Re: [PATCH 2/2] thermal/drivers/loongson2: Add thermal driver support for Loongson-2K0300

Hi, Binbin,

On Fri, Jul 10, 2026 at 4:25 PM Binbin Zhou <[email protected]> wrote:
>
> The Loongson-2K0300 SoC uses a new thermal sensor that requires reading
> a separate CPU ID register to obtain hardware version information. This
> version info is used as a correction factor (fix_data) in the
> temperature calculation formula.
>
> Its thermal sensor requires the following hardware-specific handling:
>  - Read chip ID register (offset 0x0 and 0x4) to get the compensation
>    value (comp_val). The value is stored in either bits [31:20] of the
>    ID0 register or bits [15:0] of the ID1 register, depending on the
>    EXTERN_ID bit.
>
>  - The compensation value is a signed 15-bit field; extract the value
>    and apply sign accordingly.
>
> Additionally, some early Loongson-2K0300 chips may have an old fuse that
> yields invalid temperature readings outside the -55 to 125 range. In
> such cases, the driver falls back to a simplified formula (raw * 569 -
> 394700) and logs a warning, ensuring the system can still function
> without crashing.
>
> Signed-off-by: Binbin Zhou <[email protected]>
> ---
>  drivers/thermal/loongson2_thermal.c | 83 ++++++++++++++++++++++++++---
>  1 file changed, 77 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/thermal/loongson2_thermal.c b/drivers/thermal/loongson2_thermal.c
> index ea4dd2fb1f47..a7eb87070aa9 100644
> --- a/drivers/thermal/loongson2_thermal.c
> +++ b/drivers/thermal/loongson2_thermal.c
> @@ -2,9 +2,11 @@
>  /*
>   * Author: zhanghongchen <[email protected]>
>   *         Yinbo Zhu <[email protected]>
> - * Copyright (C) 2022-2023 Loongson Technology Corporation Limited
> + *         Binbin Zhou <[email protected]>
> + * Copyright (C) 2022-2026 Loongson Technology Corporation Limited
>   */
>
> +#include <linux/bitfield.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/minmax.h>
> @@ -23,27 +25,44 @@
>  #define LOONGSON2_THSENS_CTRL_LOW_REG  0x8
>  #define LOONGSON2_THSENS_STATUS_REG    0x10
>  #define LOONGSON2_THSENS_OUT_REG       0x14
> +#define LOONGSON2_THSENS_CFG_REG       0x18
>
>  #define LOONGSON2_THSENS_INT_LO                BIT(0)
>  #define LOONGSON2_THSENS_INT_HIGH      BIT(1)
>  #define LOONGSON2_THSENS_INT_EN                (LOONGSON2_THSENS_INT_LO | \
>                                          LOONGSON2_THSENS_INT_HIGH)
>  #define LOONGSON2_THSENS_OUT_MASK      0xFF
> +#define LS2K0300_THSENS_OUT_MASK       GENMASK(10, 0)
The naming is a little strange, maybe use LOONGSON2_THSENS_OUT_8B_MASK
and LOONGSON2_THSENS_OUT_10B_MASK?

> +
> +#define LS2K0300_CHIP_ID1              0x4
Also define LS2K0300_CHIP_ID0 here?

> +#define LS2K0300_EXTERN_ID             BIT(4)
> +#define LS2K0300_ID0_VAL_MASK          GENMASK(31, 20)
> +#define LS2K0300_ID1_VAL_MASK          GENMASK(15, 0)
> +
> +#define LS2K0300_COMP_VAL_MASK         GENMASK(14, 0)
> +#define LS2K0300_COMP_SIGN_BIT         BIT(15)
> +
> +#define LS2K0300_LOWEST_VALID_TEMP     (-55000)
> +#define LS2K0300_HIGHEST_VALID_TEMP    (125000)
>
>  /*
>   * This flag is used to indicate the temperature reading
>   * method of the Loongson-2K2000
>   */
>  #define LS2K2000_THSENS_OUT_FLAG       BIT(0)
> +#define LS2K0300_CHIP_ID_FLAG          BIT(1)
>
>  struct loongson2_thermal_chip_data {
>         unsigned int thermal_sensor_sel;
>         unsigned int flags;
> +       const struct thermal_zone_device_ops *thermal_ops;
>  };
>
>  struct loongson2_thermal_data {
> +       struct device *dev;
>         void __iomem *ctrl_reg;
>         void __iomem *temp_reg;
> +       void __iomem *id_reg;
>         const struct loongson2_thermal_chip_data *chip_data;
>  };
>
> @@ -71,6 +90,38 @@ static int loongson2_thermal_set(struct loongson2_thermal_data *data,
>         return 0;
>  }
>
> +static int loongson2_2k0300_get_temp(struct thermal_zone_device *tz, int *temp)
> +{
> +       struct loongson2_thermal_data *tdata = thermal_zone_device_priv(tz);
> +       int calib_data, calib_offset, temp_mc, raw_adc;
> +       u32 chip_id0, chip_id1;
> +
> +       raw_adc = FIELD_GET(LS2K0300_THSENS_OUT_MASK,
> +                           readl(tdata->ctrl_reg + LOONGSON2_THSENS_OUT_REG));
> +       chip_id0 = readl(tdata->id_reg);
> +       chip_id1 = readl(tdata->id_reg + LS2K0300_CHIP_ID1);
> +
> +       if (chip_id0 & LS2K0300_EXTERN_ID)
> +               calib_data = FIELD_GET(LS2K0300_ID1_VAL_MASK, chip_id1);
> +       else
> +               calib_data = FIELD_GET(LS2K0300_ID0_VAL_MASK, chip_id0);
> +
> +       calib_offset = FIELD_GET(LS2K0300_COMP_VAL_MASK, calib_data);
> +       if (calib_data & LS2K0300_COMP_SIGN_BIT)
> +               calib_offset = -calib_offset;
> +
> +       temp_mc = (raw_adc + calib_offset) * 570 - 394700;
> +
> +       /* For old fuse which can not read right thermal data */
> +       if (temp_mc < LS2K0300_LOWEST_VALID_TEMP || temp_mc > LS2K0300_HIGHEST_VALID_TEMP) {
Is there a better way to detect the old fuse? Because I think temp_mc
between LS2K0300_LOWEST_VALID_TEMP and  LS2K0300_HIGHEST_VALID_TEMP is
also not valid for the old fuse.

