[PATCH v2 2/4] iio: adc: Add driver for Renesas RZ/G2L A/D converter

[Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>]

Add ADC driver support for Renesas RZ/G2L A/D converter in SW
trigger mode.

A/D Converter block is a successive approximation analog-to-digital
converter with a 12-bit accuracy and supports a maximum of 8 input
channels.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 MAINTAINERS                 |   8 +
 drivers/iio/adc/Kconfig     |  10 +
 drivers/iio/adc/Makefile    |   1 +
 drivers/iio/adc/rzg2l_adc.c | 545 ++++++++++++++++++++++++++++++++++++
 4 files changed, 564 insertions(+)
 create mode 100644 drivers/iio/adc/rzg2l_adc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c8be735cc91..6a52f9f4604c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15839,6 +15839,14 @@ L:	linux-renesas-soc@vger.kernel.org
 S:	Maintained
 F:	drivers/phy/renesas/phy-rcar-gen3-usb*.c
 
+RENESAS RZ/G2L A/D DRIVER
+M:	Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
+L:	linux-iio@vger.kernel.org
+L:	linux-renesas-soc@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/iio/adc/renesas,rzg2l-adc.yaml
+F:	drivers/iio/adc/rzg2l_adc.c
+
 RESET CONTROLLER FRAMEWORK
 M:	Philipp Zabel <p.zabel@pengutronix.de>
 S:	Maintained
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index db0c8fb60515..af168e1c9fdb 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -887,6 +887,16 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config RZG2L_ADC
+	tristate "Renesas RZ/G2L ADC driver"
+	depends on ARCH_R9A07G044 || COMPILE_TEST
+	help
+	  Say yes here to build support for the ADC found in Renesas
+	  RZ/G2L family.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rzg2l_adc.
+
 config SC27XX_ADC
 	tristate "Spreadtrum SC27xx series PMICs ADC"
 	depends on MFD_SC27XX_PMIC || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index f70d877c555a..d68550f493e3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_QCOM_PM8XXX_XOADC) += qcom-pm8xxx-xoadc.o
 obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_RN5T618_ADC) += rn5t618-adc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
+obj-$(CONFIG_RZG2L_ADC) += rzg2l_adc.o
 obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
 obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
 obj-$(CONFIG_STX104) += stx104.o
diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
new file mode 100644
index 000000000000..033cdec9e976
--- /dev/null
+++ b/drivers/iio/adc/rzg2l_adc.c
@@ -0,0 +1,545 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RZ/G2L A/D Converter driver
+ *
+ *  Copyright (c) 2021 Renesas Electronics Europe GmbH
+ *
+ * Author: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+
+#define DRIVER_NAME		"rzg2l-adc"
+
+#define RZG2L_ADM(n)			((n) * 0x4)
+#define RZG2L_ADM0_ADCE			BIT(0)
+#define RZG2L_ADM0_ADBSY		BIT(1)
+#define RZG2L_ADM0_PWDWNB		BIT(2)
+#define RZG2L_ADM0_SRESB		BIT(15)
