iio: iadc: Qualcomm SPMI PMIC current ADC driver

The current ADC is peripheral of Qualcomm SPMI PMIC chips. It has
16 bits resolution and register space inside PMIC accessible across
SPMI bus.

The driver registers itself through IIO interface.

Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 610 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 88bdc8f612e2..d0924f3cfa25 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -206,6 +206,20 @@ config NAU7802
 	  To compile this driver as a module, choose M here: the
 	  module will be called nau7802.
 
+config QCOM_SPMI_IADC
+	tristate "Qualcomm SPMI PMIC current ADC"
+	depends on SPMI
+	select REGMAP_SPMI
+	help
+	  This is the IIO Current ADC driver for Qualcomm QPNP IADC Chip.
+
+	  The driver supports single mode operation to read from one of two
+	  channels (external or internal). Hardware have additional
+	  channels internally used for gain and offset calibration.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called qcom-spmi-iadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index cb88a6a23b8f..c06718b9d8ce 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
+obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
diff --git a/drivers/iio/adc/qcom-spmi-iadc.c b/drivers/iio/adc/qcom-spmi-iadc.c
new file mode 100644
index 000000000000..b9666f2f5e51
--- /dev/null
+++ b/drivers/iio/adc/qcom-spmi-iadc.c
@@ -0,0 +1,595 @@
+/*
+ * Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* IADC register and bit definition */
+#define IADC_REVISION2				0x1
+#define IADC_REVISION2_SUPPORTED_IADC		1
+
+#define IADC_PERPH_TYPE				0x4
+#define IADC_PERPH_TYPE_ADC			8
+
+#define IADC_PERPH_SUBTYPE			0x5
+#define IADC_PERPH_SUBTYPE_IADC			3
+
+#define IADC_STATUS1				0x8
+#define IADC_STATUS1_OP_MODE			4
+#define IADC_STATUS1_REQ_STS			BIT(1)
+#define IADC_STATUS1_EOC			BIT(0)
+#define IADC_STATUS1_REQ_STS_EOC_MASK		0x3
+
+#define IADC_MODE_CTL				0x40
+#define IADC_OP_MODE_SHIFT			3
+#define IADC_OP_MODE_NORMAL			0
+#define IADC_TRIM_EN				BIT(0)
+
+#define IADC_EN_CTL1				0x46
+#define IADC_EN_CTL1_SET			BIT(7)
+
+#define IADC_CH_SEL_CTL				0x48
+
+#define IADC_DIG_PARAM				0x50
+#define IADC_DIG_DEC_RATIO_SEL_SHIFT		2
+
+#define IADC_HW_SETTLE_DELAY			0x51
+
+#define IADC_CONV_REQ				0x52
+#define IADC_CONV_REQ_SET			BIT(7)
+
+#define IADC_FAST_AVG_CTL			0x5a
+#define IADC_FAST_AVG_EN			0x5b
+#define IADC_FAST_AVG_EN_SET			BIT(7)
+
+#define IADC_PERH_RESET_CTL3			0xda
+#define IADC_FOLLOW_WARM_RB			BIT(2)
+
+#define IADC_DATA				0x60	/* 16 bits */
+
+#define IADC_SEC_ACCESS				0xd0
+#define IADC_SEC_ACCESS_DATA			0xa5
+
+#define IADC_NOMINAL_RSENSE			0xf4
+#define IADC_NOMINAL_RSENSE_SIGN_MASK		BIT(7)
+
+#define IADC_REF_GAIN_MICRO_VOLTS		17857
+
+#define IADC_INT_RSENSE_DEVIATION		15625	/* nano Ohms per bit */
+
+#define IADC_INT_RSENSE_IDEAL_VALUE		10000	/* micro Ohms */
+#define IADC_INT_RSENSE_DEFAULT_VALUE		7800	/* micro Ohms */
+#define IADC_INT_RSENSE_DEFAULT_GF		9000	/* micro Ohms */
+#define IADC_INT_RSENSE_DEFAULT_SMIC		9700	/* micro Ohms */
+
+#define IADC_CONV_TIME_MIN_US			2000
+#define IADC_CONV_TIME_MAX_US			2100
+
+#define IADC_DEF_PRESCALING			0 /* 1:1 */
+#define IADC_DEF_DECIMATION			0 /* 512 */
+#define IADC_DEF_HW_SETTLE_TIME			0 /* 0 us */
+#define IADC_DEF_AVG_SAMPLES			0 /* 1 sample */
+
+/* IADC channel list */
+#define IADC_INT_RSENSE				0
+#define IADC_EXT_RSENSE				1
+#define IADC_GAIN_17P857MV			3
+#define IADC_EXT_OFFSET_CSP_CSN			5
+#define IADC_INT_OFFSET_CSP2_CSN2		6
+
+/**
+ * struct iadc_chip - IADC Current ADC device structure.
