Re: [PATCH v7 2/2] counter: add IRQ or GPIO based counter

Oleksij Rempel
2021-02-26T12:16:27Z

Hi,

On Fri, Feb 26, 2021 at 06:45:20PM +0900, William Breathitt Gray wrote:
> On Fri, Feb 26, 2021 at 10:08:30AM +0100, Oleksij Rempel wrote:
> > Add simple IRQ or GPIO base 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.rempel@pengutronix.de>
> > Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>
> Hi Oleksij,
>
> We're almost there, but I spotted a couple of mistakes below.
>
> > ---
> > MAINTAINERS | 7 +
> > drivers/counter/Kconfig | 10 ++
> > drivers/counter/Makefile | 1 +
> > drivers/counter/interrupt-cnt.c | 243 ++++++++++++++++++++++++++++++++
> > 4 files changed, 261 insertions(+)
> > create mode 100644 drivers/counter/interrupt-cnt.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index a50a543e3c81..ad0a4455afec 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -9217,6 +9217,13 @@ F: include/dt-bindings/interconnect/
> > F: include/linux/interconnect-provider.h
> > F: include/linux/interconnect.h
> >
> > +INTERRUPT COUNTER DRIVER
> > +M: Oleksij Rempel <o.rempel@pengutronix.de>
> > +R: Pengutronix Kernel Team <kernel@pengutronix.de>
> > +L: linux-iio@vger.kernel.org
> > +F: Documentation/devicetree/bindings/counter/interrupt-counter.yaml
> > +F: drivers/counter/interrupt-cnt.c
> > +
> > INVENSENSE ICM-426xx IMU DRIVER
> > M: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
> > L: linux-iio@vger.kernel.org
> > diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> > index 2de53ab0dd25..dcad13229134 100644
> > --- a/drivers/counter/Kconfig
> > +++ b/drivers/counter/Kconfig
> > @@ -29,6 +29,16 @@ config 104_QUAD_8
> > The base port addresses for the devices may be configured via the base
> > array module parameter.
> >
> > +config INTERRUPT_CNT
> > + tristate "Interrupt counter driver"
> > + depends on GPIOLIB
> > + help
> > + Select this option to enable interrupt counter driver. Any interrupt
> > + source can be used by this driver as the event source.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called interrupt-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..cb646ed2f039 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-$(CONFIG_INTERRUPT_CNT) += interrupt-cnt.o
> > obj-$(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/interrupt-cnt.c b/drivers/counter/interrupt-cnt.c
> > new file mode 100644
> > index 000000000000..550383b6b591
> > --- /dev/null
> > +++ b/drivers/counter/interrupt-cnt.c
> > @@ -0,0 +1,243 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2021 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
> > + */
> > +
> > +#include <linux/counter.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +
> > +#define INTERRUPT_CNT_NAME "interrupt-cnt"
> > +
> > +struct interrupt_cnt_priv {
> > + atomic_t count;
> > + struct counter_device counter;
> > + struct gpio_desc *gpio;
> > + int irq;
> > + bool enabled;
> > + struct counter_signal signals;
> > + struct counter_synapse synapses;
> > + struct counter_count cnts;
> > +};
> > +
> > +static irqreturn_t interrupt_cnt_isr(int irq, void *dev_id)
> > +{
> > + struct interrupt_cnt_priv *priv = dev_id;
> > +
> > + atomic_inc(&priv->count);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static ssize_t interrupt_cnt_enable_read(struct counter_device *counter,
> > + struct counter_count *count,
> > + void *private, char *buf)
> > +{
> > + struct interrupt_cnt_priv *priv = counter->priv;
> > +
> > + return sysfs_emit(buf, "%d\n", priv->enabled);
> > +}
> > +
> > +static ssize_t interrupt_cnt_enable_write(struct counter_device *counter,
> > + struct counter_count *count,
> > + void *private, const char *buf,
> > + size_t len)
> > +{
> > + struct interrupt_cnt_priv *priv = counter->priv;
> > + bool enable;
> > + ssize_t ret;
> > +
> > + ret = kstrtobool(buf, &enable);
> > + if (ret)
> > + return ret;
> > +
> > + if (priv->enabled == enable)
> > + return len;
> > +
> > + if (enable) {
> > + priv->enabled = true;
> > + enable_irq(priv->irq);
> > + } else {
> > + disable_irq(priv->irq);
> > + priv->enabled = false;
> > + }
> > +
> > + return len;
> > +}
> > +
> > +static const struct counter_count_ext interrupt_cnt_ext[] = {
> > + {
> > + .name = "enable",
> > + .read = interrupt_cnt_enable_read,
> > + .write = interrupt_cnt_enable_write,
> > + },
> > +};
> > +
> > +static enum counter_synapse_action interrupt_cnt_synapse_actionss[] = {
> > + COUNTER_SYNAPSE_ACTION_RISING_EDGE,
> > +};
> > +
> > +static int interrupt_cnt_action_get(struct counter_device *counter,
> > + struct counter_count *count,
> > + struct counter_synapse *synapse,
> > + size_t *action)
> > +{
> > + *action = interrupt_cnt_synapse_actionss[0];
>
> This needs to be set to the index of the element, not the value:
>
> *action = 0;
>
> > +
> > + return 0;
> > +}
> > +
> > +static int interrupt_cnt_read(struct counter_device *counter,
> > + struct counter_count *count, unsigned long *val)
> > +{
> > + struct interrupt_cnt_priv *priv = counter->priv;
> > +
> > + *val = atomic_read(&priv->count);
> > +
> > + return 0;
> > +}
> > +
> > +static int interrupt_cnt_write(struct counter_device *counter,
> > + struct counter_count *count,
> > + const unsigned long val)
> > +{
> > + struct interrupt_cnt_priv *priv = counter->priv;
> > +
> > + atomic_set(&priv->count, val);
> > +
> > + return 0;
> > +}
> > +
> > +static enum counter_count_function interrupt_cnt_functions[] = {
> > + COUNTER_COUNT_FUNCTION_INCREASE,
> > +};
> > +
> > +static int interrupt_cnt_function_get(struct counter_device *counter,
> > + struct counter_count *count,
> > + size_t *function)
> > +{
> > + *function = interrupt_cnt_functions[0];
>
> Same problem as action_get(); needs to be index, not value:
>
> *function = 0;