+#define RZG2L_ADM1_TRG			BIT(0)
+#define RZG2L_ADM1_MS			BIT(2)
+#define RZG2L_ADM1_BS			BIT(4)
+#define RZG2L_ADM1_EGA_CLEAR		~GENMASK(13, 12)
+#define RZG2L_ADM2_CHSEL_CLEAR		~GENMASK(7, 0)
+#define RZG2L_ADM3_ADSMP		0x578
+#define RZG2L_ADM3_ADCMP		(0xe << 16)
+#define RZG2L_ADM3_ADIL_CLEAR		~GENMASK(31, 24)
+
+#define RZG2L_ADINT			0x20
+#define RZG2L_ADINT_CH_CLEAR		~GENMASK(7, 0)
+#define RZG2L_ADINT_CSEEN		BIT(16)
+#define RZG2L_ADINT_INTS		BIT(31)
+#define RZG2L_ADSTS			0x24
+#define RZG2L_ADINT_INTST_MASK		GENMASK(7, 0)
+#define RZG2L_ADSTS_CSEST		BIT(16)
+#define RZG2L_ADIVC			0x28
+#define RZG2L_ADIVC_DIVADC_CLEAR	~GENMASK(8, 0)
+#define RZG2L_ADIVC_DIVADC_4		0x4
+#define RZG2L_ADFIL			0x2c
+#define RZG2L_ADCR(n)			(0x30 + ((n) * 0x4))
+#define RZG2L_ADCR_AD_MASK		GENMASK(11, 0)
+
+#define RZG2L_ADC_MAX_CHANNELS		8
+#define RZG2L_ADC_CHN_MASK		0x7
+#define RZG2L_ADC_TIMEOUT		usecs_to_jiffies(1 * 4)
+
+struct rzg2l_adc_data {
+	const struct iio_chan_spec *channels;
+	u8 num_channels;
+};
+
+struct rzg2l_adc {
+	void __iomem *base;
+	struct clk *pclk;
+	struct clk *adclk;
+	struct reset_control *presetn;
+	struct reset_control *adrstn;
+	struct completion completion;
+	const struct rzg2l_adc_data *data;
+	u16 last_val[RZG2L_ADC_MAX_CHANNELS];
+};
+
+static const char * const rzg2l_adc_channel_name[] = {
+	"adc0",
+	"adc1",
+	"adc2",
+	"adc3",
+	"adc4",
+	"adc5",
+	"adc6",
+	"adc7",
+};
+
+static unsigned int rzg2l_adc_readl(struct rzg2l_adc *adc, u32 reg)
+{
+	return readl(adc->base + reg);
+}
+
+static void rzg2l_adc_writel(struct rzg2l_adc *adc, unsigned int reg, u32 val)
+{
+	writel(val, adc->base + reg);
+}
+
+static void rzg2l_adc_pwr(struct rzg2l_adc *adc, bool on)
+{
+	u32 reg;
+
+	reg = rzg2l_adc_readl(adc, RZG2L_ADM(0));
+	if (on)
+		reg |= RZG2L_ADM0_PWDWNB;
+	else
+		reg &= ~RZG2L_ADM0_PWDWNB;
+	rzg2l_adc_writel(adc, RZG2L_ADM(0), reg);
+	udelay(2);
+}
+
+static void rzg2l_adc_start_stop(struct rzg2l_adc *adc, bool start)
+{
+	int timeout = 5;
+	u32 reg;
+
+	/* stop A/D conversion */
+	reg = rzg2l_adc_readl(adc, RZG2L_ADM(0));
+	if (start)
+		reg |= RZG2L_ADM0_ADCE;
+	else
+		reg &= ~RZG2L_ADM0_ADCE;
+	rzg2l_adc_writel(adc, RZG2L_ADM(0), reg);
+
+	if (start)
+		return;
+
+	do {
+		usleep_range(100, 200);
+		reg = rzg2l_adc_readl(adc, RZG2L_ADM(0));
+		timeout--;
+		if (!timeout) {
+			pr_err("%s stopping ADC timed out\n", __func__);
+			break;
+		}
+	} while (((reg & RZG2L_ADM0_ADBSY) || (reg & RZG2L_ADM0_ADCE)));
+}
+
+static void rzg2l_set_trigger(struct rzg2l_adc *adc)
+{
+	u32 reg;
+
+	/* SW trigger */
+	reg = rzg2l_adc_readl(adc, RZG2L_ADM(1));
+	reg &= RZG2L_ADM1_EGA_CLEAR;
+	reg &= ~RZG2L_ADM1_BS;
+	reg |= RZG2L_ADM1_MS;
+	reg &= ~RZG2L_ADM1_TRG;
+	rzg2l_adc_writel(adc, RZG2L_ADM(1), reg);
+}
+
+static int rzg2l_adc_conversion_setup(struct rzg2l_adc *adc, u8 ch)
+{
+	u32 reg;
+
+	if (rzg2l_adc_readl(adc, RZG2L_ADM(0)) & RZG2L_ADM0_ADBSY)
