Message-Id: <1468350252-11405-2-git-send-email-alexandre.belloni@free-electrons.com>
Date:	Tue, 12 Jul 2016 21:04:12 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Jonathan Cameron <jic23@...nel.org>
Cc:	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, linux-iio@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Subject: [PATCH v2 2/2] iio: adc: sun4i_lradc: new driver

Add an IIO driver for the Allwinner Low Resolution ADC. This ADC is usually
used for physical buttons connected using a resistor ladder.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
---
Changes in v2:
 - prefixed defines with SUN4I_LRADC_
 - removed sun4i_lradc_write_raw_get_fmt
 - set indio_dev->dev.of_node
 - pushed devm_iio_device_register() at the end of the probe function
 - added a remove function to call regulator_disable()

 drivers/iio/adc/Kconfig       |  10 ++
 drivers/iio/adc/Makefile      |   3 +-
 drivers/iio/adc/sun4i_lradc.c | 323 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 335 insertions(+), 1 deletion(-)
 create mode 100644 drivers/iio/adc/sun4i_lradc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 25378c5882e2..87aaac6a5f44 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -384,6 +384,16 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config SUN4I_LRADC
+	tristate "Allwinner sun4i LRADC driver"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	select IIO_TRIGGER
+	help
+	  Say yes here to build support for the LRADC found on Allwinner SoCs.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called sun4i_lradc.
+
 config TI_ADC081C
 	tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 38638d46f972..a3b165af6bde 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -1,4 +1,4 @@
-#
+
 # Makefile for IIO ADC drivers
 #
 
