| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * pwm-fan.c - Hwmon driver for fans connected to PWM lines. |
| * |
| * Copyright (c) 2014 Samsung Electronics Co., Ltd. |
| * |
| * Author: Kamil Debski <k.debski@samsung.com> |
| */ |
| |
| #include <linux/hwmon.h> |
| #include <linux/interrupt.h> |
| #include <linux/module.h> |
| #include <linux/mutex.h> |
| #include <linux/of.h> |
| #include <linux/platform_device.h> |
| #include <linux/pwm.h> |
| #include <linux/regulator/consumer.h> |
| #include <linux/sysfs.h> |
| #include <linux/thermal.h> |
| #include <linux/timer.h> |
| |
| #define MAX_PWM 255 |
| |
| struct pwm_fan_tach { |
| int irq; |
| atomic_t pulses; |
| unsigned int rpm; |
| u8 pulses_per_revolution; |
| }; |
| |
| enum pwm_fan_enable_mode { |
| pwm_off_reg_off, |
| pwm_disable_reg_enable, |
| pwm_enable_reg_enable, |
| pwm_disable_reg_disable, |
| }; |
| |
| struct pwm_fan_ctx { |
| struct device *dev; |
| |
| struct mutex lock; |
| struct pwm_device *pwm; |
| struct pwm_state pwm_state; |
| struct regulator *reg_en; |
| enum pwm_fan_enable_mode enable_mode; |
| bool regulator_enabled; |
| bool enabled; |
| |
| int tach_count; |
| struct pwm_fan_tach *tachs; |
| ktime_t sample_start; |
| struct timer_list rpm_timer; |
| |
| unsigned int pwm_value; |
| unsigned int pwm_fan_state; |
| unsigned int pwm_fan_max_state; |
| unsigned int *pwm_fan_cooling_levels; |
| struct thermal_cooling_device *cdev; |
| |
| struct hwmon_chip_info info; |
| struct hwmon_channel_info fan_channel; |
| }; |
| |
| /* This handler assumes self resetting edge triggered interrupt. */ |
| static irqreturn_t pulse_handler(int irq, void *dev_id) |
| { |
| struct pwm_fan_tach *tach = dev_id; |
| |
| atomic_inc(&tach->pulses); |
| |
| return IRQ_HANDLED; |
| } |
| |
| static void sample_timer(struct timer_list *t) |
| { |
| struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer); |
| unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start); |
| int i; |
| |
| if (delta) { |
| for (i = 0; i < ctx->tach_count; i++) { |
| struct pwm_fan_tach *tach = &ctx->tachs[i]; |
| int pulses; |
| |
| pulses = atomic_read(&tach->pulses); |
| atomic_sub(pulses, &tach->pulses); |
| tach->rpm = (unsigned int)(pulses * 1000 * 60) / |
| (tach->pulses_per_revolution * delta); |
| } |
| |
| ctx->sample_start = ktime_get(); |
| } |
| |
| mod_timer(&ctx->rpm_timer, jiffies + HZ); |
| } |
| |
| static void pwm_fan_enable_mode_2_state(int enable_mode, |
| struct pwm_state *state, |
| bool *enable_regulator) |
| { |
| switch (enable_mode) { |
| case pwm_disable_reg_enable: |
| /* disable pwm, keep regulator enabled */ |
| state->enabled = false; |
| *enable_regulator = true; |
| break; |
| case pwm_enable_reg_enable: |
| /* keep pwm and regulator enabled */ |
| state->enabled = true; |
| *enable_regulator = true; |
| break; |
| case pwm_off_reg_off: |
| case pwm_disable_reg_disable: |
| /* disable pwm and regulator */ |
| state->enabled = false; |
| *enable_regulator = false; |
| } |
| } |
| |
| static int pwm_fan_switch_power(struct pwm_fan_ctx *ctx, bool on) |
| { |
| int ret = 0; |
| |
| if (!ctx->reg_en) |
| return ret; |
| |
| if (!ctx->regulator_enabled && on) { |
| ret = regulator_enable(ctx->reg_en); |
| if (ret == 0) |
| ctx->regulator_enabled = true; |
| } else if (ctx->regulator_enabled && !on) { |
