[RFC] hwmon: ina2xx: port to using remap, improve bandwidth.

From: Marc Titinger
Date: Fri Oct 23 2015 - 12:14:17 EST

With the current implementation, the driver will prevent a readout at a
pace faster than the default conversion time (2ms) times the averaging
setting, min AVG being 1:1.

Any sysfs "show" read access from the client app faster than 500 Hz will be
'cached' by the driver, but actually since do_update reads all 8 registers,
the best achievable measurement rate is roughly 8*800 us (for the time
spent in i2c-core) i.e. <= 156Hz with Beagle Bone Black.

Registers are now accessed individually through the regmap facility.
For four measurements the readout rate is now around
(1/(4*800us) = 312 Hz.

Signed-off-by: Marc Titinger <mtitinger@xxxxxxxxxxxx>
---
drivers/hwmon/ina2xx.c | 359 ++++++++++++++++++++++---------------------------
1 file changed, 159 insertions(+), 200 deletions(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 4d28150..e7c1aaa 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -37,6 +37,7 @@
#include <linux/of.h>
#include <linux/delay.h>
#include <linux/util_macros.h>
+#include <linux/regmap.h>

#include <linux/platform_data/ina2xx.h>

@@ -48,32 +49,25 @@
#define INA2XX_CURRENT 0x04 /* readonly */
#define INA2XX_CALIBRATION 0x05

-/* INA226 register definitions */
-#define INA226_MASK_ENABLE 0x06
-#define INA226_ALERT_LIMIT 0x07
-#define INA226_DIE_ID 0xFF
-
-/* register count */
-#define INA219_REGISTERS 6
-#define INA226_REGISTERS 8
-
-#define INA2XX_MAX_REGISTERS 8
+/* CONFIG register fields */
+#define INA2XX_AVG_MASK 0x0E00
+#define INA2XX_AVG_SHFT 9

/* settings - depend on use case */
#define INA219_CONFIG_DEFAULT 0x399F /* PGA=8 */
#define INA226_CONFIG_DEFAULT 0x4527 /* averages=16 */

/* worst case is 68.10 ms (~14.6Hz, ina219) */
-#define INA2XX_CONVERSION_RATE 15
#define INA2XX_MAX_DELAY 69 /* worst case delay in ms */

#define INA2XX_RSHUNT_DEFAULT 10000

-/* bit mask for reading the averaging setting in the configuration register */
-#define INA226_AVG_RD_MASK 0x0E00
-
-#define INA226_READ_AVG(reg) (((reg) & INA226_AVG_RD_MASK) >> 9)
-#define INA226_SHIFT_AVG(val) ((val) << 9)
+/* Currently only handling common register set */
+static const struct regmap_config INA2XX_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 16,
+ .max_register = INA2XX_CALIBRATION,
+};

/* common attrs, ina226 attrs and NULL */
#define INA2XX_MAX_ATTRIBUTE_GROUPS 3
@@ -89,7 +83,6 @@ enum ina2xx_ids { ina219, ina226 };
struct ina2xx_config {
u16 config_default;
int calibration_factor;
- int registers;
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb; /* uV */
@@ -99,25 +92,16 @@ struct ina2xx_config {
struct ina2xx_data {
struct i2c_client *client;
const struct ina2xx_config *config;
-
+ struct regmap *regmap;
long rshunt;
- u16 curr_config;
-
- struct mutex update_lock;
- bool valid;
- unsigned long last_updated;
- int update_interval; /* in jiffies */
-
- int kind;
+ int valid;
const struct attribute_group *groups[INA2XX_MAX_ATTRIBUTE_GROUPS];
- u16 regs[INA2XX_MAX_REGISTERS];
};

static const struct ina2xx_config ina2xx_config[] = {
[ina219] = {
.config_default = INA219_CONFIG_DEFAULT,
.calibration_factor = 40960000,
- .registers = INA219_REGISTERS,
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
@@ -126,7 +110,6 @@ static const struct ina2xx_config ina2xx_config[] = {
[ina226] = {
.config_default = INA226_CONFIG_DEFAULT,
.calibration_factor = 5120000,
- .registers = INA226_REGISTERS,
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
@@ -142,9 +125,9 @@ static const struct ina2xx_config ina2xx_config[] = {
*/
static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };

-static int ina226_reg_to_interval(u16 config)
+static int ina226_field_to_interval(int field)
{
- int avg = ina226_avg_tab[INA226_READ_AVG(config)];
+ int avg = ina226_avg_tab[field];

/*
* Multiply the total conversion time by the number of averages.
@@ -153,24 +136,11 @@ static int ina226_reg_to_interval(u16 config)
return DIV_ROUND_CLOSEST(avg * INA226_TOTAL_CONV_TIME_DEFAULT, 1000);
}

-static u16 ina226_interval_to_reg(int interval, u16 config)
-{
- int avg, avg_bits;
-
- avg = DIV_ROUND_CLOSEST(interval * 1000,
- INA226_TOTAL_CONV_TIME_DEFAULT);
- avg_bits = find_closest(avg, ina226_avg_tab,
- ARRAY_SIZE(ina226_avg_tab));
-
- return (config & ~INA226_AVG_RD_MASK) | INA226_SHIFT_AVG(avg_bits);
-}
-
-static void ina226_set_update_interval(struct ina2xx_data *data)
+static int ina226_interval_to_field(int interval)
{
- int ms;
-
- ms = ina226_reg_to_interval(data->curr_config);
- data->update_interval = msecs_to_jiffies(ms);
+ int avg = DIV_ROUND_CLOSEST(interval * 1000,
+ INA226_TOTAL_CONV_TIME_DEFAULT);
+ return find_closest(avg, ina226_avg_tab, ARRAY_SIZE(ina226_avg_tab));
}

static int ina2xx_calibrate(struct ina2xx_data *data)
@@ -178,8 +148,7 @@ static int ina2xx_calibrate(struct ina2xx_data *data)
u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
data->rshunt);

- return i2c_smbus_write_word_swapped(data->client,
- INA2XX_CALIBRATION, val);
+ return regmap_write(data->regmap, INA2XX_CALIBRATION, val);
}

/*
@@ -187,15 +156,10 @@ static int ina2xx_calibrate(struct ina2xx_data *data)
*/
static int ina2xx_init(struct ina2xx_data *data)
{
- struct i2c_client *client = data->client;
- int ret;
-
- /* device configuration */
- ret = i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
- data->curr_config);
- if (ret < 0)
+ int ret = regmap_write(data->regmap, INA2XX_CONFIG,
+ data->config->config_default);
+ if (ret)
return ret;
-
/*
* Set current LSB to 1mA, shunt is in uOhms
* (equation 13 in datasheet).
@@ -203,22 +167,22 @@ static int ina2xx_init(struct ina2xx_data *data)
return ina2xx_calibrate(data);
}

-static int ina2xx_do_update(struct device *dev)
+static int ina2xx_show_common(struct device *dev, int index, int *val)
{
struct ina2xx_data *data = dev_get_drvdata(dev);
- struct i2c_client *client = data->client;
- int i, rv, retry;
+ int err, retry;

- dev_dbg(&client->dev, "Starting ina2xx update\n");
+ if (unlikely(!val))
+ return -EINVAL;

for (retry = 5; retry; retry--) {
- /* Read all registers */
- for (i = 0; i < data->config->registers; i++) {
- rv = i2c_smbus_read_word_swapped(client, i);
- if (rv < 0)
- return rv;
- data->regs[i] = rv;
- }
+
+ /* Check for remaining registers in mask. */
+ err = regmap_read(data->regmap, index, val);
+ if (err)
+ return err;
+
+ dev_dbg(dev, "read %d, val = 0x%04x\n", index, *val);