@@ -37,6 +37,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
+obj-$(CONFIG_SUN4I_LRADC) += sun4i_lradc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
diff --git a/drivers/iio/adc/sun4i_lradc.c b/drivers/iio/adc/sun4i_lradc.c
new file mode 100644
index 000000000000..cd42e1a994b9
--- /dev/null
+++ b/drivers/iio/adc/sun4i_lradc.c
@@ -0,0 +1,323 @@
+/*
+ * Driver for the LRADC present on the  Allwinner sun4i
+ *
+ * Copyright 2016 Free Electrons
+ *
+ * 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/bitops.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/regulator/consumer.h>
+
+#define SUN4I_LRADC_CTRL		0x00
+#define SUN4I_LRADC_INTC		0x04
+#define SUN4I_LRADC_INTS		0x08
+#define SUN4I_LRADC_DATA0		0x0c
+#define SUN4I_LRADC_DATA1		0x10
+
+/* LRADC_CTRL bits */
+#define SUN4I_LRADC_FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
+#define SUN4I_LRADC_CHAN_SELECT(x)		((x) << 22) /* 2 bits */
+#define SUN4I_LRADC_CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
+#define SUN4I_LRADC_KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
+#define SUN4I_LRADC_LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
+#define SUN4I_LRADC_HOLD_EN			BIT(6)
+#define SUN4I_LRADC_LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
+#define SUN4I_LRADC_SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
+#define SUN4I_LRADC_EN				BIT(0)
+
+/* LRADC_INTC and LRADC_INTS bits */
+#define SUN4I_LRADC_CHAN1_KEYUP_IRQ		BIT(12)
+#define SUN4I_LRADC_CHAN1_ALRDY_HOLD_IRQ	BIT(11)
+#define SUN4I_LRADC_CHAN1_HOLD_IRQ		BIT(10)
+#define	SUN4I_LRADC_CHAN1_KEYDOWN_IRQ	BIT(9)
+#define SUN4I_LRADC_CHAN1_DATA_IRQ		BIT(8)
+#define SUN4I_LRADC_CHAN0_KEYUP_IRQ		BIT(4)
+#define SUN4I_LRADC_CHAN0_ALRDY_HOLD_IRQ	BIT(3)
+#define SUN4I_LRADC_CHAN0_HOLD_IRQ		BIT(2)
+#define	SUN4I_LRADC_CHAN0_KEYDOWN_IRQ	BIT(1)
+#define SUN4I_LRADC_CHAN0_DATA_IRQ		BIT(0)
+
+#define NUM_SUN4I_LRADC_CHANS		2
+
+struct sun4i_lradc_state {
+	void __iomem *base;
+	struct regulator *vref_supply;
+	u32 vref_mv;
+	struct completion data_ok[NUM_SUN4I_LRADC_CHANS];
+	spinlock_t lock;
+};
+
+#define SUN4I_LRADC_CHANNEL(chan) {				\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = (chan),					\
+	.scan_index = (chan),					\
+	.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 sun4i_lradc_chan_array[] = {
+	SUN4I_LRADC_CHANNEL(0),
+	SUN4I_LRADC_CHANNEL(1),
+};
+
+static const struct {
+	int val;
+	int val2;
+} sun4i_lradc_sample_freq_avail[] = {
+	{250, 0},
+	{125, 0},
+	{62, 500000},
+	{32, 250000},
+};
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("32.25 62.5 125 250");
+
+static struct attribute *sun4i_lradc_attributes[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group sun4i_lradc_attribute_group = {
+	.attrs = sun4i_lradc_attributes,
+};
+
+static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct sun4i_lradc_state *st = iio_priv(indio_dev);
+	u32 ints, intc;
+
+	spin_lock(&st->lock);
+
+	ints = readl(st->base + SUN4I_LRADC_INTS);
+	intc = readl(st->base + SUN4I_LRADC_INTC);
+
+	if (ints & SUN4I_LRADC_CHAN0_DATA_IRQ)
+		complete_all(&st->data_ok[0]);
+
+	if (ints & SUN4I_LRADC_CHAN1_DATA_IRQ)
+		complete_all(&st->data_ok[1]);
+
+	intc &= ~ints;
+	writel(intc, st->base + SUN4I_LRADC_INTC);
+	writel(ints, st->base + SUN4I_LRADC_INTS);
+
+	spin_unlock(&st->lock);
+
+	return IRQ_HANDLED;
+}
+
+static int sun4i_lradc_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct sun4i_lradc_state *st = iio_priv(indio_dev);
+	int ret, tmp, idx;
+	unsigned long flags;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		reinit_completion(&st->data_ok[chan->channel]);
+		spin_lock_irqsave(&st->lock, flags);
+		tmp = readl(st->base + SUN4I_LRADC_INTC);
+
+		if (chan->channel)
+			tmp |= SUN4I_LRADC_CHAN1_DATA_IRQ;
+		else
+			tmp |= SUN4I_LRADC_CHAN0_DATA_IRQ;
+
+		writel(tmp, st->base + SUN4I_LRADC_INTC);
+		spin_unlock_irqrestore(&st->lock, flags);
+
+		ret = wait_for_completion_interruptible_timeout(
+			&st->data_ok[chan->channel],
+			msecs_to_jiffies(1000));
+		if (ret == 0)
+			return -ETIMEDOUT;
+
+		if (chan->channel)
+			*val = readl(st->base + SUN4I_LRADC_DATA1);
+		else
+			*val = readl(st->base + SUN4I_LRADC_DATA0);
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->vref_mv;
+		*val2 = 6;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		tmp = readl(st->base + SUN4I_LRADC_CTRL);
+		idx = (tmp >> 2) & 0x3;
+		*val = sun4i_lradc_sample_freq_avail[idx].val;
+		*val2 = sun4i_lradc_sample_freq_avail[idx].val2;
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static int sun4i_lradc_write_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int val, int val2, long mask)
+{
+	struct sun4i_lradc_state *st = iio_priv(indio_dev);
+	u32 ctrl;
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		for (i = 0; i < ARRAY_SIZE(sun4i_lradc_sample_freq_avail); i++)
+			if (sun4i_lradc_sample_freq_avail[i].val == val &&
+			    sun4i_lradc_sample_freq_avail[i].val2 == val2)
+				break;
+		if (i == ARRAY_SIZE(sun4i_lradc_sample_freq_avail))
+			return -EINVAL;
+
+		ctrl = readl(st->base + SUN4I_LRADC_CTRL);
+		ctrl &= ~SUN4I_LRADC_SAMPLE_RATE(0x3);
+		writel(ctrl | SUN4I_LRADC_SAMPLE_RATE(i),
+		       st->base + SUN4I_LRADC_CTRL);
+
+		return 0;
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info sun4i_lradc_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = sun4i_lradc_read_raw,
+	.write_raw = sun4i_lradc_write_raw,
+	.attrs = &sun4i_lradc_attribute_group,
+};
+
+static int sun4i_lradc_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct device *dev = &pdev->dev;
+	struct sun4i_lradc_state *st;
+	int err;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = dev->of_node;
+	indio_dev->name = dev_name(dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &sun4i_lradc_info;
+
+	st->vref_supply = devm_regulator_get(dev, "vref");
+	if (IS_ERR(st->vref_supply))
+		return PTR_ERR(st->vref_supply);
+
+	st->base = devm_ioremap_resource(dev,
+			platform_get_resource(pdev, IORESOURCE_MEM, 0));
+	if (IS_ERR(st->base))
+		return PTR_ERR(st->base);
+
+	/* Disable then clear all interrupts */
+	writel(0, st->base + SUN4I_LRADC_INTC);
+	writel(0xffffffff, st->base + SUN4I_LRADC_INTS);
+
+	err = devm_request_irq(dev, platform_get_irq(pdev, 0),
+			       sun4i_lradc_irq, 0,
+			       "sun4i-a10-lradc", indio_dev);
+	if (err)
+		return err;
+
+	/* Setup the ADC channels available on the board */
+	indio_dev->num_channels = ARRAY_SIZE(sun4i_lradc_chan_array);
+	indio_dev->channels = sun4i_lradc_chan_array;
+
+	err = regulator_enable(st->vref_supply);
+	if (err)
+		return err;
+
+	/* lradc Vref internally is divided by 2/3 */
+	st->vref_mv = regulator_get_voltage(st->vref_supply) * 2 / 3000;
+
+	init_completion(&st->data_ok[0]);
+	init_completion(&st->data_ok[1]);
+	spin_lock_init(&st->lock);
+
+	/* Continuous mode on both channels */
+	writel(SUN4I_LRADC_CHAN_SELECT(0x3) | SUN4I_LRADC_KEY_MODE_SEL(0x2) |
+	       SUN4I_LRADC_SAMPLE_RATE(0x00) | SUN4I_LRADC_EN,
+	       st->base + SUN4I_LRADC_CTRL);
+
+	err = devm_iio_device_register(dev, indio_dev);
+	if (err < 0) {
+		dev_err(dev, "Couldn't register the device.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int sun4i_lradc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct sun4i_lradc_state *st = iio_priv(indio_dev);
+
+	regulator_disable(st->vref_supply);
+
+	return 0;
+}
+
+static const struct of_device_id sun4i_lradc_of_match[] = {
+	{ .compatible = "allwinner,sun4i-a10-lradc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
+
+static struct platform_driver sun4i_lradc_driver = {
+	.probe	= sun4i_lradc_probe,
+	.remove = sun4i_lradc_remove,
+	.driver = {
+		.name	= "sun4i-a10-lradc",
+		.of_match_table = of_match_ptr(sun4i_lradc_of_match),
+	},
+};
+
+module_platform_driver(sun4i_lradc_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Allwinner sun4i low resolution ADC driver");
+MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@...e-electrons.com>");
-- 
2.8.1

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