hwmon: (tmp102) Improve handling of initial read delay
If the chip was in shutdown mode when the driver was loaded, the first conversion is ready no more than 35 milli-seconds after the chip was taken out of shutdown. The driver delay was so far set to 333 ms (HZ / 3), which is much higher than the maximum time needed by the chip. Reduce the time to 35 milli-seconds. Introduce a 'valid' flag to ensure that sensor data is actually read even if requested less than 333 ms after the driver was loaded. Acked-by: Nishanth Menon <nm@ti.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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@ -13,6 +13,7 @@
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* GNU General Public License for more details.
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*/
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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@ -46,13 +47,16 @@
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#define TMP102_TLOW_REG 0x02
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#define TMP102_THIGH_REG 0x03
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#define CONVERSION_TIME_MS 35 /* in milli-seconds */
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struct tmp102 {
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struct i2c_client *client;
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struct mutex lock;
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u16 config_orig;
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unsigned long last_update;
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unsigned long ready_time;
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bool valid;
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int temp[3];
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bool first_time;
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};
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/* convert left adjusted 13-bit TMP102 register value to milliCelsius */
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@ -73,13 +77,14 @@ static const u8 tmp102_reg[] = {
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TMP102_THIGH_REG,
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};
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static struct tmp102 *tmp102_update_device(struct device *dev)
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static void tmp102_update_device(struct device *dev)
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{
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struct tmp102 *tmp102 = dev_get_drvdata(dev);
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struct i2c_client *client = tmp102->client;
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mutex_lock(&tmp102->lock);
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if (time_after(jiffies, tmp102->last_update + HZ / 3)) {
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if (!tmp102->valid ||
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time_after(jiffies, tmp102->last_update + HZ / 3)) {
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int i;
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for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) {
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int status = i2c_smbus_read_word_swapped(client,
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@ -88,22 +93,22 @@ static struct tmp102 *tmp102_update_device(struct device *dev)
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tmp102->temp[i] = tmp102_reg_to_mC(status);
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}
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tmp102->last_update = jiffies;
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tmp102->first_time = false;
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tmp102->valid = true;
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}
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mutex_unlock(&tmp102->lock);
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return tmp102;
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}
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static int tmp102_read_temp(void *dev, int *temp)
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{
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struct tmp102 *tmp102 = tmp102_update_device(dev);
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struct tmp102 *tmp102 = dev_get_drvdata(dev);
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/* Is it too early even to return a conversion? */
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if (tmp102->first_time) {
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if (time_before(jiffies, tmp102->ready_time)) {
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dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
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return -EAGAIN;
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}
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tmp102_update_device(dev);
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*temp = tmp102->temp[0];
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return 0;
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@ -114,12 +119,13 @@ static ssize_t tmp102_show_temp(struct device *dev,
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char *buf)
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{
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struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
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struct tmp102 *tmp102 = tmp102_update_device(dev);
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struct tmp102 *tmp102 = dev_get_drvdata(dev);
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/* Is it too early even to return a read? */
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if (tmp102->first_time)
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if (time_before(jiffies, tmp102->ready_time))
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return -EAGAIN;
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tmp102_update_device(dev);
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return sprintf(buf, "%d\n", tmp102->temp[sda->index]);
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}
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@ -224,11 +230,18 @@ static int tmp102_probe(struct i2c_client *client,
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dev_err(dev, "config settings did not stick\n");
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return -ENODEV;
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}
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tmp102->last_update = jiffies;
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/* Mark that we are not ready with data until conversion is complete */
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tmp102->first_time = true;
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mutex_init(&tmp102->lock);
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tmp102->ready_time = jiffies;
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if (tmp102->config_orig & TMP102_CONF_SD) {
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/*
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* Mark that we are not ready with data until the first
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* conversion is complete
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*/
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tmp102->ready_time += msecs_to_jiffies(CONVERSION_TIME_MS);
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}
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
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tmp102,
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tmp102_groups);
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@ -261,12 +274,15 @@ static int tmp102_suspend(struct device *dev)
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static int tmp102_resume(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct tmp102 *tmp102 = i2c_get_clientdata(client);
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int config;
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config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
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if (config < 0)
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return config;
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tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
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config &= ~TMP102_CONF_SD;
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return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
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}
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