| ret = regulator_disable(ctx->reg_en); |
| if (ret == 0) |
| ctx->regulator_enabled = false; |
| } |
| return ret; |
| } |
| |
| static int pwm_fan_power_on(struct pwm_fan_ctx *ctx) |
| { |
| struct pwm_state *state = &ctx->pwm_state; |
| int ret; |
| |
| if (ctx->enabled) |
| return 0; |
| |
| ret = pwm_fan_switch_power(ctx, true); |
| if (ret < 0) { |
| dev_err(ctx->dev, "failed to enable power supply\n"); |
| return ret; |
| } |
| |
| state->enabled = true; |
| ret = pwm_apply_might_sleep(ctx->pwm, state); |
| if (ret) { |
| dev_err(ctx->dev, "failed to enable PWM\n"); |
| goto disable_regulator; |
| } |
| |
| ctx->enabled = true; |
| |
| return 0; |
| |
| disable_regulator: |
| pwm_fan_switch_power(ctx, false); |
| return ret; |
| } |
| |
| static int pwm_fan_power_off(struct pwm_fan_ctx *ctx) |
| { |
| struct pwm_state *state = &ctx->pwm_state; |
| bool enable_regulator = false; |
| int ret; |
| |
| if (!ctx->enabled) |
| return 0; |
| |
| pwm_fan_enable_mode_2_state(ctx->enable_mode, |
| state, |
| &enable_regulator); |
| |
| state->enabled = false; |
| state->duty_cycle = 0; |
| ret = pwm_apply_might_sleep(ctx->pwm, state); |
| if (ret) { |
| dev_err(ctx->dev, "failed to disable PWM\n"); |
| return ret; |
| } |
| |
| pwm_fan_switch_power(ctx, enable_regulator); |
| |
| ctx->enabled = false; |
| |
| return 0; |
| } |
| |
| static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) |
| { |
| struct pwm_state *state = &ctx->pwm_state; |
| unsigned long period; |
| int ret = 0; |
| |
| if (pwm > 0) { |
| if (ctx->enable_mode == pwm_off_reg_off) |
| /* pwm-fan hard disabled */ |
| return 0; |
| |
| period = state->period; |
| 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); |
| } else { |
| ret = pwm_fan_power_off(ctx); |
| } |
| if (!ret) |
| ctx->pwm_value = pwm; |
| |
| return ret; |
| } |
| |
| static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) |
| { |
| int ret; |
| |
| mutex_lock(&ctx->lock); |
| ret = __set_pwm(ctx, pwm); |
| mutex_unlock(&ctx->lock); |
| |
| return ret; |
| } |
| |
| static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm) |
| { |
| int i; |
| |
| for (i = 0; i < ctx->pwm_fan_max_state; ++i) |
| if (pwm < ctx->pwm_fan_cooling_levels[i + 1]) |
| break; |
| |
| ctx->pwm_fan_state = i; |
| } |
| |
| static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val) |
| { |
| int ret = 0; |
| int old_val; |
| |
| mutex_lock(&ctx->lock); |
| |
| if (ctx->enable_mode == val) |
| goto out; |
| |
| old_val = ctx->enable_mode; |
| ctx->enable_mode = val; |
| |
| if (val == 0) { |
| /* Disable pwm-fan unconditionally */ |
| if (ctx->enabled) |
| ret = __set_pwm(ctx, 0); |
| else |
| ret = pwm_fan_switch_power(ctx, false); |
| if (ret) |
| ctx->enable_mode = old_val; |
| pwm_fan_update_state(ctx, 0); |
| } else { |
| /* |
| * Change PWM and/or regulator state if currently disabled |
| * Nothing to do if currently enabled |
| */ |
| if (!ctx->enabled) { |
| struct pwm_state *state = &ctx->pwm_state; |
| bool enable_regulator = false; |
| |
| state->duty_cycle = 0; |
| pwm_fan_enable_mode_2_state(val, |
| state, |
| &enable_regulator); |
| |
| pwm_apply_might_sleep(ctx->pwm, state); |
| pwm_fan_switch_power(ctx, enable_regulator); |
| pwm_fan_update_state(ctx, 0); |
| } |
| } |
| out: |
| mutex_unlock(&ctx->lock); |
| |
| return ret; |
| } |
| |
