Date:   Tue, 26 Mar 2019 15:33:32 +0900
From:   Shinji Kanematsu <kanematsu.shinji@...ionext.com>
To:     jic23@...nel.org
Cc:     knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        masami.hiramatsu@...aro.org, jaswinder.singh@...aro.org,
        orito.takao@...ionext.com, sugaya.taichi@...ionext.com,
        kasai.kazuhiro@...ionext.com, kanematsu.shinji@...ionext.com
Subject: [PATCH 2/2] iio: counter: Add support for Milbeaut Updown Counter

Add support for Milbeaut Updown Counter, that can be used as counter
or quadrature encoder.

Signed-off-by: Shinji Kanematsu <kanematsu.shinji@...ionext.com>
---
 drivers/iio/counter/Kconfig               |  12 +
 drivers/iio/counter/Makefile              |   1 +
 drivers/iio/counter/milbeaut-updown.h     |  38 +++
 drivers/iio/counter/milbeaut-updown_cnt.c | 385 ++++++++++++++++++++++++++++++
 4 files changed, 436 insertions(+)
 create mode 100644 drivers/iio/counter/milbeaut-updown.h
 create mode 100644 drivers/iio/counter/milbeaut-updown_cnt.c

diff --git a/drivers/iio/counter/Kconfig b/drivers/iio/counter/Kconfig
index bf1e559..a665f61 100644
--- a/drivers/iio/counter/Kconfig
+++ b/drivers/iio/counter/Kconfig
@@ -31,4 +31,16 @@ config STM32_LPTIMER_CNT
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called stm32-lptimer-cnt.
+
+config MILBEAUT_UPDOWN_CNT
+	tristate "Milbeaut Updown Counter driver"
+	depends on OF
+	depends on ARCH_MILBEAUT || COMPILE_TEST
+	help
+	  Select this option to enable Milbeaut Updown Counter quadrature encoder
+	  and counter driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called milbeaut-updown-cnt.
+
 endmenu
diff --git a/drivers/iio/counter/Makefile b/drivers/iio/counter/Makefile
index 1b9a896..0cb708b 100644
--- a/drivers/iio/counter/Makefile
+++ b/drivers/iio/counter/Makefile
@@ -6,3 +6,4 @@
 
 obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
 obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o
+obj-$(CONFIG_MILBEAUT_UPDOWN_CNT)	+= milbeaut-updown_cnt.o
diff --git a/drivers/iio/counter/milbeaut-updown.h b/drivers/iio/counter/milbeaut-updown.h
new file mode 100644
index 0000000..9a038ad
--- /dev/null
+++ b/drivers/iio/counter/milbeaut-updown.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Milbeaut Updown parent driver
+ * Copyright (C) 2019 Socionext Inc.
+ */
+
+#ifndef _LINUX_MILBEAUT_UPDOWN_H_
+#define _LINUX_MILBEAUT_UPDOWN_H_
+
+#define MLB_UPDOWN_UDCR		0x0		/* Updown Count Reg		*/
+#define MLB_UPDOWN_RCR		0x4		/* Reload Compare Reg	*/
+#define MLB_UPDOWN_CSR		0xC		/* Counter Status Reg	*/
+#define MLB_UPDOWN_CCR		0x14	/* Counter Control Reg	*/
+
+/* MLB_UPDOWN_CSR - bit fields */
+#define MLB_UPDOWN_CSTR		BIT(7)
+#define MLB_UPDOWN_UDIE		BIT(5)
+#define MLB_UPDOWN_CMPF		BIT(4)
+#define MLB_UPDOWN_OVFF		BIT(3)
+#define MLB_UPDOWN_UDFF		BIT(2)
+
+/* MLB_UPDOWN_CCR - bit fields */
+#define MLB_UPDOWN_FIXED	BIT(15)
+#define MLB_UPDOWN_CMS		GENMASK(11, 10)
+#define MLB_UPDOWN_CES		GENMASK(9, 8)
+#define MLB_UPDOWN_CTUT		BIT(6)
+#define MLB_UPDOWN_RLDE		BIT(4)
+
+/* MLB_UPDOWN max count value */
+#define MLB_UPDOWN_MAX_COUNT	0xFFFF
+
+/* MLB_UPDOWN rising edge detection */
+#define MLB_UPDOWN_RISING_EDGE		BIT(9)
+
+/* MLB_UPDOWN mode */
+#define MLB_UPDOWN_MODE		1
+
+#endif
diff --git a/drivers/iio/counter/milbeaut-updown_cnt.c b/drivers/iio/counter/milbeaut-updown_cnt.c
new file mode 100644
index 0000000..a58709a
--- /dev/null
+++ b/drivers/iio/counter/milbeaut-updown_cnt.c
@@ -0,0 +1,385 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Milbeaut Updown counter driver
+ *
+ * Copyright (C) 2019 Socionext Inc.