+		return -EBUSY;
+
+	rzg2l_set_trigger(adc);
+
+	/* select channel */
+	reg = rzg2l_adc_readl(adc, RZG2L_ADM(2));
+	reg &= RZG2L_ADM2_CHSEL_CLEAR;
+	reg |= BIT(ch);
+	rzg2l_adc_writel(adc, RZG2L_ADM(2), reg);
+
+	reg = rzg2l_adc_readl(adc, RZG2L_ADM(3));
+	reg &= RZG2L_ADM3_ADIL_CLEAR;
+	reg |= RZG2L_ADM3_ADCMP;
+	reg |= RZG2L_ADM3_ADSMP;
+	rzg2l_adc_writel(adc, RZG2L_ADM(3), reg);
+
+	reg = rzg2l_adc_readl(adc, RZG2L_ADIVC);
+	reg &= RZG2L_ADIVC_DIVADC_CLEAR;
+	reg |= RZG2L_ADIVC_DIVADC_4;
+	rzg2l_adc_writel(adc, RZG2L_ADIVC, reg);
+
+	reg = rzg2l_adc_readl(adc, RZG2L_ADINT);
+	reg &= ~RZG2L_ADINT_INTS;
+	reg &= RZG2L_ADINT_CH_CLEAR;
+	reg |= RZG2L_ADINT_CSEEN;
+	reg |= BIT(ch);
+	rzg2l_adc_writel(adc, RZG2L_ADINT, reg);
+
+	return 0;
+}
+
+static int rzg2l_adc_set_power(struct iio_dev *indio_dev, bool on)
+{
+	struct device *dev = indio_dev->dev.parent;
+
+	if (on)
+		return pm_runtime_resume_and_get(dev);
+
+	return pm_runtime_put_sync(dev);
+}
+
+static int rzg2l_adc_conversion(struct iio_dev *indio_dev, struct rzg2l_adc *adc, u8 ch)
+{
+	int ret;
+
+	ret = rzg2l_adc_set_power(indio_dev, true);
+	if (ret)
+		return ret;
+
+	ret = rzg2l_adc_conversion_setup(adc, ch);
+	if (ret) {
+		rzg2l_adc_set_power(indio_dev, false);
+		return ret;
+	}
+
+	reinit_completion(&adc->completion);
+
+	rzg2l_adc_start_stop(adc, true);
+
+	if (!wait_for_completion_timeout(&adc->completion, RZG2L_ADC_TIMEOUT)) {
+		rzg2l_adc_writel(adc, RZG2L_ADINT,
+				 rzg2l_adc_readl(adc, RZG2L_ADINT) & RZG2L_ADINT_CH_CLEAR);
+		rzg2l_adc_start_stop(adc, false);
+		rzg2l_adc_set_power(indio_dev, false);
+		return -ETIMEDOUT;
+	}
+
+	return rzg2l_adc_set_power(indio_dev, false);
+}
+
+static int rzg2l_adc_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int *val, int *val2, long mask)
+{
+	struct rzg2l_adc *adc = iio_priv(indio_dev);
+	int ret;
+	u8 ch;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_VOLTAGE)
+			return -EINVAL;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		ch = chan->channel & RZG2L_ADC_CHN_MASK;
+		ret = rzg2l_adc_conversion(indio_dev, adc, ch);
+		if (ret) {
+			iio_device_release_direct_mode(indio_dev);
+			return ret;
+		}
+		*val = adc->last_val[ch];
+		iio_device_release_direct_mode(indio_dev);
+
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rzg2l_adc_read_label(struct iio_dev *iio_dev,
+				const struct iio_chan_spec *chan,
+				char *label)
+{
+	if (chan->channel >= RZG2L_ADC_MAX_CHANNELS)
+		return -EINVAL;
+
+	return snprintf(label, PAGE_SIZE, "%s\n", rzg2l_adc_channel_name[chan->channel]);
+}
+
+static const struct iio_info rzg2l_adc_iio_info = {
+	.read_raw = rzg2l_adc_read_raw,
+	.read_label = rzg2l_adc_read_label,
+};
+
+static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
+{
+	struct rzg2l_adc *adc = (struct rzg2l_adc *)dev_id;
+	u8 intst;
+	u32 reg;
+	u8 i;
+
+	reg = rzg2l_adc_readl(adc, RZG2L_ADSTS);
+	if (reg & RZG2L_ADSTS_CSEST) {