| static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type, |
| u32 attr, int channel, long val) |
| { |
| struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); |
| int ret; |
| |
| switch (attr) { |
| case hwmon_pwm_input: |
| if (val < 0 || val > MAX_PWM) |
| return -EINVAL; |
| ret = set_pwm(ctx, val); |
| if (ret) |
| return ret; |
| pwm_fan_update_state(ctx, val); |
| break; |
| case hwmon_pwm_enable: |
| if (val < 0 || val > 3) |
| ret = -EINVAL; |
| else |
| ret = pwm_fan_update_enable(ctx, val); |
| |
| return ret; |
| default: |
| return -EOPNOTSUPP; |
| } |
| |
| return 0; |
| } |
| |
| static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type, |
| u32 attr, int channel, long *val) |
| { |
| struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); |
| |
| switch (type) { |
| case hwmon_pwm: |
| switch (attr) { |
| case hwmon_pwm_input: |
| *val = ctx->pwm_value; |
| return 0; |
| case hwmon_pwm_enable: |
| *val = ctx->enable_mode; |
| return 0; |
| } |
| return -EOPNOTSUPP; |
| case hwmon_fan: |
| *val = ctx->tachs[channel].rpm; |
| return 0; |
| |
| default: |
| return -ENOTSUPP; |
| } |
| } |
| |
| static umode_t pwm_fan_is_visible(const void *data, |
| enum hwmon_sensor_types type, |
| u32 attr, int channel) |
| { |
| switch (type) { |
| case hwmon_pwm: |
| return 0644; |
| |
| case hwmon_fan: |
| return 0444; |
| |
| default: |
| return 0; |
| } |
| } |
| |
| static const struct hwmon_ops pwm_fan_hwmon_ops = { |
| .is_visible = pwm_fan_is_visible, |
| .read = pwm_fan_read, |
| .write = pwm_fan_write, |
| }; |
| |
| /* thermal cooling device callbacks */ |
| static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev, |
| unsigned long *state) |
| { |
| struct pwm_fan_ctx *ctx = cdev->devdata; |
| |
| if (!ctx) |
| return -EINVAL; |
| |
| *state = ctx->pwm_fan_max_state; |
| |
| return 0; |
| } |
| |
| static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev, |
| unsigned long *state) |
| { |
| struct pwm_fan_ctx *ctx = cdev->devdata; |
| |
| if (!ctx) |
| return -EINVAL; |
| |
| *state = ctx->pwm_fan_state; |
| |
| return 0; |
| } |
| |
| static int |
| pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state) |
| { |
| struct pwm_fan_ctx *ctx = cdev->devdata; |
| int ret; |
| |
| if (!ctx || (state > ctx->pwm_fan_max_state)) |
| return -EINVAL; |
| |
| if (state == ctx->pwm_fan_state) |
| return 0; |
| |
| ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]); |
| if (ret) { |
| dev_err(&cdev->device, "Cannot set pwm!\n"); |
| return ret; |
| } |
| |
| ctx->pwm_fan_state = state; |
| |
| return ret; |
| } |
| |
| static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = { |
| .get_max_state = pwm_fan_get_max_state, |
| .get_cur_state = pwm_fan_get_cur_state, |
| .set_cur_state = pwm_fan_set_cur_state, |
| }; |
| |
| static int pwm_fan_of_get_cooling_data(struct device *dev, |
| struct pwm_fan_ctx *ctx) |
| { |
| struct device_node *np = dev->of_node; |
| int num, i, ret; |
| |
| if (!of_property_present(np, "cooling-levels")) |
| return 0; |
| |
| ret = of_property_count_u32_elems(np, "cooling-levels"); |
| if (ret <= 0) { |
| dev_err(dev, "Wrong data!\n"); |
| return ret ? : -EINVAL; |
| } |
| |
| num = ret; |
| ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32), |
| GFP_KERNEL); |
| if (!ctx->pwm_fan_cooling_levels) |
| return -ENOMEM; |
| |
| ret = of_property_read_u32_array(np, "cooling-levels", |
