Hi Jonathan, On Sun, Jan 24, 2021 at 02:47:37PM +0000, Jonathan Cameron wrote: > On Fri, 22 Jan 2021 12:24:34 +0100 > Oleksij Rempel <o.rem...@pengutronix.de> wrote: > > > Add simple GPIO base pulse counter. This device is used to measure > > rotation speed of some agricultural devices, so no high frequency on the > > counter pin is expected. > > > > The maximal measurement frequency depends on the CPU and system load. On > > the idle iMX6S I was able to measure up to 20kHz without count drops. > > > > Signed-off-by: Oleksij Rempel <o.rem...@pengutronix.de> > > Hi Oleksij, > > A few comments inline. > > Thanks, > > Jonathan > > > --- > > drivers/counter/Kconfig | 9 ++ > > drivers/counter/Makefile | 1 + > > drivers/counter/gpio-pulse-cnt.c | 244 +++++++++++++++++++++++++++++++ > > 3 files changed, 254 insertions(+) > > create mode 100644 drivers/counter/gpio-pulse-cnt.c > > > > diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig > > index 2de53ab0dd25..9ad1d9d49dd1 100644 > > --- a/drivers/counter/Kconfig > > +++ b/drivers/counter/Kconfig > > @@ -29,6 +29,15 @@ config 104_QUAD_8 > > The base port addresses for the devices may be configured via the base > > array module parameter. > > > > +config GPIO_PULSE_CNT > > + tristate "GPIO pulse counter driver" > > + depends on GPIOLIB > > + help > > + Select this option to enable GPIO pulse counter driver. > > + > > + To compile this driver as a module, choose M here: the > > + module will be called gpio-pulse-cnt. > > + > > config STM32_TIMER_CNT > > tristate "STM32 Timer encoder counter driver" > > depends on MFD_STM32_TIMERS || COMPILE_TEST > > diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile > > index 0a393f71e481..6a5c3fc6f2a0 100644 > > --- a/drivers/counter/Makefile > > +++ b/drivers/counter/Makefile > > @@ -6,6 +6,7 @@ > > obj-$(CONFIG_COUNTER) += counter.o > > > > obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o > > +obj-$(CONFIG_GPIO_PULSE_CNT) += gpio-pulse-cnt.o > > obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o > > obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o > > obj-$(CONFIG_TI_EQEP) += ti-eqep.o > > diff --git a/drivers/counter/gpio-pulse-cnt.c > > b/drivers/counter/gpio-pulse-cnt.c > > new file mode 100644 > > index 000000000000..9454345c77ad > > --- /dev/null > > +++ b/drivers/counter/gpio-pulse-cnt.c > > @@ -0,0 +1,244 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Copyright (c) 2021 Pengutronix, Oleksij Rempel <ker...@pengutronix.de> > > + */ > > + > > +#include <linux/counter.h> > > +#include <linux/gpio/consumer.h> > > +#include <linux/interrupt.h> > > +#include <linux/module.h> > > +#include <linux/of_device.h> > > why of_device.h? Probably want mod_devicetable.h instead.
done > > +#include <linux/platform_device.h> > > + > > +#define GPIO_PULSE_NAME "gpio-pulse-counter" > > + > > +struct gpio_pulse_priv { > > + struct counter_device counter; > > + struct gpio_desc *gpio; > > + int irq; > > + bool enabled; > > + atomic_t count; > > +}; > > + > > +static irqreturn_t gpio_pulse_irq_isr(int irq, void *dev_id) > > +{ > > + struct gpio_pulse_priv *priv = dev_id; > > + > > + if (!priv->enabled) > > + return IRQ_NONE; > > + > > + atomic_inc(&priv->count); > > + > > + return IRQ_HANDLED; > > +} > > + > > +static ssize_t gpio_pulse_count_enable_read(struct counter_device *counter, > > + struct counter_count *count, > > + void *private, char *buf) > > +{ > > + struct gpio_pulse_priv *priv = counter->priv; > > + > > + return sysfs_emit(buf, "%d\n", priv->enabled); > > +} > > + > > +static ssize_t gpio_pulse_count_enable_write(struct counter_device > > *counter, > > + struct counter_count *count, > > + void *private, > > + const char *buf, size_t len) > > +{ > > + struct gpio_pulse_priv *priv = counter->priv; > > + bool enable; > > + ssize_t ret; > > + > > + ret = kstrtobool(buf, &enable); > > + if (ret) > > + return ret; > > + > > + if (priv->enabled == enable) > > + return len; > > + > > + priv->enabled = enable; > > + > > + if (enable) > > + enable_irq(priv->irq); > > + else > > + disable_irq(priv->irq); > > As pointed out by Ahmad, this is all racy. > Personally I'd just let the race happen, and don't > bother with the priv->enabled at all. yes, i forgot about existence of IRQ_NOAUTOEN > We aren't going to be dealing with shared interrupts > here so if we get a race, it's between userspace write > getting through to enable / disable the interrupt and > a pulse coming in. The userspace part is so unpredictable on > timing etc the race isn't pretty meaningless (you might count > one extra, but then if userspace took a bit longer you might > do that anyway). > > > > + > > + return len; > > +} > > + > > +static const struct counter_count_ext gpio_pulse_count_ext[] = { > > + { > > + .name = "enable", > > + .read = gpio_pulse_count_enable_read, > > + .write = gpio_pulse_count_enable_write, > > + }, > > +}; > > + > > +static enum counter_synapse_action gpio_pulse_synapse_actions[] = { > > + COUNTER_SYNAPSE_ACTION_RISING_EDGE, > > +}; > > + > > +static int gpio_pulse_action_get(struct counter_device *counter, > > + struct counter_count *count, > > + struct counter_synapse *synapse, > > + size_t *action) > > +{ > > + *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE; > > + > > + return 0; > > +} > > + > > +static int gpio_pulse_count_read(struct counter_device *counter, > > + struct counter_count *count, > > + unsigned long *val) > > +{ > > + struct gpio_pulse_priv *priv = counter->priv; > > + > > + *val = atomic_read(&priv->count); > > + > > + return 0; > > +} > > + > > +static int gpio_pulse_count_write(struct counter_device *counter, > > + struct counter_count *count, > > + const unsigned long val) > > +{ > > + struct gpio_pulse_priv *priv = counter->priv; > > + > > + atomic_set(&priv->count, val); > > + > > + return 0; > > +} > > + > > +static int gpio_pulse_count_function_get(struct counter_device *counter, > > + struct counter_count *count, > > + size_t *function) > > +{ > > + *function = COUNTER_COUNT_FUNCTION_INCREASE; > > + > > + return 0; > > +} > > + > > +static int gpio_pulse_count_signal_read(struct counter_device *counter, > > + struct counter_signal *signal, > > + enum counter_signal_value *val) > > +{ > > + struct gpio_pulse_priv *priv = counter->priv; > > + int ret; > > + > > + ret = gpiod_get_value(priv->gpio); > > + if (ret < 0) > > + return ret; > > + > > + *val = ret ? COUNTER_SIGNAL_HIGH : COUNTER_SIGNAL_LOW; > > + > > + return 0; > > +} > > + > > +static const struct counter_ops gpio_pulse_cnt_ops = { > > + .action_get = gpio_pulse_action_get, > > + .count_read = gpio_pulse_count_read, > > + .count_write = gpio_pulse_count_write, > > + .function_get = gpio_pulse_count_function_get, > > + .signal_read = gpio_pulse_count_signal_read, > > +}; > > + > > +static struct counter_signal gpio_pulse_signals[] = { > > + { > > + .id = 0, > > + .name = "Channel 0 signal", > > + }, > > +}; > > + > > +static struct counter_synapse gpio_pulse_count_synapses[] = { > > + { > > + .actions_list = gpio_pulse_synapse_actions, > > + .num_actions = ARRAY_SIZE(gpio_pulse_synapse_actions), > > + .signal = &gpio_pulse_signals[0] > > + }, > > +}; > > + > > +static enum counter_count_function