Re: [v0 2/2] cpufreq: qcom-fw: Add support for QCOM cpufreq FW driver

[Amit Kucheria <amit.kucheria@linaro.org>]

On Thu, May 17, 2018 at 12:30 PM, Taniya Das <tdas@codeaurora.org> wrote:
> The CPUfreq FW present in some QCOM chipsets offloads the steps necessary
> for hanging the frequency of CPUs. The driver implements the cpufreq driver

s/hanging/changing :-)

> interface for this firmware.
>
> Signed-off-by: Taniya Das <tdas@codeaurora.org>
> ---
>  drivers/cpufreq/Kconfig.arm       |   9 ++
>  drivers/cpufreq/Makefile          |   1 +
>  drivers/cpufreq/qcom-cpufreq-fw.c | 318 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 328 insertions(+)
>  create mode 100644 drivers/cpufreq/qcom-cpufreq-fw.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 96b35b8..a50aa6e 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -301,3 +301,12 @@ config ARM_PXA2xx_CPUFREQ
>           This add the CPUFreq driver support for Intel PXA2xx SOCs.
>
>           If in doubt, say N.
> +
> +config ARM_QCOM_CPUFREQ_FW
> +       tristate "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 8d24ade..a3edbce 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_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..67996d5
> --- /dev/null
> +++ b/drivers/cpufreq/qcom-cpufreq-fw.c
> @@ -0,0 +1,318 @@
> +// 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;
> +
> +       if (index >= LUT_MAX_ENTRIES) {
> +               dev_err(c->dev,
> +               "Passing an index (%u) that's greater than max (%d)\n",
> +                                       index, LUT_MAX_ENTRIES - 1);
> +               return -EINVAL;
> +       }
> +
> +       writel_relaxed(index, c->perf_base);
> +
> +       /* Make sure the write goes through before proceeding */
> +       mb();
> +       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 -ENODEV;
> +
> +       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;
> +       int ret;
> +
> +       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->table = c->table;
> +       policy->driver_data = c;
> +
> +       return ret;
> +}
> +
> +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,
> +       .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 = 0;


Get rid of prev_cc variable initialisation here and in other places
through out the code

> +
> +       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;
> +
> +               c->table[i].driver_data = 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)
> +                       c->table[i].frequency = CPUFREQ_ENTRY_INVALID;
> +
> +               /*
> +                * Two of the same frequencies with the same core counts means
> +                * end of table.
> +                */
> +               if (i > 0 && c->table[i - 1].driver_data ==
> +                                       c->table[i].driver_data
> +                                       && prev_cc == core_count) {
> +                       struct cpufreq_frequency_table *prev = &c->table[i - 1];
> +
> +                       if (prev->frequency == CPUFREQ_ENTRY_INVALID) {
> +                               prev->flags = CPUFREQ_BOOST_FREQ;
> +                               prev->frequency = prev->driver_data;
> +                       }
> +
> +                       break;
> +               }
> +               prev_cc = core_count;
> +       }
> +       c->table[i].frequency = CPUFREQ_TABLE_END;
> +
> +       return 0;
> +}
> +
> +static int qcom_get_related_cpus(struct device_node *np, struct cpumask *m)
> +{
> +       struct device_node *dev_phandle;
> +       struct device *cpu_dev;
> +       int cpu, i = 0, ret = -ENOENT;
> +
> +       dev_phandle = of_parse_phandle(np, "qcom,cpulist", i++);
> +       while (dev_phandle) {
> +               for_each_possible_cpu(cpu) {
> +                       cpu_dev = get_cpu_device(cpu);
> +                       if (cpu_dev && cpu_dev->of_node == dev_phandle) {
> +                               cpumask_set_cpu(cpu, m);
> +                               ret = 0;
> +                               break;
> +                       }
> +               }
> +               dev_phandle = of_parse_phandle(np, "qcom,cpulist", i++);
> +       }
> +
> +       return ret;
> +}
> +
> +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 = 0, ret;
> +
> +       c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);

Check if memory allocated successfully?

> +
> +       res = platform_get_resource_byname(dev, IORESOURCE_MEM, "en_base");
> +       if (!res) {
> +               dev_err(dev, "Enable base not defined for %s\n", np->name);
> +               return ret;
> +       }


This is not going to build. Did you build-test this on a 4.17-rc kenel ?

> +
> +       en_base = devm_ioremap(dev, res->start, resource_size(res));
> +       if (!en_base) {
> +               dev_err(dev, "Unable to map %s en-base\n", np->name);
> +               return -ENOMEM;
> +       }
> +
> +       /* FW should be 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_base");
> +       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_base");
> +       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);
> +               return ret;
> +       }
> +
> +       c->max_cores = cpumask_weight(&c->related_cpus);
> +
> +       ret = qcom_read_lut(pdev, c);
> +       if (ret) {
> +               dev_err(dev, "%s failed to read LUT\n", np->name);
> +               return ret;
> +       }
> +
> +       for_each_cpu(cpu, &c->related_cpus)
> +               qcom_freq_domain_map[cpu] = c;
> +
> +       return 0;
> +}
> +
> +static int qcom_resources_init(struct platform_device *pdev)
> +{
> +       struct device_node *np;
> +       int ret = -ENODEV;
> +
> +       for_each_available_child_of_node(pdev->dev.of_node, np) {
> +               if (of_device_is_compatible(np, "cpufreq")) {
> +                       ret = qcom_cpu_resources_init(pdev, np);
> +                       if (ret)
> +                               return ret;
> +               }
> +       }
> +
> +       return ret;
> +}
> +
> +static int qcom_cpufreq_fw_driver_probe(struct platform_device *pdev)
> +{
> +       int rc = 0;
> +
> +       /* 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");
> +
> +       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);
> +
> +static void __exit qcom_cpufreq_fw_exit(void)
> +{
> +       platform_driver_unregister(&qcom_cpufreq_fw_driver);
> +}
> +module_exit(qcom_cpufreq_fw_exit);
> +
> +MODULE_DESCRIPTION("QCOM CPU Frequency FW");
> +MODULE_LICENSE("GPL v2");
> --
> Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc.is a member
> of the Code Aurora Forum, hosted by the  Linux Foundation.
>