Huacai

> +               dev_warn_once(tdata->dev, "It's an old fuse, thermal %d is not right\n", temp_mc);
> +               temp_mc = raw_adc * 569 - 394700;
> +       }
> +       *temp = temp_mc;
> +
> +       return 0;
> +}
> +
>  static int loongson2_2k1000_get_temp(struct thermal_zone_device *tz, int *temp)
>  {
>         int val;
> @@ -112,6 +163,11 @@ static int loongson2_thermal_set_trips(struct thermal_zone_device *tz, int low,
>         return loongson2_thermal_set(data, low/MILLI, high/MILLI, true);
>  }
>
> +static const struct thermal_zone_device_ops loongson2_2k0300_of_thermal_ops = {
> +       .get_temp = loongson2_2k0300_get_temp,
> +       .set_trips = loongson2_thermal_set_trips,
> +};
> +
>  static const struct thermal_zone_device_ops loongson2_2k1000_of_thermal_ops = {
>         .get_temp = loongson2_2k1000_get_temp,
>         .set_trips = loongson2_thermal_set_trips,
> @@ -124,7 +180,6 @@ static const struct thermal_zone_device_ops loongson2_2k2000_of_thermal_ops = {
>
>  static int loongson2_thermal_probe(struct platform_device *pdev)
>  {
> -       const struct thermal_zone_device_ops *thermal_ops;
>         struct device *dev = &pdev->dev;
>         struct loongson2_thermal_data *data;
>         struct thermal_zone_device *tzd;
> @@ -134,6 +189,7 @@ static int loongson2_thermal_probe(struct platform_device *pdev)
>         if (!data)
>                 return -ENOMEM;
>
> +       data->dev = dev;
>         data->chip_data = device_get_match_data(dev);
>
>         data->ctrl_reg = devm_platform_ioremap_resource(pdev, 0);
> @@ -145,10 +201,13 @@ static int loongson2_thermal_probe(struct platform_device *pdev)
>                 data->temp_reg = devm_platform_ioremap_resource(pdev, 1);
>                 if (IS_ERR(data->temp_reg))
>                         return PTR_ERR(data->temp_reg);
> +       }
>
> -               thermal_ops = &loongson2_2k2000_of_thermal_ops;
> -       } else {
> -               thermal_ops = &loongson2_2k1000_of_thermal_ops;
> +       /* The chip id register is needed for Loongson-2K0300 */
> +       if (data->chip_data->flags & LS2K0300_CHIP_ID_FLAG) {
> +               data->id_reg = devm_platform_ioremap_resource(pdev, 1);
> +               if (IS_ERR(data->id_reg))
> +                       return PTR_ERR(data->id_reg);
>         }
>
>         irq = platform_get_irq(pdev, 0);
> @@ -160,7 +219,7 @@ static int loongson2_thermal_probe(struct platform_device *pdev)
>         loongson2_thermal_set(data, 0, 0, false);
>
>         for (i = 0; i <= LOONGSON2_MAX_SENSOR_SEL_NUM; i++) {
> -               tzd = devm_thermal_of_zone_register(dev, i, data, thermal_ops);
> +               tzd = devm_thermal_of_zone_register(dev, i, data, data->chip_data->thermal_ops);
>
>                 if (!IS_ERR(tzd))
>                         break;
> @@ -181,17 +240,29 @@ static int loongson2_thermal_probe(struct platform_device *pdev)
>         return 0;
>  }
>
> +static const struct loongson2_thermal_chip_data loongson2_thermal_ls2k0300_data = {
> +       .thermal_sensor_sel = 0,
> +       .flags = LS2K0300_CHIP_ID_FLAG,
> +       .thermal_ops = &loongson2_2k0300_of_thermal_ops,
> +};
> +
>  static const struct loongson2_thermal_chip_data loongson2_thermal_ls2k1000_data = {
>         .thermal_sensor_sel = 0,
>         .flags = 0,
> +       .thermal_ops = &loongson2_2k1000_of_thermal_ops,
>  };
>
>  static const struct loongson2_thermal_chip_data loongson2_thermal_ls2k2000_data = {
>         .thermal_sensor_sel = 0,
>         .flags = LS2K2000_THSENS_OUT_FLAG,
> +       .thermal_ops = &loongson2_2k2000_of_thermal_ops,
>  };
>
>  static const struct of_device_id of_loongson2_thermal_match[] = {
> +       {
> +               .compatible = "loongson,ls2k0300-thermal",
> +               .data = &loongson2_thermal_ls2k0300_data,
> +       },
>         {
>                 .compatible = "loongson,ls2k1000-thermal",
>                 .data = &loongson2_thermal_ls2k1000_data,
> --
> 2.52.0
>