Subject: [PATCH v3 2/6] iio: pulse: add TI ECAP driver

From: [email-masked] (Jonathan Cameron)
Date: Mon, 28 Mar 2016 16:30:00 +0100

On 05/02/14 19:01, Matt Porter wrote:
> Adds support for capturing PWM signals using the TI ECAP peripheral.
> This driver supports triggered buffer capture of pulses on multiple
> ECAP instances. In addition, the driver supports configurable polarity
> of the signal to be captured.
> 
> Signed-off-by: Matt Porter <[email-masked]>
Hi Matt,

Given I had a personal message asking about this a few weeks ago, I thought I'd
ask... Any plans to resurrect this?
> ---
>  drivers/iio/pulse/Kconfig  |  20 ++
>  drivers/iio/pulse/Makefile |   6 +
>  drivers/iio/pulse/tiecap.c | 491 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 517 insertions(+)
>  create mode 100644 drivers/iio/pulse/Kconfig
>  create mode 100644 drivers/iio/pulse/Makefile
>  create mode 100644 drivers/iio/pulse/tiecap.c
> 
> diff --git a/drivers/iio/pulse/Kconfig b/drivers/iio/pulse/Kconfig
> new file mode 100644
> index 0000000..9864d4b
> --- /dev/null
> +++ b/drivers/iio/pulse/Kconfig
> @@ -0,0 +1,20 @@
> +#
> +# Pulse Capture Devices
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Pulse Capture Devices"
> +
> +config IIO_TIECAP
> +	tristate "TI ECAP Pulse Capture"
> +	depends on SOC_AM33XX
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	 If you say yes here you get support for the TI ECAP peripheral
> +	 in pulse capture mode.
> +
> +	 This driver can also be built as a module.  If so, the module
> +	 will be called tiecap
> +
> +endmenu
> diff --git a/drivers/iio/pulse/Makefile b/drivers/iio/pulse/Makefile
> new file mode 100644
> index 0000000..94d4b00
> --- /dev/null
> +++ b/drivers/iio/pulse/Makefile
> @@ -0,0 +1,6 @@
> +#
> +# Makefile for IIO PWM Capture Devices
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_IIO_TIECAP)	+= tiecap.o
> diff --git a/drivers/iio/pulse/tiecap.c b/drivers/iio/pulse/tiecap.c
> new file mode 100644
> index 0000000..fd96745
> --- /dev/null
> +++ b/drivers/iio/pulse/tiecap.c
> @@ -0,0 +1,491 @@
> +/*
> + * ECAP IIO pulse capture driver
> + *
> + * Copyright (C) 2014 Linaro Limited
> + * Author: Matt Porter <[email-masked]>
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "../../pwm/pwm-tipwmss.h"
> +
> +/* ECAP regs and bits */
> +#define CAP1			0x08
> +#define CAP2			0x0c
> +#define ECCTL1			0x28
> +#define ECCTL1_RUN_FREE		BIT(15)
> +#define ECCTL1_CAPLDEN		BIT(8)
> +#define ECCTL1_CAP2POL		BIT(2)
> +#define ECCTL1_CTRRST1		BIT(1)
> +#define ECCTL1_CAP1POL		BIT(0)
> +#define ECCTL2			0x2a
> +#define ECCTL2_SYNCO_SEL_DIS	BIT(7)
> +#define ECCTL2_TSCTR_FREERUN	BIT(4)
> +#define ECCTL2_REARM		BIT(3)
> +#define ECCTL2_STOP_WRAP_2	BIT(1)
> +#define ECEINT			0x2c
> +#define ECFLG			0x2e
> +#define ECCLR			0x30
> +#define ECINT_CTRCMP		BIT(7)
> +#define ECINT_CTRPRD		BIT(6)
> +#define ECINT_CTROVF		BIT(5)
> +#define ECINT_CEVT4		BIT(4)
> +#define ECINT_CEVT3		BIT(3)
> +#define ECINT_CEVT2		BIT(2)
> +#define ECINT_CEVT1		BIT(1)
> +#define ECINT_ALL		(ECINT_CTRCMP |	\
> +				ECINT_CTRPRD |	\
> +				ECINT_CTROVF |	\
> +				ECINT_CEVT4 |	\
> +				ECINT_CEVT3 |	\
> +				ECINT_CEVT2 |	\
> +				ECINT_CEVT1)
> +
> +/* ECAP driver flags */
> +#define ECAP_POLARITY_HIGH	BIT(1)
> +#define ECAP_ENABLED		BIT(0)
> +
> +struct ecap_context {
> +	u32	cap1;
> +	u32	cap2;
> +	u16	ecctl1;
> +	u16	ecctl2;
> +	u16	eceint;
> +};
> +
> +struct ecap_state {
> +	unsigned long		flags;
> +	unsigned int		clk_rate;
> +	void __iomem		*regs;
> +	u32			*buf;
> +	struct ecap_context	ctx;
> +};
> +
