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    SubjectRe: [PATCH v4 1/2] thermal: add support for the MCU controlled FAN on Khadas boards
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    Date
    On 18/06/2020 15:38, Neil Armstrong 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@baylibre.com>
    > Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
    > ---
    > Hi Lee,
    >
    > Could you apply this patch via the MFD tree since it depends on
    > the linux/mfd/khadas-mcu.h header ?
    >
    > This patch is unchanged from the v3 serie.
    >
    > Thanks,
    > Neil
    >
    > 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 3eb2348e5242..0125561488c9 100644
    > --- a/drivers/thermal/Kconfig
    > +++ b/drivers/thermal/Kconfig
    > @@ -500,4 +500,15 @@ 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 0c8b84a09b9a..4b6aabaa7e31 100644
    > --- a/drivers/thermal/Makefile
    > +++ b/drivers/thermal/Makefile
    > @@ -61,3 +61,4 @@ 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@baylibre.com>
    > + */
    > +
    > +#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;

    It is pointless to check 'ctx' is NULL, that was done at probe time.

    > + *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;

    Ditto

    > + *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;

    Ditto

    > + 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;

    Nitpicking : move the save section to suspend.

    > + 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);

    Out of curiosity, did you check the fan is not continuously spinning
    after a resume when the suspend happened during a mitigation phase?

    > +}
    > +#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@baylibre.com>");
    > +MODULE_DESCRIPTION("Khadas MCU FAN driver");
    > +MODULE_LICENSE("GPL");
    >


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