Commit 412e29c1 authored by Vivien Didelot's avatar Vivien Didelot Committed by Guenter Roeck
Browse files

hwmon: (sht15) check GPIO directions 



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: default avatarVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 9e3970fb

drivers/hwmon/sht15.c

+88 −47
Original line number Diff line number Diff line
@@ -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;

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