[PATCH v3 4/5] iio/adc/axp288: add support for axp288 gpadc

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

Platform driver for XPowers AXP288 ADC, which is a sub-device of the
customized PMIC for Intel Baytrail-CR platforms. GPADC device enumerates
as one of the MFD cell devices. It uses IIO infrastructure to communicate
with userspace and consumer drivers.

Usages of ADC channels include battery charging and thermal sensors.

Based on initial work by:
Ramakrishna Pallala <ramakrishna.pallala@intel.com>

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/iio/adc/Kconfig        |   8 ++
 drivers/iio/adc/Makefile       |   1 +
 drivers/iio/adc/axp288_gpadc.c | 238 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 247 insertions(+)
 create mode 100644 drivers/iio/adc/axp288_gpadc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 11b048a..d02a08e 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -127,6 +127,14 @@ config AT91_ADC
 	help
 	  Say yes here to build support for Atmel AT91 ADC.
 
+config AXP288_GPADC
+	tristate "X-Power AXP288 GPADC driver"
+	depends on MFD_AXP2XX
+	help
+	  Say yes here to have support for X-Power power management IC (PMIC) ADC
+	  device. Depending on platform configuration, this general purpose ADC can
+	  be used for sampling sensors such as thermal resistors.
+
 config EXYNOS_ADC
 	tristate "Exynos ADC driver support"
 	depends on ARCH_EXYNOS || (OF && COMPILE_TEST)
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index ad81b51..8bf0104 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -30,3 +30,4 @@ obj-$(CONFIG_VF610_ADC) += vf610_adc.o
 obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
 xilinx-xadc-y := xilinx-xadc-core.o xilinx-xadc-events.o
 obj-$(CONFIG_XILINX_XADC) += xilinx-xadc.o
+obj-$(CONFIG_AXP288_GPADC) += axp288_gpadc.o
diff --git a/drivers/iio/adc/axp288_gpadc.c b/drivers/iio/adc/axp288_gpadc.c
new file mode 100644
index 0000000..aaa24b0
--- /dev/null
+++ b/drivers/iio/adc/axp288_gpadc.c
@@ -0,0 +1,238 @@
+/*
+ * axp288_gpadc.c - Xpower AXP288 PMIC GPADC Driver
+ *
+ * Copyright (C) 2014 Intel Corporation
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * 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; version 2 of the License.
+ *
+ * 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/module.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/axp2xx.h>
+#include <linux/platform_device.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/machine.h>
+#include <linux/iio/driver.h>
+
+#define AXP288_ADC_EN_MASK		       0xF1
+#define AXP288_ADC_TS_PIN_GPADC                0xF2
+#define AXP288_ADC_TS_PIN_ON                   0xF3
+
+enum axp288_adc_id {
+	AXP288_ADC_TS,
+	AXP288_ADC_PMIC,
+	AXP288_ADC_GP,
+	AXP288_ADC_BATT_CHRG_I,
+	AXP288_ADC_BATT_DISCHRG_I,
+	AXP288_ADC_BATT_V,
+	AXP288_ADC_NR_CHAN,
+};
+
+static const int axp288_scale[AXP288_ADC_NR_CHAN] = {
+	[AXP288_ADC_BATT_CHRG_I] = 1,
+	[AXP288_ADC_BATT_DISCHRG_I] = 1,
+	[AXP288_ADC_BATT_V] = 1,
+};
+
+struct gpadc_info {
+	int irq;
+	struct device *dev;
+	struct regmap *regmap;
+};
+
+#define ADC_CHANNEL(_type, _channel, _address, _info_mask)		\
+	{								\
+		.indexed = 1,						\
+		.type = _type,						\
+		.channel = _channel,					\
+		.address = _address,					\
+		.datasheet_name = "CH"#_channel,			\
+		.info_mask_separate = _info_mask,		        \
+	}
+
+static const struct iio_chan_spec const axp288_adc_channels[] = {
+	ADC_CHANNEL(IIO_TEMP, 0, AXP288_TS_ADC_H, 0),
+	ADC_CHANNEL(IIO_TEMP, 1, AXP288_PMIC_ADC_H, 0),
+	ADC_CHANNEL(IIO_TEMP, 2, AXP288_GP_ADC_H, 0),
+	ADC_CHANNEL(IIO_CURRENT, 3, AXP20X_BATT_CHRG_I_H,
+		(BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE))),
+	ADC_CHANNEL(IIO_CURRENT, 4, AXP20X_BATT_DISCHRG_I_H,
+		(BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE))),
+	ADC_CHANNEL(IIO_VOLTAGE, 5, AXP20X_BATT_V_H,
+		(BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE))),
+};
+
+#define ADC_MAP(_adc_channel_label,				\
+		     _consumer_dev_name,			\
+		     _consumer_channel)				\
+	{							\
+		.adc_channel_label = _adc_channel_label,	\
