[PATCH v2 17/18] cpufreq: add support for CPU DVFS based on SCMI message protocol
Sudeep Holla
sudeep.holla at arm.com
Wed Aug 9 02:59:50 PDT 2017
On 09/08/17 05:18, Viresh Kumar wrote:
> On 04-08-17, 15:31, Sudeep Holla wrote:
>
> I don't think its the Microsoft exchange server which screwed up tabs and
> spaces, but you.
>
Indeed, copy paste to blame ;)
>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>> index 2011fec2d6ad..c34633855bc7 100644
>> --- a/drivers/cpufreq/Kconfig.arm
>> +++ b/drivers/cpufreq/Kconfig.arm
>> @@ -215,6 +215,17 @@ config ARM_SA1100_CPUFREQ
>> config ARM_SA1110_CPUFREQ
>> bool
>>
>> +config ARM_SCMI_CPUFREQ
>> + tristate "SCMI based CPUfreq driver"
>
> You have used spaces here instead of tab and at multiple other places, can you
> please fix them all ?
>
Done locally.
>> + depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
>> + select PM_OPP
>> + help
>> + This adds the CPUfreq driver support for ARM platforms using SCMI
>> + protocol for CPU power management.
>> +
>> + This driver uses SCMI Message Protocol driver to interact with the
>> + firmware providing the CPU DVFS functionality.
>> +
>> config ARM_SCPI_CPUFREQ
>> tristate "SCPI based CPUfreq driver"
>> depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL && COMMON_CLK_SCPI
>> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
>> index ab3a42cd29ef..4810b45568d3 100644
>> --- a/drivers/cpufreq/Makefile
>> +++ b/drivers/cpufreq/Makefile
>> @@ -72,6 +72,7 @@ obj-$(CONFIG_ARM_S3C64XX_CPUFREQ) += s3c64xx-cpufreq.o
>> obj-$(CONFIG_ARM_S5PV210_CPUFREQ) += s5pv210-cpufreq.o
>> obj-$(CONFIG_ARM_SA1100_CPUFREQ) += sa1100-cpufreq.o
>> obj-$(CONFIG_ARM_SA1110_CPUFREQ) += sa1110-cpufreq.o
>> +obj-$(CONFIG_ARM_SCMI_CPUFREQ) += scmi-cpufreq.o
>> obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi-cpufreq.o
>> obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o
>> obj-$(CONFIG_ARM_STI_CPUFREQ) += sti-cpufreq.o
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> new file mode 100644
>> index 000000000000..034359cafea5
>> --- /dev/null
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -0,0 +1,268 @@
>> +/*
>> + * System Control and Power Interface (SCMI) based CPUFreq Interface driver
>> + *
>> + * Copyright (C) 2017 ARM Ltd.
>> + * Sudeep Holla <sudeep.holla at arm.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether express or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>> +
>> +#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/pm_opp.h>
>> +#include <linux/slab.h>
>> +#include <linux/scmi_protocol.h>
>> +#include <linux/types.h>
>> +
>> +struct scmi_data {
>> + int domain_id;
>> + struct device *cpu_dev;
>> + struct thermal_cooling_device *cdev;
>> + const struct scmi_handle *handle;
>
> This stores the same handle pointer which is stored in the global variable
> below. Right? Why keep a local variable here at all ?
>
Yes, you are right. Initially, started with just private pointers and
then added global. I was thinking of calling devm_scmi_handle_get per
policy to reflect the refcount correctly and drop global variable. Let
me know what you think.
>> +};
>> +
>> +static const struct scmi_handle *handle;
>> +
>> +unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
>> +{
>> + int ret;
>> + unsigned long rate;
>> + struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
>> + struct scmi_data *priv = policy->driver_data;
>> + struct scmi_perf_ops *perf_ops = priv->handle->perf_ops;
>
> Normally people prefer to keep these definitions in decreasing order of their
> lengths. i.e. ret and rate would be defined in the last line. Though I would
> leave it to you to decide.
>
I too prefer that, will fix that.
>> +
>> + ret = perf_ops->freq_get(priv->handle, priv->domain_id, &rate, false);
>> + if (ret)
>> + return CPUFREQ_ENTRY_INVALID;
>
> This is something special which is used only when we are returning indexes and
> I am not sure if this will have benefit here. I will rather return 0 here.
> That's what other drivers are doing.
>
Indeed had 0 initially but changed as per Juri's suggestion. But is 0
treated as failure and still running at current OPP ? and not 0KHz I assume.
>> + return rate / 1000;
>> +}
>> +
>> +static int
>> +scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
>> +{
>> + struct scmi_data *priv = policy->driver_data;
>> + struct scmi_perf_ops *perf_ops = priv->handle->perf_ops;
>> + u64 freq = policy->freq_table[index].frequency * 1000;
>> +
>> + return perf_ops->freq_set(priv->handle, priv->domain_id, freq, false);
>> +}
>
> I suppose any CPU can change the frequency of any other CPU here, right? You
> must set policy->dvfs_possible_from_any_cpu = true, from ->init() then.
