iio: counter: Add support for STM32 LPTimer (d8958824) · Commits · e / devices / android_kernel_xiaomi_nabu

Documentation/ABI/testing/sysfs-bus-iio-lptimer-stm32

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		What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset
		KernelVersion: 4.13
		Contact: fabrice.gasnier@st.com
		Description:
		Reading returns the current preset value. Writing sets the
		preset value. Encoder counts continuously from 0 to preset
		value, depending on direction (up/down).

		What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
		KernelVersion: 4.13
		Contact: fabrice.gasnier@st.com
		Description:
		Reading returns the list possible quadrature modes.

		What: /sys/bus/iio/devices/iio:deviceX/in_count0_quadrature_mode
		KernelVersion: 4.13
		Contact: fabrice.gasnier@st.com
		Description:
		Configure the device counter quadrature modes:
		- non-quadrature:
		Encoder IN1 input servers as the count input (up
		direction).
		- quadrature:
		Encoder IN1 and IN2 inputs are mixed to get direction
		and count.

		What: /sys/bus/iio/devices/iio:deviceX/in_count_polarity_available
		KernelVersion: 4.13
		Contact: fabrice.gasnier@st.com
		Description:
		Reading returns the list possible active edges.

		What: /sys/bus/iio/devices/iio:deviceX/in_count0_polarity
		KernelVersion: 4.13
		Contact: fabrice.gasnier@st.com
		Description:
		Configure the device encoder/counter active edge:
		- rising-edge
		- falling-edge
		- both-edges

		In non-quadrature mode, device counts up on active edge.
		In quadrature mode, encoder counting scenarios are as follows:
		----------------------------------------------------------------
		\| Active \| Level on \| IN1 signal \| IN2 signal \|
		\| edge \| opposite \|------------------------------------------
		\| \| signal \| Rising \| Falling \| Rising \| Falling \|
		----------------------------------------------------------------
		\| Rising \| High -> \| Down \| - \| Up \| - \|
		\| edge \| Low -> \| Up \| - \| Down \| - \|
		----------------------------------------------------------------
		\| Falling \| High -> \| - \| Up \| - \| Down \|
		\| edge \| Low -> \| - \| Down \| - \| Up \|
		----------------------------------------------------------------
		\| Both \| High -> \| Down \| Up \| Up \| Down \|
		\| edges \| Low -> \| Up \| Down \| Down \| Up \|
		----------------------------------------------------------------

drivers/iio/counter/Kconfig

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		@@ -21,4 +21,13 @@ config 104_QUAD_8
		The base port addresses for the devices may be configured via the base
		array module parameter.

		config STM32_LPTIMER_CNT
		tristate "STM32 LP Timer encoder counter driver"
		depends on MFD_STM32_LPTIMER \|\| COMPILE_TEST
		help
		Select this option to enable STM32 Low-Power Timer quadrature encoder
		and counter driver.

		To compile this driver as a module, choose M here: the
		module will be called stm32-lptimer-cnt.
		endmenu

drivers/iio/counter/Makefile

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		@@ -5,3 +5,4 @@
		# When adding new entries keep the list in alphabetical order

		obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o
		obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o

drivers/iio/counter/stm32-lptimer-cnt.c

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		/*
		* STM32 Low-Power Timer Encoder and Counter driver
		*
		* Copyright (C) STMicroelectronics 2017
		*
		* Author: Fabrice Gasnier <fabrice.gasnier@st.com>
		*
		* Inspired by 104-quad-8 and stm32-timer-trigger drivers.
		*
		* License terms: GNU General Public License (GPL), version 2
		*/

		#include <linux/bitfield.h>
		#include <linux/iio/iio.h>
		#include <linux/mfd/stm32-lptimer.h>
		#include <linux/module.h>
		#include <linux/platform_device.h>

		struct stm32_lptim_cnt {
		struct device *dev;
		struct regmap *regmap;
		struct clk *clk;
		u32 preset;
		u32 polarity;
		u32 quadrature_mode;
		};

		static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
		{
		u32 val;
		int ret;

		ret = regmap_read(priv->regmap, STM32_LPTIM_CR, &val);
		if (ret)
		return ret;

		return FIELD_GET(STM32_LPTIM_ENABLE, val);
		}

		static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
		int enable)
		{
		int ret;
		u32 val;

		val = FIELD_PREP(STM32_LPTIM_ENABLE, enable);
		ret = regmap_write(priv->regmap, STM32_LPTIM_CR, val);
		if (ret)
		return ret;

		if (!enable) {
		clk_disable(priv->clk);
		return 0;
		}

		/* LP timer must be enabled before writing CMP & ARR */
		ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, priv->preset);
		if (ret)
		return ret;

		ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, 0);
		if (ret)
		return ret;

