Date:   Thu, 11 Apr 2019 01:44:43 +0800
From:   Frank Lee <tiny.windzz@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        robh+dt@...nel.org, mark.rutland@....com,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, rjw@...ysocki.net,
        davem@...emloft.net, mchehab+samsung@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        nicolas.ferre@...rochip.com, Linux PM <linux-pm@...r.kernel.org>,
        devicetree@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] cpufreq: Add sunxi nvmem based CPU scaling driver

On Wed, Apr 10, 2019 at 11:24 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 09-04-19, 13:25, Yangtao Li wrote:
> > +static const struct sunxi_cpufreq_soc_data sun50i_h6_data = {
> > +     .efuse_xlate = sun50i_efuse_xlate,
> > +     .nvmem_mask = 0x7,
> > +     .nvmem_shift = 5,
> > +};
> > +
> > +static const struct of_device_id sunxi_cpufreq_match_list[] = {
> > +     { .compatible = "allwinner,sun50i-h6", .data = &sun50i_h6_data },
> > +     {}
> > +};
> > +
> > +static const struct of_device_id *sunxi_cpufreq_match_node(void)
> > +{
> > +     struct device_node *np;
> > +     const struct of_device_id *match;
> > +
> > +     np = of_find_node_by_path("/");
> > +     match = of_match_node(sunxi_cpufreq_match_list, np);
> > +     of_node_put(np);
> > +
> > +     return match;
> > +}
> > +
>
> Above code can be placed just above sunxi_cpufreq_init(), if you ...
>
> > +static int sunxi_cpufreq_nvmem_probe(struct platform_device *pdev)
> > +{
> > +     const struct sunxi_cpufreq_soc_data *soc_data;
> > +     struct opp_table **opp_tables;
> > +     const struct of_device_id *match;
> > +     char name[MAX_NAME_LEN];
> > +     unsigned int cpu;
> > +     u32 speed = 0;
> > +     int ret;
> > +
> > +     opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
> > +                          GFP_KERNEL);
> > +     if (!opp_tables)
> > +             return -ENOMEM;
> > +
> > +     match = sunxi_cpufreq_match_node();
>
> ... avoid this and ...
>
> > +     soc_data = match->data;
> > +     if (!soc_data)
> > +             return -EINVAL;
> > +
> > +     ret = sunxi_cpufreq_get_efuse(soc_data, &speed);
> > +     if (ret)
> > +             return ret;
> > +
> > +     snprintf(name, MAX_NAME_LEN, "speed%d", speed);
> > +
> > +     for_each_possible_cpu(cpu) {
> > +             struct device *cpu_dev = get_cpu_device(cpu);
> > +
> > +             if (NULL == cpu_dev) {
> > +                     ret = -ENODEV;
> > +                     goto free_opp;
> > +             }
> > +
> > +             opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
> > +             if (IS_ERR(opp_tables[cpu])) {
> > +                     ret = PTR_ERR(opp_tables[cpu]);
> > +                     pr_err("Failed to set prop name\n");
> > +                     goto free_opp;
> > +             }
> > +     }
> > +
> > +     cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
> > +                                                       NULL, 0);
> > +     if (!IS_ERR(cpufreq_dt_pdev)) {
> > +             platform_set_drvdata(pdev, opp_tables);
> > +             return 0;
> > +     }
> > +
> > +     ret = PTR_ERR(cpufreq_dt_pdev);
> > +     pr_err("Failed to register platform device\n");
> > +
> > +free_opp:
> > +     for_each_possible_cpu(cpu) {
> > +             if (IS_ERR_OR_NULL(opp_tables[cpu]))
> > +                     break;
> > +             dev_pm_opp_put_prop_name(opp_tables[cpu]);
> > +     }
> > +     kfree(opp_tables);
> > +
> > +     return ret;
> > +}
> > +
> > +static int sunxi_cpufreq_nvmem_remove(struct platform_device *pdev)
> > +{
> > +     struct opp_table **opp_tables = platform_get_drvdata(pdev);
> > +     unsigned int cpu;
> > +
> > +     platform_device_unregister(cpufreq_dt_pdev);
> > +
> > +     for_each_possible_cpu(cpu)
> > +             dev_pm_opp_put_prop_name(opp_tables[cpu]);
> > +
> > +     kfree(opp_tables);
> > +
> > +     return 0;
> > +}
> > +
> > +static struct platform_driver sunxi_cpufreq_driver = {
> > +     .probe = sunxi_cpufreq_nvmem_probe,
> > +     .remove = sunxi_cpufreq_nvmem_remove,
> > +     .driver = {
> > +             .name = "sunxi-cpufreq-nvmem",
> > +     },
> > +};
> > +
> > +/*
> > + * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
> > + * all the real activity is done in the probe, which may be defered as well.
> > + * The init here is only registering the driver and the platform device.
> > + */
> > +static int __init sunxi_cpufreq_init(void)
> > +{
> > +     const struct of_device_id *match;
> > +     int ret;
> > +
> > +     match = sunxi_cpufreq_match_node();
> > +     if (!match)
> > +             return -ENODEV;
> > +
> > +     ret = platform_driver_register(&sunxi_cpufreq_driver);
> > +     if (unlikely(ret < 0))
> > +             return ret;
> > +
> > +     sunxi_cpufreq_pdev = platform_device_register_simple(
> > +             "sunxi-cpufreq-nvmem", -1, NULL, 0);
>
> ... pass match->data as platform device's data here..
Yead, it is.

Thanks,
Yangtao
>
> > +     ret = PTR_ERR_OR_ZERO(sunxi_cpufreq_pdev);
> > +     if (0 == ret)
> > +             return 0;
> > +
> > +     platform_driver_unregister(&sunxi_cpufreq_driver);
> > +     return ret;
> > +}
> > +module_init(sunxi_cpufreq_init);
> > +
> > +static void __exit sunxi_cpufreq_exit(void)
> > +{
> > +     platform_device_unregister(sunxi_cpufreq_pdev);
> > +     platform_driver_unregister(&sunxi_cpufreq_driver);
> > +}
> > +module_exit(sunxi_cpufreq_exit);
> > +
> > +MODULE_DESCRIPTION("Sunxi cpufreq driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.17.0
>
> --
> viresh

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