Re: [PATCH 2/2] cpufreq: qcom-fw: Add support for QCOM cpufreq FW driver
From: Taniya Das
Date: Thu Jun 07 2018 - 03:18:34 EST
Hello Viresh,
Thank you for the review comments.
On 6/6/2018 11:31 AM, Viresh Kumar wrote:
On 04-06-18, 16:16, Taniya Das wrote:
The CPUfreq FW present in some QCOM chipsets offloads the steps necessary
for changing the frequency of CPUs. The driver implements the cpufreq
driver interface for this firmware.
Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
Signed-off-by: Taniya Das <tdas@xxxxxxxxxxxxxx>
---
drivers/cpufreq/Kconfig.arm | 9 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/qcom-cpufreq-fw.c | 316 ++++++++++++++++++++++++++++++++++++++
3 files changed, 326 insertions(+)
create mode 100644 drivers/cpufreq/qcom-cpufreq-fw.c
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index c7ce928..82c391e 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -312,3 +312,12 @@ config ARM_PXA2xx_CPUFREQ
This add the CPUFreq driver support for Intel PXA2xx SOCs.
If in doubt, say N.
+
+config ARM_QCOM_CPUFREQ_FW
+ bool "QCOM CPUFreq FW driver"
+ help
+ Support for the CPUFreq FW driver.
+ The CPUfreq FW preset in some QCOM chipsets offloads the steps
+ necessary for changing the frequency of CPUs. The driver
+ implements the cpufreq driver interface for this firmware.
+ Say Y if you want to support CPUFreq FW.
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index fb4a2ec..34691a2 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -86,6 +86,7 @@ obj-$(CONFIG_ARM_TEGRA124_CPUFREQ) += tegra124-cpufreq.o
obj-$(CONFIG_ARM_TEGRA186_CPUFREQ) += tegra186-cpufreq.o
obj-$(CONFIG_ARM_TI_CPUFREQ) += ti-cpufreq.o
obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
+obj-$(CONFIG_ARM_QCOM_CPUFREQ_FW) += qcom-cpufreq-fw.o
##################################################################################
diff --git a/drivers/cpufreq/qcom-cpufreq-fw.c b/drivers/cpufreq/qcom-cpufreq-fw.c
new file mode 100644
index 0000000..2135a08
--- /dev/null
+++ b/drivers/cpufreq/qcom-cpufreq-fw.c
@@ -0,0 +1,316 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
+#define INIT_RATE 300000000UL
+#define XO_RATE 19200000UL
+#define LUT_MAX_ENTRIES 40U
+#define CORE_COUNT_VAL(val) (((val) & (GENMASK(18, 16))) >> 16)
+#define LUT_ROW_SIZE 32
+
+struct cpufreq_qcom {
+ struct cpufreq_frequency_table *table;
+ struct device *dev;
+ void __iomem *perf_base;
+ void __iomem *lut_base;
+ cpumask_t related_cpus;
+ unsigned int max_cores;
+};
+
+static struct cpufreq_qcom *qcom_freq_domain_map[NR_CPUS];
+
+static int
+qcom_cpufreq_fw_target_index(struct cpufreq_policy *policy,
+ unsigned int index)
+{
+ struct cpufreq_qcom *c = policy->driver_data;
+
+ writel_relaxed(index, c->perf_base);
+
+ return 0;
+}
+
+static unsigned int qcom_cpufreq_fw_get(unsigned int cpu)
+{
+ struct cpufreq_qcom *c;
+ unsigned int index;
+
+ c = qcom_freq_domain_map[cpu];
+ if (!c)
+ return 0;
+
+ index = readl_relaxed(c->perf_base);
+ index = min(index, LUT_MAX_ENTRIES - 1);
+
+ return c->table[index].frequency;
+}
+
+static int qcom_cpufreq_fw_cpu_init(struct cpufreq_policy *policy)
+{
+ struct cpufreq_qcom *c;
+
+ c = qcom_freq_domain_map[policy->cpu];
+ if (!c) {
+ pr_err("No scaling support for CPU%d\n", policy->cpu);
+ return -ENODEV;
+ }
+
+ cpumask_copy(policy->cpus, &c->related_cpus);
+
+ policy->freq_table = c->table;
+ policy->driver_data = c;
What about fast cpufreq switching ? I think you can enable that option as well
here..
Sure I will take a look and update.
+
+ return 0;
+}
+
+static struct freq_attr *qcom_cpufreq_fw_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ &cpufreq_freq_attr_scaling_boost_freqs,
+ NULL
+};
+
+static struct cpufreq_driver cpufreq_qcom_fw_driver = {
+ .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+ CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = qcom_cpufreq_fw_target_index,
+ .get = qcom_cpufreq_fw_get,
+ .init = qcom_cpufreq_fw_cpu_init,
What about CPU hotplug ? We can still do that, right ? So what will happen if
all CPUs of a freq-domain are removed (hence cpufreq policy is removed) and then
someone calls qcom_cpufreq_fw_get() ? You should really work on cpufreq_policy
there to get 'c'.
