[PATCH v2 0/2] Add Richtek RTQ6056 support

[PATCH v2 0/2] Add Richtek RTQ6056 support

[cy_huang]

From: ChiYuan Huang <cy_huang@richtek.com>

This patch series is to enable Richtek RTQ6056 support.

The RTQ6056 is a high accuracy current-sense monitor with I2C interface, and
the device provides full information for system by reading out the load current
and power.

Since v2
- Change the resistor property name to be generic 'shunt-resistor-micro-ohms'.
- Rename file from 'rtq6056-adc' to 'rtq6056'.
- Refine the ABI, if generic already defined it, remove it and check the channel
  report unit.
- Add copyright text.
- include the correct header.
- change the property parsing name.
- To use iio_chan_spec address field.
- Refine each channel separate and shared_by_all.
- Use pm_runtime and pm_runtime_autosuspend.
- Remove the shutdown callback. From the HW suggestion, it's not recommended to
  use battery as the power supply.
- Check all scale unit (voltage->mV, current->mA, power->milliWatt).
- Use the read_avail to provide the interface for attribute value list.
- Add comma for the last element in the const integer array.
- Refine each ADC label text.
- In read_label callback, replace snprintf to sysfs_emit.


ChiYuan Huang (2):
  dt-bindings: iio: adc: Add rtq6056 adc support
  iio: adc: Add rtq6056 support

 .../ABI/testing/sysfs-bus-iio-adc-rtq6056          |   6 +
 .../bindings/iio/adc/richtek,rtq6056.yaml          |  56 ++
 drivers/iio/adc/Kconfig                            |  15 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rtq6056.c                          | 670 +++++++++++++++++++++
 5 files changed, 748 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-rtq6056
 create mode 100644 Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
 create mode 100644 drivers/iio/adc/rtq6056.c

-- 
2.7.4

[PATCH v2 1/2] dt-bindings: iio: adc: Add rtq6056 adc support

[cy_huang]

From: ChiYuan Huang <cy_huang@richtek.com>

Add the documentation for Richtek rtq6056.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
---
Since v2
- Change the resistor property name to be generic 'shunt-resistor-micro-ohms'.

---
 .../bindings/iio/adc/richtek,rtq6056.yaml          | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
new file mode 100644
index 00000000..fe45d8b
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/richtek,rtq6056.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RTQ6056 Bi-Directional Current and Power Monitor with 16-bit ADC
+
+maintainers:
+  - ChiYuan Huang <cy_huang@richtek.com>
+
+description: |
+  The RTQ6056 is a high accuracy current-sense monitor with I2C and SMBus
+  interface, and the device provides full information for system by reading
+  out the loading current and power.
+
+  The device monitors both of the drops across sense resistor and the BUS
+  voltage, converts into the current in amperes, and power in watts through
+  internal analog-to-digital converter ADC. The programmable calibration,
+  adjustable conversion time, and averaging function are also built in for
+  more design flexibility.
+
+  Datasheet is available at
+  https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
+
+properties:
+  compatible:
+    const: richtek,rtq6056
+
+  reg:
+    maxItems: 1
+
+  "#io-channel-cells":
+    const: 1
+
+  shunt-resistor-micro-ohms:
+    description: Shunt IN+/IN- sensing node resistor
+
+required:
+  - compatible
+  - reg
+  - "#io-channel-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      rtq6056@40 {
+        compatible = "richtek,rtq6056";
+        reg = <0x40>;
+        #io-channel-cells = <1>;
+      };
+    };
-- 
2.7.4

[PATCH v2 2/2] iio: adc: Add rtq6056 support

[cy_huang]

From: ChiYuan Huang <cy_huang@richtek.com>

Add Richtek rtq6056 supporting.

It can be used for the system to monitor load current and power with 16-bit
resolution.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
---
Since v2
- Rename file from 'rtq6056-adc' to 'rtq6056'.
- Refine the ABI, if generic already defined it, remove it and check the channel
  report unit.
- Add copyright text.
- include the correct header.
- change the property parsing name.
- To use iio_chan_spec address field.
- Refine each channel separate and shared_by_all.
- Use pm_runtime and pm_runtime_autosuspend.
- Remove the shutdown callback. From the HW suggestion, it's not recommended to
  use battery as the power supply.
- Check all scale unit (voltage->mV, current->mA, power->milliWatt).
- Use the read_avail to provide the interface for attribute value list.
- Add comma for the last element in the const integer array.
- Refine each ADC label text.
- In read_label callback, replace snprintf to sysfs_emit.

