Re: [PATCH v8 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver
From: Taniya Das
Date: Thu Oct 11 2018 - 07:19:38 EST
Hello Viresh,
Thanks for your review comments.
On 10/5/2018 4:25 PM, Viresh Kumar wrote:
On 23-09-18, 16:03, Taniya Das wrote:
The CPUfreq HW present in some QCOM chipsets offloads the steps necessary
for changing the frequency of CPUs. The driver implements the cpufreq
driver interface for this hardware engine.
Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
Signed-off-by: Taniya Das <tdas@xxxxxxxxxxxxxx>
---
drivers/cpufreq/Kconfig.arm | 11 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/qcom-cpufreq-hw.c | 354 ++++++++++++++++++++++++++++++++++++++
3 files changed, 366 insertions(+)
create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 0cd8eb7..93a9d72 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -298,3 +298,14 @@ config ARM_PXA2xx_CPUFREQ
This add the CPUFreq driver support for Intel PXA2xx SOCs.
If in doubt, say N.
+
+config ARM_QCOM_CPUFREQ_HW
+ bool "QCOM CPUFreq HW driver"
+ depends on ARCH_QCOM
+ help
+ Support for the CPUFreq HW driver.
+ Some QCOM chipsets have a HW engine to offload the steps
+ necessary for changing the frequency of the CPUs. Firmware loaded
+ in this engine exposes a programming interface to the OS.
+ The driver implements the cpufreq interface for this HW engine.
+ Say Y if you want to support CPUFreq HW.
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index c1ffeab..ca48a1d 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -85,6 +85,7 @@ 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_HW) += qcom-cpufreq-hw.o
##################################################################################
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
new file mode 100644
index 0000000..43107ab
--- /dev/null
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -0,0 +1,354 @@
+// 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 LUT_MAX_ENTRIES 40U
+#define CORE_COUNT_VAL(val) (((val) & (GENMASK(18, 16))) >> 16)
+#define LUT_ROW_SIZE 32
+#define CLK_HW_DIV 2
+
+enum {
+ REG_ENABLE,
+ REG_LUT_TABLE,
+ REG_PERF_STATE,
+
+ REG_ARRAY_SIZE,
+};
+
+struct cpufreq_qcom {
+ struct cpufreq_frequency_table *table;
+ void __iomem *reg_bases[REG_ARRAY_SIZE];
+ cpumask_t related_cpus;
+ unsigned int max_cores;
+ unsigned long xo_rate;
+ unsigned long cpu_hw_rate;
+};
+
+static const u16 cpufreq_qcom_std_offsets[REG_ARRAY_SIZE] = {
+ [REG_ENABLE] = 0x0,
+ [REG_LUT_TABLE] = 0x110,
+ [REG_PERF_STATE] = 0x920,
+};
+
+static struct cpufreq_qcom *qcom_freq_domain_map[NR_CPUS];
+
+static int
+qcom_cpufreq_hw_target_index(struct cpufreq_policy *policy,
+ unsigned int index)
+{
+ struct cpufreq_qcom *c = policy->driver_data;
+
+ writel_relaxed(index, c->reg_bases[REG_PERF_STATE]);
+
+ return 0;
+}
+
+static unsigned int qcom_cpufreq_hw_get(unsigned int cpu)
+{
+ struct cpufreq_qcom *c;
+ struct cpufreq_policy *policy;
+ unsigned int index;
+
+ policy = cpufreq_cpu_get_raw(cpu);
+ if (!policy)
+ return 0;
+
+ c = policy->driver_data;
+
+ index = readl_relaxed(c->reg_bases[REG_PERF_STATE]);
+ index = min(index, LUT_MAX_ENTRIES - 1);
+
+ return policy->freq_table[index].frequency;
+}
+
+static unsigned int
+qcom_cpufreq_hw_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ struct cpufreq_qcom *c = policy->driver_data;
+ int index;
+
+ index = policy->cached_resolved_idx;
+ if (index < 0)
+ return 0;
+
+ writel_relaxed(index, c->reg_bases[REG_PERF_STATE]);
+
+ return policy->freq_table[index].frequency;
+}
+
+static int qcom_cpufreq_hw_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->fast_switch_possible = true;
+ policy->freq_table = c->table;
+ policy->driver_data = c;
+
+ return 0;
+}
+
+static struct freq_attr *qcom_cpufreq_hw_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ &cpufreq_freq_attr_scaling_boost_freqs,
+ NULL
+};
+
+static struct cpufreq_driver cpufreq_qcom_hw_driver = {
+ .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+ CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = qcom_cpufreq_hw_target_index,
+ .get = qcom_cpufreq_hw_get,
+ .init = qcom_cpufreq_hw_cpu_init,
+ .fast_switch = qcom_cpufreq_hw_fast_switch,
+ .name = "qcom-cpufreq-hw",
+ .attr = qcom_cpufreq_hw_attr,
+ .boost_enabled = true,
+};
+
+static int qcom_cpufreq_hw_read_lut(struct platform_device *pdev,
+ struct cpufreq_qcom *c)
+{
+ struct device *dev = &pdev->dev;
+ void __iomem *base;
+ 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;
+
+ base = c->reg_bases[REG_LUT_TABLE];
+
+ for (i = 0; i < LUT_MAX_ENTRIES; i++) {
+ data = readl_relaxed(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 = c->xo_rate * lval / 1000;
+ else
+ c->table[i].frequency = c->cpu_hw_rate / 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;
+ }
The logic here always surprises me, why does the firmware keeps the
table this way instead of simplifying it ?
