Without this patch, the SHT15 driver may fail silently with a
non-bidirectional data line and/or an input-only clock line.
This patch checks the return value of gpio_direction_* function calls
and returns the error code (if any) to the caller. If an error occurs in
the read work function (work_funct_t), we wake the queue up directly
without updating the data->state flag, to notice the waiter of the I/O
error.
The patch also makes minor cleanups: s/error_ret/unlock for some labels
and uses devm_gpio_request_one() for the clock line.
Signed-off-by: Vivien Didelot <vivien.didelot@xxxxxxxxxxxxxxxxxxxx>
---
drivers/hwmon/sht15.c | 135 ++++++++++++++++++++++++++++++++------------------
1 file changed, 88 insertions(+), 47 deletions(-)
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
index 9a594e6..bfe326e 100644
--- a/drivers/hwmon/sht15.c
+++ b/drivers/hwmon/sht15.c
@@ -212,11 +212,13 @@ static u8 sht15_crc8(struct sht15_data *data,
*
* This implements section 3.4 of the data sheet
*/
-static void sht15_connection_reset(struct sht15_data *data)
+static int sht15_connection_reset(struct sht15_data *data)
{
- int i;
+ int i, err;
- gpio_direction_output(data->pdata->gpio_data, 1);
+ err = gpio_direction_output(data->pdata->gpio_data, 1);
+ if (err)
+ return err;
ndelay(SHT15_TSCKL);
gpio_set_value(data->pdata->gpio_sck, 0);
ndelay(SHT15_TSCKL);
@@ -226,6 +228,7 @@ static void sht15_connection_reset(struct sht15_data *data)
gpio_set_value(data->pdata->gpio_sck, 0);
ndelay(SHT15_TSCKL);
}
+ return 0;
}
/**
@@ -251,10 +254,14 @@ static inline void sht15_send_bit(struct sht15_data *data, int val)
* conservative ones used in implementation. This implements
* figure 12 on the data sheet.
*/
-static void sht15_transmission_start(struct sht15_data *data)
+static int sht15_transmission_start(struct sht15_data *data)
{
+ int err;
+
/* ensure data is high and output */
- gpio_direction_output(data->pdata->gpio_data, 1);
+ err = gpio_direction_output(data->pdata->gpio_data, 1);
+ if (err)
+ return err;
ndelay(SHT15_TSU);
gpio_set_value(data->pdata->gpio_sck, 0);
ndelay(SHT15_TSCKL);
@@ -270,6 +277,7 @@ static void sht15_transmission_start(struct sht15_data *data)
ndelay(SHT15_TSU);
gpio_set_value(data->pdata->gpio_sck, 0);
ndelay(SHT15_TSCKL);
+ return 0;
}
/**
@@ -293,13 +301,19 @@ static void sht15_send_byte(struct sht15_data *data, u8 byte)
*/
static int sht15_wait_for_response(struct sht15_data *data)
{
- gpio_direction_input(data->pdata->gpio_data);
+ int err;
+
+ err = gpio_direction_input(data->pdata->gpio_data);
+ if (err)
+ return err;
gpio_set_value(data->pdata->gpio_sck, 1);
ndelay(SHT15_TSCKH);
if (gpio_get_value(data->pdata->gpio_data)) {
gpio_set_value(data->pdata->gpio_sck, 0);
dev_err(data->dev, "Command not acknowledged\n");
- sht15_connection_reset(data);
+ err = sht15_connection_reset(data);
+ if (err)
+ return err;
return -EIO;
}
gpio_set_value(data->pdata->gpio_sck, 0);
@@ -317,12 +331,13 @@ static int sht15_wait_for_response(struct sht15_data *data)
*/
static int sht15_send_cmd(struct sht15_data *data, u8 cmd)
{
- int ret = 0;
+ int err;
- sht15_transmission_start(data);
+ err = sht15_transmission_start(data);
+ if (err)
+ return err;
sht15_send_byte(data, cmd);
- ret = sht15_wait_for_response(data);
- return ret;
+ return sht15_wait_for_response(data);
}
/**
@@ -352,9 +367,13 @@ static int sht15_soft_reset(struct sht15_data *data)
* Each byte of data is acknowledged by pulling the data line
* low for one clock pulse.
