On Wed, Apr 14, 2010 at 10:46:48AM +0200, Jean Delvare wrote:
> Hi Ira,
>
> On Tue, 13 Apr 2010 15:54:28 -0700, Ira W. Snyder wrote:
> > The adm1031 chip is capable of using a runtime configurable sampling rate,
> > using the fan filter register. Add support for reading and setting the
> > update rate via sysfs.
> >
> > Signed-off-by: Ira W. Snyder <iws@xxxxxxxxxxxxxxxx>
> > ---
> > drivers/hwmon/adm1031.c | 82 +++++++++++++++++++++++++++++++++++++++++++++-
> > 1 files changed, 80 insertions(+), 2 deletions(-)
>
> First a review, before I propose an alternative patch:
>
> >
> > diff --git a/drivers/hwmon/adm1031.c b/drivers/hwmon/adm1031.c
> > index 1644b92..3366881 100644
> > --- a/drivers/hwmon/adm1031.c
> > +++ b/drivers/hwmon/adm1031.c
> > @@ -36,6 +36,7 @@
> > #define ADM1031_REG_FAN_DIV(nr) (0x20 + (nr))
> > #define ADM1031_REG_PWM (0x22)
> > #define ADM1031_REG_FAN_MIN(nr) (0x10 + (nr))
> > +#define ADM1031_REG_FAN_FILTER (0x23)
> >
> > #define ADM1031_REG_TEMP_OFFSET(nr) (0x0d + (nr))
> > #define ADM1031_REG_TEMP_MAX(nr) (0x14 + 4 * (nr))
> > @@ -61,6 +62,8 @@
> > #define ADM1031_CONF2_TACH2_ENABLE 0x08
> > #define ADM1031_CONF2_TEMP_ENABLE(chan) (0x10 << (chan))
> >
> > +#define ADM1031_UPDATE_RATE_MASK 0x1c
> > +
> > /* Addresses to scan */
> > static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, I2C_CLIENT_END };
> >
> > @@ -75,6 +78,7 @@ struct adm1031_data {
> > int chip_type;
> > char valid; /* !=0 if following fields are valid */
> > unsigned long last_updated; /* In jiffies */
> > + unsigned int update_rate; /* In milliseconds */
> > /* The chan_select_table contains the possible configurations for
> > * auto fan control.
> > */
> > @@ -738,6 +742,58 @@ static SENSOR_DEVICE_ATTR(temp3_crit_alarm, S_IRUGO, show_alarm, NULL, 12);
> > static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_alarm, NULL, 13);
> > static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 14);
> >
> > +/* Update Rate */
> > +static ssize_t show_update_rate(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct adm1031_data *data = i2c_get_clientdata(client);
> > +
> > + return snprintf(buf, PAGE_SIZE, "%u\n", data->update_rate);
>
> The driver is using sprintf everywhere else, and it's definitely safe.
>
> > +}
> > +
> > +static ssize_t set_update_rate(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct adm1031_data *data = i2c_get_clientdata(client);
> > + unsigned int rates[] = { 125, 250, 500, 1000, 2000, 4000, 8000, 16000 };
>
> Could be const.
>
> > + unsigned int regvals[] = { 0x1c, 0x18, 0x14, 0x10, 0xc, 0x8, 0x4, 0x0 };
>
> You don't really need this array, as the values are linear.
>
> > + unsigned int reg;
> > + int val, i;
> > +
> > + /* both arrays must have the same number of values */
> > + BUILD_BUG_ON(ARRAY_SIZE(rates) != ARRAY_SIZE(regvals));
> > +
> > + /* find the update rate from the table */
> > + val = simple_strtol(buf, NULL, 10);
>
> We try moving to strict_strto(l|ul) these days. You'd better use an
> unsigned here, BTW.
>
> > + for (i = 0; i < ARRAY_SIZE(rates); i++) {
> > + if (val == rates[i])
> > + break;
> > + }
> > +
> > + /* if the update rate was not found, the value is invalid */
> > + if (i == ARRAY_SIZE(rates))
> > + return -EINVAL;
>
> I'd rather do a loose comparison (<= or =>) and pick the nearest best
> value. The caller don't necessarily know the exact discrete values
> supported by the device. Same we do for PWM frequencies, for example.
>
> > +
> > + mutex_lock(&data->update_lock);
> > +
> > + /* set the new update rate while preserving other settings */
> > + reg = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
> > + reg &= ~ADM1031_UPDATE_RATE_MASK;
> > + reg |= regvals[i];
> > +
> > + adm1031_write_value(client, ADM1031_REG_FAN_FILTER, reg);
>
> Not sure why you need to hold update_lock for this? The update function
> doesn't touch this register.