+ * @regmap: regmap for register read/write.
+ * @dev: This device pointer.
+ * @base: base offset for the ADC peripheral.
+ * @rsense: Values of the internal and external sense resister in micro Ohms.
+ * @poll_eoc: Poll for end of conversion instead of waiting for IRQ.
+ * @offset: Raw offset values for the internal and external channels.
+ * @gain: Raw gain of the channels.
+ * @lock: ADC lock for access to the peripheral.
+ * @complete: ADC notification after end of conversion interrupt is received.
+ */
+struct iadc_chip {
+	struct regmap	*regmap;
+	struct device	*dev;
+	u16		base;
+	bool		poll_eoc;
+	u32		rsense[2];
+	u16		offset[2];
+	u16		gain;
+	struct mutex	lock;
+	struct completion complete;
+};
+
+static int iadc_read(struct iadc_chip *iadc, u16 offset, u8 *data)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(iadc->regmap, iadc->base + offset, &val);
+	if (ret < 0)
+		return ret;
+
+	*data = val;
+	return 0;
+}
+
+static int iadc_write(struct iadc_chip *iadc, u16 offset, u8 data)
+{
+	return regmap_write(iadc->regmap, iadc->base + offset, data);
+}
+
+static int iadc_reset(struct iadc_chip *iadc)
+{
+	u8 data;
+	int ret;
+
+	ret = iadc_write(iadc, IADC_SEC_ACCESS, IADC_SEC_ACCESS_DATA);
+	if (ret < 0)
+		return ret;
+
+	ret = iadc_read(iadc, IADC_PERH_RESET_CTL3, &data);
+	if (ret < 0)
+		return ret;
+
+	ret = iadc_write(iadc, IADC_SEC_ACCESS, IADC_SEC_ACCESS_DATA);
+	if (ret < 0)
+		return ret;
+
+	data |= IADC_FOLLOW_WARM_RB;
+
+	return iadc_write(iadc, IADC_PERH_RESET_CTL3, data);
+}
+
+static int iadc_set_state(struct iadc_chip *iadc, bool state)
+{
+	return iadc_write(iadc, IADC_EN_CTL1, state ? IADC_EN_CTL1_SET : 0);
+}
+
+static void iadc_status_show(struct iadc_chip *iadc)
+{
+	u8 mode, sta1, chan, dig, en, req;
+	int ret;
+
+	ret = iadc_read(iadc, IADC_MODE_CTL, &mode);
+	if (ret < 0)
+		return;
+
+	ret = iadc_read(iadc, IADC_DIG_PARAM, &dig);
+	if (ret < 0)
+		return;
+
+	ret = iadc_read(iadc, IADC_CH_SEL_CTL, &chan);
+	if (ret < 0)
+		return;
+
+	ret = iadc_read(iadc, IADC_CONV_REQ, &req);
+	if (ret < 0)
+		return;
+
+	ret = iadc_read(iadc, IADC_STATUS1, &sta1);
+	if (ret < 0)
+		return;
+
+	ret = iadc_read(iadc, IADC_EN_CTL1, &en);
+	if (ret < 0)
+		return;
+
+	dev_err(iadc->dev,
+		"mode:%02x en:%02x chan:%02x dig:%02x req:%02x sta1:%02x\n",
+		mode, en, chan, dig, req, sta1);
+}
+
+static int iadc_configure(struct iadc_chip *iadc, int channel)
+{
+	u8 decim, mode;
+	int ret;
+
+	/* Mode selection */
+	mode = (IADC_OP_MODE_NORMAL << IADC_OP_MODE_SHIFT) | IADC_TRIM_EN;
+	ret = iadc_write(iadc, IADC_MODE_CTL, mode);
+	if (ret < 0)
+		return ret;
+
+	/* Channel selection */
+	ret = iadc_write(iadc, IADC_CH_SEL_CTL, channel);
+	if (ret < 0)
+		return ret;
+