| ctx->pwm_fan_cooling_levels, num); |
| if (ret) { |
| dev_err(dev, "Property 'cooling-levels' cannot be read!\n"); |
| return ret; |
| } |
| |
| for (i = 0; i < num; i++) { |
| if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) { |
| dev_err(dev, "PWM fan state[%d]:%d > %d\n", i, |
| ctx->pwm_fan_cooling_levels[i], MAX_PWM); |
| return -EINVAL; |
| } |
| } |
| |
| ctx->pwm_fan_max_state = num - 1; |
| |
| return 0; |
| } |
| |
| static void pwm_fan_cleanup(void *__ctx) |
| { |
| struct pwm_fan_ctx *ctx = __ctx; |
| |
| del_timer_sync(&ctx->rpm_timer); |
| /* Switch off everything */ |
| ctx->enable_mode = pwm_disable_reg_disable; |
| pwm_fan_power_off(ctx); |
| } |
| |
| static int pwm_fan_probe(struct platform_device *pdev) |
| { |
| struct thermal_cooling_device *cdev; |
| struct device *dev = &pdev->dev; |
| struct pwm_fan_ctx *ctx; |
| struct device *hwmon; |
| int ret; |
| const struct hwmon_channel_info **channels; |
| u32 *fan_channel_config; |
| int channel_count = 1; /* We always have a PWM channel. */ |
| int i; |
| |
| ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL); |
| if (!ctx) |
| return -ENOMEM; |
| |
| mutex_init(&ctx->lock); |
| |
| ctx->dev = &pdev->dev; |
| ctx->pwm = devm_pwm_get(dev, NULL); |
| if (IS_ERR(ctx->pwm)) |
| return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n"); |
| |
| platform_set_drvdata(pdev, ctx); |
| |
| ctx->reg_en = devm_regulator_get_optional(dev, "fan"); |
| if (IS_ERR(ctx->reg_en)) { |
| if (PTR_ERR(ctx->reg_en) != -ENODEV) |
| return PTR_ERR(ctx->reg_en); |
| |
| ctx->reg_en = NULL; |
| } |
| |
| pwm_init_state(ctx->pwm, &ctx->pwm_state); |
| |
| /* |
| * PWM fans are controlled solely by the duty cycle of the PWM signal, |
| * they do not care about the exact timing. Thus set usage_power to true |
| * to allow less flexible hardware to work as a PWM source for fan |
| * control. |
| */ |
| ctx->pwm_state.usage_power = true; |
| |
| /* |
| * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned |
| * long. Check this here to prevent the fan running at a too low |
| * frequency. |
| */ |
| if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) { |
| dev_err(dev, "Configured period too big\n"); |
| return -EINVAL; |
| } |
| |
| ctx->enable_mode = pwm_disable_reg_enable; |
| |
| /* |
| * Set duty cycle to maximum allowed and enable PWM output as well as |
| * the regulator. In case of error nothing is changed |
| */ |
| ret = set_pwm(ctx, MAX_PWM); |
| if (ret) { |
| dev_err(dev, "Failed to configure PWM: %d\n", ret); |
| return ret; |
| } |
| timer_setup(&ctx->rpm_timer, sample_timer, 0); |
| ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx); |
| if (ret) |
| return ret; |
| |
| ctx->tach_count = platform_irq_count(pdev); |
| if (ctx->tach_count < 0) |
| return dev_err_probe(dev, ctx->tach_count, |
| "Could not get number of fan tachometer inputs\n"); |
| dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count); |
| |
| if (ctx->tach_count) { |
| channel_count++; /* We also have a FAN channel. */ |
| |
| ctx->tachs = devm_kcalloc(dev, ctx->tach_count, |
| sizeof(struct pwm_fan_tach), |
| GFP_KERNEL); |
| if (!ctx->tachs) |
| return -ENOMEM; |
| |
| ctx->fan_channel.type = hwmon_fan; |
| fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1, |
| sizeof(u32), GFP_KERNEL); |
