Hi Guenter, > From: Guenter Roeck [mailto:linux@xxxxxxxxxxxx] > Sent: Wednesday, July 16, 2014 3:53 PM > To: Kamil Debski; devicetree@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; lm-sensors@xxxxxxxxxxxxxx > Cc: t.figa@xxxxxxxxxxx; m.szyprowski@xxxxxxxxxxx; tklauser@xxxxxxxxxx; > linux-pwm@xxxxxxxxxxxxxxx; varkabhadram@xxxxxxxxx > Subject: Re: [PATCH v4] hwmon: pwm-fan: Add pwm-fan driver > > Hi Kamil, > > comments inline. Thank you for your review :-) > > Thanks, > Guenter > > On 07/16/2014 03:03 AM, Kamil Debski wrote: > > The pwm-fan driver enables control of fans connected to PWM lines. > > This driver uses the PWM framework, so it is compatible with all PWM > > devices that provide drivers through the PWM framework. > > > > Signed-off-by: Kamil Debski <k.debski@xxxxxxxxxxx> > > --- > > Changes since v3: > > - fix missing "\n" in error messages > > - remove of_match_ptr which was not necessary > > - change error returned in case of failed allocation to -ENOMEM > > Changes since v2: > > - add CONFIG_PM_SLEEP around pwm_fan_suspend and pwm_fan_resume > > Changes since v1: > > - added documentation to Documentation/hwmon > > - fix checkpatch errors > > - added extra description to Kconfig > > - removed whitespace errors > > - include files rearranged to be in alphabetical order > > - remove unused sysfs entry pwm1_enable > > - changed the behavior of the set_pwm function > > - when 0 PWM value is set pwm_disable is run > > - pwm_config return value is checked for errors > > - use of ATTRIBUTE_GROUPS was added > > - removed "Not enouch memory" error message > > - fixed probe return value in case of devm_of_pwm_get error > > - changed hwmon_device_register_with_groups to > > devm_hwmon_device_register_with_groups > > - changes suspend/resume to use pwm_disable/enable > > - removed unnecessary CONFIG_PM_SLEEP ifdefs > > --- > > .../devicetree/bindings/hwmon/pwm-fan.txt | 12 ++ > > Documentation/hwmon/pwm-fan | 17 ++ > > drivers/hwmon/Kconfig | 11 ++ > > drivers/hwmon/Makefile | 1 + > > drivers/hwmon/pwm-fan.c | 202 > ++++++++++++++++++++ > > 5 files changed, 243 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/hwmon/pwm- > fan.txt > > create mode 100644 Documentation/hwmon/pwm-fan > > create mode 100644 drivers/hwmon/pwm-fan.c > > > > diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt > > b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt > > new file mode 100644 > > index 0000000..610757c > > --- /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 0000000..18529d2 > > --- /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@xxxxxxxxxxx> > > + > > +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 > > 02d3d85..4ac13ab 100644 > > --- a/drivers/hwmon/Kconfig > > +++ b/drivers/hwmon/Kconfig > > @@ -1105,6 +1105,17 @@ 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 > > 3dc0f02..3967ecf 100644 > > --- a/drivers/hwmon/Makefile > > +++ b/drivers/hwmon/Makefile > > @@ -120,6 +120,7 @@ obj-$(CONFIG_SENSORS_NTC_THERMISTOR) += > ntc_thermistor.o > > obj-$(CONFIG_SENSORS_PC87360) += pc87360.o > > obj-$(CONFIG_SENSORS_PC87427) += pc87427.o > > obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.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 0000000..cacb20a > > --- /dev/null > > +++ b/drivers/hwmon/pwm-fan.c > > @@ -0,0 +1,202 @@ > > +/* > > + * pwm-fan.c - Hwmon driver for fans connected to PWM lines. > > + * > > + * Copyright (c) 2014 Samsung Electronics Co., Ltd. > > + * > > + * Author: Kamil Debski <k.debski@xxxxxxxxxxx> > > + * > > + * 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 device *hwmon; > > + struct mutex lock; > > + struct platform_device *pdev; > > Neither hwmon nor pdev are used anywhere and are thus unnecessary. Right. > > > + struct pwm_device *pwm; > > + unsigned int duty_cycle; > > duty_cycle is only used in the probe function, and is thus unnecessary > as well. I agree. > > > + 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; > > + int ret; I also changed this to ssize_t ret to match the return value of the function. > > + > > + if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM) > > + return -EINVAL; > > + > > + mutex_lock(&ctx->lock); > > + > > + if (ctx->pwm_value == pwm) > > + goto exit_set_pwm; > > + > > + if (pwm == 0) { > > + pwm_disable(ctx->pwm); > > + ctx->pwm_value = pwm; > > + goto exit_set_pwm; > > You can add another label below to save the double assignment. Good idea, thanks. > > > + } > > + > > + duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM); > > + ret = pwm_config(ctx->pwm, duty, ctx->pwm->period); > > + if (ret) { > > + count = ret; /* Set the return value */ > > Subtle problem: count is of type size_t which is unsigned. Sure it may > well be that the negative value is converted to unsigned and then > converted back to signed on return, but it is not a good idea to depend > on it. I would suggest to return ret and assign > ret = count; > in the success case further below. You'll need an extra label for the > success cases above. Good idea. > > + goto exit_set_pwm; > > + } > > + > > + if (ctx->pwm_value == 0) > > + ret = pwm_enable(ctx->pwm); > > + if (ret) { > > + count = ret; /* Set the return value */ > > + goto exit_set_pwm; > > + } > > This check for ret should really be within the if() statement. Right, I missed it. > > > + > > + ctx->duty_cycle = duty; > > + ctx->pwm_value = pwm; > > + > > +exit_set_pwm: > > + mutex_unlock(&ctx->lock); > > + return count; > > +} > > + > > +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); > > + > Continuation line is not needed here. Ok. > > > +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 pwm_fan_ctx *ctx; > > + int ret; > > + > > + ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); > > + if (!ctx) > > + return -ENOMEM; > > + > > + ctx->pdev = pdev; > > + mutex_init(&ctx->lock); > > + > > + ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, 0); > > + 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 */ > > + ctx->duty_cycle = ctx->pwm->period - 1; > > + ctx->pwm_value = MAX_PWM; > > + > > + ret = pwm_config(ctx->pwm, ctx->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; > > + } > > + > > + ctx->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, > > + "pwmfan", ctx, > > + pwm_fan_groups); > > + > > + if (IS_ERR(ctx->hwmon)) { > > + dev_err(&pdev->dev, "Failed to register hwmon device\n"); > > + pwm_disable(ctx->pwm); > > + return PTR_ERR(ctx->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@xxxxxxxxxxx>"); > > +MODULE_ALIAS("platform:pwm-fan"); > > +MODULE_DESCRIPTION("PWM FAN driver"); MODULE_LICENSE("GPL"); > > Best wishes, -- Kamil Debski Samsung R&D Institute Poland -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