---
 .../ABI/testing/sysfs-bus-iio-adc-rtq6056          |   6 +
 drivers/iio/adc/Kconfig                            |  15 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/rtq6056.c                          | 670 +++++++++++++++++++++
 4 files changed, 692 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-rtq6056
 create mode 100644 drivers/iio/adc/rtq6056.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-rtq6056 b/Documentation/ABI/testing/sysfs-bus-iio-adc-rtq6056
new file mode 100644
index 00000000..db54343
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-rtq6056
@@ -0,0 +1,6 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage0_integration_time
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage1_integration_time
+KernelVersion:	5.15.31
+Contact:	cy_huang@richtek.com
+Description:
+		Each voltage conversion time in uS
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 48ace74..caebd1a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -908,6 +908,21 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config RICHTEK_RTQ6056
+	tristate "Richtek RTQ6056 Current and Power Monitor ADC"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to enable RQT6056 ADC support.
+	  RTQ6056 is a high accuracy current-sense monitor with I2C and SMBus
+	  compatible interface, and the device provides full information for
+	  system by reading out the load current and power.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called rtq6056.
+
 config RZG2L_ADC
 	tristate "Renesas RZ/G2L ADC driver"
 	depends on ARCH_RZG2L || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 39d806f..cda7580 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -84,6 +84,7 @@ 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-$(CONFIG_RICHTEK_RTQ6056) += rtq6056.o
 obj-$(CONFIG_RZG2L_ADC) += rzg2l_adc.o
 obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
 obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
diff --git a/drivers/iio/adc/rtq6056.c b/drivers/iio/adc/rtq6056.c
new file mode 100644
index 00000000..80b9c5f
--- /dev/null
+++ b/drivers/iio/adc/rtq6056.c
@@ -0,0 +1,670 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Richtek Technology Corp.
+ *
+ * ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/util_macros.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define RTQ6056_REG_CONFIG	0x00
+#define RTQ6056_REG_SHUNTVOLT	0x01
+#define RTQ6056_REG_BUSVOLT	0x02
+#define RTQ6056_REG_POWER	0x03
+#define RTQ6056_REG_CURRENT	0x04
+#define RTQ6056_REG_CALIBRATION	0x05
+#define RTQ6056_REG_MASKENABLE	0x06
+#define RTQ6056_REG_ALERTLIMIT	0x07
+#define RTQ6056_REG_MANUFACTID	0xFE
+#define RTQ6056_REG_DIEID	0xFF
+
+#define RTQ6056_VENDOR_ID	0x1214
+#define RTQ6056_DEFAULT_CONFIG	0x4127
+#define RTQ6056_CONT_ALLON	7
+
+enum {
+	RTQ6056_CH_VSHUNT = 0,
+	RTQ6056_CH_VBUS,
+	RTQ6056_CH_POWER,
+	RTQ6056_CH_CURRENT,
+	RTQ6056_MAX_CHANNEL
+};
+
+enum {
+	F_OPMODE = 0,
+	F_VSHUNTCT,
+	F_VBUSCT,
+	F_AVG,
+	F_RESET,
+	F_MAX_FIELDS
+};
+
+struct rtq6056_priv {
+	struct device *dev;
+	struct regmap *regmap;
+	struct regmap_field *rm_fields[F_MAX_FIELDS];
+	u32 shunt_resistor_uohm;
+	int vshuntct_us;
+	int vbusct_us;
+	int avg_sample;
+};
+
+static const struct reg_field rtq6056_reg_fields[F_MAX_FIELDS] = {
+	[F_OPMODE] = REG_FIELD(RTQ6056_REG_CONFIG, 0, 2),
+	[F_VSHUNTCT] = REG_FIELD(RTQ6056_REG_CONFIG, 3, 5),
+	[F_VBUSCT] = REG_FIELD(RTQ6056_REG_CONFIG, 6, 8),
+	[F_AVG]	= REG_FIELD(RTQ6056_REG_CONFIG, 9, 11),
+	[F_RESET] = REG_FIELD(RTQ6056_REG_CONFIG, 15, 15),
+};
+
+static const struct iio_chan_spec rtq6056_channels[RTQ6056_MAX_CHANNEL + 1] = {
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 0,
+		.address = RTQ6056_REG_SHUNTVOLT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+					   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 1,
+		.address = RTQ6056_REG_BUSVOLT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+					   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_POWER,
+		.indexed = 1,
+		.channel = 2,
+		.address = RTQ6056_REG_POWER,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+					   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 2,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_CURRENT,
+		.indexed = 1,
+		.channel = 3,
+		.address = RTQ6056_REG_CURRENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+					   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.scan_index = 3,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(RTQ6056_MAX_CHANNEL),
+};
+
+static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
+				    struct iio_chan_spec const *ch,
+				    int *val)
+{
+	struct device *dev = priv->dev;
+	unsigned int addr = ch->address;
+	unsigned int regval;
+	int ret;
+
+	pm_runtime_get_sync(dev);
+
+	ret = regmap_read(priv->regmap, addr, &regval);
+	if (ret) {
+		pm_runtime_put(dev);
+		return ret;
+	}
+
+	/* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
+	if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
+		*val = regval;
+	else
+		*val = sign_extend32(regval, 16);
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put(dev);
+
+	return IIO_VAL_INT;
+}
+
+static int rtq6056_adc_read_scale(struct iio_chan_spec const *ch, int *val,
+				  int *val2)
+{
+	switch (ch->address) {
+	case RTQ6056_REG_SHUNTVOLT:
+		/* VSHUNT lsb  2.5uV */
+		*val = 2500;
+		*val2 = 1000000000;
+		return IIO_VAL_FRACTIONAL;
+	case RTQ6056_REG_BUSVOLT:
+		/* VBUS lsb 1.25mV */
+		*val = 1250;
+		*val2 = 1000;
+		return IIO_VAL_FRACTIONAL;
+	case RTQ6056_REG_POWER:
+		/* Power lsb 25mV */
+		*val = 25;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * Conversion time in uS for channel VSHUNT and VBUS. The indices correspond
+ * with the bit value expected by the chip. And it can be found at
+ * https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
+ */
+static const int rtq6056_conv_time_list[] = {
+	139, 203, 269, 525, 1037, 2061, 4109, 8205,
+};
+
+static int rtq6056_adc_set_conv_time(struct rtq6056_priv *priv,
+				     struct iio_chan_spec const *ch,
+				     int val)
+{
+	struct regmap_field *rm_field;
+	unsigned int selector;
+	int *ct, ret;
+
+	if (val > 8205 || val < 139)
+		return -EINVAL;
+
+	if (ch->address == RTQ6056_REG_SHUNTVOLT) {
+		rm_field = priv->rm_fields[F_VSHUNTCT];
+		ct = &priv->vshuntct_us;
+	} else {
+		rm_field = priv->rm_fields[F_VBUSCT];
+		ct = &priv->vbusct_us;
+	}
+
+	selector = find_closest(val, rtq6056_conv_time_list,
+				ARRAY_SIZE(rtq6056_conv_time_list));
+
+	ret = regmap_field_write(rm_field, selector);
+	if (ret)
+		return ret;
+
+	*ct = rtq6056_conv_time_list[selector];
+
+	return 0;
+}
+
+/*
+ * Available averaging rate for rtq6056. The indices correspond with the bit
+ * value expected by the chip. And it can be found at
+ * https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
+ */
+static const int rtq6056_avg_sample_list[] = {
+	1, 4, 16, 64, 128, 256, 512, 1024,
+};
+
+static int rtq6056_adc_set_average(struct rtq6056_priv *priv, int val)
+{
+	unsigned int selector;
+	int ret;
+
+	if (val > 1024 || val < 1)
+		return -EINVAL;
+
+	selector = find_closest(val, rtq6056_avg_sample_list,
+				ARRAY_SIZE(rtq6056_avg_sample_list));
+
+	ret = regmap_field_write(priv->rm_fields[F_AVG], selector);
+	if (ret)
+		return ret;
+
+	priv->avg_sample = rtq6056_avg_sample_list[selector];
+
+	return 0;
+}
+
+static int rtq6056_adc_get_sample_freq(struct rtq6056_priv *priv, int *val)
+{
+	int sample_time;
+
+	sample_time = priv->vshuntct_us + priv->vbusct_us;
+	sample_time *= priv->avg_sample;
+
+	*val = DIV_ROUND_UP(1000000, sample_time);
+
+	return IIO_VAL_INT;
+}
+
+static int rtq6056_adc_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan, int *val,
+				int *val2, long mask)
+{
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return rtq6056_adc_read_channel(priv, chan, val);
+	case IIO_CHAN_INFO_SCALE:
+		return rtq6056_adc_read_scale(chan, val, val2);
+	case IIO_CHAN_INFO_INT_TIME:
+		if (chan->address == RTQ6056_REG_SHUNTVOLT)
+			*val = priv->vshuntct_us;
+		else
+			*val = priv->vbusct_us;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = priv->avg_sample;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return rtq6056_adc_get_sample_freq(priv, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rtq6056_adc_read_avail(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan,