>
> > + data->update_rate = rates[i];
> > +
> > + mutex_unlock(&data->update_lock);
> > + return count;
> > +}
> > +
> > +static DEVICE_ATTR(update_rate, S_IRUGO | S_IWUSR, show_update_rate,
> > + set_update_rate);
> > +
> > static struct attribute *adm1031_attributes[] = {
> > &sensor_dev_attr_fan1_input.dev_attr.attr,
> > &sensor_dev_attr_fan1_div.dev_attr.attr,
> > @@ -774,6 +830,7 @@ static struct attribute *adm1031_attributes[] = {
> >
> > &sensor_dev_attr_auto_fan1_min_pwm.dev_attr.attr,
> >
> > + &dev_attr_update_rate.attr,
> > &dev_attr_alarms.attr,
> >
> > NULL
> > @@ -901,6 +958,9 @@ static void adm1031_init_client(struct i2c_client *client)
> > unsigned int read_val;
> > unsigned int mask;
> > struct adm1031_data *data = i2c_get_clientdata(client);
> > + unsigned int rates[] = { 125, 250, 500, 1000, 2000, 4000, 8000, 16000 };
>
> You don't want to have the same lookup table twice in the driver. If it
> is needed more than once, make it a static global.
>
> > + unsigned int regvals[] = { 0x1c, 0x18, 0x14, 0x10, 0xc, 0x8, 0x4, 0x0 };
> > + int i;
> >
> > mask = (ADM1031_CONF2_PWM1_ENABLE | ADM1031_CONF2_TACH1_ENABLE);
> > if (data->chip_type == adm1031) {
> > @@ -919,18 +979,36 @@ static void adm1031_init_client(struct i2c_client *client)
> > ADM1031_CONF1_MONITOR_ENABLE);
> > }
> >
> > + /* Read the chip's update rate */
> > + mask = ADM1031_UPDATE_RATE_MASK;
> > + read_val = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
> > +
> > + /* Find the update rate from the table */
> > + for (i = 0; i < ARRAY_SIZE(regvals); i++) {
> > + if ((read_val & mask) == regvals[i])
> > + break;
> > + }
> > +
> > + /* the update rate was not found, use the default */
> > + if (i == ARRAY_SIZE(regvals)) {
> > + data->update_rate = 1000;
> > + return;
> > + }
>
> This simply can't happen... The look-up table covers all possible
> values for a 3-bit mask.
>
> > +
> > + data->update_rate = rates[i];
> > }
> >
> > static struct adm1031_data *adm1031_update_device(struct device *dev)
> > {
> > struct i2c_client *client = to_i2c_client(dev);
> > struct adm1031_data *data = i2c_get_clientdata(client);
> > + unsigned long next_update;
> > int chan;
> >
> > mutex_lock(&data->update_lock);
> >
> > - if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
> > - || !data->valid) {
> > + next_update = data->last_updated + msecs_to_jiffies(data->update_rate);
> > + if (time_after(jiffies, next_update) || !data->valid) {
> >
> > dev_dbg(&client->dev, "Starting adm1031 update\n");
> > for (chan = 0;
>
> Here is how I'd do it:
>
> ---
> drivers/hwmon/adm1031.c | 68 +++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 66 insertions(+), 2 deletions(-)
>
> --- linux-2.6.34-rc4.orig/drivers/hwmon/adm1031.c 2010-02-25 09:12:22.000000000 +0100
> +++ linux-2.6.34-rc4/drivers/hwmon/adm1031.c 2010-04-14 10:11:04.000000000 +0200
> @@ -36,6 +36,7 @@
> #define ADM1031_REG_FAN_DIV(nr) (0x20 + (nr))
> #define ADM1031_REG_PWM (0x22)
> #define ADM1031_REG_FAN_MIN(nr) (0x10 + (nr))
> +#define ADM1031_REG_FAN_FILTER (0x23)
>
> #define ADM1031_REG_TEMP_OFFSET(nr) (0x0d + (nr))
> #define ADM1031_REG_TEMP_MAX(nr) (0x14 + 4 * (nr))
> @@ -61,6 +62,9 @@
> #define ADM1031_CONF2_TACH2_ENABLE 0x08
> #define ADM1031_CONF2_TEMP_ENABLE(chan) (0x10 << (chan))
>
> +#define ADM1031_UPDATE_RATE_MASK 0x1c
> +#define ADM1031_UPDATE_RATE_SHIFT 2
> +
> /* Addresses to scan */
> static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, I2C_CLIENT_END };
>
> @@ -75,6 +79,7 @@ struct adm1031_data {
> int chip_type;
> char valid; /* !=0 if following fields are valid */
> unsigned long last_updated; /* In jiffies */
> + unsigned int update_rate; /* In milliseconds */
> /* The chan_select_table contains the possible configurations for
> * auto fan control.