+	/* Digital parameter setup */
+	decim = IADC_DEF_DECIMATION << IADC_DIG_DEC_RATIO_SEL_SHIFT;
+	ret = iadc_write(iadc, IADC_DIG_PARAM, decim);
+	if (ret < 0)
+		return ret;
+
+	/* HW settle time delay */
+	ret = iadc_write(iadc, IADC_HW_SETTLE_DELAY, IADC_DEF_HW_SETTLE_TIME);
+	if (ret < 0)
+		return ret;
+
+	ret = iadc_write(iadc, IADC_FAST_AVG_CTL, IADC_DEF_AVG_SAMPLES);
+	if (ret < 0)
+		return ret;
+
+	if (IADC_DEF_AVG_SAMPLES)
+		ret = iadc_write(iadc, IADC_FAST_AVG_EN, IADC_FAST_AVG_EN_SET);
+	else
+		ret = iadc_write(iadc, IADC_FAST_AVG_EN, 0);
+
+	if (ret < 0)
+		return ret;
+
+	if (!iadc->poll_eoc)
+		reinit_completion(&iadc->complete);
+
+	ret = iadc_set_state(iadc, true);
+	if (ret < 0)
+		return ret;
+
+	/* Request conversion */
+	return iadc_write(iadc, IADC_CONV_REQ, IADC_CONV_REQ_SET);
+}
+
+static int iadc_poll_wait_eoc(struct iadc_chip *iadc, unsigned int interval_us)
+{
+	unsigned int count, retry;
+	int ret;
+	u8 sta1;
+
+	retry = interval_us / IADC_CONV_TIME_MIN_US;
+
+	for (count = 0; count < retry; count++) {
+		ret = iadc_read(iadc, IADC_STATUS1, &sta1);
+		if (ret < 0)
+			return ret;
+
+		sta1 &= IADC_STATUS1_REQ_STS_EOC_MASK;
+		if (sta1 == IADC_STATUS1_EOC)
+			return 0;
+
+		usleep_range(IADC_CONV_TIME_MIN_US, IADC_CONV_TIME_MAX_US);
+	}
+
+	iadc_status_show(iadc);
+
+	return -ETIMEDOUT;
+}
+
+static int iadc_read_result(struct iadc_chip *iadc, u16 *data)
+{
+	return regmap_bulk_read(iadc->regmap, iadc->base + IADC_DATA, data, 2);
+}
+
+static int iadc_do_conversion(struct iadc_chip *iadc, int chan, u16 *data)
+{
+	unsigned int wait;
+	int ret;
+
+	ret = iadc_configure(iadc, chan);
+	if (ret < 0)
+		goto exit;
+
+	wait = BIT(IADC_DEF_AVG_SAMPLES) * IADC_CONV_TIME_MIN_US * 2;
+
+	if (iadc->poll_eoc) {
+		ret = iadc_poll_wait_eoc(iadc, wait);
+	} else {
+		ret = wait_for_completion_timeout(&iadc->complete, wait);
+		if (!ret)
+			ret = -ETIMEDOUT;
+		else
+			/* double check conversion status */
+			ret = iadc_poll_wait_eoc(iadc, IADC_CONV_TIME_MIN_US);
+	}
+
+	if (!ret)
+		ret = iadc_read_result(iadc, data);
+exit:
+	iadc_set_state(iadc, false);
+	if (ret < 0)
+		dev_err(iadc->dev, "conversion failed\n");
+
+	return ret;
+}
+
+static int iadc_read_raw(struct iio_dev *indio_dev,
+			 struct iio_chan_spec const *chan,
+			 int *val, int *val2, long mask)
+{
+	struct iadc_chip *iadc = iio_priv(indio_dev);
+	s32 isense_ua, vsense_uv;
+	u16 adc_raw, vsense_raw;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&iadc->lock);
+		ret = iadc_do_conversion(iadc, chan->channel, &adc_raw);
+		mutex_unlock(&iadc->lock);
+		if (ret < 0)
+			return ret;
+
+		vsense_raw = adc_raw - iadc->offset[chan->channel];
+
+		vsense_uv = vsense_raw * IADC_REF_GAIN_MICRO_VOLTS;
