[PATCH 14/15] OMAP: PM CONSTRAINTS: implement the devices wake-up latency constraints

jean.pihet
2011-08-16T13:44:14Z

Implement the devices wake-up latency constraints using the global
device PM QoS notification handler which applies the constraints to the
underlying layer by calling the corresponding function at hwmod level.

Note: the bus throughput function is implemented but currently is
a no-op. A new PM QoS class for the bus throughput needs to be
added.

Tested on OMAP3 Beagleboard and OMAP4 Pandaboard in RET/OFF using wake-up
latency constraints on MPU, CORE and PER.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
---
arch/arm/plat-omap/include/plat/omap-pm.h | 128 ---------------------
arch/arm/plat-omap/omap-pm-constraints.c | 173 +++++++++++++---------------
arch/arm/plat-omap/omap-pm-noop.c | 89 ---------------
3 files changed, 80 insertions(+), 310 deletions(-)

diff --git a/arch/arm/plat-omap/include/plat/omap-pm.h b/arch/arm/plat-omap/include/plat/omap-pm.h
index 0840df8..d276082 100644
--- a/arch/arm/plat-omap/include/plat/omap-pm.h
+++ b/arch/arm/plat-omap/include/plat/omap-pm.h
@@ -62,136 +62,8 @@ 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
- * omap_pm_set_max_dev_wakeup_lat()
- *
- * 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.
- *
- * 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.
- */
-int 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 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.
- *
- * Returns -EINVAL for an invalid argument, -ERANGE if the constraint
- * is not satisfiable, or 0 upon success.
- */
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
- * @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 @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 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.
- *
- * Returns -EINVAL for an invalid argument, -ERANGE if the constraint
- * is not satisfiable, or 0 upon success.
- */
-int omap_pm_set_max_dev_wakeup_lat(struct device *req_dev, 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.
- *
- * Returns -EINVAL for an invalid argument, -ERANGE if the constraint
- * is not satisfiable, or 0 upon success.
- */
-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
diff --git a/arch/arm/plat-omap/omap-pm-constraints.c b/arch/arm/plat-omap/omap-pm-constraints.c
index c8b4e4c..efec5df 100644
--- a/arch/arm/plat-omap/omap-pm-constraints.c
+++ b/arch/arm/plat-omap/omap-pm-constraints.c
@@ -17,132 +17,112 @@
#undef DEBUG

#include <linux/init.h>
+#include <linux/notifier.h>
#include <linux/cpufreq.h>
#include <linux/device.h>
#include <linux/platform_device.h>
+#include <linux/pm_qos.h>

/* Interface documentation is in mach/omap-pm.h */
#include <plat/omap-pm.h>
#include <plat/omap_device.h>
+#include <plat/common.h>
+#include <plat/omap_hwmod.h>

static bool off_mode_enabled;
static u32 dummy_context_loss_counter;

-/*
- * Device-driver-originated constraints (via board-*.c files)
- */
+static int _dev_pm_qos_wakeup_latency_handler(struct notifier_block *,
+ unsigned long, void *);
+static struct notifier_block _dev_pm_qos_wakeup_latency_notifier = {
+ .notifier_call = _dev_pm_qos_wakeup_latency_handler,
+};

-int omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t)
+
+static int _apply_dev_pm_qos_constraint(void *req, unsigned long new_value)
{
- if (!dev || t < -1) {
- WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
- return -EINVAL;
- };
+ struct omap_device *od;
+ struct omap_hwmod *oh;
+ struct platform_device *pdev;
+ struct dev_pm_qos_request *dev_pm_qos_req = req;

- 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);
+ pr_debug("OMAP PM CONSTRAINTS: req@0x%p, new_value=%lu\n",
+ req, new_value);

- /*
- * 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.
- */
+ /* Look for the platform device for the constraint target device */
+ pdev = to_platform_device(dev_pm_qos_req->dev);

- return 0;
-}
+ /* Try to catch non platform devices */
+ if (pdev->name == NULL) {
+ pr_err("%s: Error: platform device for device %s not valid\n",
+ __func__, dev_name(dev_pm_qos_req->dev));
+ return -EINVAL;
+ }

-int 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(1, "OMAP PM: %s: invalid parameter(s)", __func__);
+ /* Find the associated omap_device for dev */
+ od = container_of(pdev, struct omap_device, pdev);
+ if (od->hwmods_cnt != 1) {
+ pr_err("%s: Error: No unique hwmod for device %s\n",
+ __func__, dev_name(dev_pm_qos_req->dev));
return -EINVAL;
- };
+ }

- 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);
+ /* Find the primary omap_hwmod for dev */
+ oh = od->hwmods[0];