> +#define dev_to_ecap_state(d)	iio_priv(dev_to_iio_dev(d))
> +
> +static const struct iio_chan_spec ecap_channels[] = {
> +	{
> +		.type		= IIO_PULSE,
> +		.info_mask_separate =
> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index	= 0,
> +		.scan_type = {
> +			.sign		= 'u',
> +			.realbits	= 32,
> +			.storagebits	= 32,
> +			.endianness	= IIO_LE,
> +		},
> +	},
> +	IIO_CHAN_SOFT_TIMESTAMP(1)
> +};
> +
> +static ssize_t ecap_attr_show(struct device *dev,
> +			      struct device_attribute *attr, char *buf)
> +{
> +	struct ecap_state *state = dev_to_ecap_state(dev);
> +
> +	return sprintf(buf, "%d\n",
> +		       test_bit(ECAP_POLARITY_HIGH, &state->flags));
> +}
> +
> +static ssize_t ecap_attr_store(struct device *dev,
> +			       struct device_attribute *attr,
> +			       const char *buf,
> +			       size_t len)
> +{
> +	int ret;
> +	bool val;
> +	struct ecap_state *state = dev_to_ecap_state(dev);
> +
> +	if (test_bit(ECAP_ENABLED, &state->flags))
> +		return -EINVAL;
> +
> +	ret = strtobool(buf, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val)
> +		set_bit(ECAP_POLARITY_HIGH, &state->flags);
> +	else
> +		clear_bit(ECAP_POLARITY_HIGH, &state->flags);
> +
> +	return len;
> +}
> +
> +static IIO_DEVICE_ATTR(pulse_polarity, S_IRUGO | S_IWUSR,
> +	ecap_attr_show, ecap_attr_store, 0);
> +
> +static struct attribute *ecap_attributes[] = {
> +	&iio_dev_attr_pulse_polarity.dev_attr.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group ecap_attribute_group = {
> +	.attrs = ecap_attributes,
> +};
> +
> +static int ecap_read_raw(struct iio_dev *idev,
> +			struct iio_chan_spec const *ch, int *val,
> +			int *val2, long mask)
> +{
> +	struct ecap_state *state = iio_priv(idev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		/*
> +		 * Always return 0 as a pulse width sample
> +		 * is only valid in a triggered condition
> +		 */
> +		*val = 0;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 0;
> +		*val2 = NSEC_PER_SEC / state->clk_rate;
> +		return IIO_VAL_INT_PLUS_NANO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info ecap_info = {
> +	.driver_module = THIS_MODULE,
> +	.attrs = &ecap_attribute_group,
> +	.read_raw = &ecap_read_raw,
> +};
> +
> +static irqreturn_t ecap_trigger_handler(int irq, void *private)
> +{
> +	struct iio_poll_func *pf = private;
> +	struct iio_dev *idev = pf->indio_dev;
> +	struct ecap_state *state = iio_priv(idev);
> +
> +	/* Read pulse counter value */
> +	*state->buf = readl(state->regs + CAP2);
> +
> +	iio_push_to_buffers_with_timestamp(idev, state->buf, iio_get_time_ns());
> +
> +	iio_trigger_notify_done(idev->trig);
> +
> +	return IRQ_HANDLED;
> +};
> +
> +
> +static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
> +	.owner = THIS_MODULE,
> +};
> +
> +static irqreturn_t ecap_interrupt_handler(int irq, void *private)
> +{
> +	struct iio_dev *idev = private;
> +	struct ecap_state *state = iio_priv(idev);
> +	u16 ints;
> +
> +	iio_trigger_poll(idev->trig, 0);
> +
> +	/* Clear CAP2 interrupt */
> +	ints = readw(state->regs + ECFLG);
> +	if (ints & ECINT_CEVT2)
> +		writew(ECINT_CEVT2, state->regs + ECCLR);
> +	else
> +		dev_warn(&idev->dev, "unhandled interrupt flagged: %04x\n",
> +			 ints);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int ecap_buffer_predisable(struct iio_dev *idev)
> +{
> +	struct ecap_state *state = iio_priv(idev);
> +	int ret = 0;
> +	u16 ecctl2;
> +
> +	/* Stop capture */
> +	clear_bit(ECAP_ENABLED, &state->flags);
> +	ecctl2 = readw(state->regs + ECCTL2) & ~ECCTL2_TSCTR_FREERUN;
> +	writew(ecctl2, state->regs + ECCTL2);
> +
> +	/* Disable and clear all interrupts */