+				  const int **vals, int *type, int *length,
+				  long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		*vals = rtq6056_conv_time_list;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(rtq6056_conv_time_list);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = rtq6056_avg_sample_list;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(rtq6056_avg_sample_list);
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int rtq6056_adc_write_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan, int val,
+				 int val2, long mask)
+{
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		return rtq6056_adc_set_conv_time(priv, chan, val);
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return rtq6056_adc_set_average(priv, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const char *rtq6056_channel_labels[RTQ6056_MAX_CHANNEL] = {
+	[RTQ6056_CH_VSHUNT] = "Vshunt",
+	[RTQ6056_CH_VBUS] = "Vbus",
+	[RTQ6056_CH_POWER] = "Power",
+	[RTQ6056_CH_CURRENT] = "Current",
+};
+
+static int rtq6056_adc_read_label(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan,
+				  char *label)
+{
+	return sysfs_emit(label, "%s\n", rtq6056_channel_labels[chan->channel]);
+}
+
+static int rtq6056_set_shunt_resistor(struct rtq6056_priv *priv,
+				      int resistor_uohm)
+{
+	unsigned int calib_val;
+	int ret;
+
+	if (resistor_uohm <= 0) {
+		dev_err(priv->dev, "Invalid resistor [%d]\n", resistor_uohm);
+		return -EINVAL;
+	}
+
+	/* calibration = 5120000 / (Rshunt (uohm) * current lsb (1mA)) */
+	calib_val = 5120000 / resistor_uohm;
+	ret = regmap_write(priv->regmap, RTQ6056_REG_CALIBRATION, calib_val);
+	if (ret)
+		return ret;
+
+	priv->shunt_resistor_uohm = resistor_uohm;
+
+	return 0;
+}
+
+static ssize_t shunt_resistor_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct rtq6056_priv *priv = iio_priv(dev_to_iio_dev(dev));
+	int vals[2] = { priv->shunt_resistor_uohm, 1000000 };
+
+	return iio_format_value(buf, IIO_VAL_FRACTIONAL, 1, vals);
+}
+
+static ssize_t shunt_resistor_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+	int val, val_fract, ret;
+
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
+	ret = iio_str_to_fixpoint(buf, 100000, &val, &val_fract);
+	if (ret)
+		return ret;
+
+	ret = rtq6056_set_shunt_resistor(priv, val * 1000000 + val_fract);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR_RW(shunt_resistor, 0);
+
+static struct attribute *rtq6056_attributes[] = {
+	&iio_dev_attr_shunt_resistor.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group rtq6056_attribute_group = {
+	.attrs = rtq6056_attributes,
+};
+
+static const struct iio_info rtq6056_info = {
+	.attrs = &rtq6056_attribute_group,
+	.read_raw = rtq6056_adc_read_raw,
+	.read_avail = rtq6056_adc_read_avail,
+	.write_raw = rtq6056_adc_write_raw,
+	.read_label = rtq6056_adc_read_label,
+};
+
+static irqreturn_t rtq6056_buffer_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct rtq6056_priv *priv = iio_priv(indio_dev);
+	struct device *dev = priv->dev;
+	struct {
+		u16 vals[RTQ6056_MAX_CHANNEL];
+		int64_t timestamp;
+	} data __aligned(8);
+	unsigned int raw;
+	int i = 0, bit, ret;
+
+	memset(&data, 0, sizeof(data));
+
+	pm_runtime_get_sync(dev);
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) {
+		unsigned int addr = rtq6056_channels[bit].address;
+
+		ret = regmap_read(priv->regmap, addr, &raw);
+		if (ret)
+			goto out;
+
+		data.vals[i++] = raw;
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &data, iio_get_time_ns(indio_dev));
+
+out:
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put(dev);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static bool rtq6056_is_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case RTQ6056_REG_CONFIG ... RTQ6056_REG_ALERTLIMIT:
+	case RTQ6056_REG_MANUFACTID ... RTQ6056_REG_DIEID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool rtq6056_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case RTQ6056_REG_CONFIG:
+	case RTQ6056_REG_CALIBRATION ... RTQ6056_REG_ALERTLIMIT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config rtq6056_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.val_format_endian = REGMAP_ENDIAN_BIG,
+	.max_register = RTQ6056_REG_DIEID,
+	.readable_reg = rtq6056_is_readable_reg,
+	.writeable_reg = rtq6056_is_writeable_reg,
+};
+
+static int rtq6056_probe(struct i2c_client *i2c)
+{
+	struct iio_dev *indio_dev;
+	struct rtq6056_priv *priv;
+	struct device *dev = &i2c->dev;
+	struct regmap *regmap;
+	unsigned int vendor_id, shunt_resistor_uohm;
+	int ret;
+
+	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -EOPNOTSUPP;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(indio_dev);
+	priv->dev = dev;
+	priv->vshuntct_us = priv->vbusct_us = 1037;
+	priv->avg_sample = 1;
+	i2c_set_clientdata(i2c, priv);
+
+	regmap = devm_regmap_init_i2c(i2c, &rtq6056_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "Failed to init regmap\n");
+
+	priv->regmap = regmap;
+
+	ret = regmap_read(regmap, RTQ6056_REG_MANUFACTID, &vendor_id);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to get manufacturer info\n");
+
+	if (vendor_id != RTQ6056_VENDOR_ID)
+		return dev_err_probe(dev, -ENODEV,
+				     "Invalid vendor id 0x%04x\n", vendor_id);
+
+	ret = devm_regmap_field_bulk_alloc(dev, regmap, priv->rm_fields,
+					   rtq6056_reg_fields, F_MAX_FIELDS);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to init regmap field\n");
+
+	/*
+	 * By default, configure average sample as 1, bus and shunt conversion
+	 * timea as 1037 microsecond, and operating mode to all on.
+	 */
+	ret = regmap_write(regmap, RTQ6056_REG_CONFIG, RTQ6056_DEFAULT_CONFIG);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable continuous sensing\n");
+
+	pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_enable(dev);
+
+	/* By default, use 2000 micro-ohm resistor */
+	shunt_resistor_uohm = 2000;
+	device_property_read_u32(dev, "shunt-resistor-micro-ohms",
+				 &shunt_resistor_uohm);
+
+	ret = rtq6056_set_shunt_resistor(priv, shunt_resistor_uohm);
+	if (ret) {
+		dev_err(dev, "Failed to init shunt resistor\n");
+		goto err_probe;
+	}
+
+	indio_dev->name = "rtq6056";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = rtq6056_channels;
+	indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
+	indio_dev->info = &rtq6056_info;
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+					      rtq6056_buffer_trigger_handler,
+					      NULL);
+	if (ret) {
+		dev_err(dev, "Failed to allocate iio trigger buffer\n");
+		goto err_probe;
+	}
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret) {
+		dev_err(dev, "Failed to allocate iio device\n");
+		goto err_probe;
+	}
+
+	return 0;
+
+err_probe:
+	pm_runtime_dont_use_autosuspend(dev);
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+
+	return ret;
+}
+
+static int rtq6056_remove(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+
+	pm_runtime_dont_use_autosuspend(dev);
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+
+	return 0;
+}
+
+static int rtq6056_runtime_suspend(struct device *dev)
+{
+	struct rtq6056_priv *priv = dev_get_drvdata(dev);
+
+	/* Configure to shutdown mode */
+	return regmap_field_write(priv->rm_fields[F_OPMODE], 0);
+}
+
+static int rtq6056_runtime_resume(struct device *dev)
+{
+	struct rtq6056_priv *priv = dev_get_drvdata(dev);
+	int sample_rdy_time_us, ret;
+
+	ret = regmap_field_write(priv->rm_fields[F_OPMODE], RTQ6056_CONT_ALLON);
+	if (ret)
+		return ret;
+
+	sample_rdy_time_us = priv->vbusct_us + priv->vshuntct_us;
+	sample_rdy_time_us *= priv->avg_sample;
+
+	usleep_range(sample_rdy_time_us, sample_rdy_time_us + 100);
+
+	return 0;
+}
+
+static const struct dev_pm_ops rtq6056_pm_ops = {
+	SET_RUNTIME_PM_OPS(rtq6056_runtime_suspend, rtq6056_runtime_resume, NULL)
+};
+
+static const struct of_device_id rtq6056_device_match[] = {
+	{ .compatible = "richtek,rtq6056", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rtq6056_device_match);
+
+static struct i2c_driver rtq6056_driver = {
+	.driver = {
+		.name = "rtq6056",
+		.of_match_table = rtq6056_device_match,
+		.pm = &rtq6056_pm_ops,
+	},
+	.probe_new = rtq6056_probe,
+	.remove = rtq6056_remove,
+};
+module_i2c_driver(rtq6056_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RTQ6056 Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Re: [PATCH v2 1/2] dt-bindings: iio: adc: Add rtq6056 adc support

