[PATCH v2 0/2] drivers: remove incorrect usage/dependency on topology_physical_package_id

[PATCH v2 0/2] drivers: remove incorrect usage/dependency on topology_physical_package_id

[Sudeep Holla]

Hi all,

There has been ongoing attempt to add ACPI topology support on ARM/ARM64
platform using PPTT. However it was discovered that the physical package
id is mapped to the so called clusters on ARM platforms and they don't
map to the physical socket as in other architectures.

In order to add the correct support for the well defined physical sockets,
we need to find remove the incorrect usage or any dependency on
topology_physical_package_id which currently maps to the clusters.

There's still one pending user of topology_physical_package_id, which is
arm_big_little driver which is used by bL switcher and by TC2 platform.
For now, we can leave that as is until we change the definition even for
ARM32 platforms as it's just used by only 32-bit platforms.

v1->v2:
	- Update change log in patch 1/2 as suggested by Lorenzo
	- Added acks from Viresh and Lorenzo

Sudeep Holla (2):
  drivers: psci: remove cluster terminology and dependency on
    physical_package_id
  cpufreq: scpi: remove arm_big_little dependency

 drivers/cpufreq/scpi-cpufreq.c  | 193 ++++++++++++++++++++++++++++++++++++----
 drivers/firmware/psci_checker.c |  46 +++++-----
 2 files changed, 200 insertions(+), 39 deletions(-)

--
2.7.4

[PATCH v2 1/2] drivers: psci: remove cluster terminology and dependency on physical_package_id

[Sudeep Holla]

Since the definition of the term "cluster" is not well defined in the
architecture, we should avoid using it. Also the physical package id
is currently mapped to so called "clusters" in ARM/ARM64 platforms which
is already argumentative.

Currently PSCI checker uses the physical package id assuming that CPU
power domains map to "clusters" and the physical package id in the code
as it stands also maps to cluster boundaries. It does that trying to
test "cluster" idle states to its best. However the CPU power domain
often but not always maps directly to the processor topology.

This patch removes the dependency on physical_package_id from the topology
in this PSCI checker. Also it replaces all the occurences of clusters to
cpu_groups which is derived from core_sibling_mask and may not directly
map to physical "cluster".

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/firmware/psci_checker.c | 46 ++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 24 deletions(-)

diff --git a/drivers/firmware/psci_checker.c b/drivers/firmware/psci_checker.c
index f3f4f810e5df..bb1c068bff19 100644
--- a/drivers/firmware/psci_checker.c
+++ b/drivers/firmware/psci_checker.c
@@ -77,8 +77,8 @@ static int psci_ops_check(void)
 	return 0;
 }
 
-static int find_clusters(const struct cpumask *cpus,
-			 const struct cpumask **clusters)
+static int find_cpu_groups(const struct cpumask *cpus,
+			   const struct cpumask **cpu_groups)
 {
 	unsigned int nb = 0;
 	cpumask_var_t tmp;
@@ -88,11 +88,11 @@ static int find_clusters(const struct cpumask *cpus,
 	cpumask_copy(tmp, cpus);
 
 	while (!cpumask_empty(tmp)) {
-		const struct cpumask *cluster =
+		const struct cpumask *cpu_group =
 			topology_core_cpumask(cpumask_any(tmp));
 
-		clusters[nb++] = cluster;
-		cpumask_andnot(tmp, tmp, cluster);
+		cpu_groups[nb++] = cpu_group;
+		cpumask_andnot(tmp, tmp, cpu_group);
 	}
 
 	free_cpumask_var(tmp);
@@ -170,24 +170,24 @@ static int hotplug_tests(void)
 {
 	int err;
 	cpumask_var_t offlined_cpus;
-	int i, nb_cluster;
-	const struct cpumask **clusters;
+	int i, nb_cpu_group;
+	const struct cpumask **cpu_groups;
 	char *page_buf;
 
 	err = -ENOMEM;
 	if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
 		return err;
-	/* We may have up to nb_available_cpus clusters. */
-	clusters = kmalloc_array(nb_available_cpus, sizeof(*clusters),
-				 GFP_KERNEL);
-	if (!clusters)
+	/* We may have up to nb_available_cpus cpu_groups. */
+	cpu_groups = kmalloc_array(nb_available_cpus, sizeof(*cpu_groups),
+				   GFP_KERNEL);
+	if (!cpu_groups)
 		goto out_free_cpus;
 	page_buf = (char *)__get_free_page(GFP_KERNEL);
 	if (!page_buf)
-		goto out_free_clusters;
+		goto out_free_cpu_groups;
 
 	err = 0;
-	nb_cluster = find_clusters(cpu_online_mask, clusters);
+	nb_cpu_group = find_cpu_groups(cpu_online_mask, cpu_groups);
 
