package/kernel/linux/riscv-unmatched-fans.patch

   1 # --- T2-COPYRIGHT-BEGIN ---
   2 # t2/package/*/linux/riscv-unmatched-fans.patch
   3 # Copyright (C) 2021 - 2025 The T2 SDE Project
   4 # SPDX-License-Identifier: GPL-2.0 or patched project license
   5 # --- T2-COPYRIGHT-END ---
   6
   7 Let's implement some minimal viable HiFive Unmatched PWM fan control.
   8
   9 Signed-off-by: René Rebe <rene@exactcode.com>
  10
  11 --- ./arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts.vanilla       2024-04-01 18:58:55.930393689 +0200
  12 +++ ./arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts       2024-04-01 20:32:34.682852300 +0200
  13 @@ -47,6 +47,18 @@
  14                 gpios = <&gpio 2 GPIO_ACTIVE_LOW>;
  15         };
  16
  17 +       fan1 {
  18 +               compatible = "pwm-fan";
  19 +               pwms = <&pwm1 2 7812500 PWM_POLARITY_INVERTED>;
  20 +               active-low;
  21 +       };
  22 +
  23 +       fan2 {
  24 +               compatible = "pwm-fan";
  25 +               pwms = <&pwm1 3 7812500 PWM_POLARITY_INVERTED>;
  26 +               active-low;
  27 +       };
  28 +
  29         led-controller-1 {
  30                 compatible = "pwm-leds";
  31
  32 --- linux-6.13/drivers/hwmon/pwm-fan.c.vanilla  2025-02-03 11:42:43.909573585 +0100
  33 +++ linux-6.13/drivers/hwmon/pwm-fan.c  2025-02-03 11:44:47.423592732 +0100
  34 @@ -45,6 +45,7 @@
  35         enum pwm_fan_enable_mode enable_mode;
  36         bool regulator_enabled;
  37         bool enabled;
  38 +       bool active_low;
  39
  40         int tach_count;
  41         struct pwm_fan_tach *tachs;
  42
  43 @@ -227,6 +227,9 @@
  44                 if (!ret && update) {
  45                         pwm = final_pwm;
  46                         state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  47 +                       if (ctx->active_low)
  48 +                               state->duty_cycle = state->period - state->duty_cycle;
  49 +
  50                         usleep_range(ctx->pwm_usec_from_stopped,
  51                                      ctx->pwm_usec_from_stopped * 2);
  52                         ret = pwm_apply_might_sleep(ctx->pwm, state);
  53 @@ -476,6 +480,7 @@
  54  {
  55         struct thermal_cooling_device *cdev;
  56         struct device *dev = &pdev->dev;
  57 +       struct device_node *np = dev->of_node;
  58         struct pwm_fan_ctx *ctx;
  59         struct device *hwmon;
  60         int ret;
  61 @@ -526,6 +532,7 @@
  62         }
  63
  64         ctx->enable_mode = pwm_disable_reg_enable;
  65 +       ctx->active_low = of_property_read_bool(np, "active-low");
  66
  67         /*
  68          * Set duty cycle to maximum allowed and enable PWM output as well as