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    SubjectRe: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver
    On Tue, May 15, 2018 at 12:13 PM, Ilia Lin <ilialin@codeaurora.org> wrote:
    > In Certain QCOM SoCs like apq8096 and msm8996 that have KRYO processors,
    > the CPU ferequencies subset and voltage value of each OPP varies

    s/ferequencies/frequency

    > based on the silicon variant in use. Qualcomm Process Voltage Scaling Tables
    > defines the voltage and frequency value based on the msm-id in SMEM
    > and speedbin blown in the efuse combination.
    > The qcom-cpufreq-kryo driver reads the msm-id and efuse value from the SoC
    > to provide the OPP framework with required information.
    > This is used to determine the voltage and frequency value for each OPP of
    > operating-points-v2 table when it is parsed by the OPP framework.
    >
    > Signed-off-by: Ilia Lin <ilialin@codeaurora.org>
    > ---
    > drivers/cpufreq/Kconfig.arm | 11 +++
    > drivers/cpufreq/Makefile | 1 +
    > drivers/cpufreq/cpufreq-dt-platdev.c | 3 +
    > drivers/cpufreq/qcom-cpufreq-kryo.c | 150 +++++++++++++++++++++++++++++++++++
    > 4 files changed, 165 insertions(+)
    > create mode 100644 drivers/cpufreq/qcom-cpufreq-kryo.c
    >
    > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
    > index de55c7d..5c16f05 100644
    > --- a/drivers/cpufreq/Kconfig.arm
    > +++ b/drivers/cpufreq/Kconfig.arm
    > @@ -124,6 +124,17 @@ config ARM_OMAP2PLUS_CPUFREQ
    > depends on ARCH_OMAP2PLUS
    > default ARCH_OMAP2PLUS
    >
    > +config ARM_QCOM_CPUFREQ_KRYO
    > + bool "Qualcomm Technologies, Inc. Kryo based CPUFreq"

    "Qualcomm Kryo CPUFreq support" should be enough. Kconfig isn't the
    place for Trademark compliance :-)

    > + depends on QCOM_QFPROM
    > + depends on QCOM_SMEM
    > + select PM_OPP
    > + help
    > + This adds the CPUFreq driver for
    > + Qualcomm Technologies, Inc. Kryo SoC based boards.
    > +
    > + If in doubt, say N.
    > +
    > config ARM_S3C_CPUFREQ
    > bool
    > help
    > diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
    > index 8d24ade..fb4a2ec 100644
    > --- a/drivers/cpufreq/Makefile
    > +++ b/drivers/cpufreq/Makefile
    > @@ -65,6 +65,7 @@ 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-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO) += qcom-cpufreq-kryo.o
    > obj-$(CONFIG_ARM_S3C2410_CPUFREQ) += s3c2410-cpufreq.o
    > obj-$(CONFIG_ARM_S3C2412_CPUFREQ) += s3c2412-cpufreq.o
    > obj-$(CONFIG_ARM_S3C2416_CPUFREQ) += s3c2416-cpufreq.o
    > diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
    > index 3b585e4..77d6ab8 100644
    > --- a/drivers/cpufreq/cpufreq-dt-platdev.c
    > +++ b/drivers/cpufreq/cpufreq-dt-platdev.c
    > @@ -118,6 +118,9 @@
    >
    > { .compatible = "nvidia,tegra124", },
    >
    > + { .compatible = "qcom,apq8096", },
    > + { .compatible = "qcom,msm8996", },
    > +
    > { .compatible = "st,stih407", },
    > { .compatible = "st,stih410", },
    >
    > diff --git a/drivers/cpufreq/qcom-cpufreq-kryo.c b/drivers/cpufreq/qcom-cpufreq-kryo.c
    > new file mode 100644
    > index 0000000..10d7236
    > --- /dev/null
    > +++ b/drivers/cpufreq/qcom-cpufreq-kryo.c
    > @@ -0,0 +1,150 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*

    Stray space here.

    > + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 and
    > + * only version 2 as published by the Free Software Foundation.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + */
    > +
    > +#include <linux/cpu.h>
    > +#include <linux/err.h>
    > +#include <linux/init.h>
    > +#include <linux/kernel.h>
    > +#include <linux/module.h>
    > +#include <linux/nvmem-consumer.h>
    > +#include <linux/of.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/pm_opp.h>
    > +#include <linux/slab.h>
    > +#include <linux/soc/qcom/smem.h>
    > +
    > +#define MSM_ID_SMEM 137
    > +#define SILVER_LEAD 0
    > +#define GOLD_LEAD 2
    > +
    > +enum _msm_id {
    > + MSM8996V3 = 0xF6ul,
    > + APQ8096V3 = 0x123ul,
    > + MSM8996SG = 0x131ul,
    > + APQ8096SG = 0x138ul,
    > +};
    > +
    > +enum _msm8996_version {
    > + MSM8996_V3,
    > + MSM8996_SG,
    > + NUM_OF_MSM8996_VERSIONS,
    > +};
    > +
    > +static enum _msm8996_version __init qcom_cpufreq_kryo_get_msm_id(void)
    > +{
    > + size_t len;
    > + u32 *msm_id;
    > + enum _msm8996_version version;
    > +
    > + msm_id = qcom_smem_get(QCOM_SMEM_HOST_ANY, MSM_ID_SMEM, &len);
    > + /* The first 4 bytes are format, next to them is the actual msm-id */
    > + msm_id++;
    > +
    > + switch ((enum _msm_id)*msm_id) {
    > + case MSM8996V3:
    > + case APQ8096V3:
    > + version = MSM8996_V3;
    > + break;
    > + case MSM8996SG:
    > + case APQ8096SG:
    > + version = MSM8996_SG;
    > + break;
    > + default:
    > + version = NUM_OF_MSM8996_VERSIONS;
    > + }
    > +
    > + return version;
    > +}
    > +
    > +static int __init qcom_cpufreq_kryo_driver_init(void)
    > +{
    > + size_t len;
    > + int ret;
    > + u32 versions;
    > + enum _msm8996_version msm8996_version;
    > + u8 *speedbin;
    > + struct device *cpu_dev;
    > + struct device_node *np;
    > + struct nvmem_cell *speedbin_nvmem;
    > + struct opp_table *opp_temp = NULL;
    > +
    > + cpu_dev = get_cpu_device(SILVER_LEAD);
    > + if (IS_ERR_OR_NULL(cpu_dev))
    > + return PTR_ERR(cpu_dev);
    > +
    > + msm8996_version = qcom_cpufreq_kryo_get_msm_id();
    > + if (NUM_OF_MSM8996_VERSIONS == msm8996_version) {
    > + dev_err(cpu_dev, "Not Snapdragon 820/821!");
    > + return -ENODEV;
    > + }

    Use tab instead of spaces.

    > +
    > + np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
    > + if (IS_ERR_OR_NULL(np))
    > + return PTR_ERR(np);
    > +
    > + if (!of_device_is_compatible(np, "operating-points-v2-kryo-cpu")) {
    > + ret = -ENOENT;
    > + goto free_np;
    > + }
    > +
    > + speedbin_nvmem = of_nvmem_cell_get(np, NULL);
    > + if (IS_ERR(speedbin_nvmem)) {
    > + ret = PTR_ERR(speedbin_nvmem);
    > + dev_err(cpu_dev, "Could not get nvmem cell: %d\n", ret);
    > + goto free_np;
    > + }
    > +
    > + speedbin = nvmem_cell_read(speedbin_nvmem, &len);
    > +
    > + switch (msm8996_version) {
    > + case MSM8996_V3:
    > + versions = 1 << (unsigned int)(*speedbin);
    > + break;
    > + case MSM8996_SG:
    > + versions = 1 << ((unsigned int)(*speedbin) + 4);
    > + break;
    > + default:
    > + BUG();
    > + break;
    > + }
    > +
    > + ret = PTR_ERR_OR_ZERO(opp_temp =
    > + dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
    > + if (0 > ret)

    Any particular reason to prefer this over (ret < 0) that is generally
    used? I've seen it used to avoid the == vs. = typos, but not for other
    comparisons.

    Suggest sticking to what is commonly used i.e. ret < 0.

    > + goto free_opp;
    > +
    > + cpu_dev = get_cpu_device(GOLD_LEAD);

    Error check cpu_dev here?

    > + ret = PTR_ERR_OR_ZERO(opp_temp =
    > + dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
    > + if (0 > ret)
    > + goto free_opp;
    > +
    > +
    > + ret = PTR_ERR_OR_ZERO(platform_device_register_simple("cpufreq-dt",
    > + -1, NULL, 0));
    > +
    > + if (0 == ret)
    > + return 0;
    > +
    > +free_opp:
    > + dev_pm_opp_put_supported_hw(opp_temp);

    This is not needed because dev_pm_opp_set_supported_hw will free
    memory in case of failure. This call in only needed in case of a
    successful get.

    > +
    > +free_np:
    > + of_node_put(np);
    > + return ret;


    Suggest something like this instead:

    .
    .

    opp_temp = dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
    if (IS_ERR(opp_temp)) {
    dev_err(cpu_dev, "Failed to set supported hardware\n");
    ret = PTR_ERR(opp_temp);
    goto free_np;
    }

    cpu_dev = get_cpu_device(GOLD_LEAD);

    opp_temp = dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
    if (IS_ERR(opp_temp)) {
    dev_err(cpu_dev, "Failed to set supported hardware\n");
    ret = PTR_ERR(opp_temp);
    goto free_np;
    }

    ret = platform_device_register_simple("cpufreq-dt", -1, NULL, 0));

    if (!IS_ERR_OR_NULL(ret))
    goto out;

    free_np:
    of_node_put(np);
    out:
    return ret;

    > +}
    > +late_initcall(qcom_cpufreq_kryo_driver_init);
    > +
    > +MODULE_DESCRIPTION("Qualcomm Technologies, Inc. Kryo CPUfreq driver");
    > +MODULE_LICENSE("GPL v2");
    > --
    > 1.9.1
    >

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