You want the _get to do something as below.
Please correct me if my understanding is wrong.
....
policy = cpufreq_cpu_get_raw(cpu);
if (!policy)
return 0;
c = policy->driver_data;
index = readl_relaxed(c->perf_base);
index = min(index, LUT_MAX_ENTRIES - 1);
return c->table[index].frequency;
....
+ .name = "qcom-cpufreq-fw",
+ .attr = qcom_cpufreq_fw_attr,
+ .boost_enabled = true,
+};
+
+static int qcom_read_lut(struct platform_device *pdev,
+ struct cpufreq_qcom *c)
+{
+ struct device *dev = &pdev->dev;
+ u32 data, src, lval, i, core_count, prev_cc, prev_freq, cur_freq;
+
+ c->table = devm_kcalloc(dev, LUT_MAX_ENTRIES + 1,
+ sizeof(*c->table), GFP_KERNEL);
+ if (!c->table)
+ return -ENOMEM;
+
+ for (i = 0; i < LUT_MAX_ENTRIES; i++) {
+ data = readl_relaxed(c->lut_base + i * LUT_ROW_SIZE);
+ src = ((data & GENMASK(31, 30)) >> 30);
+ lval = (data & GENMASK(7, 0));
+ core_count = CORE_COUNT_VAL(data);
+
+ if (!src)
+ c->table[i].frequency = INIT_RATE / 1000;
+ else
+ c->table[i].frequency = XO_RATE * lval / 1000;
+
+ cur_freq = c->table[i].frequency;
+
+ dev_dbg(dev, "index=%d freq=%d, core_count %d\n",
+ i, c->table[i].frequency, core_count);
+
+ if (core_count != c->max_cores)
+ cur_freq = CPUFREQ_ENTRY_INVALID;
+
+ /*
+ * Two of the same frequencies with the same core counts means
+ * end of table.
+ */
+ if (i > 0 && c->table[i - 1].frequency ==
+ c->table[i].frequency && prev_cc == core_count) {
+ struct cpufreq_frequency_table *prev = &c->table[i - 1];
+
+ if (prev_freq == CPUFREQ_ENTRY_INVALID)
+ prev->flags = CPUFREQ_BOOST_FREQ;
+ break;
+ }
+ prev_cc = core_count;
+ prev_freq = cur_freq;
+ }
+
+ c->table[i].frequency = CPUFREQ_TABLE_END;
+
+ return 0;
+}
Looks like there are many problems here.
- You are assigning prev_freq with cur_freq (which may be uninitialized local
variable here).
- In this version, you never write CPUFREQ_ENTRY_INVALID to table[i].frequency,
which looks wrong as well.
- The code to detect boost, would only enter for i > 0 and the prev_freq
would be initialized with the cur_freq.
- In the case where the core_count != max_cores, the cur_freq is marked
INVALID, and when both prev_freq == cur_freq && prev_cc && cur_cc match,
that is the time the prev table flags need to be updated. Marking the
table[i].frequency as INVALID is not required as cur_freq is already
marked with the same. Please correct me if you think otherwise.
+
+static int qcom_get_related_cpus(struct device_node *np, struct cpumask *m)
+{
+ struct device_node *cpu_dev;
s/cpu_dev/cpu_np/
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ cpu_dev = of_cpu_device_node_get(cpu);
+ if (!cpu_dev)
+ continue;
+ cpu_dev = of_parse_phandle(cpu_dev, "qcom,freq-domain", 0);
What's returned here is a pointer to the qcom,freq-domain node, and you assign
that to a variable named cpu_dev. Either use two variables for different node
types, or rename it to temp_np or something similar.
I would use a different node.
+ if (!cpu_dev)
+ continue;
+ if (cpu_dev == np)
+ cpumask_set_cpu(cpu, m);
+ }
+
+ if (cpumask_empty(m))
+ return -ENOENT;
+
+ return 0;
+}
+
+static int qcom_cpu_resources_init(struct platform_device *pdev,
+ struct device_node *np)
+{
+ struct cpufreq_qcom *c;
+ struct resource res;
+ struct device *dev = &pdev->dev;
+ void __iomem *en_base;
+ int cpu, index, ret;
+
+ c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ index = of_property_match_string(np, "reg-names", "enable");
+ if (index < 0)
+ return index;
+
+ if (of_address_to_resource(np, index, &res))
+ return -ENOMEM;
+
+ en_base = devm_ioremap(dev, res.start, resource_size(&res));
+ if (!en_base) {
+ dev_err(dev, "Unable to map %s enable-base\n", np->name);
+ return -ENOMEM;
+ }
+
+ /* FW should be in enabled state to proceed */
+ if (!(readl_relaxed(en_base) & 0x1)) {
+ dev_err(dev, "%s firmware not enabled\n", np->name);
+ return -ENODEV;
+ }
+ devm_iounmap(&pdev->dev, en_base);
+
+ index = of_property_match_string(np, "reg-names", "perf");
+ if (index < 0)
+ return index;
+
+ if (of_address_to_resource(np, index, &res))
+ return -ENOMEM;
+
+ c->perf_base = devm_ioremap(dev, res.start, resource_size(&res));
+ if (!c->perf_base) {
+ dev_err(dev, "Unable to map %s perf-base\n", np->name);
+ return -ENOMEM;
+ }
+
+ index = of_property_match_string(np, "reg-names", "lut");
+ if (index < 0)
+ return index;
+
+ if (of_address_to_resource(np, index, &res))
+ return -ENOMEM;
+
+ c->lut_base = devm_ioremap(dev, res.start, resource_size(&res));
+ if (!c->lut_base) {
+ dev_err(dev, "Unable to map %s lut-base\n", np->name);
+ return -ENOMEM;
+ }
+
+ ret = qcom_get_related_cpus(np, &c->related_cpus);
+ if (ret) {
+ dev_err(dev, "%s failed to get core phandles\n", np->name);
Maybe write a more relevant error message here ?