gpio_pulse_count_functions[] = { > > + COUNTER_COUNT_FUNCTION_INCREASE, > > +}; > > + > > +static struct counter_count gpio_pulse_counts[] = { > > + { > > + .id = 0, > > + .name = "Channel 1 Count", > > + .functions_list = gpio_pulse_count_functions, > > + .num_functions = ARRAY_SIZE(gpio_pulse_count_functions), > > + .synapses = gpio_pulse_count_synapses, > > + .num_synapses = ARRAY_SIZE(gpio_pulse_count_synapses), > > + .ext = gpio_pulse_count_ext, > > + .num_ext = ARRAY_SIZE(gpio_pulse_count_ext), > > + }, > > +}; > > + > > +static int gpio_pulse_cnt_probe(struct platform_device *pdev) > > +{ > > + struct device *dev = &pdev->dev; > > + struct gpio_pulse_priv *priv; > > + int ret; > > + > > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > > + if (!priv) > > + return -ENOMEM; > > + > > + if (gpiod_count(dev, NULL) != 1) { > > + dev_err(dev, "Error, need exactly 1 gpio for device\n"); > > + return -EINVAL; > > + } > > + > > + priv->gpio = devm_gpiod_get(dev, NULL, GPIOD_IN); > > + if (IS_ERR(priv->gpio)) > > + return dev_err_probe(dev, PTR_ERR(priv->gpio), "failed to get > > gpio\n"); > > My gut feeling here is that it probably makes sense to drop > the direct read of the signal level, and hence allow the driver > to be provided with an interrupt instead of a gpio. > > Afterall, not all gpio lines are interrupt capable. Hm, .. I need to be able to sense GPIO level for diagnostic interface. So, in this case i'll need to get irq and gpio separately > > + > > + priv->irq = gpiod_to_irq(priv->gpio); > > + if (priv->irq < 0) { > > + dev_err(dev, "failed to map GPIO to IRQ: %d\n", priv->irq); > > + return priv->irq; > > + } > > + > > + priv->counter.name = dev_name(dev); > > + priv->counter.parent = dev; > > + priv->counter.ops = &gpio_pulse_cnt_ops; > > + priv->counter.counts = gpio_pulse_counts; > > + priv->counter.num_counts = ARRAY_SIZE(gpio_pulse_counts); > > + priv->counter.signals = gpio_pulse_signals; > > + priv->counter.num_signals = ARRAY_SIZE(gpio_pulse_signals); > > + priv->counter.priv = priv; > > + > > + ret = devm_request_irq(dev, priv->irq, gpio_pulse_irq_isr, > > + IRQF_TRIGGER_RISING | IRQF_NO_THREAD, > > + GPIO_PULSE_NAME, priv); > > + if (ret) > > + return ret; > > + > > + disable_irq(priv->irq); > > Race condition here (messy at least) that we can close down. ACK > Note there is ongoing work to try and do this in a nice generic > fashion, but in the meantime call > > irq_set_status_flags(priv->irq, IRQ_NOAUTOEN); ^^ yes! this is what i was seeking! Thx. > before the devm_request_irq() > > https://lore.kernel.org/lkml/20210107223926.35284-2-song.bao....@hisilicon.com/ Nice! > There are a lot of cases that series will tidy up, but let us do the best > we can in the meantime! > > > + > > + platform_set_drvdata(pdev, priv); > > + > > + return devm_counter_register(dev, &priv->counter); > > +} > > + > > +static const struct of_device_id gpio_pulse_cnt_of_match[] = { > > + { .compatible = "virtual,gpio-pulse-counter", }, > > + {} > > +}; > > +MODULE_DEVICE_TABLE(of, gpio_pulse_cnt_of_match); > > + > > +static struct platform_driver gpio_pulse_cnt_driver = { > > + .probe = gpio_pulse_cnt_probe, > > + .driver = { > > + .name = GPIO_PULSE_NAME, > > + .of_match_table = gpio_pulse_cnt_of_match, > > + }, > > +}; > > +module_platform_driver(gpio_pulse_cnt_driver); > > + > > +MODULE_ALIAS("platform:gpio-pulse-counter"); > > +MODULE_AUTHOR("Oleksij Rempel <o.rem...@pengutronix.de>"); > > +MODULE_DESCRIPTION("GPIO pulse counter driver"); > > +MODULE_LICENSE("GPL v2"); Thank you. Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |