iio: light: opt3001: enable operation w/o IRQ

Enable operation of the TI OPT3001 light sensor without having an
interrupt line available to connect the INT pin to.

In this operation mode, we issue a conversion request and simply wait
for the conversion time available as timeout value, determined from
integration time configuration and the worst-case time given in the data
sheet (sect. 6.5, table on p. 5):

  short integration time (100ms): 110ms + 3ms = 113ms
   long integration time (800ms): 880ms + 3ms = 883ms

This change is transparent as behaviour defaults to using the interrupt
method if an interrupt no. is configured via device tree. Interrupt-less
operation mode is performed when no valid interrupt no. is given.

Signed-off-by: Alexander Koch <mail@alexanderkoch.net>
Signed-off-by: Michael Hornung <mhornung.linux@gmail.com>
Tested-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/light/opt3001.c b/drivers/iio/light/opt3001.c
index b05c484a16468878d3f57c0428f292e3b814fe20..b776c8ed4387dc289eef2b5810b4217346c8f10f 100644 (file)
--- a/drivers/iio/light/opt3001.c
+++ b/drivers/iio/light/opt3001.c
@@ -70,9 +70,12 @@
 
 /*
  * Time to wait for conversion result to be ready. The device datasheet
- * worst-case max value is 880ms. Add some slack to be on the safe side.
+ * sect. 6.5 states results are ready after total integration time plus 3ms.
+ * This results in worst-case max values of 113ms or 883ms, respectively.
+ * Add some slack to be on the safe side.
  */
-#define OPT3001_RESULT_READY_TIMEOUT   msecs_to_jiffies(1000)
+#define OPT3001_RESULT_READY_SHORT     150
+#define OPT3001_RESULT_READY_LONG      1000
 
 struct opt3001 {
        struct i2c_client       *client;
@@ -92,6 +95,8 @@ struct opt3001 {
 
        u8                      high_thresh_exp;
        u8                      low_thresh_exp;
+
+       bool                    use_irq;
 };
 
 struct opt3001_scale {
@@ -230,26 +235,30 @@ static int opt3001_get_lux(struct opt3001 *opt, int *val, int *val2)
        u16 reg;
        u8 exponent;
        u16 value;
+       long timeout;
 
-       /*
-        * Enable the end-of-conversion interrupt mechanism. Note that doing
-        * so will overwrite the low-level limit value however we will restore
-        * this value later on.
-        */
-       ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
-                       OPT3001_LOW_LIMIT_EOC_ENABLE);
-       if (ret < 0) {
-               dev_err(opt->dev, "failed to write register %02x\n",
-                               OPT3001_LOW_LIMIT);
-               return ret;
+       if (opt->use_irq) {
+               /*
+                * Enable the end-of-conversion interrupt mechanism. Note that
+                * doing so will overwrite the low-level limit value however we
+                * will restore this value later on.
+                */
+               ret = i2c_smbus_write_word_swapped(opt->client,
+                                       OPT3001_LOW_LIMIT,
+                                       OPT3001_LOW_LIMIT_EOC_ENABLE);
+               if (ret < 0) {
+                       dev_err(opt->dev, "failed to write register %02x\n",
+                                       OPT3001_LOW_LIMIT);
+                       return ret;
+               }
+
+               /* Allow IRQ to access the device despite lock being set */
+               opt->ok_to_ignore_lock = true;
        }
 
-       /* Reset data-ready indicator flag (will be set in the IRQ routine) */
+       /* Reset data-ready indicator flag */
        opt->result_ready = false;
 
-       /* Allow IRQ to access the device despite lock being set */
-       opt->ok_to_ignore_lock = true;
-
        /* Configure for single-conversion mode and start a new conversion */
        ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
        if (ret < 0) {
@@ -269,32 +278,69 @@ static int opt3001_get_lux(struct opt3001 *opt, int *val, int *val2)
                goto err;
        }
 
-       /* Wait for the IRQ to indicate the conversion is complete */
-       ret = wait_event_timeout(opt->result_ready_queue, opt->result_ready,
-                       OPT3001_RESULT_READY_TIMEOUT);
+       if (opt->use_irq) {
+               /* Wait for the IRQ to indicate the conversion is complete */
+               ret = wait_event_timeout(opt->result_ready_queue,
+                               opt->result_ready,
+                               msecs_to_jiffies(OPT3001_RESULT_READY_LONG));
+       } else {
+               /* Sleep for result ready time */
+               timeout = (opt->int_time == OPT3001_INT_TIME_SHORT) ?
+                       OPT3001_RESULT_READY_SHORT : OPT3001_RESULT_READY_LONG;
+               msleep(timeout);
+
+               /* Check result ready flag */
+               ret = i2c_smbus_read_word_swapped(opt->client,
+                                                 OPT3001_CONFIGURATION);
+               if (ret < 0) {
+                       dev_err(opt->dev, "failed to read register %02x\n",
+                               OPT3001_CONFIGURATION);
+                       goto err;
+               }
+
+               if (!(ret & OPT3001_CONFIGURATION_CRF)) {
+                       ret = -ETIMEDOUT;
+                       goto err;
+               }
+
+               /* Obtain value */
+               ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_RESULT);
+               if (ret < 0) {
+                       dev_err(opt->dev, "failed to read register %02x\n",
+                               OPT3001_RESULT);
+                       goto err;
+               }
+               opt->result = ret;
+               opt->result_ready = true;
+       }
 
 err:
-       /* Disallow IRQ to access the device while lock is active */
-       opt->ok_to_ignore_lock = false;
+       if (opt->use_irq)
+               /* Disallow IRQ to access the device while lock is active */
+               opt->ok_to_ignore_lock = false;
 
        if (ret == 0)
                return -ETIMEDOUT;
        else if (ret < 0)
                return ret;
 
-       /*
-        * Disable the end-of-conversion interrupt mechanism by restoring the
-        * low-level limit value (clearing OPT3001_LOW_LIMIT_EOC_ENABLE). Note
-        * that selectively clearing those enable bits would affect the actual
-        * limit value due to bit-overlap and therefore can't be done.
-        */
-       value = (opt->low_thresh_exp << 12) | opt->low_thresh_mantissa;
-       ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
-                       value);
-       if (ret < 0) {
-               dev_err(opt->dev, "failed to write register %02x\n",
-                               OPT3001_LOW_LIMIT);
-               return ret;
+       if (opt->use_irq) {
+               /*
+                * Disable the end-of-conversion interrupt mechanism by
+                * restoring the low-level limit value (clearing
+                * OPT3001_LOW_LIMIT_EOC_ENABLE). Note that selectively clearing
+                * those enable bits would affect the actual limit value due to
+                * bit-overlap and therefore can't be done.
+                */
+               value = (opt->low_thresh_exp << 12) | opt->low_thresh_mantissa;
+               ret = i2c_smbus_write_word_swapped(opt->client,
+                                                  OPT3001_LOW_LIMIT,
+                                                  value);
+               if (ret < 0) {
+                       dev_err(opt->dev, "failed to write register %02x\n",
+                                       OPT3001_LOW_LIMIT);
+                       return ret;
+               }
        }
 
        exponent = OPT3001_REG_EXPONENT(opt->result);
@@ -736,12 +782,18 @@ static int opt3001_probe(struct i2c_client *client,
                return ret;
        }
 
-       ret = request_threaded_irq(irq, NULL, opt3001_irq,
-                       IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
-                       "opt3001", iio);
-       if (ret) {
-               dev_err(dev, "failed to request IRQ #%d\n", irq);
-               return ret;
+       /* Make use of INT pin only if valid IRQ no. is given */
+       if (irq > 0) {
+               ret = request_threaded_irq(irq, NULL, opt3001_irq,
+                               IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+                               "opt3001", iio);
+               if (ret) {
+                       dev_err(dev, "failed to request IRQ #%d\n", irq);
+                       return ret;
+               }
+               opt->use_irq = true;
+       } else {
+               dev_dbg(opt->dev, "enabling interrupt-less operation\n");
        }
 
        return 0;
@@ -754,7 +806,8 @@ static int opt3001_remove(struct i2c_client *client)
        int ret;
        u16 reg;
 
-       free_irq(client->irq, iio);
+       if (opt->use_irq)
+               free_irq(client->irq, iio);
 
        ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
        if (ret < 0) {