Sure, would take care of it in the next patch.
+ return ret;
+ }
+
+ c->max_cores = cpumask_weight(&c->related_cpus);
Maybe remove the error checking conditional from qcom_get_related_cpus() and
check !c->max_cores here for the same.
I would update it in the next patch.
+
+ ret = qcom_read_lut(pdev, c);
+ if (ret) {
+ dev_err(dev, "%s failed to read LUT\n", np->name);
+ return ret;
+ }
Enter a blank line here.
I would update in the next patch.
+ for_each_cpu(cpu, &c->related_cpus)
+ qcom_freq_domain_map[cpu] = c;
This whole setup looks a bit confusing to me. This is what you are doing
essentially:
qcom_resources_init()
{
for_each_possible_cpu() {
qcom_cpu_resources_init()
{
populate c->related_cpus;
for_each_related_cpu() {
qcom_freq_domain_map[cpu] = c;
}
}
}
}
So if there are 4 CPUs that share a freq domain, then you are allocating 'c' 4
times and (over)writing qcom_freq_domain_map[] for all these CPUs 4 times and
finally keeping value of 'c' only once.
You must be running most of the work done in qcom_resources_init() only once per
freq-domain.
Thanks, you are correct, I carried the earlier logic, would cleanup in
the next patch.
+
+ return 0;
+}
+
+static int qcom_resources_init(struct platform_device *pdev)
+{
+ struct device_node *np, *cpu_dev;
cpu_dev is normally used in kernel for struct device *, maybe use cpu_np ?
I would update it in the next patch.
+ unsigned int cpu;
+ int ret;
+
+ for_each_possible_cpu(cpu) {
+ cpu_dev = of_cpu_device_node_get(cpu);
+ if (!cpu_dev) {
+ dev_err(&pdev->dev, "Failed to get cpu %d device\n",
+ cpu);
+ continue;
+ }
+
+ np = of_parse_phandle(cpu_dev, "qcom,freq-domain", 0);
+ if (!np) {
+ dev_err(&pdev->dev, "Failed to get freq-domain device\n");
+ continue;
I am not sure if we should continue or error out here. Why would you want only a
group of CPUs to have this property set ? Or if you really have a case for that
currently ?
I don't have any usecase, but I was of the opinion in case there is no
freq domains attached to a cluster. But it might be better I error out.
+ }
+
+ of_node_put(cpu_dev);
+
+ ret = qcom_cpu_resources_init(pdev, np);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int qcom_cpufreq_fw_driver_probe(struct platform_device *pdev)
+{
+ int rc;
+
+ /* Get the bases of cpufreq for domains */
+ rc = qcom_resources_init(pdev);
+ if (rc) {
+ dev_err(&pdev->dev, "CPUFreq resource init failed\n");
+ return rc;
+ }
+
+ rc = cpufreq_register_driver(&cpufreq_qcom_fw_driver);
+ if (rc) {
+ dev_err(&pdev->dev, "CPUFreq FW driver failed to register\n");
+ return rc;
+ }
+
+ dev_info(&pdev->dev, "QCOM CPUFreq FW driver inited\n");
s/inited/initialized/ ?
Sure, will fix in the next patch.
+
+ return 0;
+}
+
+static const struct of_device_id match_table[] = {
+ { .compatible = "qcom,cpufreq-fw" },
+ {}
+};
+
+static struct platform_driver qcom_cpufreq_fw_driver = {
+ .probe = qcom_cpufreq_fw_driver_probe,
+ .driver = {
+ .name = "qcom-cpufreq-fw",
+ .of_match_table = match_table,
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init qcom_cpufreq_fw_init(void)
+{
+ return platform_driver_register(&qcom_cpufreq_fw_driver);
+}
+subsys_initcall(qcom_cpufreq_fw_init);
+
+MODULE_DESCRIPTION("QCOM CPU Frequency FW");
+MODULE_LICENSE("GPL v2");
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QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation.
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