[Krzysztof Kozlowski]

On 29/06/2022 04:20, cy_huang wrote:
> From: ChiYuan Huang <cy_huang@richtek.com>
> 
> Add the documentation for Richtek rtq6056.
> 
> Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> ---
> Since v2
> - Change the resistor property name to be generic 'shunt-resistor-micro-ohms'.
> 
> ---
>  .../bindings/iio/adc/richtek,rtq6056.yaml          | 56 ++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> new file mode 100644
> index 00000000..fe45d8b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> @@ -0,0 +1,56 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/richtek,rtq6056.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: RTQ6056 Bi-Directional Current and Power Monitor with 16-bit ADC
> +
> +maintainers:
> +  - ChiYuan Huang <cy_huang@richtek.com>
> +
> +description: |
> +  The RTQ6056 is a high accuracy current-sense monitor with I2C and SMBus
> +  interface, and the device provides full information for system by reading
> +  out the loading current and power.
> +
> +  The device monitors both of the drops across sense resistor and the BUS
> +  voltage, converts into the current in amperes, and power in watts through
> +  internal analog-to-digital converter ADC. The programmable calibration,
> +  adjustable conversion time, and averaging function are also built in for
> +  more design flexibility.
> +
> +  Datasheet is available at
> +  https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
> +
> +properties:
> +  compatible:
> +    const: richtek,rtq6056
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#io-channel-cells":
> +    const: 1
> +
> +  shunt-resistor-micro-ohms:
> +    description: Shunt IN+/IN- sensing node resistor
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#io-channel-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +      rtq6056@40 {

This was not fixed.


Best regards,
Krzysztof

Re: [PATCH v2 1/2] dt-bindings: iio: adc: Add rtq6056 adc support

[ChiYuan Huang]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> 於 2022年6月29日 週三 下午4:25寫道：
>
> On 29/06/2022 04:20, cy_huang wrote:
> > From: ChiYuan Huang <cy_huang@richtek.com>
> >
> > Add the documentation for Richtek rtq6056.
> >
> > Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> > ---
> > Since v2
> > - Change the resistor property name to be generic 'shunt-resistor-micro-ohms'.
> >
> > ---
> >  .../bindings/iio/adc/richtek,rtq6056.yaml          | 56 ++++++++++++++++++++++
> >  1 file changed, 56 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> > new file mode 100644
> > index 00000000..fe45d8b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> > @@ -0,0 +1,56 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/adc/richtek,rtq6056.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: RTQ6056 Bi-Directional Current and Power Monitor with 16-bit ADC
> > +
> > +maintainers:
> > +  - ChiYuan Huang <cy_huang@richtek.com>
> > +
> > +description: |
> > +  The RTQ6056 is a high accuracy current-sense monitor with I2C and SMBus
> > +  interface, and the device provides full information for system by reading
> > +  out the loading current and power.
> > +
> > +  The device monitors both of the drops across sense resistor and the BUS
> > +  voltage, converts into the current in amperes, and power in watts through
> > +  internal analog-to-digital converter ADC. The programmable calibration,
> > +  adjustable conversion time, and averaging function are also built in for
> > +  more design flexibility.
> > +
> > +  Datasheet is available at
> > +  https://www.richtek.com/assets/product_file/RTQ6056/DSQ6056-00.pdf
> > +
> > +properties:
> > +  compatible:
> > +    const: richtek,rtq6056
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  "#io-channel-cells":
> > +    const: 1
> > +
> > +  shunt-resistor-micro-ohms:
> > +    description: Shunt IN+/IN- sensing node resistor
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "#io-channel-cells"
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    i2c {
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      rtq6056@40 {
>
> This was not fixed.
>
Sorry, too many changes to check. I really forgot it.
>
> Best regards,
> Krzysztof

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[Andy Shevchenko]

On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:

> Add Richtek rtq6056 supporting.
>
> It can be used for the system to monitor load current and power with 16-bit
> resolution.

...

> +static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
> +                                   struct iio_chan_spec const *ch,
> +                                   int *val)
> +{
> +       struct device *dev = priv->dev;
> +       unsigned int addr = ch->address;
> +       unsigned int regval;
> +       int ret;
> +
> +       pm_runtime_get_sync(dev);
> +
> +       ret = regmap_read(priv->regmap, addr, &regval);
> +       if (ret) {
> +               pm_runtime_put(dev);
> +               return ret;
> +       }

You can optimize this to

       pm_runtime_get_sync(dev);
       ret = regmap_read(priv->regmap, addr, &regval);
       pm_runtime_mark_last_busy(dev);
       pm_runtime_put(dev);
       if (ret)
           return ret;

> +       /* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
> +       if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
> +               *val = regval;
> +       else
> +               *val = sign_extend32(regval, 16);

> +       pm_runtime_mark_last_busy(dev);
> +       pm_runtime_put(dev);

...and get rid of these.

> +       return IIO_VAL_INT;
> +}

...

> +               *val2 = 1000000000;

NANO ?

...

> +               *val2 = 1000;

MILLI ?

> +       *val = DIV_ROUND_UP(1000000, sample_time);

USEC_PER_SEC ?

> +
> +       return IIO_VAL_INT;
> +}

...

> +static int rtq6056_adc_read_label(struct iio_dev *indio_dev,
> +                                 struct iio_chan_spec const *chan,
> +                                 char *label)
> +{
> +       return sysfs_emit(label, "%s\n", rtq6056_channel_labels[chan->channel]);
> +}

...