+ *
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "milbeaut-updown.h"
+
+#define MILBEAUT_UPDOWN_IRQ_NAME		"milbeaut_updown_event"
+#define MILBEAUT_UPDOWN_MAX_REGISTER	0x1f
+
+static const struct regmap_config milbeaut_updown_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = MILBEAUT_UPDOWN_MAX_REGISTER,
+};
+struct milbeaut_updown_cnt {
+	struct device *dev;
+	struct regmap *regmap;
+	struct clk *clk;
+	u32 preset;
+	u32 polarity;
+	u32 quadrature_mode;
+};
+
+static int milbeaut_updown_is_enabled(struct milbeaut_updown_cnt *priv)
+{
+	u32 val;
+	int ret;
+
+	ret = regmap_read(priv->regmap, MLB_UPDOWN_CSR, &val);
+	if (ret)
+		return ret;
+
+	return FIELD_GET(MLB_UPDOWN_CSTR, val);
+}
+
+static int milbeaut_updown_setup(struct milbeaut_updown_cnt *priv,
+									int val)
+{
+	int ret;
+
+	if (val) {
+		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
+				MLB_UPDOWN_CMS | MLB_UPDOWN_RLDE,
+				FIELD_PREP(MLB_UPDOWN_CMS, priv->quadrature_mode) |
+				MLB_UPDOWN_RLDE);
+		if (ret)
+			return ret;
+
+		if (priv->quadrature_mode == MLB_UPDOWN_MODE) {
+			ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
+					MLB_UPDOWN_CES, MLB_UPDOWN_RISING_EDGE);
+			if (ret)
+				return ret;
+		}
+
+		ret = regmap_write(priv->regmap, MLB_UPDOWN_RCR, priv->preset);
+		if (ret)
+			return ret;
+
+		/* interrupt */
+		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
+						MLB_UPDOWN_UDIE, MLB_UPDOWN_UDIE);
+		if (ret)
+			return ret;
+
+		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
+			MLB_UPDOWN_CTUT | MLB_UPDOWN_FIXED,
+			MLB_UPDOWN_CTUT | MLB_UPDOWN_FIXED);
+		if (ret)
+			return ret;
+
+		val = MLB_UPDOWN_CSTR;
+	}
+
+	return regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
+								MLB_UPDOWN_CSTR, val);
+}
+
+static int milbeaut_updown_write_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int val, int val2, long mask)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_ENABLE:
+		if (val < 0 || val > 1)
+			return -EINVAL;
+
+		ret = milbeaut_updown_is_enabled(priv);
+		if (val && ret)
+			return -EBUSY;
+
+		ret = milbeaut_updown_setup(priv, val);
+
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int milbeaut_updown_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+	u32 dat;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_read(priv->regmap, MLB_UPDOWN_UDCR, &dat);
+		if (ret)
+			return ret;
+		*val = dat;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_ENABLE:
+		ret = milbeaut_updown_is_enabled(priv);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info milbeaut_updown_cnt_iio_info = {
+	.read_raw = milbeaut_updown_read_raw,
+	.write_raw = milbeaut_updown_write_raw,
+};
+
+static const char *const milbeaut_updown_quadrature_modes[] = {
+	"non-quadrature",
+	"quadrature",
+};
+
+static int milbeaut_updown_get_quadrature_mode(struct iio_dev *indio_dev,
+					   const struct iio_chan_spec *chan)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+
+	return priv->quadrature_mode;
+}
+
+static int milbeaut_updown_set_quadrature_mode(struct iio_dev *indio_dev,
+					   const struct iio_chan_spec *chan,
+					   unsigned int type)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+
+	if (milbeaut_updown_is_enabled(priv))
+		return -EBUSY;
+
+	priv->quadrature_mode = type;
+
+	return 0;
+}
+
+static const struct iio_enum milbeaut_updown_quadrature_mode_en = {
+	.items = milbeaut_updown_quadrature_modes,
+	.num_items = ARRAY_SIZE(milbeaut_updown_quadrature_modes),
+	.get = milbeaut_updown_get_quadrature_mode,
+	.set = milbeaut_updown_set_quadrature_mode,
+};
+
+static const char * const milbeaut_updown_cnt_polarity[] = {
+	"rising-edge", "falling-edge", "both-edges",
+};
+
+static int milbeaut_updown_cnt_get_polarity(struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+
+	return priv->polarity;
+}
+
+static int milbeaut_updown_cnt_set_polarity(struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan,
+					unsigned int type)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+
+	if (milbeaut_updown_is_enabled(priv))
+		return -EBUSY;
+
+	priv->polarity = type;
+
+	return 0;
+}
+
+static const struct iio_enum milbeaut_updown_cnt_polarity_en = {
+	.items = milbeaut_updown_cnt_polarity,
+	.num_items = ARRAY_SIZE(milbeaut_updown_cnt_polarity),
+	.get = milbeaut_updown_cnt_get_polarity,