| if (!fan_channel_config) |
| return -ENOMEM; |
| ctx->fan_channel.config = fan_channel_config; |
| } |
| |
| channels = devm_kcalloc(dev, channel_count + 1, |
| sizeof(struct hwmon_channel_info *), GFP_KERNEL); |
| if (!channels) |
| return -ENOMEM; |
| |
| channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE); |
| |
| for (i = 0; i < ctx->tach_count; i++) { |
| struct pwm_fan_tach *tach = &ctx->tachs[i]; |
| u32 ppr = 2; |
| |
| tach->irq = platform_get_irq(pdev, i); |
| if (tach->irq == -EPROBE_DEFER) |
| return tach->irq; |
| if (tach->irq > 0) { |
| ret = devm_request_irq(dev, tach->irq, pulse_handler, 0, |
| pdev->name, tach); |
| if (ret) { |
| dev_err(dev, |
| "Failed to request interrupt: %d\n", |
| ret); |
| return ret; |
| } |
| } |
| |
| of_property_read_u32_index(dev->of_node, |
| "pulses-per-revolution", |
| i, |
| &ppr); |
| tach->pulses_per_revolution = ppr; |
| if (!tach->pulses_per_revolution) { |
| dev_err(dev, "pulses-per-revolution can't be zero.\n"); |
| return -EINVAL; |
| } |
| |
| fan_channel_config[i] = HWMON_F_INPUT; |
| |
| dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n", |
| i, tach->irq, tach->pulses_per_revolution); |
| } |
| |
| if (ctx->tach_count > 0) { |
| ctx->sample_start = ktime_get(); |
| mod_timer(&ctx->rpm_timer, jiffies + HZ); |
| |
| channels[1] = &ctx->fan_channel; |
| } |
| |
| ctx->info.ops = &pwm_fan_hwmon_ops; |
| ctx->info.info = channels; |
| |
| hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan", |
| ctx, &ctx->info, NULL); |
| if (IS_ERR(hwmon)) { |
| dev_err(dev, "Failed to register hwmon device\n"); |
| return PTR_ERR(hwmon); |
| } |
| |
| ret = pwm_fan_of_get_cooling_data(dev, ctx); |
| if (ret) |
| return ret; |
| |
| ctx->pwm_fan_state = ctx->pwm_fan_max_state; |
| if (IS_ENABLED(CONFIG_THERMAL)) { |
| cdev = devm_thermal_of_cooling_device_register(dev, |
| dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops); |
| if (IS_ERR(cdev)) { |
| ret = PTR_ERR(cdev); |
| dev_err(dev, |
| "Failed to register pwm-fan as cooling device: %d\n", |
| ret); |
| return ret; |
| } |
| ctx->cdev = cdev; |
| } |
| |
| return 0; |
| } |
| |
| static void pwm_fan_shutdown(struct platform_device *pdev) |
| { |
| struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev); |
| |
| pwm_fan_cleanup(ctx); |
| } |
| |
| static int pwm_fan_suspend(struct device *dev) |
| { |
| struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); |
| |
| return pwm_fan_power_off(ctx); |
| } |
| |
| static int pwm_fan_resume(struct device *dev) |
| { |
| struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); |
| |
| return set_pwm(ctx, ctx->pwm_value); |
| } |
| |
| static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume); |
| |
| static const struct of_device_id of_pwm_fan_match[] = { |
| { .compatible = "pwm-fan", }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, of_pwm_fan_match); |
| |
| static struct platform_driver pwm_fan_driver = { |
| .probe = pwm_fan_probe, |
| .shutdown = pwm_fan_shutdown, |
| .driver = { |
| .name = "pwm-fan", |
| .pm = pm_sleep_ptr(&pwm_fan_pm), |
| .of_match_table = of_pwm_fan_match, |
| }, |
| }; |
| |
| module_platform_driver(pwm_fan_driver); |
| |
| MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>"); |
| MODULE_ALIAS("platform:pwm-fan"); |
| MODULE_DESCRIPTION("PWM FAN driver"); |
| MODULE_LICENSE("GPL"); |