Re: [PATCH v12 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver

Matthias Kaehlcke
2018-12-13T19:43:56Z

On Thu, Dec 13, 2018 at 01:19:54PM +0530, 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: Stephen Boyd <swboyd@chromium.org>
> Signed-off-by: Taniya Das <tdas@codeaurora.org>
> ---
> drivers/cpufreq/Kconfig.arm | 11 ++
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/qcom-cpufreq-hw.c | 305 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 317 insertions(+)
> create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 4e1131e..688f102 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -114,6 +114,17 @@ config ARM_QCOM_CPUFREQ_KRYO
>
> If in doubt, say N.
>
> +config ARM_QCOM_CPUFREQ_HW
> + tristate "QCOM CPUFreq HW driver"
> + depends on ARCH_QCOM || COMPILE_TEST
> + 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.
> +
> config ARM_S3C_CPUFREQ
> bool
> help
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index d5ee456..08c071b 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -61,6 +61,7 @@ obj-$(CONFIG_MACH_MVEBU_V7) += mvebu-cpufreq.o
> obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += omap-cpufreq.o
> obj-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o
> obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o
> +obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW) += qcom-cpufreq-hw.o
> obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO) += qcom-cpufreq-kryo.o
> obj-$(CONFIG_ARM_S3C2410_CPUFREQ) += s3c2410-cpufreq.o
> obj-$(CONFIG_ARM_S3C2412_CPUFREQ) += s3c2412-cpufreq.o
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> new file mode 100644
> index 0000000..a65d0ae
> --- /dev/null
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -0,0 +1,305 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/bitfield.h>
> +#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>
> +#include <linux/slab.h>
> +
> +#define LUT_MAX_ENTRIES 40U
> +#define LUT_SRC GENMASK(31, 30)
> +#define LUT_L_VAL GENMASK(7, 0)
> +#define LUT_CORE_COUNT GENMASK(18, 16)
> +#define LUT_ROW_SIZE 32
> +#define CLK_HW_DIV 2
> +
> +/* Register offsets */
> +#define REG_ENABLE 0x0
> +#define REG_LUT_TABLE 0x110
> +#define REG_PERF_STATE 0x920
> +
> +static unsigned long cpu_hw_rate, xo_rate;
> +static struct platform_device *global_pdev;
> +
> +static int qcom_cpufreq_hw_target_index(struct cpufreq_policy *policy,
> + unsigned int index)
> +{
> + void __iomem *perf_state_reg = policy->driver_data;
> +
> + writel_relaxed(index, perf_state_reg);
> +
> + return 0;
> +}
> +
> +static unsigned int qcom_cpufreq_hw_get(unsigned int cpu)
> +{
> + void __iomem *perf_state_reg;
> + struct cpufreq_policy *policy;
> + unsigned int index;
> +
> + policy = cpufreq_cpu_get_raw(cpu);
> + if (!policy)
> + return 0;
> +
> + perf_state_reg = policy->driver_data;
> +
> + index = readl_relaxed(perf_state_reg);
> + 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)
> +{
> + void __iomem *perf_state_reg = policy->driver_data;
> + int index;
> +
> + index = policy->cached_resolved_idx;
> + if (index < 0)
> + return 0;
> +
> + writel_relaxed(index, perf_state_reg);
> +
> + return policy->freq_table[index].frequency;
> +}
> +
> +static int qcom_cpufreq_hw_read_lut(struct device *dev,
> + struct cpufreq_policy *policy,
> + void __iomem *base)
> +{
> + u32 data, src, lval, i, core_count, prev_cc = 0, prev_freq = 0, freq;
> + unsigned int max_cores = cpumask_weight(policy->cpus);
> + struct cpufreq_frequency_table *table;
> +
> + table = kcalloc(LUT_MAX_ENTRIES + 1, sizeof(*table), GFP_KERNEL);
> + if (!table)
> + return -ENOMEM;
> +
> + for (i = 0; i < LUT_MAX_ENTRIES; i++) {
> + data = readl_relaxed(base + REG_LUT_TABLE + i * LUT_ROW_SIZE);
> + src = FIELD_GET(LUT_SRC, data);
> + lval = FIELD_GET(LUT_L_VAL, data);
> + core_count = FIELD_GET(LUT_CORE_COUNT, data);
> +
> + if (src)
> + freq = xo_rate * lval / 1000;
> + else
> + freq = cpu_hw_rate / 1000;
> +
> + /* Ignore boosts in the middle of the table */
> + if (core_count != max_cores) {
> + table[i].frequency = CPUFREQ_ENTRY_INVALID;
> + } else {
> + table[i].frequency = freq;
> + dev_dbg(dev, "index=%d freq=%d, core_count %d\n", i,
> + freq, core_count);
> + }
> +
> + /*