+		rzg2l_adc_writel(adc, RZG2L_ADSTS, reg);
+		return IRQ_HANDLED;
+	}
+
+	intst = reg & RZG2L_ADINT_INTST_MASK;
+	if (!intst)
+		return IRQ_HANDLED;
+
+	for (i = 0; i < RZG2L_ADC_MAX_CHANNELS; i++) {
+		if (intst & BIT(i))
+			adc->last_val[i] = rzg2l_adc_readl(adc, RZG2L_ADCR(i)) & RZG2L_ADCR_AD_MASK;
+	}
+
+	rzg2l_adc_writel(adc, RZG2L_ADSTS, reg);
+
+	complete(&adc->completion);
+
+	return IRQ_HANDLED;
+}
+
+static int rzg2l_adc_parse_of(struct platform_device *pdev, struct rzg2l_adc *adc)
+{
+	struct iio_chan_spec *chan_array;
+	struct fwnode_handle *fwnode;
+	struct rzg2l_adc_data *data;
+	unsigned int channel;
+	int num_channels;
+	int ret;
+	u8 i;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	num_channels = device_get_child_node_count(&pdev->dev);
+	if (!num_channels) {
+		dev_err(&pdev->dev, "no channel children\n");
+		return -ENODEV;
+	}
+
+	if (num_channels > RZG2L_ADC_MAX_CHANNELS) {
+		dev_err(&pdev->dev, "num of channel children out of range\n");
+		return -EINVAL;
+	}
+
+	chan_array = devm_kcalloc(&pdev->dev, num_channels, sizeof(*chan_array),
+				  GFP_KERNEL);
+	if (!chan_array)
+		return -ENOMEM;
+
+	i = 0;
+	device_for_each_child_node(&pdev->dev, fwnode) {
+		ret = fwnode_property_read_u32(fwnode, "reg", &channel);
+		if (ret)
+			return ret;
+
+		if (channel >= RZG2L_ADC_MAX_CHANNELS)
+			return -EINVAL;
+
+		chan_array[i].type = IIO_VOLTAGE;
+		chan_array[i].indexed = 1;
+		chan_array[i].channel = channel;
+		chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+		chan_array[i].datasheet_name = rzg2l_adc_channel_name[channel];
+		i++;
+	}
+
+	data->num_channels = num_channels;
+	data->channels = chan_array;
+	adc->data = data;
+
+	return 0;
+}
+
+static int rzg2l_adc_sw_reset(struct rzg2l_adc *adc)
+{
+	int timeout = 5;
+	u32 val;
+
+	val = rzg2l_adc_readl(adc, RZG2L_ADM(0));
+	val |= RZG2L_ADM0_SRESB;
+	rzg2l_adc_writel(adc, RZG2L_ADM(0), val);
+
+	while (!(rzg2l_adc_readl(adc, RZG2L_ADM(0)) & RZG2L_ADM0_SRESB)) {
+		if (!timeout)
+			return -EBUSY;
+		timeout--;
+		usleep_range(100, 200);
+	}
+
+	return 0;
+}
+
+static int rzg2l_adc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct rzg2l_adc *adc;
+	int ret;
+	int irq;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+
+	ret = rzg2l_adc_parse_of(pdev, adc);
+	if (ret)
+		return ret;
+
+	adc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(adc->base))
+		return PTR_ERR(adc->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev, "no irq resource\n");
+		return irq;
+	}
+
+	adc->pclk = devm_clk_get(dev, "pclk");
+	if (IS_ERR(adc->pclk)) {
+		dev_err(dev, "Failed to get pclk");
+		return PTR_ERR(adc->pclk);
+	}
+
+	adc->adclk = devm_clk_get(dev, "adclk");
+	if (IS_ERR(adc->adclk)) {
+		dev_err(dev, "Failed to get adclk");
+		return PTR_ERR(adc->adclk);
+	}
+
+	adc->adrstn = devm_reset_control_get_exclusive(dev, "adrst-n");
+	if (IS_ERR(adc->adrstn)) {
+		dev_err(dev, "failed to get adrstn\n");
