iio: adc: npcm: add NPCM ADC driver

Added device tree binding documentation for Nuvoton BMC NPCM Analog-to-Digital Converter(ADC).

Signed-off-by Tomer Maimon <[email protected]>

---
 .../bindings/iio/adc/nuvoton,npcm-adc.txt          | 35 ++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt

Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt new file +35 -0

new file mode 100644
index 000000000000..1b8132cd9060
@@ -0,0 +1,35 @@
+Nuvoton NPCM Analog to Digital Converter (ADC)
+
+The NPCM ADC is a 10-bit converter for eight channel inputs.
+
+Required properties:
+- compatible: "nuvoton,npcm750-adc" for the NPCM7XX BMC.
+- reg: specifies physical base address and size of the registers.
+- interrupts: Contain the ADC interrupt with flags for falling edge.
+
+Optional properties:
+- clocks: phandle of ADC reference clock, in case the clock is not
+		  added the ADC will use the default ADC sample rate.
+- vref-supply: The regulator supply ADC reference voltage, in case the
+			   vref-supply is not added the ADC will use internal voltage
+			   reference.
+
+Required Node in the NPCM7xx BMC:
+An additional register is present in the NPCM7xx SOC which is
+assumed to be in the same device tree, with and marked as
+compatible with "nuvoton,npcm750-rst".
+
+Example:
+
+adc: adc@f000c000 {
+	compatible = "nuvoton,npcm750-adc";
+	reg = <0xf000c000 0x8>;
+	interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&clk NPCM7XX_CLK_ADC>;
+};
+
+rst: rst@f0801000 {
+	compatible = "nuvoton,npcm750-rst", "syscon",
+	"simple-mfd";
+	reg = <0xf0801000 0x6C>;
+};

Added device tree binding documentation for Nuvoton BMC NPCM Analog-to-Digital Converter(ADC).

Signed-off-by Tomer Maimon <[email protected]>

---
 .../bindings/iio/adc/nuvoton,npcm-adc.txt          | 35 ++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt

Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt new file +12 -0

+adc: adc@f000c000 {
+       compatible = "nuvoton,npcm750-adc";
+       reg = <0xf000c000 0x8>;
+       interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>;
+       clocks = <&clk NPCM7XX_CLK_ADC>;
+};
 
+
+rst: rst@f0801000 {
+       compatible = "nuvoton,npcm750-rst", "syscon",
+       "simple-mfd";
+       reg = <0xf0801000 0x6C>;
+};

Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt line 20

Quoted 4 lines · Tomer Maimon

Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt new file +4 -0

+Required Node in the NPCM7xx BMC:
+An additional register is present in the NPCM7xx SOC which is
+assumed to be in the same device tree, with and marked as
+compatible with "nuvoton,npcm750-rst".

Is there a reason you don't include a phandle to the reset node?

I think doing that would make more sense.

Quoted 13 lines

Documentation/devicetree/bindings/iio/adc/nuvoton,npcm-adc.txt new file +12 -0

+adc: adc@f000c000 {
+       compatible = "nuvoton,npcm750-adc";
+       reg = <0xf000c000 0x8>;
+       interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>;
+       clocks = <&clk NPCM7XX_CLK_ADC>;
+};
 
+
+rst: rst@f0801000 {
+       compatible = "nuvoton,npcm750-rst", "syscon",
+       "simple-mfd";
+       reg = <0xf0801000 0x6C>;
+};

Hi Joel,

Thanks for bringing this to my attention,

I think I will leave it the same way it is now because I will like to develop the reset driver and to handle the NPCM7xx SOC resets.

Quoted 5 lines · Tomer Maimon

Hi Joel,

Thanks for bringing this to my attention,

Quoted 1 line

I think I will leave it the same way it is now because I will like to develop the reset driver and to handle the NPCM7xx SOC resets.

You could also do that.

But I was suggesting you use a phandle, so you could then find the node you want without searching the entire device tree for the node with the correct compatible.

Quoted 8 lines · Joel Stanley

Quoted 6 lines · Tomer Maimon

Hi Joel,

Thanks for bringing this to my attention,

I think I will leave it the same way it is now because I will like to

develop the reset driver and to handle the NPCM7xx SOC resets.

Quoted 6 lines

You could also do that.

But I was suggesting you use a phandle, so you could then find the node you want without searching the entire device tree for the node with the correct compatible.

That's not really any more efficient. You just search the entire tree for the matching phandle number instead. Well, that was true until we recently added the phandle cache.

In any case, it you plan to move to the reset binding (which would be good), then it's better to have nothing in the DT and add something rather than change the DT binding.

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 <[email protected]>

---
 drivers/iio/adc/Kconfig    |  10 ++
 drivers/iio/adc/Makefile   |   1 +
 drivers/iio/adc/npcm_adc.c | 338 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 349 insertions(+)
 create mode 100644 drivers/iio/adc/npcm_adc.c

drivers/iio/adc/Kconfig +10 -0

index 7a3ca4ec0cb7..2d1e70a7d5c4 100644
@@ -576,6 +576,16 @@ 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 +1 -0

index 07df37f621bd..3337eb1f4c30 100644
@@ -55,6 +55,7 @@ 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 new file +198 -0

new file mode 100644
index 000000000000..c364f2dbd702
@@ -0,0 +1,338 @@
+// 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_ADC_DEFAULT_SAMPLE_RATE	12500000
+#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;

drivers/iio/adc/npcm_adc.c new file +45 -0

+	} else {
+		/* 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;
+		}
+	}
+
+	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);
+	}
+

drivers/iio/adc/npcm_adc.c new file +47 -0

+		dev_err(dev, "failed requesting interrupt\n");
+		goto err_disable_vref_reg;
+	}
+
+	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_disable_vref_reg;
+	}
+
+	pr_info("NPCM ADC driver probed\n");
+
+	return 0;
+
+err_disable_vref_reg:
+	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;

drivers/iio/adc/npcm_adc.c new file +18 -0

+
+	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 <[email protected]>");
+MODULE_LICENSE("GPL v2");