/*
* If the current value in the calibration register is 0, the
@@ -226,24 +190,24 @@ static int ina2xx_do_update(struct device *dev)
* the chip has been reset let's check the calibration
* register and reinitialize if needed.
*/
- if (data->regs[INA2XX_CALIBRATION] == 0) {
- dev_warn(dev, "chip not calibrated, reinitializing\n");
-
- rv = ina2xx_init(data);
- if (rv < 0)
- return rv;
+ if (!data->valid) {
+ dev_warn(dev,
+ "chip needs calibration, reinitializing\n");

+ err = ina2xx_calibrate(data);
+ if (err)
+ return err;
/*
* Let's make sure the power and current registers
* have been updated before trying again.
*/
msleep(INA2XX_MAX_DELAY);
+
+ /* data valid once we have a cal value. */
+ regmap_read(data->regmap, INA2XX_CALIBRATION,
+ &data->valid);
continue;
}
-
- data->last_updated = jiffies;
- data->valid = 1;
-
return 0;
}

@@ -256,86 +220,89 @@ static int ina2xx_do_update(struct device *dev)
return -ENODEV;
}

-static struct ina2xx_data *ina2xx_update_device(struct device *dev)
+static ssize_t ina2xx_show_shunt(struct device *dev,
+ struct device_attribute *da, char *buf)
{
struct ina2xx_data *data = dev_get_drvdata(dev);
- struct ina2xx_data *ret = data;
- unsigned long after;
- int rv;
+ int val, err;

- mutex_lock(&data->update_lock);
+ err = ina2xx_show_common(dev, INA2XX_SHUNT_VOLTAGE, &val);
+ if (err)
+ return err;

- after = data->last_updated + data->update_interval;
- if (time_after(jiffies, after) || !data->valid) {
- rv = ina2xx_do_update(dev);
- if (rv < 0)
- ret = ERR_PTR(rv);
- }
+ val = DIV_ROUND_CLOSEST((s16) val, data->config->shunt_div);
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t ina2xx_show_bus(struct device *dev,
+ struct device_attribute *da, char *buf)
+{
+ struct ina2xx_data *data = dev_get_drvdata(dev);
+ int val, err;
+
+ err = ina2xx_show_common(dev, INA2XX_BUS_VOLTAGE, &val);
+ if (err)
+ return err;

- mutex_unlock(&data->update_lock);
- return ret;
+ val = (val >> data->config->bus_voltage_shift)
+ * data->config->bus_voltage_lsb;
+ val = DIV_ROUND_CLOSEST(val, 1000);
+
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

-static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
+static ssize_t ina2xx_show_pow(struct device *dev,
+ struct device_attribute *da, char *buf)
{
- int val;
-
- switch (reg) {
- case INA2XX_SHUNT_VOLTAGE:
- /* signed register */
- val = DIV_ROUND_CLOSEST((s16)data->regs[reg],
- data->config->shunt_div);
- break;
- case INA2XX_BUS_VOLTAGE:
- val = (data->regs[reg] >> data->config->bus_voltage_shift)
- * data->config->bus_voltage_lsb;
- val = DIV_ROUND_CLOSEST(val, 1000);
- break;
- case INA2XX_POWER:
- val = data->regs[reg] * data->config->power_lsb;
- break;
- case INA2XX_CURRENT:
- /* signed register, LSB=1mA (selected), in mA */
- val = (s16)data->regs[reg];
- break;
- case INA2XX_CALIBRATION:
- val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
- data->regs[reg]);
- break;
- default:
- /* programmer goofed */
- WARN_ON_ONCE(1);
- val = 0;
- break;
- }
+ struct ina2xx_data *data = dev_get_drvdata(dev);
+ int val, err;
+
+ err = ina2xx_show_common(dev, INA2XX_POWER, &val);
+ if (err)
+ return err;
+
+ val *= data->config->power_lsb;

- return val;
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

-static ssize_t ina2xx_show_value(struct device *dev,
- struct device_attribute *da, char *buf)
+static ssize_t ina2xx_show_curr(struct device *dev,
+ struct device_attribute *da, char *buf)
{
- struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct ina2xx_data *data = ina2xx_update_device(dev);
+ int val, err;

