1 files changed, 414 insertions, 0 deletions
diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c
new file mode 100644
index 000000000..12dec68c1
--- /dev/null
+++ b/drivers/iio/dac/stm32-dac.c
@@ -0,0 +1,414 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file is part of STM32 DAC driver
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Authors: Amelie Delaunay <amelie.delaunay@st.com>
+ *	    Fabrice Gasnier <fabrice.gasnier@st.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include "stm32-dac-core.h"
+
+#define STM32_DAC_CHANNEL_1		1
+#define STM32_DAC_CHANNEL_2		2
+#define STM32_DAC_IS_CHAN_1(ch)		((ch) & STM32_DAC_CHANNEL_1)
+
+#define STM32_DAC_AUTO_SUSPEND_DELAY_MS	2000
+
+/**
+ * struct stm32_dac - private data of DAC driver
+ * @common:		reference to DAC common data
+ * @lock:		lock to protect against potential races when reading
+ *			and update CR, to keep it in sync with pm_runtime
+ */
+struct stm32_dac {
+	struct stm32_dac_common *common;
+	struct mutex		lock;
+};
+
+static int stm32_dac_is_enabled(struct iio_dev *indio_dev, int channel)
+{
+	struct stm32_dac *dac = iio_priv(indio_dev);
+	u32 en, val;
+	int ret;
+
+	ret = regmap_read(dac->common->regmap, STM32_DAC_CR, &val);
+	if (ret < 0)
+		return ret;
+	if (STM32_DAC_IS_CHAN_1(channel))
+		en = FIELD_GET(STM32_DAC_CR_EN1, val);
+	else
+		en = FIELD_GET(STM32_DAC_CR_EN2, val);
+
+	return !!en;
+}
+
+static int stm32_dac_set_enable_state(struct iio_dev *indio_dev, int ch,
+				      bool enable)
+{
+	struct stm32_dac *dac = iio_priv(indio_dev);
+	struct device *dev = indio_dev->dev.parent;
+	u32 msk = STM32_DAC_IS_CHAN_1(ch) ? STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2;
+	u32 en = enable ? msk : 0;
+	int ret;
+
+	/* already enabled / disabled ? */
+	mutex_lock(&dac->lock);
+	ret = stm32_dac_is_enabled(indio_dev, ch);
+	if (ret < 0 || enable == !!ret) {
+		mutex_unlock(&dac->lock);
+		return ret < 0 ? ret : 0;
+	}
+
+	if (enable) {
+		ret = pm_runtime_get_sync(dev);
+		if (ret < 0) {
+			pm_runtime_put_noidle(dev);
+			mutex_unlock(&dac->lock);
+			return ret;
+		}
+	}
+
+	ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, msk, en);
+	mutex_unlock(&dac->lock);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "%s failed\n", en ?
+			"Enable" : "Disable");
+		goto err_put_pm;
+	}
+
+	/*
+	 * When HFSEL is set, it is not allowed to write the DHRx register
+	 * during 8 clock cycles after the ENx bit is set. It is not allowed
+	 * to make software/hardware trigger during this period either.
+	 */
+	if (en && dac->common->hfsel)
+		udelay(1);
+
+	if (!enable) {
+		pm_runtime_mark_last_busy(dev);
+		pm_runtime_put_autosuspend(dev);
+	}
+
+	return 0;
+
+err_put_pm:
+	if (enable) {
+		pm_runtime_mark_last_busy(dev);
+		pm_runtime_put_autosuspend(dev);
+	}
+
+	return ret;
+}
+
+static int stm32_dac_get_value(struct stm32_dac *dac, int channel, int *val)
+{
+	int ret;
+
+	if (STM32_DAC_IS_CHAN_1(channel))
+		ret = regmap_read(dac->common->regmap, STM32_DAC_DOR1, val);
+	else
+		ret = regmap_read(dac->common->regmap, STM32_DAC_DOR2, val);
+
+	return ret ? ret : IIO_VAL_INT;
+}
+
+static int stm32_dac_set_value(struct stm32_dac *dac, int channel, int val)
+{
+	int ret;
+
+	if (STM32_DAC_IS_CHAN_1(channel))
+		ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R1, val);
+	else
+		ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R2, val);
+
+	return ret;
+}
+
+static int stm32_dac_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int *val, int *val2, long mask)
+{
+	struct stm32_dac *dac = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return stm32_dac_get_value(dac, chan->channel, val);
+	case IIO_CHAN_INFO_SCALE:
+		*val = dac->common->vref_mv;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int stm32_dac_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int val, int val2, long mask)
+{
+	struct stm32_dac *dac = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return stm32_dac_set_value(dac, chan->channel, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int stm32_dac_debugfs_reg_access(struct iio_dev *indio_dev,
+					unsigned reg, unsigned writeval,
+					unsigned *readval)
+{
+	struct stm32_dac *dac = iio_priv(indio_dev);
+
+	if (!readval)
+		return regmap_write(dac->common->regmap, reg, writeval);
+	else
+		return regmap_read(dac->common->regmap, reg, readval);
+}
+
+static const struct iio_info stm32_dac_iio_info = {
+	.read_raw = stm32_dac_read_raw,
+	.write_raw = stm32_dac_write_raw,
+	.debugfs_reg_access = stm32_dac_debugfs_reg_access,
+};
+
+static const char * const stm32_dac_powerdown_modes[] = {
+	"three_state",
+};
+
+static int stm32_dac_get_powerdown_mode(struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan)
+{
+	return 0;
+}
+
+static int stm32_dac_set_powerdown_mode(struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan,
+					unsigned int type)
+{
+	return 0;
+}
+
+static ssize_t stm32_dac_read_powerdown(struct iio_dev *indio_dev,
+					uintptr_t private,
+					const struct iio_chan_spec *chan,
+					char *buf)
+{
+	int ret = stm32_dac_is_enabled(indio_dev, chan->channel);
+
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%d\n", ret ? 0 : 1);
+}
+
+static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
+					 uintptr_t private,
+					 const struct iio_chan_spec *chan,
+					 const char *buf, size_t len)
+{
+	bool powerdown;
+	int ret;
+
+	ret = strtobool(buf, &powerdown);
+	if (ret)
+		return ret;
+
+	ret = stm32_dac_set_enable_state(indio_dev, chan->channel, !powerdown);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static const struct iio_enum stm32_dac_powerdown_mode_en = {
+	.items = stm32_dac_powerdown_modes,
+	.num_items = ARRAY_SIZE(stm32_dac_powerdown_modes),
+	.get = stm32_dac_get_powerdown_mode,
+	.set = stm32_dac_set_powerdown_mode,
+};
+
+static const struct iio_chan_spec_ext_info stm32_dac_ext_info[] = {
+	{
+		.name = "powerdown",
+		.read = stm32_dac_read_powerdown,
+		.write = stm32_dac_write_powerdown,
+		.shared = IIO_SEPARATE,
+	},
+	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &stm32_dac_powerdown_mode_en),
+	IIO_ENUM_AVAILABLE("powerdown_mode", &stm32_dac_powerdown_mode_en),
+	{},
+};
+
+#define STM32_DAC_CHANNEL(chan, name) {			\
+	.type = IIO_VOLTAGE,				\
+	.indexed = 1,					\
+	.output = 1,					\
+	.channel = chan,				\
+	.info_mask_separate =				\
+		BIT(IIO_CHAN_INFO_RAW) |		\
+		BIT(IIO_CHAN_INFO_SCALE),		\
+	/* scan_index is always 0 as num_channels is 1 */ \
+	.scan_type = {					\
+		.sign = 'u',				\
+		.realbits = 12,				\
+		.storagebits = 16,			\
+	},						\
+	.datasheet_name = name,				\
+	.ext_info = stm32_dac_ext_info			\
+}
+
+static const struct iio_chan_spec stm32_dac_channels[] = {
+	STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_1, "out1"),
+	STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_2, "out2"),
+};
+
+static int stm32_dac_chan_of_init(struct iio_dev *indio_dev)
+{
+	struct device_node *np = indio_dev->dev.of_node;
+	unsigned int i;
+	u32 channel;
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &channel);
+	if (ret) {
+		dev_err(&indio_dev->dev, "Failed to read reg property\n");
+		return ret;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(stm32_dac_channels); i++) {
+		if (stm32_dac_channels[i].channel == channel)
+			break;
+	}
+	if (i >= ARRAY_SIZE(stm32_dac_channels)) {
+		dev_err(&indio_dev->dev, "Invalid reg property\n");
+		return -EINVAL;
+	}
+
+	indio_dev->channels = &stm32_dac_channels[i];
+	/*
+	 * Expose only one channel here, as they can be used independently,
+	 * with separate trigger. Then separate IIO devices are instantiated
+	 * to manage this.
+	 */
+	indio_dev->num_channels = 1;
+
+	return 0;
+};
+
+static int stm32_dac_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct stm32_dac *dac;
+	int ret;
+
+	if (!np)
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
+	if (!indio_dev)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, indio_dev);
+
+	dac = iio_priv(indio_dev);
+	dac->common = dev_get_drvdata(pdev->dev.parent);
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->dev.of_node = pdev->dev.of_node;
+	indio_dev->info = &stm32_dac_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	mutex_init(&dac->lock);
+
+	ret = stm32_dac_chan_of_init(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	/* Get stm32-dac-core PM online */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_set_autosuspend_delay(dev, STM32_DAC_AUTO_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_enable(dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto err_pm_put;
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return 0;
+
+err_pm_put:
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+	pm_runtime_put_noidle(dev);
+
+	return ret;
+}
+
+static int stm32_dac_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+	iio_device_unregister(indio_dev);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_dac_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	int channel = indio_dev->channels[0].channel;
+	int ret;
+
+	/* Ensure DAC is disabled before suspend */
+	ret = stm32_dac_is_enabled(indio_dev, channel);
+	if (ret)
+		return ret < 0 ? ret : -EBUSY;
+
+	return pm_runtime_force_suspend(dev);
+}
+
+static const struct dev_pm_ops stm32_dac_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_dac_suspend, pm_runtime_force_resume)
+};
+
+static const struct of_device_id stm32_dac_of_match[] = {
+	{ .compatible = "st,stm32-dac", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stm32_dac_of_match);
+
+static struct platform_driver stm32_dac_driver = {
+	.probe = stm32_dac_probe,
+	.remove = stm32_dac_remove,
+	.driver = {
+		.name = "stm32-dac",
+		.of_match_table = stm32_dac_of_match,
+		.pm = &stm32_dac_pm_ops,
+	},
+};
+module_platform_driver(stm32_dac_driver);
+
+MODULE_ALIAS("platform:stm32-dac");
+MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 DAC driver");
+MODULE_LICENSE("GPL v2");