+		vsense_uv /= (s32)iadc->gain - iadc->offset[chan->channel];
+
+		isense_ua = vsense_uv / iadc->rsense[chan->channel];
+
+		dev_dbg(iadc->dev, "off %d gain %d adc %d %duV I %duA\n",
+			iadc->offset[chan->channel], iadc->gain,
+			adc_raw, vsense_uv, isense_ua);
+
+		*val = isense_ua;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info iadc_info = {
+	.read_raw = iadc_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static irqreturn_t iadc_isr(int irq, void *dev_id)
+{
+	struct iadc_chip *iadc = dev_id;
+
+	complete(&iadc->complete);
+
+	return IRQ_HANDLED;
+}
+
+static int iadc_update_offset(struct iadc_chip *iadc)
+{
+	int ret;
+
+	ret = iadc_do_conversion(iadc, IADC_GAIN_17P857MV, &iadc->gain);
+	if (ret < 0)
+		return ret;
+
+	ret = iadc_do_conversion(iadc, IADC_INT_OFFSET_CSP2_CSN2,
+				 &iadc->offset[IADC_INT_RSENSE]);
+	if (ret < 0)
+		return ret;
+
+	if (iadc->gain == iadc->offset[IADC_INT_RSENSE]) {
+		dev_err(iadc->dev, "error: internal offset == gain %d\n",
+			iadc->gain);
+		return -EINVAL;
+	}
+
+	ret = iadc_do_conversion(iadc, IADC_EXT_OFFSET_CSP_CSN,
+				 &iadc->offset[IADC_EXT_RSENSE]);
+	if (ret < 0)
+		return ret;
+
+	if (iadc->gain == iadc->offset[IADC_EXT_RSENSE]) {
+		dev_err(iadc->dev, "error: external offset == gain %d\n",
+			iadc->gain);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int iadc_version_check(struct iadc_chip *iadc)
+{
+	u8 val;
+	int ret;
+
+	ret = iadc_read(iadc, IADC_PERPH_TYPE, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val < IADC_PERPH_TYPE_ADC) {
+		dev_err(iadc->dev, "%d is not ADC\n", val);
+		return -EINVAL;
+	}
+
+	ret = iadc_read(iadc, IADC_PERPH_SUBTYPE, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val < IADC_PERPH_SUBTYPE_IADC) {
+		dev_err(iadc->dev, "%d is not IADC\n", val);
+		return -EINVAL;
+	}
+
+	ret = iadc_read(iadc, IADC_REVISION2, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val < IADC_REVISION2_SUPPORTED_IADC) {
+		dev_err(iadc->dev, "revision %d not supported\n", val);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int iadc_rsense_read(struct iadc_chip *iadc, struct device_node *node)
+{
+	int ret, sign, int_sense;
+	u8 deviation;
+
+	ret = of_property_read_u32(node, "qcom,external-resistor-micro-ohms",
+				   &iadc->rsense[IADC_EXT_RSENSE]);
+	if (ret < 0)
+		iadc->rsense[IADC_EXT_RSENSE] = IADC_INT_RSENSE_IDEAL_VALUE;
+
+	if (!iadc->rsense[IADC_EXT_RSENSE]) {
+		dev_err(iadc->dev, "external resistor can't be zero Ohms");
+		return -EINVAL;
+	}
+
+	ret = iadc_read(iadc, IADC_NOMINAL_RSENSE, &deviation);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Deviation value stored is an offset from 10 mili Ohms, bit 7 is
+	 * the sign, the remaining bits have an LSB of 15625 nano Ohms.