+	.set = milbeaut_updown_cnt_set_polarity,
+};
+
+static ssize_t milbeaut_updown_cnt_get_preset(struct iio_dev *indio_dev,
+					  uintptr_t private,
+					  const struct iio_chan_spec *chan,
+					  char *buf)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset);
+}
+
+static ssize_t milbeaut_updown_cnt_set_preset(struct iio_dev *indio_dev,
+					  uintptr_t private,
+					  const struct iio_chan_spec *chan,
+					  const char *buf, size_t len)
+{
+	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
+	u32 check_preset;
+	int ret;
+
+	if (milbeaut_updown_is_enabled(priv))
+		return -EBUSY;
+
+	ret = kstrtouint(buf, 0, &check_preset);
+	if (ret)
+		return ret;
+
+	if (check_preset > MLB_UPDOWN_MAX_COUNT)
+		return -EINVAL;
+
+	ret = kstrtouint(buf, 0, &priv->preset);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static const struct iio_chan_spec_ext_info milbeaut_updown_cnt_ext_info[] = {
+	{
+		.name = "preset",
+		.shared = IIO_SEPARATE,
+		.read = milbeaut_updown_cnt_get_preset,
+		.write = milbeaut_updown_cnt_set_preset,
+	},
+	IIO_ENUM("polarity", IIO_SEPARATE, &milbeaut_updown_cnt_polarity_en),
+	IIO_ENUM_AVAILABLE("polarity", &milbeaut_updown_cnt_polarity_en),
+	{}
+};
+
+static const struct iio_event_spec milbeaut_updown_cnt_event = {
+	.type = IIO_EV_TYPE_ROC,
+	.dir = IIO_EV_DIR_RISING,
+	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
+	.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
+};
+
+static const struct iio_chan_spec milbeaut_updown_cnt_channels = {
+	.type = IIO_COUNT,
+	.channel = 0,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			      BIT(IIO_CHAN_INFO_ENABLE) |
+			      BIT(IIO_CHAN_INFO_SCALE),
+	.ext_info = milbeaut_updown_cnt_ext_info,
+	.indexed = 1,
+	.event_spec = &milbeaut_updown_cnt_event,
+	.num_event_specs = 1,
+};
+
+static irqreturn_t milbeaut_updown_event_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct milbeaut_updown_cnt *priv;
+	int ret;
+
+	priv = iio_priv(indio_dev);
+
+	ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
+			MLB_UPDOWN_CMPF | MLB_UPDOWN_OVFF | MLB_UPDOWN_UDFF,
+			0);
+	WARN_ON_ONCE(ret < 0);
+
+	iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_INCLI, 0, 1,
+						  IIO_EV_TYPE_ROC, IIO_EV_DIR_RISING),
+			       iio_get_time_ns(indio_dev));
+
+	return IRQ_HANDLED;
+}
+
+static int milbeaut_updown_cnt_probe(struct platform_device *pdev)
+{
+	struct milbeaut_updown_cnt *priv;
+	struct iio_dev *indio_dev;
+	struct resource *res;
+	void __iomem *mmio;
+	int ret;
+	int irq;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(indio_dev);
+	priv->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mmio = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mmio))
+		return PTR_ERR(mmio);
+
+	priv->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "mux", mmio,
+							  &milbeaut_updown_regmap_cfg);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
+	priv->preset = MLB_UPDOWN_MAX_COUNT;
+	ret = of_property_read_u32(priv->dev->of_node,
+				"cms_type", &priv->quadrature_mode);
+	if (ret)
+		return -ENODEV;
+
+	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 = &milbeaut_updown_cnt_iio_info;
+	indio_dev->channels = &milbeaut_updown_cnt_channels;
+	indio_dev->num_channels = 1;
+
+	/* setting request irq */
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_request_threaded_irq(&pdev->dev, irq,
+			NULL, milbeaut_updown_event_handler,
+			IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+			MILBEAUT_UPDOWN_IRQ_NAME, indio_dev);
+	if (ret < 0) {
+		pr_err("%s request irq failed\n", __func__);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static const struct of_device_id milbeaut_updown_cnt_of_match[] = {
+	{ .compatible = "socionext,milbeaut-updown-counter", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, milbeaut_updown_cnt_of_match);
+
+static struct platform_driver milbeaut_updown_cnt_driver = {
+	.probe = milbeaut_updown_cnt_probe,
+	.driver = {
+		.name = "milbeaut-updown-counter",
+		.of_match_table = milbeaut_updown_cnt_of_match,
+	},
+};
+module_platform_driver(milbeaut_updown_cnt_driver);
+
+MODULE_AUTHOR("Shinji Kanematsu <kanematsu.shinji@...ionext.com>");
+MODULE_DESCRIPTION("Milbeaut Updown counter");
+MODULE_ALIAS("platform:milbeaut_updown_counter");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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