		/* ensure CMP & ARR registers are properly written */
		ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
		(val & STM32_LPTIM_CMPOK_ARROK),
		100, 1000);
		if (ret)
		return ret;

		ret = regmap_write(priv->regmap, STM32_LPTIM_ICR,
		STM32_LPTIM_CMPOKCF_ARROKCF);
		if (ret)
		return ret;

		ret = clk_enable(priv->clk);
		if (ret) {
		regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
		return ret;
		}

		/* Start LP timer in continuous mode */
		return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
		STM32_LPTIM_CNTSTRT, STM32_LPTIM_CNTSTRT);
		}

		static int stm32_lptim_setup(struct stm32_lptim_cnt *priv, int enable)
		{
		u32 mask = STM32_LPTIM_ENC \| STM32_LPTIM_COUNTMODE \|
		STM32_LPTIM_CKPOL \| STM32_LPTIM_PRESC;
		u32 val;

		/* Setup LP timer encoder/counter and polarity, without prescaler */
		if (priv->quadrature_mode)
		val = enable ? STM32_LPTIM_ENC : 0;
		else
		val = enable ? STM32_LPTIM_COUNTMODE : 0;
		val \|= FIELD_PREP(STM32_LPTIM_CKPOL, enable ? priv->polarity : 0);

		return regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, val);
		}

		static int stm32_lptim_write_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val, int val2, long mask)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
		int ret;

		switch (mask) {
		case IIO_CHAN_INFO_ENABLE:
		if (val < 0 \|\| val > 1)
		return -EINVAL;

		/* Check nobody uses the timer, or already disabled/enabled */
		ret = stm32_lptim_is_enabled(priv);
		if ((ret < 0) \|\| (!ret && !val))
		return ret;
		if (val && ret)
		return -EBUSY;

		ret = stm32_lptim_setup(priv, val);
		if (ret)
		return ret;
		return stm32_lptim_set_enable_state(priv, val);

		default:
		return -EINVAL;
		}
		}

		static int stm32_lptim_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val, int val2, long mask)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
		u32 dat;
		int ret;

		switch (mask) {
		case IIO_CHAN_INFO_RAW:
		ret = regmap_read(priv->regmap, STM32_LPTIM_CNT, &dat);
		if (ret)
		return ret;
		*val = dat;
		return IIO_VAL_INT;

		case IIO_CHAN_INFO_ENABLE:
		ret = stm32_lptim_is_enabled(priv);
		if (ret < 0)
		return ret;
		*val = ret;
		return IIO_VAL_INT;

		case IIO_CHAN_INFO_SCALE:
		/* Non-quadrature mode: scale = 1 */
		*val = 1;
		*val2 = 0;
		if (priv->quadrature_mode) {
		/*
		* Quadrature encoder mode:
		* - both edges, quarter cycle, scale is 0.25
		* - either rising/falling edge scale is 0.5
		*/
		if (priv->polarity > 1)
		*val2 = 2;
		else
		*val2 = 1;
		}
		return IIO_VAL_FRACTIONAL_LOG2;

		default:
		return -EINVAL;
		}
		}

		static const struct iio_info stm32_lptim_cnt_iio_info = {
		.read_raw = stm32_lptim_read_raw,
		.write_raw = stm32_lptim_write_raw,
		.driver_module = THIS_MODULE,
		};

		static const char *const stm32_lptim_quadrature_modes[] = {
		"non-quadrature",
		"quadrature",
		};

		static int stm32_lptim_get_quadrature_mode(struct iio_dev *indio_dev,
		const struct iio_chan_spec *chan)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);

		return priv->quadrature_mode;
		}

		static int stm32_lptim_set_quadrature_mode(struct iio_dev *indio_dev,
		const struct iio_chan_spec *chan,
		unsigned int type)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);

		if (stm32_lptim_is_enabled(priv))
		return -EBUSY;

		priv->quadrature_mode = type;

		return 0;
		}

		static const struct iio_enum stm32_lptim_quadrature_mode_en = {
		.items = stm32_lptim_quadrature_modes,
		.num_items = ARRAY_SIZE(stm32_lptim_quadrature_modes),
		.get = stm32_lptim_get_quadrature_mode,
		.set = stm32_lptim_set_quadrature_mode,
		};

		static const char * const stm32_lptim_cnt_polarity[] = {
		"rising-edge", "falling-edge", "both-edges",
		};

		static int stm32_lptim_cnt_get_polarity(struct iio_dev *indio_dev,
		const struct iio_chan_spec *chan)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);

		return priv->polarity;
		}

		static int stm32_lptim_cnt_set_polarity(struct iio_dev *indio_dev,
		const struct iio_chan_spec *chan,
		unsigned int type)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);

		if (stm32_lptim_is_enabled(priv))
		return -EBUSY;

		priv->polarity = type;