 	/*
 	 * Of course the last CPU cannot be powered down and cpu_down() should
@@ -197,24 +197,22 @@ static int hotplug_tests(void)
 	err += down_and_up_cpus(cpu_online_mask, offlined_cpus);
 
 	/*
-	 * Take down CPUs by cluster this time. When the last CPU is turned
-	 * off, the cluster itself should shut down.
+	 * Take down CPUs by cpu group this time. When the last CPU is turned
+	 * off, the cpu group itself should shut down.
 	 */
-	for (i = 0; i < nb_cluster; ++i) {
-		int cluster_id =
-			topology_physical_package_id(cpumask_any(clusters[i]));
+	for (i = 0; i < nb_cpu_group; ++i) {
 		ssize_t len = cpumap_print_to_pagebuf(true, page_buf,
-						      clusters[i]);
+						      cpu_groups[i]);
 		/* Remove trailing newline. */
 		page_buf[len - 1] = '\0';
-		pr_info("Trying to turn off and on again cluster %d "
-			"(CPUs %s)\n", cluster_id, page_buf);
-		err += down_and_up_cpus(clusters[i], offlined_cpus);
+		pr_info("Trying to turn off and on again group %d (CPUs %s)\n",
+			i, page_buf);
+		err += down_and_up_cpus(cpu_groups[i], offlined_cpus);
 	}
 
 	free_page((unsigned long)page_buf);
-out_free_clusters:
-	kfree(clusters);
+out_free_cpu_groups:
+	kfree(cpu_groups);
 out_free_cpus:
 	free_cpumask_var(offlined_cpus);
 	return err;
-- 
2.7.4

[PATCH v2 2/2] cpufreq: scpi: remove arm_big_little dependency

[Sudeep Holla]

The dependency on physical_package_id from the topology to get the
cluster identifier is wrong. The concept of cluster used in ARM topology
is unfortunately not well defined in the architecture, we should avoid
using it. Further the frequency domain need not be mapped to so called
"clusters" one to one.

SCPI already provides means to obtain the frequency domain id from the
device tree. In order to support some new topologies(e.g. DSU which
contains 2 frequency domains within the physical cluster), pseudo
clusters are created to make this driver work which is wrong again.

In order to solve those issues and also remove dependency of topological
physical id for frequency domain, this patch removes the arm_big_little
dependency from scpi driver.

Cc: linux-amlogic at lists.infradead.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/cpufreq/scpi-cpufreq.c | 193 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 178 insertions(+), 15 deletions(-)

Hi AmLogic team,

I would like to get tested-by tag so that there's no last minute surprise
from this patch on Amlogic platforms.

Regards,
Sudeep

diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
index 05d299052c5c..247fcbfa4cb5 100644
--- a/drivers/cpufreq/scpi-cpufreq.c
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -18,27 +18,89 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/clk.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_cooling.h>
+#include <linux/export.h>
 #include <linux/module.h>
-#include <linux/platform_device.h>
+#include <linux/of_platform.h>
 #include <linux/pm_opp.h>
 #include <linux/scpi_protocol.h>
+#include <linux/slab.h>
 #include <linux/types.h>
 
-#include "arm_big_little.h"
+struct scpi_data {
+	struct clk *clk;
+	struct device *cpu_dev;
+	struct thermal_cooling_device *cdev;
+};
 
 static struct scpi_ops *scpi_ops;
 
-static int scpi_get_transition_latency(struct device *cpu_dev)
+static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
+	struct scpi_data *priv = policy->driver_data;
+	unsigned long rate = clk_get_rate(priv->clk);
+
+	return rate / 1000;
+}
+
+static int
+scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	struct scpi_data *priv = policy->driver_data;
+	u64 rate = policy->freq_table[index].frequency * 1000;
+	int ret;
+
+	ret = clk_set_rate(priv->clk, rate);
+	if (!ret && (clk_get_rate(priv->clk) != rate))
+		ret = -EIO;
+
+	return ret;
+}
+
+static int
+scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
 {
-	return scpi_ops->get_transition_latency(cpu_dev);
+	int cpu, domain, tdomain;
+	struct device *tcpu_dev;
+
+	domain = scpi_ops->device_domain_id(cpu_dev);
+	if (domain < 0)
+		return domain;
+
+	for_each_possible_cpu(cpu) {
+		if (cpu == cpu_dev->id)
+			continue;
+
+		tcpu_dev = get_cpu_device(cpu);
+		if (!tcpu_dev)
+			continue;
+
+		tdomain = scpi_ops->device_domain_id(tcpu_dev);
+		if (tdomain == domain)
+			cpumask_set_cpu(cpu, cpumask);
+	}
+
+	return 0;
 }
 
