5 files changed, 235 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
new file mode 100644
index 000000000000..610757ce4492
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
@@ -0,0 +1,12 @@
+Bindings for a fan connected to the PWM lines
+
+Required properties:
+- compatible    : "pwm-fan"
+- pwms          : the PWM that is used to control the PWM fan
+
+Example:
+        pwm-fan {
+                compatible = "pwm-fan";
+                status = "okay";
+                pwms = <&pwm 0 10000 0>;
+        };
diff --git a/Documentation/hwmon/pwm-fan b/Documentation/hwmon/pwm-fan
new file mode 100644
index 000000000000..18529d2e3bcf
--- /dev/null
+++ b/Documentation/hwmon/pwm-fan
@@ -0,0 +1,17 @@
+Kernel driver pwm-fan
+=====================
+
+This driver enables the use of a PWM module to drive a fan. It uses the
+generic PWM interface thus it is hardware independent. It can be used on
+many SoCs, as long as the SoC supplies a PWM line driver that exposes
+the generic PWM API.
+
+Author: Kamil Debski <k.debski@samsung.com>
+
+Description
+-----------
+
+The driver implements a simple interface for driving a fan connected to
+a PWM output. It uses the generic PWM interface, thus it can be used with
+a range of SoCs. The driver exposes the fan to the user space through
+the hwmon's sysfs interface.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index c0aec8db462f..b93ab97732c0 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1128,6 +1128,17 @@ config SENSORS_PCF8591
 
 source drivers/hwmon/pmbus/Kconfig
 
+config SENSORS_PWM_FAN
+        tristate "PWM fan"
+        depends on PWM
+        help
+          If you say yes here you get support for fans connected to PWM lines.
+          The driver uses the generic PWM interface, thus it will work on a
+          variety of SoCs.
+
+          This driver can also be built as a module.  If so, the module
+          will be called pwm-fan.
+
 config SENSORS_SHT15
         tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
         depends on GPIOLIB
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f4435ea6b169..be28152c9848 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
 obj-$(CONFIG_SENSORS_PC87427)   += pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)   += pcf8591.o
 obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
+obj-$(CONFIG_SENSORS_PWM_FAN)   += pwm-fan.o
 obj-$(CONFIG_SENSORS_S3C)       += s3c-hwmon.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)   += sch5627.o
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
new file mode 100644
index 000000000000..af30dd63de6a
--- /dev/null
+++ b/drivers/hwmon/pwm-fan.c
@@ -0,0 +1,194 @@
+/*
+ * 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>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/sysfs.h>
+
+#define MAX_PWM 255
+
+struct pwm_fan_ctx {
+        struct mutex lock;
+        struct pwm_device *pwm;
+        unsigned char pwm_value;
+};
+
+static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
+                       const char *buf, size_t count)
+{
+        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+        unsigned long pwm, duty;
+        ssize_t ret;
+
+        if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
+                return -EINVAL;
+
+        mutex_lock(&ctx->lock);
+
+        if (ctx->pwm_value == pwm)
+                goto exit_set_pwm_no_change;
+
+        if (pwm == 0) {
+                pwm_disable(ctx->pwm);
+                goto exit_set_pwm;
+        }
+
+        duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
+        ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+        if (ret)
+                goto exit_set_pwm_err;
+
+        if (ctx->pwm_value == 0) {
+                ret = pwm_enable(ctx->pwm);
+                if (ret)
+                        goto exit_set_pwm_err;
+        }
+
+exit_set_pwm:
+        ctx->pwm_value = pwm;
+exit_set_pwm_no_change:
+        ret = count;
+exit_set_pwm_err:
+        mutex_unlock(&ctx->lock);
+        return ret;
+}
+
+static ssize_t show_pwm(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%u\n", ctx->pwm_value);
+}
+
+
+static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
+
+static struct attribute *pwm_fan_attrs[] = {
+        &sensor_dev_attr_pwm1.dev_attr.attr,
+        NULL,
+};
+
+ATTRIBUTE_GROUPS(pwm_fan);
+
+static int pwm_fan_probe(struct platform_device *pdev)
+{
+        struct device *hwmon;
+        struct pwm_fan_ctx *ctx;
+        int duty_cycle;
+        int ret;
+
+        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+        if (!ctx)
+                return -ENOMEM;
+
+        mutex_init(&ctx->lock);
+
+        ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
+        if (IS_ERR(ctx->pwm)) {
+                dev_err(&pdev->dev, "Could not get PWM\n");
+                return PTR_ERR(ctx->pwm);
+        }
+
+        dev_set_drvdata(&pdev->dev, ctx);
+        platform_set_drvdata(pdev, ctx);
+
+        /* Set duty cycle to maximum allowed */
+        duty_cycle = ctx->pwm->period - 1;
+        ctx->pwm_value = MAX_PWM;
+
+        ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
+        if (ret) {
+                dev_err(&pdev->dev, "Failed to configure PWM\n");
+                return ret;
+        }
+
+        /* Enbale PWM output */
+        ret = pwm_enable(ctx->pwm);
+        if (ret) {
+                dev_err(&pdev->dev, "Failed to enable PWM\n");
+                return ret;
+        }
+
+        hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
+                                                       ctx, pwm_fan_groups);
+        if (IS_ERR(hwmon)) {
+                dev_err(&pdev->dev, "Failed to register hwmon device\n");
+                pwm_disable(ctx->pwm);
+                return PTR_ERR(hwmon);
+        }
+        return 0;
+}
+
+static int pwm_fan_remove(struct platform_device *pdev)
+{
+        struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
+
+        if (ctx->pwm_value)
+                pwm_disable(ctx->pwm);
+        return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pwm_fan_suspend(struct device *dev)
+{
+        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+        if (ctx->pwm_value)
+                pwm_disable(ctx->pwm);
+        return 0;
+}
+
+static int pwm_fan_resume(struct device *dev)
+{
+        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+        if (ctx->pwm_value)
+                return pwm_enable(ctx->pwm);
+        return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
+
+static struct of_device_id of_pwm_fan_match[] = {
+        { .compatible = "pwm-fan", },
+        {},
+};
+
+static struct platform_driver pwm_fan_driver = {
+        .probe          = pwm_fan_probe,
+        .remove         = pwm_fan_remove,
+        .driver = {
+                .name           = "pwm-fan",
+                .pm             = &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");