Hi Marco, On Mon, Oct 29, 2018 at 03:35:21PM +0100, Marco Felsch wrote: > Most the time low voltage detection happens on a external device > e.g. a pmic or any other hw-logic. Some of such devices can pass the > power state (good/bad) to the host via i2c or by toggling a gpio. > > This patch adds the support to evaluate a gpio line to determine > the power good/bad state. The state is represented by the > in0_lcrit_alarm. Furthermore the driver supports to release device from > their driver upon a low voltage detection. This feature is supported by > OF-based firmware only. >
NACK, sorry. hwmon is strictly about monitoring, not about taking any action, and much less about removing devices from the system after some status change, it be a gpio pin value or anything else. Other than that, the driver simply maps a gpio pin to a (pretty much arbitrary) sysfs attribute, for which a driver isn't really needed. I don't know if there is a space in the kernel for handling the problem you are trying to solve, but it isn't hwmon. Guenter > Signed-off-by: Marco Felsch <[email protected]> > --- > Documentation/hwmon/gpio-brownout | 14 +++ > drivers/hwmon/Kconfig | 23 ++++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/gpio-brownout.c | 195 ++++++++++++++++++++++++++++++ > 4 files changed, 233 insertions(+) > create mode 100644 Documentation/hwmon/gpio-brownout > create mode 100644 drivers/hwmon/gpio-brownout.c > > diff --git a/Documentation/hwmon/gpio-brownout > b/Documentation/hwmon/gpio-brownout > new file mode 100644 > index 000000000000..61d6a781af47 > --- /dev/null > +++ b/Documentation/hwmon/gpio-brownout > @@ -0,0 +1,14 @@ > +Kernel driver gpio-brownout > +=========================== > + > +Author: Marco Felsch <[email protected]> > + > +Description > +----------- > + > +This driver checks a GPIO line to detect a undervoltage condition. > + > +Sysfs entries > +------------- > + > +in0_lcrit_alarm Undervoltage alarm > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 81da17a42dc9..a2712452ba8b 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -558,6 +558,29 @@ config SENSORS_G762 > This driver can also be built as a module. If so, the module > will be called g762. > > +config SENSORS_GPIO_BROWNOUT > + tristate "Generic GPIO Brownout detection support" > + depends on GPIOLIB > + help > + If you say yes here you get support for GPIO based brownout detection. > + > + If unsure, say N. > + > + To compile this driver as a module, choose M here: the > + module will be called gpio-brownout. > + > +if SENSORS_GPIO_BROWNOUT > + > +config SENSORS_GPIO_BROWNOUT_UNBIND > + bool "OF I2C/SPI device unbinding support" > + depends on OF && I2C && SPI > + help > + Enable support to unbind devices upon a brownout detection. > + > + If unsure, say N. > + > +endif > + > config SENSORS_GPIO_FAN > tristate "GPIO fan" > depends on OF_GPIO > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 93f7f41ea4ad..6b217b39e0e0 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -71,6 +71,7 @@ obj-$(CONFIG_SENSORS_G760A) += g760a.o > obj-$(CONFIG_SENSORS_G762) += g762.o > obj-$(CONFIG_SENSORS_GL518SM) += gl518sm.o > obj-$(CONFIG_SENSORS_GL520SM) += gl520sm.o > +obj-$(CONFIG_SENSORS_GPIO_BROWNOUT) += gpio-brownout.o > obj-$(CONFIG_SENSORS_GPIO_FAN) += gpio-fan.o > obj-$(CONFIG_SENSORS_HIH6130) += hih6130.o > obj-$(CONFIG_SENSORS_ULTRA45) += ultra45_env.o > diff --git a/drivers/hwmon/gpio-brownout.c b/drivers/hwmon/gpio-brownout.c > new file mode 100644 > index 000000000000..00d6ff8b1490 > --- /dev/null > +++ b/drivers/hwmon/gpio-brownout.c > @@ -0,0 +1,195 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * gpio-brownout.c - gpio based low voltage detection > + * > + * Copyright (C) 2018 Pengutronix, Marco Felsch <[email protected]> > + */ > + > +#include <linux/gpio/consumer.h> > +#include <linux/i2c.h> > +#include <linux/hwmon.h> > +#include <linux/hwmon-sysfs.h> > +#include <linux/interrupt.h> > +#include <linux/kernel.h> > +#include <linux/list.