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Date: Sat, 16 Jan 2016 17:14:38 +0100
From: Alexander Koch <mail@...xanderkoch.net>
To: jic23@...nel.org
Cc: knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
mhornung.linux@...il.com, dannenberg@...com, balbi@...com,
fengguang.wu@...el.com, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org,
Alexander Koch <mail@...xanderkoch.net>
Subject: [PATCH v2 3/3] 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@...xanderkoch.net>
Signed-off-by: Michael Hornung <mhornung.linux@...il.com>
---
drivers/iio/light/opt3001.c | 137 ++++++++++++++++++++++++++++++--------------
1 file changed, 95 insertions(+), 42 deletions(-)
diff --git a/drivers/iio/light/opt3001.c b/drivers/iio/light/opt3001.c
index b05c484..2a2340d 100644
--- 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_info(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) {
--
2.7.0
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