the current minimum MPU frequency
+ * @f: MPU frequency in Hz
+ *
+ * Set the current minimum CPU frequency. The actual CPU frequency
+ * used could end up higher if the DSP requested a higher OPP.
+ * Intended to be called by plat-omap/cpu_omap.c:omap_target(). No
+ * return value.
+ */
+void omap_pm_cpu_set_freq(unsigned long f);
+
+/**
+ * omap_pm_cpu_get_freq - report the current CPU frequency
+ *
+ * Returns the current MPU frequency, or 0 upon error.
+ */
+unsigned long omap_pm_cpu_get_freq(void);
+
+
+/*
+ * Powerdomain usecounting hooks
+ */
+
+/**
+ * omap_pm_pwrdm_active - indicate that a power domain has become active
+ * @pwrdm: struct powerdomain *
+ *
+ * Notify the OMAP PM layer that the power domain 'pwrdm' has become active,
+ * presumably due to a device driver enabling an underlying clock. This
+ * function is intended to be called by a clockdomain node in the clock
+ * framework. No return value.
+ */
+void omap_pm_pwrdm_active(struct powerdomain *pwrdm);
+
+
+/**
+ * omap_pm_pwrdm_inactive - indicate that a power domain has become inactive
+ * @pwrdm: struct powerdomain *
+ *
+ * Notify the OMAP PM layer that the power domain 'pwrdm' has become
+ * inactive, presumably due to a device driver disabling an underlying
+ * clock. This function is intended to be called by a clockdomain
+ * node in the clock framework. No return value.
+ */
+void omap_pm_pwrdm_inactive(struct powerdomain *pwrdm);
+
+
+#endif
--
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