> */
> @@ -738,6 +743,57 @@ static SENSOR_DEVICE_ATTR(temp3_crit_ala
> static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_alarm, NULL, 13);
> static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 14);
>
> +/* Update Rate */
> +static const unsigned int update_rates[] = {
> + 16000, 8000, 4000, 2000, 1000, 500, 250, 125,
> +};
> +
> +static ssize_t show_update_rate(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adm1031_data *data = i2c_get_clientdata(client);
> +
> + return sprintf(buf, "%u\n", data->update_rate);
> +}
> +
> +static ssize_t set_update_rate(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adm1031_data *data = i2c_get_clientdata(client);
> + unsigned long val;
> + int i, err;
> + u8 reg;
> +
> + err = strict_strtoul(buf, 10, &val);
> + if (err)
> + return err;
> +
> + /* find the nearest update rate from the table */
> + for (i = 0; i < ARRAY_SIZE(update_rates) - 1; i++) {
> + if (val >= update_rates[i])
> + break;
> + }
> + /* if not found, we point to the last entry (lowest update rate) */
> +
> + /* set the new update rate while preserving other settings */
> + reg = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
> + reg &= ~ADM1031_UPDATE_RATE_MASK;
> + reg |= i << ADM1031_UPDATE_RATE_SHIFT;
> + adm1031_write_value(client, ADM1031_REG_FAN_FILTER, reg);
> +
> + mutex_lock(&data->update_lock);
> + data->update_rate = update_rates[i];
> + mutex_unlock(&data->update_lock);
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(update_rate, S_IRUGO | S_IWUSR, show_update_rate,
> + set_update_rate);
> +
> static struct attribute *adm1031_attributes[] = {
> &sensor_dev_attr_fan1_input.dev_attr.attr,
> &sensor_dev_attr_fan1_div.dev_attr.attr,
> @@ -774,6 +830,7 @@ static struct attribute *adm1031_attribu
>
> &sensor_dev_attr_auto_fan1_min_pwm.dev_attr.attr,
>
> + &dev_attr_update_rate.attr,
> &dev_attr_alarms.attr,
>
> NULL
> @@ -900,6 +957,7 @@ static void adm1031_init_client(struct i
> {
> unsigned int read_val;
> unsigned int mask;
> + int i;
> struct adm1031_data *data = i2c_get_clientdata(client);
>
> mask = (ADM1031_CONF2_PWM1_ENABLE | ADM1031_CONF2_TACH1_ENABLE);
> @@ -919,18 +977,24 @@ static void adm1031_init_client(struct i
> ADM1031_CONF1_MONITOR_ENABLE);
> }
>
> + /* Read the chip's update rate */
> + mask = ADM1031_UPDATE_RATE_MASK;
> + read_val = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
> + i = (read_val & mask) >> ADM1031_UPDATE_RATE_SHIFT;
> + data->update_rate = update_rates[i];
> }
>
> static struct adm1031_data *adm1031_update_device(struct device *dev)
> {
> struct i2c_client *client = to_i2c_client(dev);
> struct adm1031_data *data = i2c_get_clientdata(client);
> + unsigned long next_update;
> int chan;
>
> mutex_lock(&data->update_lock);
>
> - if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
> - || !data->valid) {
> + next_update = data->last_updated + msecs_to_jiffies(data->update_rate);
> + if (time_after(jiffies, next_update) || !data->valid) {
>
> dev_dbg(&client->dev, "Starting adm1031 update\n");
> for (chan = 0;
>
>
> This looks nice enough to me. What do you think?
>
This is much better than my patch. I tested it on my board, and it works
exactly as expected. You've got my Reviewed-by and Tested-by on this
patch.
If you'd like, I'm happy to generate a v2 patch series rolling the name
and update_rate attributes into a "General Attributes" section in the
documentation, as well as using this patch for adm1031 support.
If you're comfortable rolling them together yourself, feel free to do
so.
Ira
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