+		.consumer_dev_name = _consumer_dev_name,	\
+		.consumer_channel = _consumer_channel,		\
+	}
+
+/* for consumer drivers */
+static struct iio_map axp288_iio_default_maps[] = {
+	ADC_MAP("TS_PIN", "axp288-batt", "axp288-batt-temp"),
+	ADC_MAP("PMIC_TEMP", "axp288-pmic", "axp288-pmic-temp"),
+	ADC_MAP("GPADC", "axp288-gpadc", "axp288-system-temp"),
+	ADC_MAP("BATT_CHG_I", "axp288-chrg", "axp288-chrg-curr"),
+	ADC_MAP("BATT_DISCHRG_I", "axp288-chrg", "axp288-chrg-d-curr"),
+	ADC_MAP("BATT_V", "axp288-batt", "axp288-batt-volt"),
+	{},
+};
+
+static int axp288_adc_read_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int *val, int *val2, long mask)
+{
+	int ret;
+	struct gpadc_info *info = iio_priv(indio_dev);
+	unsigned int th, tl;
+
+	mutex_lock(&indio_dev->mlock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/* special case for GPADC sample */
+		if (chan->address == AXP288_GP_ADC_H)
+			regmap_write(info->regmap, AXP288_ADC_TS_PIN_CTRL,
+				AXP288_ADC_TS_PIN_GPADC);
+		ret = regmap_read(info->regmap, chan->address, &th);
+		if (ret) {
+			dev_err(&indio_dev->dev, "sample raw data high failed\n");
+			break;
+		}
+		ret = regmap_read(info->regmap, chan->address + 1, &tl);
+		if (ret) {
+			dev_err(&indio_dev->dev, "sample raw data low failed\n");
+			break;
+		}
+
+		*val = (th << 4) + ((tl >> 4) & 0x0F);
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = axp288_scale[chan->channel];
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (IIO_CHAN_INFO_RAW && chan->address == AXP288_GP_ADC_H)
+		regmap_write(info->regmap, AXP288_ADC_TS_PIN_CTRL,
+			AXP288_ADC_TS_PIN_ON);
+
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static int axp288_gpadc_enable(struct regmap *regmap, bool enable)
+{
+	unsigned int pin_on, adc_en;
+
+	if (enable) {
+		pin_on = AXP288_ADC_TS_PIN_ON;
+		adc_en = AXP288_ADC_EN_MASK;
+	} else {
+		pin_on = ~AXP288_ADC_TS_PIN_ON;
+		adc_en = ~AXP288_ADC_EN_MASK;
+	}
+	if (regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, pin_on))
+		return -EIO;
+
+	return regmap_write(regmap, AXP20X_ADC_EN1, ~AXP288_ADC_EN_MASK);
+}
+
+static const struct iio_info axp288_iio_info = {
+	.read_raw = &axp288_adc_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int axp288_gpadc_probe(struct platform_device *pdev)
+{
+	int err;
+	struct gpadc_info *info;
+	struct iio_dev *indio_dev;
+	struct axp2xx_dev *axp2xx = dev_get_drvdata(pdev->dev.parent);
+	int irq;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	info = iio_priv(indio_dev);
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no irq resource?\n");
+		return irq;
+	}
+	info->irq = irq;
+	platform_set_drvdata(pdev, indio_dev);
+	info->regmap = axp2xx->regmap;
+	axp288_gpadc_enable(axp2xx->regmap, true);
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->name = pdev->name;
+	indio_dev->channels = axp288_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(axp288_adc_channels);
+	indio_dev->info = &axp288_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	/* REVISIT: override default map with platform data */
+	err = iio_map_array_register(indio_dev, axp288_iio_default_maps);
+	if (err)
+		goto err_disable_dev;
+
+	err = iio_device_register(indio_dev);
+	if (err < 0) {
+		dev_err(&pdev->dev, "unable to register iio device\n");
+		goto err_array_unregister;
+	}
+	return 0;
+
+err_array_unregister:
+	iio_map_array_unregister(indio_dev);
+err_disable_dev:
+	axp288_gpadc_enable(axp2xx->regmap, false);
+	return err;
+}
+
+static int axp288_gpadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+
+	iio_device_unregister(indio_dev);
+	iio_map_array_unregister(indio_dev);
+
+	return 0;
+}
+
+static struct platform_driver axp288_gpadc_driver = {
+	.probe = axp288_gpadc_probe,
+	.remove = axp288_gpadc_remove,
+	.driver = {
+		.name = "axp288_adc",
+		.owner = THIS_MODULE,
+	},
+};
+
+module_platform_driver(axp288_gpadc_driver);
+
+MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@linux.intel.com>");
+MODULE_DESCRIPTION("Dollar Cove Xpower AXP288 General Purpose ADC Driver");
+MODULE_LICENSE("GPL");
-- 
1.9.1