		return 0;
		}

		static const struct iio_enum stm32_lptim_cnt_polarity_en = {
		.items = stm32_lptim_cnt_polarity,
		.num_items = ARRAY_SIZE(stm32_lptim_cnt_polarity),
		.get = stm32_lptim_cnt_get_polarity,
		.set = stm32_lptim_cnt_set_polarity,
		};

		static ssize_t stm32_lptim_cnt_get_preset(struct iio_dev *indio_dev,
		uintptr_t private,
		const struct iio_chan_spec *chan,
		char *buf)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);

		return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset);
		}

		static ssize_t stm32_lptim_cnt_set_preset(struct iio_dev *indio_dev,
		uintptr_t private,
		const struct iio_chan_spec *chan,
		const char *buf, size_t len)
		{
		struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
		int ret;

		if (stm32_lptim_is_enabled(priv))
		return -EBUSY;

		ret = kstrtouint(buf, 0, &priv->preset);
		if (ret)
		return ret;

		if (priv->preset > STM32_LPTIM_MAX_ARR)
		return -EINVAL;

		return len;
		}

		/* LP timer with encoder */
		static const struct iio_chan_spec_ext_info stm32_lptim_enc_ext_info[] = {
		{
		.name = "preset",
		.shared = IIO_SEPARATE,
		.read = stm32_lptim_cnt_get_preset,
		.write = stm32_lptim_cnt_set_preset,
		},
		IIO_ENUM("polarity", IIO_SEPARATE, &stm32_lptim_cnt_polarity_en),
		IIO_ENUM_AVAILABLE("polarity", &stm32_lptim_cnt_polarity_en),
		IIO_ENUM("quadrature_mode", IIO_SEPARATE,
		&stm32_lptim_quadrature_mode_en),
		IIO_ENUM_AVAILABLE("quadrature_mode", &stm32_lptim_quadrature_mode_en),
		{}
		};

		static const struct iio_chan_spec stm32_lptim_enc_channels = {
		.type = IIO_COUNT,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
		BIT(IIO_CHAN_INFO_ENABLE) \|
		BIT(IIO_CHAN_INFO_SCALE),
		.ext_info = stm32_lptim_enc_ext_info,
		.indexed = 1,
		};

		/* LP timer without encoder (counter only) */
		static const struct iio_chan_spec_ext_info stm32_lptim_cnt_ext_info[] = {
		{
		.name = "preset",
		.shared = IIO_SEPARATE,
		.read = stm32_lptim_cnt_get_preset,
		.write = stm32_lptim_cnt_set_preset,
		},
		IIO_ENUM("polarity", IIO_SEPARATE, &stm32_lptim_cnt_polarity_en),
		IIO_ENUM_AVAILABLE("polarity", &stm32_lptim_cnt_polarity_en),
		{}
		};

		static const struct iio_chan_spec stm32_lptim_cnt_channels = {
		.type = IIO_COUNT,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
		BIT(IIO_CHAN_INFO_ENABLE) \|
		BIT(IIO_CHAN_INFO_SCALE),
		.ext_info = stm32_lptim_cnt_ext_info,
		.indexed = 1,
		};

		static int stm32_lptim_cnt_probe(struct platform_device *pdev)
		{
		struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
		struct stm32_lptim_cnt *priv;
		struct iio_dev *indio_dev;

		if (IS_ERR_OR_NULL(ddata))
		return -EINVAL;

		indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
		if (!indio_dev)
		return -ENOMEM;

		priv = iio_priv(indio_dev);
		priv->dev = &pdev->dev;
		priv->regmap = ddata->regmap;
		priv->clk = ddata->clk;
		priv->preset = STM32_LPTIM_MAX_ARR;

		indio_dev->name = dev_name(&pdev->dev);
		indio_dev->dev.parent = &pdev->dev;
		indio_dev->dev.of_node = pdev->dev.of_node;
		indio_dev->info = &stm32_lptim_cnt_iio_info;
		if (ddata->has_encoder)
		indio_dev->channels = &stm32_lptim_enc_channels;
		else
		indio_dev->channels = &stm32_lptim_cnt_channels;
		indio_dev->num_channels = 1;

		platform_set_drvdata(pdev, priv);

		return devm_iio_device_register(&pdev->dev, indio_dev);
		}

		static const struct of_device_id stm32_lptim_cnt_of_match[] = {
		{ .compatible = "st,stm32-lptimer-counter", },
		{},
		};
		MODULE_DEVICE_TABLE(of, stm32_lptim_cnt_of_match);

		static struct platform_driver stm32_lptim_cnt_driver = {
		.probe = stm32_lptim_cnt_probe,
		.driver = {
		.name = "stm32-lptimer-counter",
		.of_match_table = stm32_lptim_cnt_of_match,
		},
		};
		module_platform_driver(stm32_lptim_cnt_driver);

		MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
		MODULE_ALIAS("platform:stm32-lptimer-counter");
		MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM counter driver");
		MODULE_LICENSE("GPL v2");