> +       /* calibration = 5120000 / (Rshunt (uohm) * current lsb (1mA)) */

uOhm

...

> +static ssize_t shunt_resistor_show(struct device *dev,
> +                                  struct device_attribute *attr, char *buf)
> +{
> +       struct rtq6056_priv *priv = iio_priv(dev_to_iio_dev(dev));
> +       int vals[2] = { priv->shunt_resistor_uohm, 1000000 };

MICRO ?

> +       return iio_format_value(buf, IIO_VAL_FRACTIONAL, 1, vals);
> +}

...

> +       ret = rtq6056_set_shunt_resistor(priv, val * 1000000 + val_fract);

MICRO ?

> +       if (ret)
> +               return ret;

...

> +       struct {
> +               u16 vals[RTQ6056_MAX_CHANNEL];
> +               int64_t timestamp;
> +       } data __aligned(8);

Hmm... alignment of this struct will be at least 4 bytes, but
shouldn't we rather be sure that the timestamp member is aligned
properly? Otherwise this seems fragile and dependent on
RTQ6056_MAX_CHANNEL % 4 == 0.

...

> +       pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
> +       pm_runtime_use_autosuspend(dev);
> +       pm_runtime_set_active(dev);
> +       pm_runtime_mark_last_busy(dev);
> +       pm_runtime_enable(dev);
> +
> +       /* By default, use 2000 micro-ohm resistor */
> +       shunt_resistor_uohm = 2000;
> +       device_property_read_u32(dev, "shunt-resistor-micro-ohms",
> +                                &shunt_resistor_uohm);
> +
> +       ret = rtq6056_set_shunt_resistor(priv, shunt_resistor_uohm);
> +       if (ret) {
> +               dev_err(dev, "Failed to init shunt resistor\n");
> +               goto err_probe;

return dev_err_probe();

(see below how)

> +       }
> +
> +       indio_dev->name = "rtq6056";
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +       indio_dev->channels = rtq6056_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
> +       indio_dev->info = &rtq6056_info;
> +
> +       ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> +                                             rtq6056_buffer_trigger_handler,
> +                                             NULL);
> +       if (ret) {
> +               dev_err(dev, "Failed to allocate iio trigger buffer\n");

Ditto.

> +               goto err_probe;

It is a sign of wrong ordering, either do not use devm_ calls after
non-devm_ or make the latter wrapped into devm_add_action_or_reset().
See below for additional information.

> +       }
> +
> +       ret = devm_iio_device_register(dev, indio_dev);
> +       if (ret) {
> +               dev_err(dev, "Failed to allocate iio device\n");
> +               goto err_probe;
> +       }
> +
> +       return 0;
> +
> +err_probe:
> +       pm_runtime_dont_use_autosuspend(dev);
> +       pm_runtime_disable(dev);
> +       pm_runtime_set_suspended(dev);
> +
> +       return ret;

...

> +static int rtq6056_remove(struct i2c_client *i2c)
> +{
> +       struct device *dev = &i2c->dev;

Another (but usually not good option) is to call devm_..._unregister() here.

> +       pm_runtime_dont_use_autosuspend(dev);
> +       pm_runtime_disable(dev);
> +       pm_runtime_set_suspended(dev);
> +
> +       return 0;
> +}

...

> +static const struct dev_pm_ops rtq6056_pm_ops = {
> +       SET_RUNTIME_PM_OPS(rtq6056_runtime_suspend, rtq6056_runtime_resume, NULL)

RUNTIME_PM_OPS()

> +};

...

> +static const struct of_device_id rtq6056_device_match[] = {
> +       { .compatible = "richtek,rtq6056", },

In this case the inner comma is not needed.

> +       {}
> +};

...

> +static struct i2c_driver rtq6056_driver = {
> +       .driver = {
> +               .name = "rtq6056",
> +               .of_match_table = rtq6056_device_match,

> +               .pm = &rtq6056_pm_ops,

pm_ptr()

> +       },

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[ChiYuan Huang]

Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
>
> On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:
>
> > Add Richtek rtq6056 supporting.
> >
> > It can be used for the system to monitor load current and power with 16-bit
> > resolution.
>
> ...
>
> > +static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
> > +                                   struct iio_chan_spec const *ch,
> > +                                   int *val)
> > +{
> > +       struct device *dev = priv->dev;
> > +       unsigned int addr = ch->address;
> > +       unsigned int regval;
> > +       int ret;
> > +
> > +       pm_runtime_get_sync(dev);
> > +
> > +       ret = regmap_read(priv->regmap, addr, &regval);
> > +       if (ret) {
> > +               pm_runtime_put(dev);
> > +               return ret;
> > +       }
>
> You can optimize this to
>
>        pm_runtime_get_sync(dev);
>        ret = regmap_read(priv->regmap, addr, &regval);
>        pm_runtime_mark_last_busy(dev);
>        pm_runtime_put(dev);
>        if (ret)
>            return ret;
>
> > +       /* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
> > +       if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
> > +               *val = regval;
> > +       else
> > +               *val = sign_extend32(regval, 16);
>
> > +       pm_runtime_mark_last_busy(dev);
> > +       pm_runtime_put(dev);
>
> ...and get rid of these.
>
> > +       return IIO_VAL_INT;
> > +}
>
> ...
>
> > +               *val2 = 1000000000;
>
> NANO ?
>
Yes, unit is 2.5 microvolt. I have all listed all unit comments in the
source code.
> ...
>
> > +               *val2 = 1000;
>
> MILLI ?
>
Yes.
> > +       *val = DIV_ROUND_UP(1000000, sample_time);
>
> USEC_PER_SEC ?
>
No, sample time is (vshunt convesion time + vbus conversion time) *
average sample.
And the sample freq returns the unit by HZ (sample frequency per second)