Unfortunately that is the only way to identify.
+
+ c->table[i].frequency = CPUFREQ_TABLE_END;
+
+ return 0;
+}
+
+static int qcom_get_related_cpus(int index, struct cpumask *m)
+{
+ struct device_node *cpu_np;
+ struct of_phandle_args args;
+ int cpu, ret;
+
+ for_each_possible_cpu(cpu) {
+ cpu_np = of_cpu_device_node_get(cpu);
+ if (!cpu_np)
+ continue;
+ of_node_put(cpu_np);
Heh, you can't do that here :)
Yes, I would take care to put it in the right place.
+
+ ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
As this code still needs to use the same pointer. It is possible that
the memory associated with cpu_np gets freed as soon as you call
of_node_put() on that. You should call of_node_put() anytime after
this routine is called.
+ "#freq-domain-cells", 0, &args);
+ if (ret < 0)
+ continue;
+
+ if (index == args.args[0])
+ cpumask_set_cpu(cpu, m);
+ }
+
+ return 0;
+}
+
+static int qcom_cpu_resources_init(struct platform_device *pdev,
+ unsigned int cpu, int index,
+ unsigned long xo_rate,
+ unsigned long cpu_hw_rate)
+{
+ struct cpufreq_qcom *c;
+ struct resource *res;
+ struct device *dev = &pdev->dev;
+ const u16 *offsets;
+ int ret, i, cpu_r;
+ void __iomem *base;
+
+ if (qcom_freq_domain_map[cpu])
+ return 0;
+
+ c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ offsets = of_device_get_match_data(&pdev->dev);
+ if (!offsets)
+ return -EINVAL;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, index);
+ base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ for (i = REG_ENABLE; i < REG_ARRAY_SIZE; i++)
+ c->reg_bases[i] = base + offsets[i];
+
+ /* HW should be in enabled state to proceed */
+ if (!(readl_relaxed(c->reg_bases[REG_ENABLE]) & 0x1)) {
+ dev_err(dev, "Domain-%d cpufreq hardware not enabled\n", index);
+ return -ENODEV;
+ }
+
+ ret = qcom_get_related_cpus(index, &c->related_cpus);
+ if (ret) {
+ dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+ return ret;
+ }
+
+ c->max_cores = cpumask_weight(&c->related_cpus);
+ if (!c->max_cores)
+ return -ENOENT;
+
+ c->xo_rate = xo_rate;
+ c->cpu_hw_rate = cpu_hw_rate;
+
+ ret = qcom_cpufreq_hw_read_lut(pdev, c);
+ if (ret) {
+ dev_err(dev, "Domain-%d failed to read LUT\n", index);
+ return ret;
+ }
+
+ for_each_cpu(cpu_r, &c->related_cpus)
+ qcom_freq_domain_map[cpu_r] = c;
+
+ return 0;
+}
+
+static int qcom_resources_init(struct platform_device *pdev)
+{
+ struct device_node *cpu_np;
+ struct of_phandle_args args;
+ struct clk *clk;
+ unsigned int cpu;
+ unsigned long xo_rate, cpu_hw_rate;
+ int ret;
+
+ clk = devm_clk_get(&pdev->dev, "xo");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ xo_rate = clk_get_rate(clk);
+
+ devm_clk_put(&pdev->dev, clk);
Why use devm_ variants if you want to put the clock anyway ?
Would move to non devm_ variants.
+ clk = devm_clk_get(&pdev->dev, "cpu_clk");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ cpu_hw_rate = clk_get_rate(clk) / CLK_HW_DIV;
+
+ devm_clk_put(&pdev->dev, clk);
same here.
+
+ for_each_possible_cpu(cpu) {
+ cpu_np = of_cpu_device_node_get(cpu);
Where is the of_node_put() corresponding to this ?
+ if (!cpu_np) {
+ dev_dbg(&pdev->dev, "Failed to get cpu %d device\n",
+ cpu);
+ continue;
+ }
+
+ ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
+ "#freq-domain-cells", 0, &args);
+ if (ret < 0)
+ return ret;
+
+ ret = qcom_cpu_resources_init(pdev, cpu, args.args[0],
+ xo_rate, cpu_hw_rate);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int qcom_cpufreq_hw_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_hw_driver);
+ if (rc) {
+ dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
+ return rc;
+ }
+
+ dev_dbg(&pdev->dev, "QCOM CPUFreq HW driver initialized\n");
+
+ return 0;
+}
+
+static const struct of_device_id qcom_cpufreq_hw_match[] = {
+ { .compatible = "qcom,cpufreq-hw", .data = &cpufreq_qcom_std_offsets },
+ {}
+};
+
+static struct platform_driver qcom_cpufreq_hw_driver = {
+ .probe = qcom_cpufreq_hw_driver_probe,
+ .driver = {
+ .name = "qcom-cpufreq-hw",
+ .of_match_table = qcom_cpufreq_hw_match,
+ },
+};
+
+static int __init qcom_cpufreq_hw_init(void)
+{
+ return platform_driver_register(&qcom_cpufreq_hw_driver);
+}
+subsys_initcall(qcom_cpufreq_hw_init);
+
+MODULE_DESCRIPTION("QCOM firmware-based CPU Frequency driver");
--
Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc.is a member
of the Code Aurora Forum, hosted by the Linux Foundation.
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation.
--