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Wysocki" , Viresh Kumar , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Stephen Boyd , Rajendra Nayak , Amit Nischal , devicetree@vger.kernel.org, robh@kernel.org, skannan@codeaurora.org, amit.kucheria@linaro.org, evgreen@google.com Subject: Re: [PATCH v7 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver Message-ID: <20180924170200.GZ22824@google.com> References: <1532428970-18122-1-git-send-email-tdas@codeaurora.org> <1532428970-18122-3-git-send-email-tdas@codeaurora.org> <20180829180122.GC10879@google.com> <8c19c840-292c-a5c4-f3d3-0c6fb14b15fb@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8c19c840-292c-a5c4-f3d3-0c6fb14b15fb@codeaurora.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 23, 2018 at 03:10:55PM +0530, Taniya Das wrote: > Hello Matthias, > > Thanks for your review comments. > > On 8/29/2018 11:31 PM, Matthias Kaehlcke wrote: > > Hi Taniya, > > > > On Tue, Jul 24, 2018 at 04:12:50PM +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 > > > Signed-off-by: Taniya Das > > > --- > > > drivers/cpufreq/Kconfig.arm | 11 ++ > > > drivers/cpufreq/Makefile | 1 + > > > drivers/cpufreq/qcom-cpufreq-hw.c | 348 ++++++++++++++++++++++++++++++++++++++ > > > 3 files changed, 360 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..ea8f7d1 > > > --- /dev/null > > > +++ b/drivers/cpufreq/qcom-cpufreq-hw.c > > > @@ -0,0 +1,348 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* > > > + * Copyright (c) 2018, The Linux Foundation. All rights reserved. > > > + */ > > > + > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +#define INIT_RATE 300000000UL > > > +#define LUT_MAX_ENTRIES 40U > > > +#define CORE_COUNT_VAL(val) (((val) & (GENMASK(18, 16))) >> 16) > > > +#define LUT_ROW_SIZE 32 > > > + > > > +enum { > > > + REG_ENABLE, > > > + REG_LUT_TABLE, > > > + REG_PERF_STATE, > > > + > > > + REG_ARRAY_SIZE, > > > +}; > > > + > > > +struct cpufreq_qcom { > > > + struct cpufreq_frequency_table *table; > > > + struct device *dev; > > > > 'dev' is not used and can be removed. > > > > Thanks, would remove in the next patch. > > > > ... > > > > > > +static int qcom_cpu_resources_init(struct platform_device *pdev, > > > + struct device_node *np, unsigned int cpu, > > > + unsigned long xo_rate) > > > +{ > > > + struct cpufreq_qcom *c; > > > + struct resource res; > > > + struct device *dev = &pdev->dev; > > > + const u16 *offsets; > > > + int ret, i, cpu_first, 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; > > > + > > > + if (of_address_to_resource(np, 0, &res)) > > > + return -ENOMEM; > > > + > > > + base = devm_ioremap_resource(dev, &res); > > > + if (!base) > > > + return -ENOMEM; > > > + > > > + 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, "%s cpufreq hardware not enabled\n", np->name); > > > + return -ENODEV; > > > + } > > > + > > > + ret = qcom_get_related_cpus(np, &c->related_cpus); > > > + if (ret) { > > > + dev_err(dev, "%s failed to get related CPUs\n", np->name); > > > + return ret; > > > + } > > > + > > > + c->max_cores = cpumask_weight(&c->related_cpus); > > > + if (!c->max_cores) > > > + return -ENOENT; > > > + > > > + c->xo_rate = xo_rate; > > > + > > > + ret = qcom_cpufreq_hw_read_lut(pdev, c); > > > + if (ret) { > > > + dev_err(dev, "%s failed to read LUT\n", np->name); > > > + return ret; > > > + } > > > + > > > + qcom_freq_domain_map[cpu] = c; > > > + > > > + /* Related CPUs */ > > > + cpu_first = cpumask_first(&c->related_cpus); > > > + > > > + for_each_cpu(cpu_r, &c->related_cpus) { > > > + if (cpu_r != cpu_first) > > > + qcom_freq_domain_map[cpu_r] = > > > + qcom_freq_domain_map[cpu_first]; > > > + } > > > > The above ten lines could be simplified to: > > > > for_each_cpu(cpu_r, &c->related_cpus) > > qcom_freq_domain_map[cpu_r] = c; > > > > Would clean it up in the next patch. > > > > ... > > > > > > +static int __init qcom_cpufreq_hw_init(void) > > > +{ > > > + return platform_driver_register(&qcom_cpufreq_hw_driver); > > > +} > > > +subsys_initcall(qcom_cpufreq_hw_init); > > > > Is subsys_initcall used for a particular reason? It will cause > > problems when registering cooling devices, since the thermal device > > class is initialized through an fs_initcall, which are executed > > later. > > > > Most cpufreq drivers use module_init, device_initcall or > > late_initcall, can't this driver use one of those? > > > > We want the CPU to be scaling to the highest frequency at the > earliest. I guess you also want thermal management for the CPU. With the subsys_initcall registration of cooling devices fails, as mentioned in my earlier comment. Do you plan to defer the registration of cooling devices? Cheers Matthias