*/
-static void sht15_ack(struct sht15_data *data)
+static int sht15_ack(struct sht15_data *data)
{
- gpio_direction_output(data->pdata->gpio_data, 0);
+ int err;
+
+ err = gpio_direction_output(data->pdata->gpio_data, 0);
+ if (err)
+ return err;
ndelay(SHT15_TSU);
gpio_set_value(data->pdata->gpio_sck, 1);
ndelay(SHT15_TSU);
@@ -362,7 +381,7 @@ static void sht15_ack(struct sht15_data *data)
ndelay(SHT15_TSU);
gpio_set_value(data->pdata->gpio_data, 1);
- gpio_direction_input(data->pdata->gpio_data);
+ return gpio_direction_input(data->pdata->gpio_data);
}
/**
@@ -371,14 +390,19 @@ static void sht15_ack(struct sht15_data *data)
*
* This is basically a NAK (single clock pulse, data high).
*/
-static void sht15_end_transmission(struct sht15_data *data)
+static int sht15_end_transmission(struct sht15_data *data)
{
- gpio_direction_output(data->pdata->gpio_data, 1);
+ int err;
+
+ err = gpio_direction_output(data->pdata->gpio_data, 1);
+ if (err)
+ return err;
ndelay(SHT15_TSU);
gpio_set_value(data->pdata->gpio_sck, 1);
ndelay(SHT15_TSCKH);
gpio_set_value(data->pdata->gpio_sck, 0);
ndelay(SHT15_TSCKL);
+ return 0;
}
/**
@@ -410,17 +434,19 @@ static u8 sht15_read_byte(struct sht15_data *data)
*/
static int sht15_send_status(struct sht15_data *data, u8 status)
{
- int ret;
-
- ret = sht15_send_cmd(data, SHT15_WRITE_STATUS);
- if (ret)
- return ret;
- gpio_direction_output(data->pdata->gpio_data, 1);
+ int err;
+
+ err = sht15_send_cmd(data, SHT15_WRITE_STATUS);
+ if (err)
+ return err;
+ err = gpio_direction_output(data->pdata->gpio_data, 1);
+ if (err)
+ return err;
ndelay(SHT15_TSU);
sht15_send_byte(data, status);
- ret = sht15_wait_for_response(data);
- if (ret)
- return ret;
+ err = sht15_wait_for_response(data);
+ if (err)
+ return err;
data->val_status = status;
return 0;
@@ -446,7 +472,7 @@ static int sht15_update_status(struct sht15_data *data)
|| !data->status_valid) {
ret = sht15_send_cmd(data, SHT15_READ_STATUS);
if (ret)
- goto error_ret;
+ goto unlock;
status = sht15_read_byte(data);
if (data->checksumming) {
@@ -458,7 +484,9 @@ static int sht15_update_status(struct sht15_data *data)
== dev_checksum);
}
- sht15_end_transmission(data);
+ ret = sht15_end_transmission(data);
+ if (ret)
+ goto unlock;
/*
* Perform checksum validation on the received data.