>
OK, I missed to see something like that exists, will do.
>> +static int
>> +scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
>> +{
>> + int cpu, domain, ret = 0;
>
> You don't need to initialize ret here and I would rather name it tdomain or
> something else. ret is a lot used to store error/success values, which isn't
> your case.
>
Agreed.
>> + struct device *tcpu_dev;
>> +
>> + domain = handle->perf_ops->device_domain_id(cpu_dev);
>> + if (domain < 0)
>> + return domain;
>> +
>> + cpumask_set_cpu(cpu_dev->id, cpumask);
>
> The mask already have this set from the core, you don't need to do it again.
>
Cool, wasn't aware of that.
>> + for_each_possible_cpu(cpu) {
>> + if (cpu == cpu_dev->id)
>> + continue;
>> +
>> + tcpu_dev = get_cpu_device(cpu);
>> + if (!tcpu_dev)
>> + continue;
>> +
>> + ret = handle->perf_ops->device_domain_id(tcpu_dev);
>> + if (ret == domain)
>> + cpumask_set_cpu(cpu, cpumask);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>> +{
>> + int ret;
>> + unsigned int latency;
>> + struct device *cpu_dev;
>> + struct scmi_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 = handle->perf_ops->add_opps_to_device(cpu_dev);
>> + if (ret) {
>> + dev_warn(cpu_dev, "failed to add opps to the device\n");
>> + return ret;
>> + }
>> +
>> + ret = scmi_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;
>> + }
>> +
>> + /*
>> + * But we need OPP table to function so if it is not there let's
>> + * give platform code chance to provide it for us.
>> + */
>
> How are we getting the OPPs? DT or non DT ?
>
Non DT :), from the firmware.
>> + 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->handle = handle;
>> + priv->cpu_dev = cpu_dev;
>> + priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
>> +
>> + 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_free_cpufreq_table;
>> + }
>> +
>> + latency = handle->perf_ops->get_transition_latency(cpu_dev);
>> + if (!latency)
>> + latency = CPUFREQ_ETERNAL;
>> +
>> + policy->cpuinfo.transition_latency = latency;
>> +
>> + return 0;
>> +
>> +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 int scmi_cpufreq_exit(struct cpufreq_policy *policy)
>> +{
>> + struct scmi_data *priv = policy->driver_data;
>> +
>> + cpufreq_cooling_unregister(priv->cdev);
>> + dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
>> + dev_pm_opp_cpumask_remove_table(policy->related_cpus);
>> + kfree(priv);
>
> I would rather swap the above two lines to keep the same order as in probe.
> Though nothing would fail with the current code as well.
>
Sure.
>> +
>> + return 0;
>> +}
>> +
>> +static void scmi_cpufreq_ready(struct cpufreq_policy *policy)
>> +{
>> + struct scmi_data *priv = policy->driver_data;
>> + struct device_node *np = of_node_get(priv->cpu_dev->of_node);
>> +
>> + if (WARN_ON(!np))
>> + return;
>> +
>> + if (of_find_property(np, "#cooling-cells", NULL)) {
>> + u32 pcoeff = 0;
>> +
>> + of_property_read_u32(np, "dynamic-power-coefficient",
>> + &pcoeff);
>> +
>> + priv->cdev = of_cpufreq_power_cooling_register(np, policy,
>> + pcoeff, NULL);
>> + if (IS_ERR(priv->cdev)) {
>> + dev_err(priv->cpu_dev,
>> + "running cpufreq without cooling device: %ld\n",
>> + PTR_ERR(priv->cdev));
>> +
>> + priv->cdev = NULL;
>> + }
>> + }
>> +
>> + of_node_put(np);
>> +}
>> +
>> +static struct cpufreq_driver scmi_cpufreq_driver = {
>> + .name = "scmi",
>> + .flags = CPUFREQ_STICKY |
>> + CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
>> + CPUFREQ_NEED_INITIAL_FREQ_CHECK,
>> + .verify = cpufreq_generic_frequency_table_verify,
>> + .attr = cpufreq_generic_attr,
>> + .target_index = scmi_cpufreq_set_target,
>> + .get = scmi_cpufreq_get_rate,
>> + .init = scmi_cpufreq_init,
>> + .exit = scmi_cpufreq_exit,
>> + .ready = scmi_cpufreq_ready,
>> +};
>
> Above block has lots of space/tab issues. Can you please use tabs before "="
> instead?
>
OK, again copy pasted from some other driver ;)
>> +static int scmi_cpufreq_probe(struct platform_device *pdev)
>> +{
>> + int ret;
>> +
>> + handle = devm_scmi_handle_get(&pdev->dev);
>
> What code is creating this pdev ?
>
SCMI driver, once it finds the performance protocol is available
and setup/initialized.
Thanks for the review.
--
Regards,
Sudeep
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