Re: [PATCH v3 3/5] thermal: add support for the MCU controlled FAN on Khadas boards

[Amit Kucheria]

On Mon, Jun 8, 2020 at 2:47 PM Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
>
> The new Khadas VIM2 and VIM3 boards controls the cooling fan via the
> on-board microcontroller.
>
> This implements the FAN control as thermal devices and as cell of the Khadas
> MCU MFD driver.
>
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>

Reviewed-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx>


> ---
>  drivers/thermal/Kconfig          |  11 ++
>  drivers/thermal/Makefile         |   1 +
>  drivers/thermal/khadas_mcu_fan.c | 174 +++++++++++++++++++++++++++++++
>  3 files changed, 186 insertions(+)
>  create mode 100644 drivers/thermal/khadas_mcu_fan.c
>
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 91af271e9bb0..53efd381f434 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -490,4 +490,15 @@ config SPRD_THERMAL
>         help
>           Support for the Spreadtrum thermal sensor driver in the Linux thermal
>           framework.
> +
> +config KHADAS_MCU_FAN_THERMAL
> +       tristate "Khadas MCU controller FAN cooling support"
> +       depends on OF || COMPILE_TEST
> +       depends on MFD_KHADAS_MCU
> +       select MFD_CORE
> +       select REGMAP
> +       help
> +         If you say yes here you get support for the FAN controlled
> +         by the Microcontroller found on the Khadas VIM boards.
> +
>  endif
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 8c8ed7b79915..460428c2122c 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -60,3 +60,4 @@ obj-$(CONFIG_ZX2967_THERMAL)  += zx2967_thermal.o
>  obj-$(CONFIG_UNIPHIER_THERMAL) += uniphier_thermal.o
>  obj-$(CONFIG_AMLOGIC_THERMAL)     += amlogic_thermal.o
>  obj-$(CONFIG_SPRD_THERMAL)     += sprd_thermal.o
> +obj-$(CONFIG_KHADAS_MCU_FAN_THERMAL)   += khadas_mcu_fan.o
> diff --git a/drivers/thermal/khadas_mcu_fan.c b/drivers/thermal/khadas_mcu_fan.c
> new file mode 100644
> index 000000000000..6995b443cad4
> --- /dev/null
> +++ b/drivers/thermal/khadas_mcu_fan.c
> @@ -0,0 +1,174 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Khadas MCU Controlled FAN driver
> + *
> + * Copyright (C) 2020 BayLibre SAS
> + * Author(s): Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/khadas-mcu.h>
> +#include <linux/regmap.h>
> +#include <linux/sysfs.h>
> +#include <linux/thermal.h>
> +
> +#define MAX_LEVEL 3
> +
> +struct khadas_mcu_fan_ctx {
> +       struct khadas_mcu *mcu;
> +       unsigned int level;
> +       struct thermal_cooling_device *cdev;
> +};
> +
> +static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
> +                                   unsigned int level)
> +{
> +       int ret;
> +
> +       ret = regmap_write(ctx->mcu->regmap, KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
> +                          level);
> +       if (ret)
> +               return ret;
> +
> +       ctx->level = level;
> +
> +       return 0;
> +}
> +
> +static int khadas_mcu_fan_get_max_state(struct thermal_cooling_device *cdev,
> +                                       unsigned long *state)
> +{
> +       struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
> +
> +       if (!ctx)
> +               return -EINVAL;
> +
> +       *state = MAX_LEVEL;
> +
> +       return 0;
> +}
> +
> +static int khadas_mcu_fan_get_cur_state(struct thermal_cooling_device *cdev,
> +                                       unsigned long *state)
> +{
> +       struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
> +
> +       if (!ctx)
> +               return -EINVAL;
> +
> +       *state = ctx->level;
> +
> +       return 0;
> +}
> +
> +static int
> +khadas_mcu_fan_set_cur_state(struct thermal_cooling_device *cdev,
> +                            unsigned long state)
> +{
> +       struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
> +
> +       if (!ctx || (state > MAX_LEVEL))
> +               return -EINVAL;
> +
> +       if (state == ctx->level)
> +               return 0;
> +
> +       return khadas_mcu_fan_set_level(ctx, state);
> +}
> +
> +static const struct thermal_cooling_device_ops khadas_mcu_fan_cooling_ops = {
> +       .get_max_state = khadas_mcu_fan_get_max_state,
> +       .get_cur_state = khadas_mcu_fan_get_cur_state,
> +       .set_cur_state = khadas_mcu_fan_set_cur_state,
> +};
> +
> +static int khadas_mcu_fan_probe(struct platform_device *pdev)
> +{
> +       struct khadas_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
> +       struct thermal_cooling_device *cdev;
> +       struct device *dev = &pdev->dev;
> +       struct khadas_mcu_fan_ctx *ctx;
> +       int ret;
> +
> +       ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> +       if (!ctx)
> +               return -ENOMEM;
> +       ctx->mcu = mcu;
> +       platform_set_drvdata(pdev, ctx);
> +
> +       cdev = devm_thermal_of_cooling_device_register(dev->parent,
> +                       dev->parent->of_node, "khadas-mcu-fan", ctx,
> +                       &khadas_mcu_fan_cooling_ops);
> +       if (IS_ERR(cdev)) {
> +               ret = PTR_ERR(cdev);
> +               dev_err(dev,
> +                               "Failed to register khadas-mcu-fan as cooling device: %d\n",
> +                               ret);
> +               return ret;
> +       }
> +       ctx->cdev = cdev;
> +       thermal_cdev_update(cdev);
> +
> +       return 0;
> +}
> +
> +static int khadas_mcu_fan_disable(struct device *dev)
> +{
> +       struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
> +       unsigned int level_save = ctx->level;
> +       int ret;
> +
> +       ret = khadas_mcu_fan_set_level(ctx, 0);
> +       if (ret)
> +               return ret;
> +
> +       ctx->level = level_save;
> +
> +       return 0;
> +}
> +
> +static void khadas_mcu_fan_shutdown(struct platform_device *pdev)
> +{
> +       khadas_mcu_fan_disable(&pdev->dev);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int khadas_mcu_fan_suspend(struct device *dev)
> +{
> +       return khadas_mcu_fan_disable(dev);
> +}
> +
> +static int khadas_mcu_fan_resume(struct device *dev)
> +{
> +       struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
> +
> +       return khadas_mcu_fan_set_level(ctx, ctx->level);
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(khadas_mcu_fan_pm, khadas_mcu_fan_suspend,
> +                        khadas_mcu_fan_resume);
> +
> +static const struct platform_device_id khadas_mcu_fan_id_table[] = {
> +       { .name = "khadas-mcu-fan-ctrl", },
> +       {},
> +};
> +MODULE_DEVICE_TABLE(platform, khadas_mcu_fan_id_table);
> +
> +static struct platform_driver khadas_mcu_fan_driver = {
> +       .probe          = khadas_mcu_fan_probe,
> +       .shutdown       = khadas_mcu_fan_shutdown,
> +       .driver = {
> +               .name           = "khadas-mcu-fan-ctrl",
> +               .pm             = &khadas_mcu_fan_pm,
> +       },
> +       .id_table       = khadas_mcu_fan_id_table,
> +};
> +
> +module_platform_driver(khadas_mcu_fan_driver);
> +
> +MODULE_AUTHOR("Neil Armstrong <narmstrong@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Khadas MCU FAN driver");
> +MODULE_LICENSE("GPL");
> --
> 2.22.0
>