iio: dac: vf610_dac: Add IIO DAC driver for Vybrid SoC

Add driver support for DAC peripheral on Vybrid SoC.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/ABI/testing/sysfs-bus-iio-vf610

@@ -5,3 +5,12 @@ Description:
 		Specifies the hardware conversion mode used. The three
 		available modes are "normal", "high-speed" and "low-power",
 		where the last is the default mode.
+
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_conversion_mode
+KernelVersion:	4.6
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Specifies the hardware conversion mode used within DAC.
+		The two available modes are "high-power" and "low-power",
+		where "low-power" mode is the default mode.

Documentation/devicetree/bindings/iio/dac/vf610-dac.txt

+Freescale vf610 Digital to Analog Converter bindings
+
+The devicetree bindings are for the new DAC driver written for
+vf610 SoCs from Freescale.
+
+Required properties:
+- compatible: Should contain "fsl,vf610-dac"
+- reg: Offset and length of the register set for the device
+- interrupts: Should contain the interrupt for the device
+- clocks: The clock is needed by the DAC controller
+- clock-names: Must contain "dac" matching entry in the clocks property.
+
+Example:
+dac0: dac@400cc000 {
+	compatible = "fsl,vf610-dac";
+	reg = <0x400cc000 0x1000>;
+	interrupts = <55 IRQ_TYPE_LEVEL_HIGH>;
+	clock-names = "dac";
+	clocks = <&clks VF610_CLK_DAC0>;
+};

drivers/iio/dac/Kconfig

@@ -217,4 +217,14 @@ config STX104
 	  addresses for the devices may be configured via the "base" module
 	  parameter array.
 
+config VF610_DAC
+	tristate "Vybrid vf610 DAC driver"
+	depends on OF
+	depends on HAS_IOMEM
+	help
+	  Say yes here to support Vybrid board digital-to-analog converter.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called vf610_dac.
+
 endmenu

drivers/iio/dac/Makefile

@@ -23,3 +23,4 @@ obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4922) += mcp4922.o
 obj-$(CONFIG_STX104) += stx104.o
+obj-$(CONFIG_VF610_DAC) += vf610_dac.o

