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iio: light: opt3001: enable operation w/o IRQ
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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>
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Alexander Koch authored and Jonathan Cameron committed Jan 30, 2016
1 parent 84e8d09 commit ac663db
Showing 1 changed file with 95 additions and 42 deletions.
137 changes: 95 additions & 42 deletions drivers/iio/light/opt3001.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -92,6 +95,8 @@ struct opt3001 {

u8 high_thresh_exp;
u8 low_thresh_exp;

bool use_irq;
};

struct opt3001_scale {
Expand Down Expand Up @@ -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) {
Expand All @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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) {
Expand Down

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