@@ -469,27 +497,27 @@ static int sht15_update_status(struct sht15_data *data)
previous_config = data->val_status & 0x07;
ret = sht15_soft_reset(data);
if (ret)
- goto error_ret;
+ goto unlock;
if (previous_config) {
ret = sht15_send_status(data, previous_config);
if (ret) {
dev_err(data->dev,
"CRC validation failed, unable "
"to restore device settings\n");
- goto error_ret;
+ goto unlock;
}
}
ret = -EAGAIN;
- goto error_ret;
+ goto unlock;
}
data->val_status = status;
data->status_valid = true;
data->last_status = jiffies;
}
-error_ret:
- mutex_unlock(&data->read_lock);
+unlock:
+ mutex_unlock(&data->read_lock);
return ret;
}
@@ -511,7 +539,9 @@ static int sht15_measurement(struct sht15_data *data,
if (ret)
return ret;
- gpio_direction_input(data->pdata->gpio_data);
+ ret = gpio_direction_input(data->pdata->gpio_data);
+ if (ret)
+ return ret;
atomic_set(&data->interrupt_handled, 0);
enable_irq(gpio_to_irq(data->pdata->gpio_data));
@@ -524,9 +554,14 @@ static int sht15_measurement(struct sht15_data *data,
ret = wait_event_timeout(data->wait_queue,
(data->state == SHT15_READING_NOTHING),
msecs_to_jiffies(timeout_msecs));
- if (ret == 0) {/* timeout occurred */
+ if (data->state != SHT15_READING_NOTHING) { /* I/O error occurred */
+ data->state = SHT15_READING_NOTHING;
+ return -EIO;
+ } else if (ret == 0) { /* timeout occurred */
disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
- sht15_connection_reset(data);
+ ret = sht15_connection_reset(data);
+ if (ret)
+ return ret;
return -ETIME;
}
@@ -570,17 +605,17 @@ static int sht15_update_measurements(struct sht15_data *data)
data->state = SHT15_READING_HUMID;
ret = sht15_measurement(data, SHT15_MEASURE_RH, 160);
if (ret)
- goto error_ret;
+ goto unlock;
data->state = SHT15_READING_TEMP;
ret = sht15_measurement(data, SHT15_MEASURE_TEMP, 400);
if (ret)
- goto error_ret;
+ goto unlock;
data->measurements_valid = true;
data->last_measurement = jiffies;
}
-error_ret:
- mutex_unlock(&data->read_lock);
+unlock:
+ mutex_unlock(&data->read_lock);
return ret;
}
@@ -818,7 +853,8 @@ static void sht15_bh_read_data(struct work_struct *work_s)
/* Read the data back from the device */
val = sht15_read_byte(data);
val <<= 8;
- sht15_ack(data);
+ if (sht15_ack(data))
+ goto wakeup;
val |= sht15_read_byte(data);
if (data->checksumming) {
@@ -826,7 +862,8 @@ static void sht15_bh_read_data(struct work_struct *work_s)
* Ask the device for a checksum and read it back.
* Note: the device sends the checksum byte reversed.
*/
- sht15_ack(data);
+ if (sht15_ack(data))
+ goto wakeup;
dev_checksum = sht15_reverse(sht15_read_byte(data));
checksum_vals[0] = (data->state == SHT15_READING_TEMP) ?
SHT15_MEASURE_TEMP : SHT15_MEASURE_RH;
@@ -837,7 +874,8 @@ static void sht15_bh_read_data(struct work_struct *work_s)
}
/* Tell the device we are done */
- sht15_end_transmission(data);
+ if (sht15_end_transmission(data))
+ goto wakeup;
switch (data->state) {
case SHT15_READING_TEMP:
@@ -851,6 +889,7 @@ static void sht15_bh_read_data(struct work_struct *work_s)
}
data->state = SHT15_READING_NOTHING;
+wakeup:
wake_up(&data->wait_queue);
}
@@ -942,17 +981,17 @@ static int sht15_probe(struct platform_device *pdev)
}
/* Try requesting the GPIOs */
- ret = devm_gpio_request(&pdev->dev, data->pdata->gpio_sck, "SHT15 sck");
+ ret = devm_gpio_request_one(&pdev->dev, data->pdata->gpio_sck,
+ GPIOF_OUT_INIT_LOW, "SHT15 sck");
if (ret) {
- dev_err(&pdev->dev, "gpio request failed\n");
+ dev_err(&pdev->dev, "clock line GPIO request failed\n");
goto err_release_reg;
}
- gpio_direction_output(data->pdata->gpio_sck, 0);
ret = devm_gpio_request(&pdev->dev, data->pdata->gpio_data,
"SHT15 data");
if (ret) {
- dev_err(&pdev->dev, "gpio request failed\n");
+ dev_err(&pdev->dev, "data line GPIO request failed\n");
goto err_release_reg;
}
@@ -966,7 +1005,9 @@ static int sht15_probe(struct platform_device *pdev)
goto err_release_reg;
}
disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
- sht15_connection_reset(data);
+ ret = sht15_connection_reset(data);
+ if (ret)
+ goto err_release_reg;
ret = sht15_soft_reset(data);
if (ret)
goto err_release_reg;
--
1.8.1.1
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