-static int scpi_init_opp_table(const struct cpumask *cpumask)
+static int scpi_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret;
-	struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
+	unsigned int latency;
+	struct device *cpu_dev;
+	struct scpi_data *priv;
+	struct cpufreq_frequency_table *freq_table;
+
+	cpu_dev = get_cpu_device(policy->cpu);
+	if (!cpu_dev) {
+		pr_err("failed to get cpu%d device\n", policy->cpu);
+		return -ENODEV;
+	}
 
 	ret = scpi_ops->add_opps_to_device(cpu_dev);
 	if (ret) {
@@ -46,32 +108,133 @@ static int scpi_init_opp_table(const struct cpumask *cpumask)
 		return ret;
 	}
 
-	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask);
-	if (ret)
+	ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus);
+	if (ret) {
+		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
+		return ret;
+	}
+
+	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
+	if (ret) {
 		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 			__func__, ret);
+		return ret;
+	}
+
+	ret = dev_pm_opp_get_opp_count(cpu_dev);
+	if (ret <= 0) {
+		dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
+		ret = -EPROBE_DEFER;
+		goto out_free_opp;
+	}
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		ret = -ENOMEM;
+		goto out_free_opp;
+	}
+
+	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+	if (ret) {
+		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
+		goto out_free_priv;
+	}
+
+	priv->cpu_dev = cpu_dev;
+	priv->clk = clk_get(cpu_dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n",
+			__func__, cpu_dev->id);
+		goto out_free_cpufreq_table;
+	}
+
+	policy->driver_data = priv;
+
+	ret = cpufreq_table_validate_and_show(policy, freq_table);
+	if (ret) {
+		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
+			ret);
+		goto out_put_clk;
+	}
+
+	/* scpi allows DVFS request for any domain from any CPU */
+	policy->dvfs_possible_from_any_cpu = true;
+
+	latency = scpi_ops->get_transition_latency(cpu_dev);
+	if (!latency)
+		latency = CPUFREQ_ETERNAL;
+
+	policy->cpuinfo.transition_latency = latency;
+
+	policy->fast_switch_possible = false;
+	return 0;
+
+out_put_clk:
+	clk_put(priv->clk);
+out_free_cpufreq_table:
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+out_free_priv:
+	kfree(priv);
+out_free_opp:
+	dev_pm_opp_cpumask_remove_table(policy->cpus);
+
 	return ret;
 }
 
-static const struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
-	.name	= "scpi",
-	.get_transition_latency = scpi_get_transition_latency,
-	.init_opp_table = scpi_init_opp_table,
-	.free_opp_table = dev_pm_opp_cpumask_remove_table,
+static int scpi_cpufreq_exit(struct cpufreq_policy *policy)
+{
+	struct scpi_data *priv = policy->driver_data;
+
+	cpufreq_cooling_unregister(priv->cdev);
+	clk_put(priv->clk);
+	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
+	kfree(priv);
+	dev_pm_opp_cpumask_remove_table(policy->related_cpus);
+
+	return 0;
+}
+
+static void scpi_cpufreq_ready(struct cpufreq_policy *policy)
+{
+	struct scpi_data *priv = policy->driver_data;
+	struct thermal_cooling_device *cdev;
+
+	cdev = of_cpufreq_cooling_register(policy);
+	if (!IS_ERR(cdev))
+		priv->cdev = cdev;
+}
+
+static struct cpufreq_driver scpi_cpufreq_driver = {
+	.name	= "scpi-cpufreq",
+	.flags	= CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+		  CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify	= cpufreq_generic_frequency_table_verify,
+	.attr	= cpufreq_generic_attr,
+	.get	= scpi_cpufreq_get_rate,
+	.init	= scpi_cpufreq_init,
+	.exit	= scpi_cpufreq_exit,
+	.ready	= scpi_cpufreq_ready,
+	.target_index	= scpi_cpufreq_set_target,
 };
 
 static int scpi_cpufreq_probe(struct platform_device *pdev)
 {
+	int ret;
+
 	scpi_ops = get_scpi_ops();
 	if (!scpi_ops)
 		return -EIO;
 
-	return bL_cpufreq_register(&scpi_cpufreq_ops);
+	ret = cpufreq_register_driver(&scpi_cpufreq_driver);
+	if (ret)
+		dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",
+			__func__, ret);
+	return ret;
 }
 
 static int scpi_cpufreq_remove(struct platform_device *pdev)
 {
-	bL_cpufreq_unregister(&scpi_cpufreq_ops);
+	cpufreq_unregister_driver(&scpi_cpufreq_driver);
 	scpi_ops = NULL;
 	return 0;
 }
-- 
2.7.4