> > +
> > +       return IIO_VAL_INT;
> > +}
>
> ...
>
> > +static int rtq6056_adc_read_label(struct iio_dev *indio_dev,
> > +                                 struct iio_chan_spec const *chan,
> > +                                 char *label)
> > +{
> > +       return sysfs_emit(label, "%s\n", rtq6056_channel_labels[chan->channel]);
> > +}
>
> ...
>
> > +       /* calibration = 5120000 / (Rshunt (uohm) * current lsb (1mA)) */
>
> uOhm
>
> ...
>
> > +static ssize_t shunt_resistor_show(struct device *dev,
> > +                                  struct device_attribute *attr, char *buf)
> > +{
> > +       struct rtq6056_priv *priv = iio_priv(dev_to_iio_dev(dev));
> > +       int vals[2] = { priv->shunt_resistor_uohm, 1000000 };
>
> MICRO ?
>
Yes, for this kind of sense resistor, it will choose 2 milli-Ohm, 1
milli-Ohms,, 0.5 milli-Ohms, or less.
> > +       return iio_format_value(buf, IIO_VAL_FRACTIONAL, 1, vals);
> > +}
>
> ...
>
> > +       ret = rtq6056_set_shunt_resistor(priv, val * 1000000 + val_fract);
>
> MICRO ?
>
Yes
> > +       if (ret)
> > +               return ret;
>
> ...
>
> > +       struct {
> > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > +               int64_t timestamp;
> > +       } data __aligned(8);
>
> Hmm... alignment of this struct will be at least 4 bytes, but
> shouldn't we rather be sure that the timestamp member is aligned
> properly? Otherwise this seems fragile and dependent on
> RTQ6056_MAX_CHANNEL % 4 == 0.
>
Yap, from the 'max channel', it already guarantee this struct will be
aligned at lease 4.
Actually, It can be removed.
> ...
>
> > +       pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
> > +       pm_runtime_use_autosuspend(dev);
> > +       pm_runtime_set_active(dev);
> > +       pm_runtime_mark_last_busy(dev);
> > +       pm_runtime_enable(dev);
> > +
> > +       /* By default, use 2000 micro-ohm resistor */
> > +       shunt_resistor_uohm = 2000;
> > +       device_property_read_u32(dev, "shunt-resistor-micro-ohms",
> > +                                &shunt_resistor_uohm);
> > +
> > +       ret = rtq6056_set_shunt_resistor(priv, shunt_resistor_uohm);
> > +       if (ret) {
> > +               dev_err(dev, "Failed to init shunt resistor\n");
> > +               goto err_probe;
>
> return dev_err_probe();
>
> (see below how)
>
> > +       }
> > +
> > +       indio_dev->name = "rtq6056";
> > +       indio_dev->modes = INDIO_DIRECT_MODE;
> > +       indio_dev->channels = rtq6056_channels;
> > +       indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
> > +       indio_dev->info = &rtq6056_info;
> > +
> > +       ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > +                                             rtq6056_buffer_trigger_handler,
> > +                                             NULL);
> > +       if (ret) {
> > +               dev_err(dev, "Failed to allocate iio trigger buffer\n");
>
> Ditto.
>
> > +               goto err_probe;
>
> It is a sign of wrong ordering, either do not use devm_ calls after
> non-devm_ or make the latter wrapped into devm_add_action_or_reset().
> See below for additional information.
>
I think the another way is to register all using devm_ and to call the
pm_runtime at the last.
> > +       }
> > +
> > +       ret = devm_iio_device_register(dev, indio_dev);
> > +       if (ret) {
> > +               dev_err(dev, "Failed to allocate iio device\n");
> > +               goto err_probe;
> > +       }
> > +
> > +       return 0;
> > +
> > +err_probe:
> > +       pm_runtime_dont_use_autosuspend(dev);
> > +       pm_runtime_disable(dev);
> > +       pm_runtime_set_suspended(dev);
> > +
> > +       return ret;
>
> ...
>
> > +static int rtq6056_remove(struct i2c_client *i2c)
> > +{
> > +       struct device *dev = &i2c->dev;
>
> Another (but usually not good option) is to call devm_..._unregister() here.
>
> > +       pm_runtime_dont_use_autosuspend(dev);
> > +       pm_runtime_disable(dev);
> > +       pm_runtime_set_suspended(dev);
> > +
> > +       return 0;
> > +}
>
> ...
>
> > +static const struct dev_pm_ops rtq6056_pm_ops = {
> > +       SET_RUNTIME_PM_OPS(rtq6056_runtime_suspend, rtq6056_runtime_resume, NULL)
>
> RUNTIME_PM_OPS()
>
> > +};
>
> ...
>
> > +static const struct of_device_id rtq6056_device_match[] = {
> > +       { .compatible = "richtek,rtq6056", },
>
> In this case the inner comma is not needed.
>
> > +       {}
> > +};
>
> ...
>
> > +static struct i2c_driver rtq6056_driver = {
> > +       .driver = {
> > +               .name = "rtq6056",
> > +               .of_match_table = rtq6056_device_match,
>
> > +               .pm = &rtq6056_pm_ops,
>
> pm_ptr()
>
> > +       },
>
> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[ChiYuan Huang]

ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：
>
> Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
> >
> > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:
> >
> > > Add Richtek rtq6056 supporting.
> > >
> > > It can be used for the system to monitor load current and power with 16-bit
> > > resolution.
> >
> > ...
> >
> > > +static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
> > > +                                   struct iio_chan_spec const *ch,
> > > +                                   int *val)
> > > +{
> > > +       struct device *dev = priv->dev;
> > > +       unsigned int addr = ch->address;
> > > +       unsigned int regval;
> > > +       int ret;
> > > +
> > > +       pm_runtime_get_sync(dev);
> > > +
> > > +       ret = regmap_read(priv->regmap, addr, &regval);
> > > +       if (ret) {
> > > +               pm_runtime_put(dev);
> > > +               return ret;
> > > +       }
> >
> > You can optimize this to
> >
> >        pm_runtime_get_sync(dev);
> >        ret = regmap_read(priv->regmap, addr, &regval);
> >        pm_runtime_mark_last_busy(dev);
> >        pm_runtime_put(dev);
> >        if (ret)
> >            return ret;
> >
> > > +       /* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
> > > +       if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
> > > +               *val = regval;
> > > +       else
> > > +               *val = sign_extend32(regval, 16);
> >
> > > +       pm_runtime_mark_last_busy(dev);
> > > +       pm_runtime_put(dev);
> >
> > ...and get rid of these.
> >
> > > +       return IIO_VAL_INT;
> > > +}
> >
> > ...
> >
> > > +               *val2 = 1000000000;
> >
> > NANO ?
> >
> Yes, unit is 2.5 microvolt. I have all listed all unit comments in the
> source code.a
Sorry, I found this scale is wrong.
For voltage channel, standard binding uses millivolt as the reported value.
From this case, It must be (val * 2500) /1000000
So the '*val2' must equal to 1000000
> > ...
> >
> > > +               *val2 = 1000;
> >
> > MILLI ?
> >
> Yes.
As the above one. Must be millivolt as the unit.
Channel unit is 2.5mV.
This value is correct and equal to (val * 2500) / 1000
> > > +       *val = DIV_ROUND_UP(1000000, sample_time);
> >
> > USEC_PER_SEC ?
> >
> No, sample time is (vshunt convesion time + vbus conversion time) *
> average sample.
> And the sample freq returns the unit by HZ (sample frequency per second)
>
The 'sample time' is unit by micro-second like as you mentioned.
> > > +
> > > +       return IIO_VAL_INT;
> > > +}
> >
> > ...
> >
> > > +static int rtq6056_adc_read_label(struct iio_dev *indio_dev,
> > > +                                 struct iio_chan_spec const *chan,
> > > +                                 char *label)
> > > +{
> > > +       return sysfs_emit(label, "%s\n", rtq6056_channel_labels[chan->channel]);
> > > +}
> >
> > ...
> >
> > > +       /* calibration = 5120000 / (Rshunt (uohm) * current lsb (1mA)) */
> >
> > uOhm
> >
> > ...
> >
> > > +static ssize_t shunt_resistor_show(struct device *dev,
> > > +                                  struct device_attribute *attr, char *buf)
> > > +{
> > > +       struct rtq6056_priv *priv = iio_priv(dev_to_iio_dev(dev));
> > > +       int vals[2] = { priv->shunt_resistor_uohm, 1000000 };
> >
> > MICRO ?
> >
> Yes, for this kind of sense resistor, it will choose 2 milli-Ohm, 1
> milli-Ohms,, 0.5 milli-Ohms, or less.
> > > +       return iio_format_value(buf, IIO_VAL_FRACTIONAL, 1, vals);
> > > +}
> >
> > ...
> >
> > > +       ret = rtq6056_set_shunt_resistor(priv, val * 1000000 + val_fract);
> >
> > MICRO ?
> >
> Yes
> > > +       if (ret)
> > > +               return ret;
> >
> > ...
> >
> > > +       struct {
> > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > +               int64_t timestamp;
> > > +       } data __aligned(8);
> >
> > Hmm... alignment of this struct will be at least 4 bytes, but
> > shouldn't we rather be sure that the timestamp member is aligned
> > properly? Otherwise this seems fragile and dependent on
> > RTQ6056_MAX_CHANNEL % 4 == 0.
> >
> Yap, from the 'max channel', it already guarantee this struct will be
> aligned at lease 4.
> Actually, It can be removed.
> > ...
> >
> > > +       pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
> > > +       pm_runtime_use_autosuspend(dev);
> > > +       pm_runtime_set_active(dev);
> > > +       pm_runtime_mark_last_busy(dev);
> > > +       pm_runtime_enable(dev);
> > > +
> > > +       /* By default, use 2000 micro-ohm resistor */
> > > +       shunt_resistor_uohm = 2000;
> > > +       device_property_read_u32(dev, "shunt-resistor-micro-ohms",
> > > +                                &shunt_resistor_uohm);
> > > +
> > > +       ret = rtq6056_set_shunt_resistor(priv, shunt_resistor_uohm);
> > > +       if (ret) {
> > > +               dev_err(dev, "Failed to init shunt resistor\n");
> > > +               goto err_probe;
> >
> > return dev_err_probe();
> >
> > (see below how)
> >
> > > +       }
> > > +
> > > +       indio_dev->name = "rtq6056";
> > > +       indio_dev->modes = INDIO_DIRECT_MODE;
> > > +       indio_dev->channels = rtq6056_channels;
> > > +       indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
> > > +       indio_dev->info = &rtq6056_info;
> > > +
> > > +       ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > > +                                             rtq6056_buffer_trigger_handler,
> > > +                                             NULL);
> > > +       if (ret) {
> > > +               dev_err(dev, "Failed to allocate iio trigger buffer\n");
> >
> > Ditto.
> >
> > > +               goto err_probe;
> >
> > It is a sign of wrong ordering, either do not use devm_ calls after
> > non-devm_ or make the latter wrapped into devm_add_action_or_reset().
> > See below for additional information.
> >
> I think the another way is to register all using devm_ and to call the
> pm_runtime at the last.
> > > +       }
> > > +
> > > +       ret = devm_iio_device_register(dev, indio_dev);
> > > +       if (ret) {
> > > +               dev_err(dev, "Failed to allocate iio device\n");
> > > +               goto err_probe;
> > > +       }
> > > +
> > > +       return 0;
> > > +
> > > +err_probe:
> > > +       pm_runtime_dont_use_autosuspend(dev);
> > > +       pm_runtime_disable(dev);
> > > +       pm_runtime_set_suspended(dev);
> > > +
> > > +       return ret;
> >
> > ...
> >
> > > +static int rtq6056_remove(struct i2c_client *i2c)
> > > +{
> > > +       struct device *dev = &i2c->dev;
> >
> > Another (but usually not good option) is to call devm_..._unregister() here.
> >
> > > +       pm_runtime_dont_use_autosuspend(dev);
> > > +       pm_runtime_disable(dev);
> > > +       pm_runtime_set_suspended(dev);
> > > +
> > > +       return 0;
> > > +}
> >
> > ...
> >
> > > +static const struct dev_pm_ops rtq6056_pm_ops = {
> > > +       SET_RUNTIME_PM_OPS(rtq6056_runtime_suspend, rtq6056_runtime_resume, NULL)
> >
> > RUNTIME_PM_OPS()
> >
> > > +};
> >
> > ...
> >
> > > +static const struct of_device_id rtq6056_device_match[] = {
> > > +       { .compatible = "richtek,rtq6056", },
> >
> > In this case the inner comma is not needed.
> >
> > > +       {}
> > > +};
> >
> > ...
> >
> > > +static struct i2c_driver rtq6056_driver = {
> > > +       .driver = {
> > > +               .name = "rtq6056",
> > > +               .of_match_table = rtq6056_device_match,
> >
> > > +               .pm = &rtq6056_pm_ops,
> >
> > pm_ptr()
> >
> > > +       },
> >
> > --
> > With Best Regards,
> > Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[Andy Shevchenko]

On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：
> > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
> > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:

...

> > > > +       *val = DIV_ROUND_UP(1000000, sample_time);
> > >
> > > USEC_PER_SEC ?
> > >
> > No, sample time is (vshunt convesion time + vbus conversion time) *
> > average sample.
> > And the sample freq returns the unit by HZ (sample frequency per second)
> >
> The 'sample time' is unit by micro-second like as you mentioned.

Ah, then it should be MICRO, so we will get Hz.

> > > > +       return IIO_VAL_INT;
> > > > +}

...

> > > > +       struct {
> > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > +               int64_t timestamp;
> > > > +       } data __aligned(8);
> > >
> > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > shouldn't we rather be sure that the timestamp member is aligned
> > > properly? Otherwise this seems fragile and dependent on
> > > RTQ6056_MAX_CHANNEL % 4 == 0.
> > >
> > Yap, from the 'max channel', it already guarantee this struct will be
> > aligned at lease 4.
> > Actually, It can be removed.

I think for the safest side it should be given to the timestamp member. No?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[ChiYuan Huang]

Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月5日 週二 清晨5:52寫道：
>
> On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> > ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：
> > > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
> > > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:
>
> ...
>
> > > > > +       *val = DIV_ROUND_UP(1000000, sample_time);
> > > >
> > > > USEC_PER_SEC ?
> > > >
> > > No, sample time is (vshunt convesion time + vbus conversion time) *
> > > average sample.
> > > And the sample freq returns the unit by HZ (sample frequency per second)
> > >
> > The 'sample time' is unit by micro-second like as you mentioned.
>
> Ah, then it should be MICRO, so we will get Hz.
>
> > > > > +       return IIO_VAL_INT;
> > > > > +}
>
> ...
>
> > > > > +       struct {
> > > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > > +               int64_t timestamp;
> > > > > +       } data __aligned(8);
> > > >
> > > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > > shouldn't we rather be sure that the timestamp member is aligned
> > > > properly? Otherwise this seems fragile and dependent on
> > > > RTQ6056_MAX_CHANNEL % 4 == 0.
> > > >
> > > Yap, from the 'max channel', it already guarantee this struct will be
> > > aligned at lease 4.
> > > Actually, It can be removed.
>
> I think for the safest side it should be given to the timestamp member. No?
>
Sorry, following your comment, Why to use 'align' for the timestamp member?
the data member already guarantee 2 * 4 = 8 byte, then timestamp will
be 8 byte aligned, right?

what you mentioned is to put __aligned(8) only for timestamp.