drivers/iio/dac/vf610_dac.c

+/*
+ * Freescale Vybrid vf610 DAC driver
+ *
+ * Copyright 2016 Toradex AG
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define VF610_DACx_STATCTRL		0x20
+
+#define VF610_DAC_DACEN			BIT(15)
+#define VF610_DAC_DACRFS		BIT(14)
+#define VF610_DAC_LPEN			BIT(11)
+
+#define VF610_DAC_DAT0(x)		((x) & 0xFFF)
+
+enum vf610_conversion_mode_sel {
+	VF610_DAC_CONV_HIGH_POWER,
+	VF610_DAC_CONV_LOW_POWER,
+};
+
+struct vf610_dac {
+	struct clk *clk;
+	struct device *dev;
+	enum vf610_conversion_mode_sel conv_mode;
+	void __iomem *regs;
+};
+
+static void vf610_dac_init(struct vf610_dac *info)
+{
+	int val;
+
+	info->conv_mode = VF610_DAC_CONV_LOW_POWER;
+	val = VF610_DAC_DACEN | VF610_DAC_DACRFS |
+		VF610_DAC_LPEN;
+	writel(val, info->regs + VF610_DACx_STATCTRL);
+}
+
+static void vf610_dac_exit(struct vf610_dac *info)
+{
+	int val;
+
+	val = readl(info->regs + VF610_DACx_STATCTRL);
+	val &= ~VF610_DAC_DACEN;
+	writel(val, info->regs + VF610_DACx_STATCTRL);
+}
+
+static int vf610_set_conversion_mode(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan,
+				unsigned int mode)
+{
+	struct vf610_dac *info = iio_priv(indio_dev);
+	int val;
+
+	mutex_lock(&indio_dev->mlock);
+	info->conv_mode = mode;
+	val = readl(info->regs + VF610_DACx_STATCTRL);
+	if (mode)
+		val |= VF610_DAC_LPEN;
+	else
+		val &= ~VF610_DAC_LPEN;
+	writel(val, info->regs + VF610_DACx_STATCTRL);
+	mutex_unlock(&indio_dev->mlock);
+
+	return 0;
+}
+
+static int vf610_get_conversion_mode(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan)
+{
+	struct vf610_dac *info = iio_priv(indio_dev);
+
+	return info->conv_mode;
+}
+
+static const char * const vf610_conv_modes[] = { "high-power", "low-power" };
+
+static const struct iio_enum vf610_conversion_mode = {
+	.items = vf610_conv_modes,
+	.num_items = ARRAY_SIZE(vf610_conv_modes),
+	.get = vf610_get_conversion_mode,
+	.set = vf610_set_conversion_mode,
+};
+
+static const struct iio_chan_spec_ext_info vf610_ext_info[] = {
+	IIO_ENUM("conversion_mode", IIO_SHARED_BY_DIR,
+		&vf610_conversion_mode),
+	{},
+};
+
+#define VF610_DAC_CHAN(_chan_type) { \
+	.type = (_chan_type), \
+	.output = 1, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+	.ext_info = vf610_ext_info, \
+}
+
+static const struct iio_chan_spec vf610_dac_iio_channels[] = {
+	VF610_DAC_CHAN(IIO_VOLTAGE),
+};
+
+static int vf610_read_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int *val, int *val2,
+			long mask)
+{
+	struct vf610_dac *info = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		*val = VF610_DAC_DAT0(readl(info->regs));
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * DACRFS is always 1 for valid reference and typical
+		 * reference voltage as per Vybrid datasheet is 3.3V
+		 * from section 9.1.2.1 of Vybrid datasheet
+		 */
+		*val = 3300 /* mV */;
+		*val2 = 12;
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int vf610_write_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int val, int val2,
+			long mask)
+{
+	struct vf610_dac *info = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+		writel(VF610_DAC_DAT0(val), info->regs);
+		mutex_unlock(&indio_dev->mlock);
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info vf610_dac_iio_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = &vf610_read_raw,
+	.write_raw = &vf610_write_raw,
+};
+
+static const struct of_device_id vf610_dac_match[] = {
+	{ .compatible = "fsl,vf610-dac", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, vf610_dac_match);
+
+static int vf610_dac_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct vf610_dac *info;
+	struct resource *mem;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev,
+					sizeof(struct vf610_dac));
+	if (!indio_dev) {
+		dev_err(&pdev->dev, "Failed allocating iio device\n");
+		return -ENOMEM;
+	}
+
+	info = iio_priv(indio_dev);
+	info->dev = &pdev->dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	info->regs = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(info->regs))
+		return PTR_ERR(info->regs);
+
+	info->clk = devm_clk_get(&pdev->dev, "dac");
+	if (IS_ERR(info->clk)) {
+		dev_err(&pdev->dev, "Failed getting clock, err = %ld\n",
+			PTR_ERR(info->clk));
+		return PTR_ERR(info->clk);
+	}
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	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 = &vf610_dac_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = vf610_dac_iio_channels;
+	indio_dev->num_channels = ARRAY_SIZE(vf610_dac_iio_channels);
+
+	ret = clk_prepare_enable(info->clk);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Could not prepare or enable the clock\n");
+		return ret;
+	}
+
+	vf610_dac_init(info);
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't register the device\n");
+		goto error_iio_device_register;
+	}
+
+	return 0;
+
+error_iio_device_register:
+	clk_disable_unprepare(info->clk);
+
+	return ret;
+}
+
+static int vf610_dac_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct vf610_dac *info = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	vf610_dac_exit(info);
+	clk_disable_unprepare(info->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int vf610_dac_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct vf610_dac *info = iio_priv(indio_dev);
+
+	vf610_dac_exit(info);
+	clk_disable_unprepare(info->clk);
+
+	return 0;
+}
+
+static int vf610_dac_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct vf610_dac *info = iio_priv(indio_dev);
+	int ret;
+
+	ret = clk_prepare_enable(info->clk);
+	if (ret)
+		return ret;
+
+	vf610_dac_init(info);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(vf610_dac_pm_ops, vf610_dac_suspend, vf610_dac_resume);
+
+static struct platform_driver vf610_dac_driver = {
+	.probe          = vf610_dac_probe,
+	.remove         = vf610_dac_remove,
+	.driver         = {
+		.name   = "vf610-dac",
+		.of_match_table = vf610_dac_match,
+		.pm     = &vf610_dac_pm_ops,
+	},
+};
+module_platform_driver(vf610_dac_driver);
+
+MODULE_AUTHOR("Sanchayan Maity <sanchayan.maity@toradex.com>");
+MODULE_DESCRIPTION("Freescale VF610 DAC driver");
+MODULE_LICENSE("GPL v2");