> + * Two of the same frequencies with the same core counts means
> + * end of table
> + */
> + if (i > 0 && prev_freq == freq && prev_cc == core_count) {
> + struct cpufreq_frequency_table *prev = &table[i - 1];
> +
> + /*
> + * Only treat the last frequency that might be a boost
> + * as the boost frequency
> + */
> + if (prev_cc != max_cores) {
> + prev->frequency = prev_freq;
> + prev->flags = CPUFREQ_BOOST_FREQ;
> + }
> +
> + break;
> + }
> +
> + prev_cc = core_count;
> + prev_freq = freq;
> + }
> +
> + table[i].frequency = CPUFREQ_TABLE_END;
> + policy->freq_table = table;
> +
> + return 0;
> +}
> +
> +static void 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;
> +
> + ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
> + "#freq-domain-cells", 0,
> + &args);
> + of_node_put(cpu_np);
> + if (ret < 0)
> + continue;
> +
> + if (index == args.args[0])
> + cpumask_set_cpu(cpu, m);
> + }
> +}
> +
> +static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
> +{
> + struct device *dev = &global_pdev->dev;
> + struct of_phandle_args args;
> + struct device_node *cpu_np;
> + struct resource *res;
> + void __iomem *base;
> + int ret, index;
> +
> + cpu_np = of_cpu_device_node_get(policy->cpu);
> + if (!cpu_np)
> + return -EINVAL;
> +
> + ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
> + "#freq-domain-cells", 0, &args);
> + of_node_put(cpu_np);
> + if (ret)
> + return ret;
> +
> + index = args.args[0];
> +
> + res = platform_get_resource(global_pdev, IORESOURCE_MEM, index);
> + base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + /* HW should be in enabled state to proceed */
> + if (!(readl_relaxed(base + REG_ENABLE) & 0x1)) {
> + dev_err(dev, "Domain-%d cpufreq hardware not enabled\n", index);
> + ret = -ENODEV;
> + goto error;
> + }
> +
> + qcom_get_related_cpus(index, policy->cpus);
> + if (!cpumask_weight(policy->cpus)) {
> + dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
> + ret = -ENOENT;
> + goto error;
> + }
> +
> + policy->driver_data = base + REG_PERF_STATE;
> +
> + ret = qcom_cpufreq_hw_read_lut(dev, policy, base);
> + if (ret) {
> + dev_err(dev, "Domain-%d failed to read LUT\n", index);
> + goto error;
> + }
> +
> + policy->fast_switch_possible = true;
> +
> + return 0;
> +error:
> + devm_iounmap(dev, base);
> + return ret;
> +}
> +
> +static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
> +{
> + void __iomem *base = policy->driver_data - REG_PERF_STATE;
> +
> + kfree(policy->freq_table);
> + devm_iounmap(&global_pdev->dev, base);
> +
> + 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,
> + .exit = qcom_cpufreq_hw_cpu_exit,
> + .fast_switch = qcom_cpufreq_hw_fast_switch,
> + .name = "qcom-cpufreq-hw",
> + .attr = qcom_cpufreq_hw_attr,
> +};
> +
> +static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
> +{
> + struct clk *clk;
> + int ret;
> +
> + clk = clk_get(&pdev->dev, "xo");
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + xo_rate = clk_get_rate(clk);
> + clk_put(clk);
> +
> + clk = clk_get(&pdev->dev, "alternate");
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + cpu_hw_rate = clk_get_rate(clk) / CLK_HW_DIV;
> + clk_put(clk);
> +
> + global_pdev = pdev;
> +
> + ret = cpufreq_register_driver(&cpufreq_qcom_hw_driver);
> + if (ret)
> + dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
> + else
> + dev_dbg(&pdev->dev, "QCOM CPUFreq HW driver initialized\n");
> +
> + return ret;
> +}
> +
> +static int qcom_cpufreq_hw_driver_remove(struct platform_device *pdev)
> +{
> + return cpufreq_unregister_driver(&cpufreq_qcom_hw_driver);
> +}
> +
> +static const struct of_device_id qcom_cpufreq_hw_match[] = {
> + { .compatible = "qcom,cpufreq-hw" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match);
> +
> +static struct platform_driver qcom_cpufreq_hw_driver = {
> + .probe = qcom_cpufreq_hw_driver_probe,
> + .remove = qcom_cpufreq_hw_driver_remove,
> + .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);
> +
> +static void __exit qcom_cpufreq_hw_exit(void)
> +{
> + platform_driver_unregister(&qcom_cpufreq_hw_driver);
> +}
> +module_exit(qcom_cpufreq_hw_exit);
> +
> +MODULE_DESCRIPTION("QCOM CPUFREQ HW Driver");
> +MODULE_LICENSE("GPL v2");

FWIW:

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>