> +	writew(0, state->regs + ECEINT);
> +	writew(ECINT_ALL, state->regs + ECCLR);
> +
> +	ret = iio_triggered_buffer_predisable(idev);
> +
> +	pm_runtime_put_sync(idev->dev.parent);
> +
> +	return ret;
> +}
> +
> +static int ecap_buffer_postenable(struct iio_dev *idev)
> +{
> +	struct ecap_state *state = iio_priv(idev);
> +	int ret = 0;
> +	u16 ecctl1, ecctl2;
> +
> +	pm_runtime_get_sync(idev->dev.parent);
> +
> +	/* Configure pulse polarity */
> +	ecctl1 = readw(state->regs + ECCTL1);
> +	if (test_bit(ECAP_POLARITY_HIGH, &state->flags)) {
> +		/* CAP1 rising, CAP2 falling */
> +		ecctl1 |= ECCTL1_CAP2POL;
> +		ecctl1 &= ~ECCTL1_CAP1POL;
> +	} else {
> +		/* CAP1 falling, CAP2 rising */
> +		ecctl1 &= ~ECCTL1_CAP2POL;
> +		ecctl1 |= ECCTL1_CAP1POL;
> +	}
> +	writew(ecctl1, state->regs + ECCTL1);
> +
> +	/* Enable CAP2 interrupt */
> +	writew(ECINT_CEVT2, state->regs + ECEINT);
> +
> +	/* Enable capture */
> +	ecctl2 = readw(state->regs + ECCTL2);
> +	ecctl2 |= ECCTL2_TSCTR_FREERUN | ECCTL2_REARM;
> +	writew(ecctl2, state->regs + ECCTL2);
> +	set_bit(ECAP_ENABLED, &state->flags);
> +
> +	ret = iio_triggered_buffer_postenable(idev);
> +
> +	return ret;
> +}
> +
> +static const struct iio_buffer_setup_ops ecap_buffer_setup_ops = {
> +	.postenable = &ecap_buffer_postenable,
> +	.predisable = &ecap_buffer_predisable,
> +};
> +
> +static void ecap_init_hw(struct iio_dev *idev)
> +{
> +	struct ecap_state *state = iio_priv(idev);
> +
> +	clear_bit(ECAP_ENABLED, &state->flags);
> +	set_bit(ECAP_POLARITY_HIGH, &state->flags);
> +
> +	writew(ECCTL1_RUN_FREE | ECCTL1_CAPLDEN |
> +	       ECCTL1_CAP2POL | ECCTL1_CTRRST1,
> +	       state->regs + ECCTL1);
> +
> +	writew(ECCTL2_SYNCO_SEL_DIS | ECCTL2_STOP_WRAP_2,
> +	       state->regs + ECCTL2);
> +}
> +
> +static const struct of_device_id ecap_of_ids[] = {
> +	{ .compatible	= "ti,am33xx-ecap" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, ecap_of_ids);
> +
> +static int ecap_probe(struct platform_device *pdev)
> +{
> +	int irq, ret;
> +	struct iio_dev *idev;
> +	struct ecap_state *state;
> +	struct resource *r;
> +	struct clk *clk;
> +	struct iio_trigger *trig;
> +	u16 status;
> +
> +	idev = devm_iio_device_alloc(&pdev->dev, sizeof(struct ecap_state));
> +	if (!idev)
> +		return -ENOMEM;
> +
> +	state = iio_priv(idev);
> +
> +	clk = devm_clk_get(&pdev->dev, "fck");
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "failed to get clock\n");
> +		return PTR_ERR(clk);
> +	}
> +
> +	state->clk_rate = clk_get_rate(clk);
> +	if (!state->clk_rate) {
> +		dev_err(&pdev->dev, "failed to get clock rate\n");
> +		return -EINVAL;
> +	}
> +
> +	platform_set_drvdata(pdev, idev);
> +
> +	idev->dev.parent = &pdev->dev;
> +	idev->name = dev_name(&pdev->dev);
> +	idev->modes = INDIO_DIRECT_MODE;
> +	idev->info = &ecap_info;
> +	idev->channels = ecap_channels;
> +	/* One h/w capture and one s/w timestamp channel per instance */
> +	idev->num_channels = ARRAY_SIZE(ecap_channels);
> +
> +	trig = devm_iio_trigger_alloc(&pdev->dev, "%s-dev%d",
> +				      idev->name, idev->id);
> +	if (!trig)
> +		return -ENOMEM;
> +	trig->dev.parent = idev->dev.parent;
> +	iio_trigger_set_drvdata(trig, idev);
> +	trig->ops = &iio_interrupt_trigger_ops;
> +
> +	ret = iio_trigger_register(trig);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to register trigger\n");
> +		return ret;
> +	}
> +
> +	ret = iio_triggered_buffer_setup(idev, NULL,
> +					 &ecap_trigger_handler,
> +					 &ecap_buffer_setup_ops);
> +	if (ret)
> +		return ret;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "no irq is specified\n");
