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SubjectRe: [PATCH v8 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver
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@codeaurora.org>
> Signed-off-by: Taniya Das <tdas@codeaurora.org>
> ---
> 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 ?

> +
> + 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 :)

> +
> + 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 ?

> + 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.

--
viresh

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