iio: adc: add NPCM ADC driver

Add Nuvoton NPCM BMC Analog-to-Digital Converter(ADC) driver.

The NPCM ADC is a 10-bit converter for eight channel inputs.
Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -603,6 +603,16 @@ config NAU7802
 	  To compile this driver as a module, choose M here: the
 	  module will be called nau7802.
 
+config NPCM_ADC
+	tristate "Nuvoton NPCM ADC driver"
+	depends on ARCH_NPCM || COMPILE_TEST
+	depends on HAS_IOMEM
+	help
+	  Say yes here to build support for Nuvoton NPCM ADC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called npcm_adc.
+
 config PALMAS_GPADC
 	tristate "TI Palmas General Purpose ADC"
 	depends on MFD_PALMAS

drivers/iio/adc/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_MESON_SARADC) += meson_saradc.o
 obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
+obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_ADC5) += qcom-spmi-adc5.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o

drivers/iio/adc/npcm_adc.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Nuvoton Technology corporation.
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/io.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+
+struct npcm_adc {
+	bool int_status;
+	u32 adc_sample_hz;
+	struct device *dev;
+	void __iomem *regs;
+	struct clk *adc_clk;
+	wait_queue_head_t wq;
+	struct regulator *vref;
+	struct regmap *rst_regmap;
+};
+
+/* NPCM7xx reset module */
+#define NPCM7XX_IPSRST1_OFFSET		0x020
+#define NPCM7XX_IPSRST1_ADC_RST		BIT(27)
+
+/* ADC registers */
+#define NPCM_ADCCON	 0x00
+#define NPCM_ADCDATA	 0x04
+
+/* ADCCON Register Bits */
+#define NPCM_ADCCON_ADC_INT_EN		BIT(21)
+#define NPCM_ADCCON_REFSEL		BIT(19)
+#define NPCM_ADCCON_ADC_INT_ST		BIT(18)
+#define NPCM_ADCCON_ADC_EN		BIT(17)
+#define NPCM_ADCCON_ADC_RST		BIT(16)
+#define NPCM_ADCCON_ADC_CONV		BIT(13)
+
+#define NPCM_ADCCON_CH_MASK		GENMASK(27, 24)
+#define NPCM_ADCCON_CH(x)		((x) << 24)
+#define NPCM_ADCCON_DIV_SHIFT		1
+#define NPCM_ADCCON_DIV_MASK		GENMASK(8, 1)
+#define NPCM_ADC_DATA_MASK(x)		((x) & GENMASK(9, 0))
+
+#define NPCM_ADC_ENABLE		(NPCM_ADCCON_ADC_EN | NPCM_ADCCON_ADC_INT_EN)
+
+/* ADC General Definition */
+#define NPCM_RESOLUTION_BITS		10
+#define NPCM_INT_VREF_MV		2000
+
+#define NPCM_ADC_CHAN(ch) {					\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = ch,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+}
+
+static const struct iio_chan_spec npcm_adc_iio_channels[] = {
+	NPCM_ADC_CHAN(0),
+	NPCM_ADC_CHAN(1),
+	NPCM_ADC_CHAN(2),
+	NPCM_ADC_CHAN(3),
+	NPCM_ADC_CHAN(4),
+	NPCM_ADC_CHAN(5),
+	NPCM_ADC_CHAN(6),
+	NPCM_ADC_CHAN(7),
+};
+
+static irqreturn_t npcm_adc_isr(int irq, void *data)
+{
+	u32 regtemp;
+	struct iio_dev *indio_dev = data;
+	struct npcm_adc *info = iio_priv(indio_dev);
+
+	regtemp = ioread32(info->regs + NPCM_ADCCON);
+	if (regtemp & NPCM_ADCCON_ADC_INT_ST) {
+		iowrite32(regtemp, info->regs + NPCM_ADCCON);
+		wake_up_interruptible(&info->wq);
+		info->int_status = true;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int npcm_adc_read(struct npcm_adc *info, int *val, u8 channel)
+{
+	int ret;
+	u32 regtemp;
+
+	/* Select ADC channel */
+	regtemp = ioread32(info->regs + NPCM_ADCCON);
+	regtemp &= ~NPCM_ADCCON_CH_MASK;
+	info->int_status = false;
+	iowrite32(regtemp | NPCM_ADCCON_CH(channel) |
+		  NPCM_ADCCON_ADC_CONV, info->regs + NPCM_ADCCON);
+
+	ret = wait_event_interruptible_timeout(info->wq, info->int_status,
+					       msecs_to_jiffies(10));
+	if (ret == 0) {
+		regtemp = ioread32(info->regs + NPCM_ADCCON);
+		if ((regtemp & NPCM_ADCCON_ADC_CONV) && info->rst_regmap) {
+			/* if conversion failed - reset ADC module */
+			regmap_write(info->rst_regmap, NPCM7XX_IPSRST1_OFFSET,
+				     NPCM7XX_IPSRST1_ADC_RST);
+			msleep(100);
+			regmap_write(info->rst_regmap, NPCM7XX_IPSRST1_OFFSET,
+				     0x0);
+			msleep(100);
+
+			/* Enable ADC and start conversion module */
+			iowrite32(NPCM_ADC_ENABLE | NPCM_ADCCON_ADC_CONV,
+				  info->regs + NPCM_ADCCON);
+			dev_err(info->dev, "RESET ADC Complete\n");
+		}
+		return -ETIMEDOUT;
+	}
+	if (ret < 0)
+		return ret;
+
+	*val = NPCM_ADC_DATA_MASK(ioread32(info->regs + NPCM_ADCDATA));
+
+	return 0;
+}
+
+static int npcm_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int *val,
+			     int *val2, long mask)
+{
+	int ret;
+	int vref_uv;
+	struct npcm_adc *info = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+		ret = npcm_adc_read(info, val, chan->channel);
+		mutex_unlock(&indio_dev->mlock);
+		if (ret) {
+			dev_err(info->dev, "NPCM ADC read failed\n");
+			return ret;
+		}