- /*
- * 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.
- */
+ pr_debug("OMAP PM CONSTRAINTS: req@0x%p, dev=0x%p, new_value=%lu\n",
+ req, dev_pm_qos_req->dev, new_value);

- return 0;
+ /* Apply the constraint */
+ return omap_hwmod_set_wkup_lat_constraint(oh, dev_pm_qos_req,
+ new_value);
}

-int omap_pm_set_max_dev_wakeup_lat(struct device *req_dev, struct device *dev,
- long t)
+/* PM QoS classes handlers */
+static int _dev_pm_qos_wakeup_latency_handler(struct notifier_block *nb,
+ unsigned long new_value,
+ void *req)
{
- if (!req_dev || !dev || t < -1) {
- WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
- return -EINVAL;
- };
-
- 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.
- */
-
- return 0;
+ return _apply_dev_pm_qos_constraint(req, new_value);
}

-int omap_pm_set_max_sdma_lat(struct device *dev, long t)
+/*
+ * omap_pm_set_min_bus_tput - set/release bus throughput constraints
+ * ToDo: currently is a no-op, to be converted to a PM QoS handler
+ * for the TPUT class
+ */
+int omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r)
{
- if (!dev || t < -1) {
+ long t;
+ struct device *req_dev = NULL;
+
+ if (!dev || (agent_id != OCP_INITIATOR_AGENT &&
+ agent_id != OCP_TARGET_AGENT)) {
WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
return -EINVAL;
};

- if (t == -1)
- pr_debug("OMAP PM: remove max DMA latency constraint: "
- "dev %s\n", dev_name(dev));
+ /*
+ * A value of r == 0 removes the constraint. Convert it to the
+ * generic _set_dev_constraint convention (-1 for constraint removal)
+ */
+ if (r == 0)
+ t = -1;
else
- pr_debug("OMAP PM: add max DMA latency constraint: "
- "dev %s, t = %ld usec\n", dev_name(dev), t);
+ t = r;

/*
- * 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.
+ * Assign the device for L3 or L4 interconnect to req_dev,
+ * based on the value of agent_id
*/
+ switch (agent_id) {
+ case OCP_INITIATOR_AGENT:
+ req_dev = omap2_get_l3_device();
+ break;
+ case OCP_TARGET_AGENT:
+ /* Fixme: need the device for L4 interconnect */
+ break;
+ }

return 0;
}
@@ -350,10 +330,17 @@ int __init omap_pm_if_early_init(void)
return 0;
}

-/* Must be called after clock framework is initialized */
+/* Must be called after the clock framework is initialized */
int __init omap_pm_if_init(void)
{
- return 0;
+ int ret;
+
+ ret = dev_pm_qos_add_global_notifier(
+ &_dev_pm_qos_wakeup_latency_notifier);
+ if (ret)
+ WARN(1, KERN_ERR "Cannot add global notifier for dev PM QoS\n");
+
+ return ret;
}

void omap_pm_if_exit(void)
diff --git a/arch/arm/plat-omap/omap-pm-noop.c b/arch/arm/plat-omap/omap-pm-noop.c
index b0471bb2..8ad902f 100644
--- a/arch/arm/plat-omap/omap-pm-noop.c
+++ b/arch/arm/plat-omap/omap-pm-noop.c
@@ -32,35 +32,6 @@ static u32 dummy_context_loss_counter;
/*
* Device-driver-originated constraints (via board-*.c files)
*/
-
-int omap_pm_set_max_mpu_wakeup_lat(struct device *dev, long t)
-{
- if (!dev || t < -1) {
- WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
- return -EINVAL;
- };
-
- 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.
- */
-
- return 0;
-}
-
int omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r)
{
if (!dev || (agent_id != OCP_INITIATOR_AGENT &&
@@ -88,66 +59,6 @@ int omap_pm_set_min_bus_tput(struct device *dev, u8 agent_id, unsigned long r)
return 0;
}

-int omap_pm_set_max_dev_wakeup_lat(struct device *req_dev, struct device *dev,
- long t)
-{
- if (!req_dev || !dev || t < -1) {
- WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
- return -EINVAL;
- };
-
- 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.
- */
-
- return 0;
-}
-
-int omap_pm_set_max_sdma_lat(struct device *dev, long t)
-{
- if (!dev || t < -1) {
- WARN(1, "OMAP PM: %s: invalid parameter(s)", __func__);
- return -EINVAL;
- };
-
- 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.
- */
-
- return 0;
-}
-
int omap_pm_set_min_clk_rate(struct device *dev, struct clk *c, long r)
{
if (!dev || !c || r < 0) {
--
1.7.4.1