+		return PTR_ERR(adc->adrstn);
+	}
+
+	adc->presetn = devm_reset_control_get_exclusive(dev, "presetn");
+	if (IS_ERR(adc->presetn)) {
+		dev_err(dev, "failed to get presetn\n");
+		return PTR_ERR(adc->presetn);
+	}
+
+	ret = reset_control_deassert(adc->adrstn);
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(adc->presetn);
+	if (ret)
+		goto assert_adrstn;
+
+	ret = clk_prepare_enable(adc->pclk);
+	if (ret)
+		goto assert_presetn;
+
+	ret = rzg2l_adc_sw_reset(adc);
+	if (ret)
+		goto unprepare_pclk;
+
+	clk_disable_unprepare(adc->pclk);
+
+	init_completion(&adc->completion);
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	ret = devm_request_irq(dev, irq, rzg2l_adc_isr,
+			       0, dev_name(dev), adc);
+	if (ret < 0)
+		goto assert_presetn;
+
+	indio_dev->name = DRIVER_NAME;
+	indio_dev->info = &rzg2l_adc_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = adc->data->channels;
+	indio_dev->num_channels = adc->data->num_channels;
+
+	pm_runtime_enable(dev);
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret)
+		goto err_iio_device_register;
+
+	return 0;
+
+unprepare_pclk:
+	clk_disable_unprepare(adc->pclk);
+err_iio_device_register:
+	pm_runtime_disable(dev);
+assert_presetn:
+	reset_control_assert(adc->presetn);
+assert_adrstn:
+	reset_control_assert(adc->adrstn);
+	return ret;
+}
+
+static int rzg2l_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct rzg2l_adc *adc = iio_priv(indio_dev);
+
+	reset_control_assert(adc->presetn);
+	reset_control_assert(adc->adrstn);
+	pm_runtime_disable(indio_dev->dev.parent);
+
+	return 0;
+}
+
+static const struct of_device_id rzg2l_adc_match[] = {
+	{ .compatible = "renesas,rzg2l-adc",},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzg2l_adc_match);
+
+static int __maybe_unused rzg2l_adc_pm_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct rzg2l_adc *adc = iio_priv(indio_dev);
+
+	rzg2l_adc_pwr(adc, false);
+	clk_disable_unprepare(adc->adclk);
+	clk_disable_unprepare(adc->pclk);
+
+	return 0;
+}
+
+static int __maybe_unused rzg2l_adc_pm_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct rzg2l_adc *adc = iio_priv(indio_dev);
+	int ret;
+
+	ret = clk_prepare_enable(adc->pclk);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(adc->adclk);
+	if (ret)
+		return ret;
+
+	rzg2l_adc_pwr(adc, true);
+
+	return 0;
+}
+
+static const struct dev_pm_ops rzg2l_adc_pm_ops = {
+	SET_RUNTIME_PM_OPS(rzg2l_adc_pm_runtime_suspend,
+			   rzg2l_adc_pm_runtime_resume,
+			   NULL)
+};
+
+static struct platform_driver rzg2l_adc_driver = {
+	.probe		= rzg2l_adc_probe,
+	.remove		= rzg2l_adc_remove,
+	.driver		= {
+		.name		= DRIVER_NAME,
+		.of_match_table = rzg2l_adc_match,
+		.pm		= &rzg2l_adc_pm_ops,
+	},
+};
+
+module_platform_driver(rzg2l_adc_driver);
+
+MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
+MODULE_DESCRIPTION("Renesas RZ/G2L ADC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1