Re: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver

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

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
>