ok

> > +
> > + return 0;
> > +}
> > +
> > +static int interrupt_cnt_signal_read(struct counter_device *counter,
> > + struct counter_signal *signal,
> > + enum counter_signal_value *val)
> > +{
> > + struct interrupt_cnt_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 interrupt_cnt_ops = {
> > + .action_get = interrupt_cnt_action_get,
> > + .count_read = interrupt_cnt_read,
> > + .count_write = interrupt_cnt_write,
> > + .function_get = interrupt_cnt_function_get,
> > + .signal_read = interrupt_cnt_signal_read,
> > +};
> > +
> > +static int interrupt_cnt_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct interrupt_cnt_priv *priv;
> > + int ret;
> > +
> > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > + if (!priv)
> > + return -ENOMEM;
> > +
> > + priv->irq = platform_get_irq_optional(pdev, 0);
> > + if (priv->irq == -ENXIO)
> > + priv->irq = 0;
> > + else if (priv->irq < 0)
> > + return dev_err_probe(dev, priv->irq, "failed to get IRQ\n");
> > +
> > + priv->gpio = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
> > + if (IS_ERR(priv->gpio))
> > + return dev_err_probe(dev, PTR_ERR(priv->gpio), "failed to get GPIO\n");
> > +
> > + if (!priv->irq && !priv->gpio) {
> > + dev_err(dev, "IRQ and GPIO are not found. At least one source should be provided\n");
> > + return -ENODEV;
> > + }
> > +
> > + if (!priv->irq) {
> > + int irq = gpiod_to_irq(priv->gpio);
> > +
> > + if (irq < 0)
> > + return dev_err_probe(dev, irq, "failed to get IRQ from GPIO\n");
> > +
> > + priv->irq = irq;
> > + }
> > +
> > + if (priv->gpio) {
>
> This if statement can be removed. There's no need to restrict this to
> just GPIO because we're always dealing with an IRQ, so allocate the
> "IRQ #" name unconditionally and set signals/num_signals.

Your previous suggestion was to no assign signals if there is no gpios.
What should I do?

Regards,
Oleksij
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