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (info->vref) {
+			vref_uv = regulator_get_voltage(info->vref);
+			*val = vref_uv / 1000;
+		} else {
+			*val = NPCM_INT_VREF_MV;
+		}
+		*val2 = NPCM_RESOLUTION_BITS;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = info->adc_sample_hz;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct iio_info npcm_adc_iio_info = {
+	.read_raw = &npcm_adc_read_raw,
+};
+
+static const struct of_device_id npcm_adc_match[] = {
+	{ .compatible = "nuvoton,npcm750-adc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, npcm_adc_match);
+
+static int npcm_adc_probe(struct platform_device *pdev)
+{
+	int ret;
+	int irq;
+	u32 div;
+	u32 reg_con;
+	struct resource *res;
+	struct npcm_adc *info;
+	struct iio_dev *indio_dev;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
+	if (!indio_dev)
+		return -ENOMEM;
+	info = iio_priv(indio_dev);
+
+	info->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	info->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(info->regs))
+		return PTR_ERR(info->regs);
+
+	info->adc_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(info->adc_clk)) {
+		dev_warn(&pdev->dev, "ADC clock failed: can't read clk\n");
+		return PTR_ERR(info->adc_clk);
+	}
+
+	/* calculate ADC clock sample rate */
+	reg_con = ioread32(info->regs + NPCM_ADCCON);
+	div = reg_con & NPCM_ADCCON_DIV_MASK;
+	div = div >> NPCM_ADCCON_DIV_SHIFT;
+	info->adc_sample_hz = clk_get_rate(info->adc_clk) / ((div + 1) * 2);
+
+	if (of_device_is_compatible(np, "nuvoton,npcm750-adc")) {
+		info->rst_regmap = syscon_regmap_lookup_by_compatible
+			("nuvoton,npcm750-rst");
+		if (IS_ERR(info->rst_regmap)) {
+			dev_err(&pdev->dev, "Failed to find nuvoton,npcm750-rst\n");
+			ret = PTR_ERR(info->rst_regmap);
+			goto err_disable_clk;
+		}
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0) {
+		dev_err(dev, "failed getting interrupt resource\n");
+		ret = -EINVAL;
+		goto err_disable_clk;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, npcm_adc_isr, 0,
+			       "NPCM_ADC", indio_dev);
+	if (ret < 0) {
+		dev_err(dev, "failed requesting interrupt\n");
+		goto err_disable_clk;
+	}
+
+	reg_con = ioread32(info->regs + NPCM_ADCCON);
+	info->vref = devm_regulator_get_optional(&pdev->dev, "vref");
+	if (!IS_ERR(info->vref)) {
+		ret = regulator_enable(info->vref);
+		if (ret) {
+			dev_err(&pdev->dev, "Can't enable ADC reference voltage\n");
+			goto err_disable_clk;
+		}
+
+		iowrite32(reg_con & ~NPCM_ADCCON_REFSEL,
+			  info->regs + NPCM_ADCCON);
+	} else {
+		/*
+		 * Any error which is not ENODEV indicates the regulator
+		 * has been specified and so is a failure case.
+		 */
+		if (PTR_ERR(info->vref) != -ENODEV) {
+			ret = PTR_ERR(info->vref);
+			goto err_disable_clk;
+		}
+
+		/* Use internal reference */
+		iowrite32(reg_con | NPCM_ADCCON_REFSEL,
+			  info->regs + NPCM_ADCCON);
+	}
+
+	init_waitqueue_head(&info->wq);
+
+	reg_con = ioread32(info->regs + NPCM_ADCCON);
+	reg_con |= NPCM_ADC_ENABLE;
+
+	/* Enable the ADC Module */
+	iowrite32(reg_con, info->regs + NPCM_ADCCON);
+
+	/* Start ADC conversion */
+	iowrite32(reg_con | NPCM_ADCCON_ADC_CONV, info->regs + NPCM_ADCCON);
+
+	platform_set_drvdata(pdev, indio_dev);
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &npcm_adc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = npcm_adc_iio_channels;
+	indio_dev->num_channels = ARRAY_SIZE(npcm_adc_iio_channels);
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't register the device.\n");
+		goto err_iio_register;
+	}
+
+	pr_info("NPCM ADC driver probed\n");
+
+	return 0;
+
+err_iio_register:
+	iowrite32(reg_con & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
+	if (!IS_ERR(info->vref))
+		regulator_disable(info->vref);
+err_disable_clk:
+	clk_disable_unprepare(info->adc_clk);
+
+	return ret;
+}
+
+static int npcm_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct npcm_adc *info = iio_priv(indio_dev);
+	u32 regtemp;
+
+	iio_device_unregister(indio_dev);
+
+	regtemp = ioread32(info->regs + NPCM_ADCCON);
+	iowrite32(regtemp & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
+	if (!IS_ERR(info->vref))
+		regulator_disable(info->vref);
+	clk_disable_unprepare(info->adc_clk);
+
+	return 0;
+}
+
+static struct platform_driver npcm_adc_driver = {
+	.probe		= npcm_adc_probe,
+	.remove		= npcm_adc_remove,
+	.driver		= {
+		.name	= "npcm_adc",
+		.of_match_table = npcm_adc_match,
+	},
+};
+
+module_platform_driver(npcm_adc_driver);
+
+MODULE_DESCRIPTION("Nuvoton NPCM ADC Driver");
+MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
+MODULE_LICENSE("GPL v2");