summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/pwm-fan.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/hwmon/pwm-fan.c')
-rw-r--r--drivers/hwmon/pwm-fan.c690
1 files changed, 690 insertions, 0 deletions
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
new file mode 100644
index 0000000000..6e4516c2ab
--- /dev/null
+++ b/drivers/hwmon/pwm-fan.c
@@ -0,0 +1,690 @@
+// 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_state(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_state(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_state(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_state(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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-09 07:53:03 +0000