+	 */
+	sign = (deviation & IADC_NOMINAL_RSENSE_SIGN_MASK) ? -1 : 1;
+
+	deviation &= ~IADC_NOMINAL_RSENSE_SIGN_MASK;
+
+	/* Scale it to nono Ohms */
+	int_sense = IADC_INT_RSENSE_IDEAL_VALUE * 1000;
+	int_sense += sign * deviation * IADC_INT_RSENSE_DEVIATION;
+	int_sense /= 1000; /* micro Ohms */
+
+	iadc->rsense[IADC_INT_RSENSE] = int_sense;
+	return 0;
+}
+
+static const struct iio_chan_spec iadc_channels[] = {
+	{
+		.type = IIO_CURRENT,
+		.datasheet_name	= "INTERNAL_RSENSE",
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.indexed = 1,
+	},
+	{
+		.type = IIO_CURRENT,
+		.datasheet_name	= "EXTERNAL_RSENSE",
+		.channel = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.indexed = 1,
+	},
+};
+
+static int iadc_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct iadc_chip *iadc;
+	int ret, irq_eoc;
+	u32 res;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*iadc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	iadc = iio_priv(indio_dev);
+	iadc->dev = dev;
+
+	iadc->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!iadc->regmap)
+		return -ENODEV;
+
+	init_completion(&iadc->complete);
+	mutex_init(&iadc->lock);
+
+	ret = of_property_read_u32(node, "reg", &res);
+	if (ret < 0)
+		return -ENODEV;
+
+	iadc->base = res;
+
+	ret = iadc_version_check(iadc);
+	if (ret < 0)
+		return -ENODEV;
+
+	ret = iadc_rsense_read(iadc, node);
+	if (ret < 0)
+		return -ENODEV;
+
+	dev_dbg(iadc->dev, "sense resistors %d and %d micro Ohm\n",
+		iadc->rsense[IADC_INT_RSENSE],
+		iadc->rsense[IADC_EXT_RSENSE]);
+
+	irq_eoc = platform_get_irq(pdev, 0);
+	if (irq_eoc == -EPROBE_DEFER)
+		return irq_eoc;
+
+	if (irq_eoc < 0)
+		iadc->poll_eoc = true;
+
+	ret = iadc_reset(iadc);
+	if (ret < 0) {
+		dev_err(dev, "reset failed\n");
+		return ret;
+	}
+
+	if (!iadc->poll_eoc) {
+		ret = devm_request_irq(dev, irq_eoc, iadc_isr, 0,
+					"spmi-iadc", iadc);
+		if (!ret)
+			enable_irq_wake(irq_eoc);
+		else
+			return ret;
+	} else {
+		device_init_wakeup(iadc->dev, 1);
+	}
+
+	ret = iadc_update_offset(iadc);
+	if (ret < 0) {
+		dev_err(dev, "failed offset calibration\n");
+		return ret;
+	}
+
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = node;
+	indio_dev->name = pdev->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &iadc_info;
+	indio_dev->channels = iadc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(iadc_channels);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id iadc_match_table[] = {
+	{ .compatible = "qcom,spmi-iadc" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, iadc_match_table);
+
+static struct platform_driver iadc_driver = {
+	.driver = {
+		   .name = "qcom-spmi-iadc",
+		   .of_match_table = iadc_match_table,
+	},
+	.probe = iadc_probe,
+};
+
+module_platform_driver(iadc_driver);
+
+MODULE_ALIAS("platform:qcom-spmi-iadc");
+MODULE_DESCRIPTION("Qualcomm SPMI PMIC current ADC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Ivan T. Ivanov <iivanov@mm-sol.com>");