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/of_device.h> > +#include <linux/platform_device.h> > +#include <linux/spi/spi.h> > +#include <linux/stat.h> > + > +#define GPIO_BROWNOUT_MOD_NAME "gpio-brownout" > + > +struct gpio_brownout_device { > + struct list_head list; > + struct device *dev; > +}; > + > +struct gpio_brownout { > + struct device *hwmon_dev; > + struct gpio_desc *gpio; > + struct list_head devices; > +}; > + > +static irqreturn_t gpio_brownout_isr(int irq, void *dev_id) > +{ > + struct gpio_brownout *gb = dev_id; > + struct gpio_brownout_device *bout_dev, *tmp; > + > + list_for_each_entry_safe(bout_dev, tmp, &gb->devices, list) { > + device_release_driver(bout_dev->dev); > + list_del(&bout_dev->list); > + } > + > + sysfs_notify(&gb->hwmon_dev->kobj, NULL, "in0_lcrit_alarm"); > + > + return IRQ_HANDLED; > +} > + > +static int gpio_brownout_probe_fw(struct gpio_brownout *gb) > +{ > + struct device *pdev = gb->hwmon_dev->parent; > + > + gb->gpio = devm_gpiod_get(pdev, "gpio-brownout,sense", GPIOD_IN); > + if (IS_ERR(gb->gpio)) > + return PTR_ERR(gb->gpio); > + > + /* > + * Register all devices which should be unbinded upon a brownout > + * detection. At the moment only i2c and spi devices are supported > + */ > + > + if (IS_ENABLED(SENSORS_GPIO_BROWNOUT_UNBIND)) { > + struct device_node *np = gb->hwmon_dev->of_node; > + struct of_phandle_iterator it; > + struct gpio_brownout_device *elem; > + struct i2c_client *i2c_c; > + struct spi_device *spi_c; > + int ret; > + > + of_for_each_phandle(&it, ret, np, > + "gpio-brownout,dev-list", NULL, 0) { > + i2c_c = of_find_i2c_device_by_node(it.node); > + spi_c = of_find_spi_device_by_node(it.node); > + > + if (!i2c_c && !spi_c) > + return -EPROBE_DEFER; > + else if (i2c_c && spi_c) > + return -EINVAL; > + > + elem = devm_kzalloc(pdev, sizeof(*elem), GFP_KERNEL); > + if (!elem) > + return -ENOMEM; > + > + elem->dev = i2c_c ? &i2c_c->dev : &spi_c->dev; > + > + INIT_LIST_HEAD(&elem->list); > + list_add_tail(&elem->list, &gb->devices); > + } > + } > + > + return 0; > +} > + > +const u32 gpio_brownout_in_config[] = { > + HWMON_I_LCRIT_ALARM, > + 0 > +}; > + > +const struct hwmon_channel_info gpio_brownout_in = { > + .type = hwmon_in, > + .config = gpio_brownout_in_config, > +}; > + > +const struct hwmon_channel_info *gpio_brownout_ch_info[] = { > + &gpio_brownout_in, > + NULL > +}; > + > +static int gpio_brownout_read(struct device *dev, enum hwmon_sensor_types > type, > + u32 attr, int channel, long *val) > +{ > + struct gpio_brownout *gb = dev_get_drvdata(dev); > + > + *val = gpiod_get_value(gb->gpio); > + return 0; > +} > + > +static umode_t gpio_brownout_is_visible(const void *drvdata, > + enum hwmon_sensor_types type, u32 attr, > + int channel) > +{ > + return 0444; > +} > + > +const struct hwmon_ops gpio_brownout_ops = { > + .is_visible = gpio_brownout_is_visible, > + .read = gpio_brownout_read, > + > +}; > + > +const struct hwmon_chip_info gpio_brownout_info = { > + .ops = &gpio_brownout_ops, > + .info = gpio_brownout_ch_info, > +}; > + > +static int gpio_brownout_probe(struct platform_device *pdev) > +{ > + struct gpio_brownout *gb; > + struct device *hwmon; > + unsigned long irq_flags; > + int ret; > + > + gb = devm_kzalloc(&pdev->dev, sizeof(*gb), GFP_KERNEL); > + if (!gb) > + return -ENOMEM; > + > + hwmon = devm_hwmon_device_register_with_info(&pdev->dev, pdev->name, gb, > + &gpio_brownout_info, NULL); > + if (IS_ERR(hwmon)) > + return PTR_ERR(hwmon); > + > + gb->hwmon_dev = hwmon; > + > + INIT_LIST_HEAD(&gb->devices); > + > + ret = gpio_brownout_probe_fw(gb); > + if (ret) > + return ret; > + > + irq_flags = IRQF_ONESHOT; > + if (gpiod_is_active_low(gb->gpio)) > + irq_flags |= IRQF_TRIGGER_FALLING; > + else > + irq_flags |= IRQF_TRIGGER_RISING; > + ret = devm_request_threaded_irq(&pdev->dev, gpiod_to_irq(gb->gpio), > + NULL, gpio_brownout_isr, irq_flags, > + GPIO_BROWNOUT_MOD_NAME, gb); > + if (ret < 0) { > + dev_err(&pdev->dev, "IRQ request failed: %d\n", ret); > + return ret; > + } > + > + return 0; > +} > + > +static const struct of_device_id __maybe_unused gpio_brownout_of_match[] = { > + { .compatible = GPIO_BROWNOUT_MOD_NAME, }, > + { }, > +}; > +MODULE_DEVICE_TABLE(of, arm_gpio_brownout_of_match); > + > +static struct platform_driver gpio_brownout_driver = { > + .driver = { > + .name = GPIO_BROWNOUT_MOD_NAME, > + .of_match_table = of_match_ptr(gpio_brownout_of_match) > + }, > + .probe = gpio_brownout_probe, > +}; > + > +module_platform_driver(gpio_brownout_driver); > + > +MODULE_AUTHOR("Marco Felsch <[email protected]>"); > +MODULE_DESCRIPTION("GPIO Brownout Detection"); > +MODULE_LICENSE("GPL v2"); > -- > 2.19.1 >