I try to put aligned in two ways ( one is only for timestamp, another
is the whole struct). the result is the same.
From my thinking, in this case, the struct is already 8 byte aligned
for timestamp member. don't you think to put 'aligned' is redundant?
> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[Andy Shevchenko]

On Tue, Jul 5, 2022 at 3:41 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月5日 週二 清晨5:52寫道：
> > On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> > > ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：
> > > > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
> > > > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:

...

> > > > > > +       struct {
> > > > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > > > +               int64_t timestamp;
> > > > > > +       } data __aligned(8);
> > > > >
> > > > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > > > shouldn't we rather be sure that the timestamp member is aligned
> > > > > properly? Otherwise this seems fragile and dependent on
> > > > > RTQ6056_MAX_CHANNEL % 4 == 0.
> > > > >
> > > > Yap, from the 'max channel', it already guarantee this struct will be
> > > > aligned at lease 4.
> > > > Actually, It can be removed.
> >
> > I think for the safest side it should be given to the timestamp member. No?
> >
> Sorry, following your comment, Why to use 'align' for the timestamp member?
> the data member already guarantee 2 * 4 = 8 byte, then timestamp will
> be 8 byte aligned, right?

Today it's true, tomorrow it might be different. Imagine if this
driver will cover a new (version of) hardware and needs an additional
channel, how do you guarantee alignment in that case? So, current
approach is working, but fragile.

> what you mentioned is to put __aligned(8) only for timestamp.

Yes.

> I try to put aligned in two ways ( one is only for timestamp, another
> is the whole struct). the result is the same.
> From my thinking, in this case, the struct is already 8 byte aligned
> for timestamp member. don't you think to put 'aligned' is redundant?

No.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[ChiYuan Huang]

Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月5日 週二 下午5:05寫道：
>
> On Tue, Jul 5, 2022 at 3:41 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月5日 週二 清晨5:52寫道：
> > > On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> > > > ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：
> > > > > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：
> > > > > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:
>
> ...
>
> > > > > > > +       struct {
> > > > > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > > > > +               int64_t timestamp;
> > > > > > > +       } data __aligned(8);
> > > > > >
> > > > > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > > > > shouldn't we rather be sure that the timestamp member is aligned
> > > > > > properly? Otherwise this seems fragile and dependent on
> > > > > > RTQ6056_MAX_CHANNEL % 4 == 0.
> > > > > >
> > > > > Yap, from the 'max channel', it already guarantee this struct will be
> > > > > aligned at lease 4.
> > > > > Actually, It can be removed.
> > >
> > > I think for the safest side it should be given to the timestamp member. No?
> > >
> > Sorry, following your comment, Why to use 'align' for the timestamp member?
> > the data member already guarantee 2 * 4 = 8 byte, then timestamp will
> > be 8 byte aligned, right?
>
> Today it's true, tomorrow it might be different. Imagine if this
> driver will cover a new (version of) hardware and needs an additional
> channel, how do you guarantee alignment in that case? So, current
> approach is working, but fragile.
>
> > what you mentioned is to put __aligned(8) only for timestamp.
>
> Yes.
>
> > I try to put aligned in two ways ( one is only for timestamp, another
> > is the whole struct). the result is the same.
> > From my thinking, in this case, the struct is already 8 byte aligned
> > for timestamp member. don't you think to put 'aligned' is redundant?
>
> No.
>
Thanks, I think I can get your point. if it need to be compatible with
others, this part will be a trap.
Then it's better to add the align for timestamp member.

I'll submit the v4 for this.

And very sorry about another mail.
I just confused about the text.

> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support

[Jonathan Cameron]

On Tue, 5 Jul 2022 09:41:39 +0800
ChiYuan Huang <u0084500@gmail.com> wrote:

> Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月5日 週二 清晨5:52寫道：
> >
> > On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:  
> > > ChiYuan Huang <u0084500@gmail.com> 於 2022年7月4日 週一 上午11:16寫道：  
> > > > Andy Shevchenko <andy.shevchenko@gmail.com> 於 2022年7月1日 週五 下午6:05寫道：  
> > > > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:  
> >
> > ...
> >  
> > > > > > +       *val = DIV_ROUND_UP(1000000, sample_time);  
> > > > >
> > > > > USEC_PER_SEC ?
> > > > >  
> > > > No, sample time is (vshunt convesion time + vbus conversion time) *
> > > > average sample.
> > > > And the sample freq returns the unit by HZ (sample frequency per second)
> > > >  
> > > The 'sample time' is unit by micro-second like as you mentioned.  
> >
> > Ah, then it should be MICRO, so we will get Hz.
> >  
> > > > > > +       return IIO_VAL_INT;
> > > > > > +}  
> >
> > ...
> >  
> > > > > > +       struct {
> > > > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > > > +               int64_t timestamp;
> > > > > > +       } data __aligned(8);  
> > > > >
> > > > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > > > shouldn't we rather be sure that the timestamp member is aligned
> > > > > properly? Otherwise this seems fragile and dependent on
> > > > > RTQ6056_MAX_CHANNEL % 4 == 0.
> > > > >  
> > > > Yap, from the 'max channel', it already guarantee this struct will be
> > > > aligned at lease 4.
> > > > Actually, It can be removed.  
> >
> > I think for the safest side it should be given to the timestamp member. No?
> >  
> Sorry, following your comment, Why to use 'align' for the timestamp member?
> the data member already guarantee 2 * 4 = 8 byte, then timestamp will
> be 8 byte aligned, right?
> 
> what you mentioned is to put __aligned(8) only for timestamp.
> 
> I try to put aligned in two ways ( one is only for timestamp, another
> is the whole struct). the result is the same.
> From my thinking, in this case, the struct is already 8 byte aligned
> for timestamp member. don't you think to put 'aligned' is redundant?

On the 8 byte alignment question...  Look up alignment of s64 on x86_32...
It's 4 byte aligned. We had a lot of 'fun' fixing this a few years ago.

So the marking of __aligned(8) for the timestamp does 2 things (and it
takes a fairly close reading of the c spec to check this).

1) Forces alignment of the timestamp. Needed so we can cheaply write
the timestamp
2) Forces alignment of the containing structure.

The combination of these 2 enforces the padding being
consistent across architectures whether or not they align s64 to
4 or 8 bytes.  This last part is the subtle element that
explains why on some architectures you need the __aligned(8) on the
timestamp not the outer structure.

Jonathan




> > --
> > With Best Regards,
> > Andy Shevchenko