diff options
Diffstat (limited to 'drivers/hwmon/pwm-fan.c')
| -rw-r--r-- | drivers/hwmon/pwm-fan.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c index c434db4656e7..53a1a968d00d 100644 --- a/drivers/hwmon/pwm-fan.c +++ b/drivers/hwmon/pwm-fan.c @@ -7,6 +7,7 @@ * Author: Kamil Debski <k.debski@samsung.com> */ +#include <linux/delay.h> #include <linux/hwmon.h> #include <linux/interrupt.h> #include <linux/mod_devicetable.h> @@ -60,6 +61,9 @@ struct pwm_fan_ctx { struct hwmon_chip_info info; struct hwmon_channel_info fan_channel; + + u64 pwm_duty_cycle_from_stopped; + u32 pwm_usec_from_stopped; }; /* This handler assumes self resetting edge triggered interrupt. */ @@ -199,7 +203,9 @@ static int pwm_fan_power_off(struct pwm_fan_ctx *ctx, bool force_disable) static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) { struct pwm_state *state = &ctx->pwm_state; + unsigned long final_pwm = pwm; unsigned long period; + bool update = false; int ret = 0; if (pwm > 0) { @@ -208,11 +214,22 @@ static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) return 0; period = state->period; - state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM); + update = state->duty_cycle < ctx->pwm_duty_cycle_from_stopped; + if (update) + state->duty_cycle = ctx->pwm_duty_cycle_from_stopped; + else + state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM); ret = pwm_apply_might_sleep(ctx->pwm, state); if (ret) return ret; ret = pwm_fan_power_on(ctx); + if (!ret && update) { + pwm = final_pwm; + state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM); + usleep_range(ctx->pwm_usec_from_stopped, + ctx->pwm_usec_from_stopped * 2); + ret = pwm_apply_might_sleep(ctx->pwm, state); + } } else { ret = pwm_fan_power_off(ctx, false); } @@ -480,6 +497,7 @@ static int pwm_fan_probe(struct platform_device *pdev) struct device *hwmon; int ret; const struct hwmon_channel_info **channels; + u32 pwm_min_from_stopped = 0; u32 *fan_channel_config; int channel_count = 1; /* We always have a PWM channel. */ int i; @@ -620,6 +638,19 @@ static int pwm_fan_probe(struct platform_device *pdev) channels[1] = &ctx->fan_channel; } + ret = of_property_read_u32(dev->of_node, "fan-stop-to-start-percent", + &pwm_min_from_stopped); + if (!ret && pwm_min_from_stopped) { + ctx->pwm_duty_cycle_from_stopped = + DIV_ROUND_UP_ULL(pwm_min_from_stopped * + (ctx->pwm_state.period - 1), + 100); + } + ret = of_property_read_u32(dev->of_node, "fan-stop-to-start-us", + &ctx->pwm_usec_from_stopped); + if (ret) + ctx->pwm_usec_from_stopped = 250000; + ctx->info.ops = &pwm_fan_hwmon_ops; ctx->info.info = channels; |