- if (IS_ERR(data))
- return PTR_ERR(data);
+ err = ina2xx_show_common(dev, INA2XX_CURRENT, &val);
+ if (err)
+ return err;

- return snprintf(buf, PAGE_SIZE, "%d\n",
- ina2xx_get_value(data, attr->index));
+ /* signed register, LSB=1mA (selected), in mA */
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t ina2xx_show_cal(struct device *dev,
+ struct device_attribute *da, char *buf)
+{
+ struct ina2xx_data *data = dev_get_drvdata(dev);
+ int val, err;
+
+ err = ina2xx_show_common(dev, INA2XX_CALIBRATION, &val);
+ if (err)
+ return err;
+
+ val = DIV_ROUND_CLOSEST(data->config->calibration_factor, val);
+
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

static ssize_t ina2xx_set_shunt(struct device *dev,
struct device_attribute *da,
const char *buf, size_t count)
{
- struct ina2xx_data *data = ina2xx_update_device(dev);
+ struct ina2xx_data *data = dev_get_drvdata(dev);
+
unsigned long val;
int status;

- if (IS_ERR(data))
- return PTR_ERR(data);
-
status = kstrtoul(buf, 10, &val);
if (status < 0)
return status;
@@ -345,12 +312,8 @@ static ssize_t ina2xx_set_shunt(struct device *dev,
val > data->config->calibration_factor)
return -EINVAL;

- mutex_lock(&data->update_lock);
data->rshunt = val;
- status = ina2xx_calibrate(data);
- mutex_unlock(&data->update_lock);
- if (status < 0)
- return status;
+ data->valid = 0;

return count;
}
@@ -370,65 +333,58 @@ static ssize_t ina226_set_interval(struct device *dev,
if (val > INT_MAX || val == 0)
return -EINVAL;

- mutex_lock(&data->update_lock);
- data->curr_config = ina226_interval_to_reg(val,
- data->regs[INA2XX_CONFIG]);
- status = i2c_smbus_write_word_swapped(data->client,
- INA2XX_CONFIG,
- data->curr_config);
+ val = ina226_interval_to_field(val);

- ina226_set_update_interval(data);
- /* Make sure the next access re-reads all registers. */
- data->valid = 0;
- mutex_unlock(&data->update_lock);
+ status = regmap_update_bits(data->regmap, INA2XX_CONFIG,
+ INA2XX_AVG_MASK, (val << INA2XX_AVG_SHFT));
if (status < 0)
return status;

+ data->valid = 0;
+
return count;
}

static ssize_t ina226_show_interval(struct device *dev,
struct device_attribute *da, char *buf)
{
- struct ina2xx_data *data = ina2xx_update_device(dev);
+ struct ina2xx_data *data = dev_get_drvdata(dev);
+ int status, val;

- if (IS_ERR(data))
- return PTR_ERR(data);
+ status = regmap_read(data->regmap, INA2XX_CONFIG, &val);
+ if (status)
+ return status;
+
+ val = (val & INA2XX_AVG_MASK) >> INA2XX_AVG_SHFT;
+ val = ina226_field_to_interval(val);

/*
- * We don't use data->update_interval here as we want to display
- * the actual interval used by the chip and jiffies_to_msecs()
- * doesn't seem to be accurate enough.
+ * We want to display the actual interval used by the chip.
*/
- return snprintf(buf, PAGE_SIZE, "%d\n",
- ina226_reg_to_interval(data->regs[INA2XX_CONFIG]));
+ return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

/* shunt voltage */
-static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL,
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_shunt, NULL,
INA2XX_SHUNT_VOLTAGE);

/* bus voltage */
-static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ina2xx_show_value, NULL,
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ina2xx_show_bus, NULL,
INA2XX_BUS_VOLTAGE);

/* calculated current */
-static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_value, NULL,
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_curr, NULL,
INA2XX_CURRENT);

/* calculated power */
-static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL,
+static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_pow, NULL,
INA2XX_POWER);

/* shunt resistance */
static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR,
- ina2xx_show_value, ina2xx_set_shunt,
+ ina2xx_show_cal, ina2xx_set_shunt,
INA2XX_CALIBRATION);

