From 412e29c135c11be6e2e4b22c0691e861b3d946c4 Mon Sep 17 00:00:00 2001 From: Vivien Didelot Date: Tue, 15 Jan 2013 13:33:06 -0500 Subject: [PATCH] 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: Vivien Didelot Signed-off-by: Guenter Roeck --- 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 9a594e6533a9..bfe326e896df 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; -- 2.30.2