> +		return irq;
> +	}
> +	ret = devm_request_irq(&pdev->dev, irq,
> +				&ecap_interrupt_handler,
> +				0, dev_name(&pdev->dev), idev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to request irq\n");
> +		goto uninit_buffer;
> +	}
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	state->regs = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(state->regs)) {
> +		dev_err(&pdev->dev, "unable to remap registers\n");
> +		ret = PTR_ERR(state->regs);
> +		goto uninit_buffer;
> +	};
> +
> +	ret = iio_device_register(idev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "unable to register device\n");
> +		goto uninit_buffer;
> +	}
> +
> +	state->buf = devm_kzalloc(&idev->dev, idev->scan_bytes, GFP_KERNEL);
> +	if (!state->buf) {
> +		ret = -ENOMEM;
> +		goto uninit_buffer;
> +	}
> +
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_get_sync(&pdev->dev);
> +
> +	status = pwmss_submodule_state_change(pdev->dev.parent,
> +			PWMSS_ECAPCLK_EN);
> +	if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
> +		dev_err(&pdev->dev, "failed to enable PWMSS config space clock\n");
> +		ret = -EINVAL;
> +		goto pwmss_clk_failure;
> +	}
> +
> +	ecap_init_hw(idev);
> +
> +	pm_runtime_put_sync(&pdev->dev);
> +
> +	return 0;
> +
> +pwmss_clk_failure:
> +	pm_runtime_put_sync(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
> +	iio_device_unregister(idev);
> +
> +uninit_buffer:
> +	iio_triggered_buffer_cleanup(idev);
> +
> +	return ret;
> +}
> +
> +static int ecap_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *idev = platform_get_drvdata(pdev);
> +
> +	pm_runtime_get_sync(&pdev->dev);
> +
> +	pwmss_submodule_state_change(pdev->dev.parent, PWMSS_ECAPCLK_STOP_REQ);
> +
> +	pm_runtime_put_sync(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
> +
> +	iio_device_unregister(idev);
> +	iio_triggered_buffer_cleanup(idev);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int ecap_suspend(struct device *dev)
> +{
> +	struct ecap_state *state = dev_to_ecap_state(dev);
> +
> +	pm_runtime_get_sync(dev);
> +	state->ctx.cap1 = readl(state->regs + CAP1);
> +	state->ctx.cap2 = readl(state->regs + CAP2);
> +	state->ctx.eceint = readw(state->regs + ECEINT);
> +	state->ctx.ecctl1 = readw(state->regs + ECCTL1);
> +	state->ctx.ecctl2 = readw(state->regs + ECCTL2);
> +	pm_runtime_put_sync(dev);
> +
> +	/* If capture was active, disable ECAP */
> +	if (test_bit(ECAP_ENABLED, &state->flags))
> +		pm_runtime_put_sync(dev);
> +
> +	return 0;
> +}
> +
> +static int ecap_resume(struct device *dev)
> +{
> +	struct ecap_state *state = dev_to_ecap_state(dev);
> +
> +	/* If capture was active, enable ECAP */
> +	if (test_bit(ECAP_ENABLED, &state->flags))
> +		pm_runtime_get_sync(dev);
> +
> +	pm_runtime_get_sync(dev);
> +	writel(state->ctx.cap1, state->regs + CAP1);
> +	writel(state->ctx.cap2, state->regs + CAP2);
> +	writew(state->ctx.eceint, state->regs + ECEINT);
> +	writew(state->ctx.ecctl1, state->regs + ECCTL1);
> +	writew(state->ctx.ecctl2, state->regs + ECCTL2);
> +	pm_runtime_put_sync(dev);
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(ecap_pm_ops, ecap_suspend, ecap_resume);
> +
> +static struct platform_driver ecap_iio_driver = {
> +	.driver = {
> +		.name		= "ecap",
> +		.owner		= THIS_MODULE,
> +		.of_match_table = of_match_ptr(ecap_of_ids),
> +		.pm		= &ecap_pm_ops,
> +	},
> +	.probe = ecap_probe,
> +	.remove = ecap_remove,
> +};
> +
> +module_platform_driver(ecap_iio_driver);
> +
> +MODULE_DESCRIPTION("ECAP IIO pulse capture driver");
> +MODULE_AUTHOR("Matt Porter <[email-masked]>");
> +MODULE_LICENSE("GPL");
>