-/* update interval (ina226 only) */
-static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
- ina226_show_interval, ina226_set_interval, 0);
-
/* pointers to created device attributes */
static struct attribute *ina2xx_attrs[] = {
&sensor_dev_attr_in0_input.dev_attr.attr,
@@ -443,6 +399,10 @@ static const struct attribute_group ina2xx_group = {
.attrs = ina2xx_attrs,
};

+/* update interval (ina226 only) */
+static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
+ ina226_show_interval, ina226_set_interval, 0);
+
static struct attribute *ina226_attrs[] = {
&sensor_dev_attr_update_interval.dev_attr.attr,
NULL,
@@ -452,65 +412,65 @@ static const struct attribute_group ina226_group = {
.attrs = ina226_attrs,
};

+
static int ina2xx_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
- struct i2c_adapter *adapter = client->adapter;
struct ina2xx_platform_data *pdata;
struct device *dev = &client->dev;
struct ina2xx_data *data;
struct device *hwmon_dev;
+ struct regmap *regmap;
u32 val;
int ret, group = 0;

- if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
- return -ENODEV;
+ /* Register regmap */
+ regmap = devm_regmap_init_i2c(client, &INA2XX_regmap_config);
+ if (IS_ERR(regmap)) {
+ dev_err(dev, "failed to allocate register map\n");
+ return PTR_ERR(regmap);
+ }

data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;

- if (dev_get_platdata(dev)) {
- pdata = dev_get_platdata(dev);
- data->rshunt = pdata->shunt_uohms;
- } else if (!of_property_read_u32(dev->of_node,
- "shunt-resistor", &val)) {
- data->rshunt = val;
- } else {
- data->rshunt = INA2XX_RSHUNT_DEFAULT;
- }
+ data->regmap = regmap;

- /* set the device type */
- data->kind = id->driver_data;
- data->config = &ina2xx_config[data->kind];
- data->curr_config = data->config->config_default;
+ /* Set config according to device type. */
+ data->config = &ina2xx_config[id->driver_data];
data->client = client;

- /*
- * Ina226 has a variable update_interval. For ina219 we
- * use a constant value.
+ /* Check for shunt resistor value.
+ * Give precedence to device tree over must-recompile.
*/
- if (data->kind == ina226)
- ina226_set_update_interval(data);
- else
- data->update_interval = HZ / INA2XX_CONVERSION_RATE;
+ if (of_property_read_u32(dev->of_node, "shunt-resistor", &val) < 0) {
+ pdata = dev_get_platdata(dev);
+ if (pdata)
+ val = pdata->shunt_uohms;
+ else
+ val = INA2XX_RSHUNT_DEFAULT;
+ }

- if (data->rshunt <= 0 ||
- data->rshunt > data->config->calibration_factor)
+ if (val <= 0 || val > data->config->calibration_factor) {
+ dev_err(dev, "Invalid shunt resistor value %li", val);
return -ENODEV;
+ }
+ data->rshunt = val;

+ /* Write config to chip, and calibrate */
ret = ina2xx_init(data);
- if (ret < 0) {
- dev_err(dev, "error configuring the device: %d\n", ret);
- return -ENODEV;
+ if (ret) {
+ dev_err(dev, "error configuring the device.\n");
+ return ret;
}

- mutex_init(&data->update_lock);
-
+ /* Set sensor group according to device type. */
data->groups[group++] = &ina2xx_group;
- if (data->kind == ina226)
+ if (ina226 == id->driver_data)
data->groups[group++] = &ina226_group;

+ /* register to hwmon */
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
data, data->groups);
if (IS_ERR(hwmon_dev))
@@ -541,7 +501,6 @@ static struct i2c_driver ina2xx_driver = {
};

module_i2c_driver(ina2xx_driver);
-
MODULE_AUTHOR("Lothar Felten <l-felten@xxxxxx>");
MODULE_DESCRIPTION("ina2xx driver");
MODULE_LICENSE("GPL");
--
1.9.1

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