staging: iio: ad5933: Protect DIRECT mode using claim/release helpers

This device operates in DIRECT_MODE and BUFFER_HARDWARE mode.
Replace usages of iio_dev->mlock with iio_device_{claim|release}_direct_mode()
helper functions to guarantee DIRECT mode and consequently protect
BUFFER mode too.

Add and use a device private lock to protect against conflicting access of the
state data.
This helps with IIO subsystem redefining iio_dev->mlock to be used by
the IIO core only for protecting device operating mode changes.
ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes.

Protect changing of attributes inside ad5933_store(). Attributes
can no longer be changed while in buffered mode.

Remove lock from ad5933_work() because buffer mode should be enabled
when we reach this, and claiming DIRECT mode in all the other places
should protect it.

Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
index 297665d3fe11e0ee5b927a4839235873966dfe40..3d539eeb0e26a3ef0867c2d419a57171332c1775 100644 (file)
--- a/drivers/staging/iio/impedance-analyzer/ad5933.c
+++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
@@ -98,6 +98,7 @@ struct ad5933_state {
        struct i2c_client               *client;
        struct regulator                *reg;
        struct delayed_work             work;
+       struct mutex                    lock; /* Protect sensor state */
        unsigned long                   mclk_hz;
        unsigned char                   ctrl_hb;
        unsigned char                   ctrl_lb;
@@ -306,9 +307,11 @@ static ssize_t ad5933_show_frequency(struct device *dev,
                u8 d8[4];
        } dat;
 
-       mutex_lock(&indio_dev->mlock);
+       ret = iio_device_claim_direct_mode(indio_dev);
+       if (ret)
+               return ret;
        ret = ad5933_i2c_read(st->client, this_attr->address, 3, &dat.d8[1]);
-       mutex_unlock(&indio_dev->mlock);
+       iio_device_release_direct_mode(indio_dev);
        if (ret < 0)
                return ret;
 
@@ -338,9 +341,11 @@ static ssize_t ad5933_store_frequency(struct device *dev,
        if (val > AD5933_MAX_OUTPUT_FREQ_Hz)
                return -EINVAL;
 
-       mutex_lock(&indio_dev->mlock);
+       ret = iio_device_claim_direct_mode(indio_dev);
+       if (ret)
+               return ret;
        ret = ad5933_set_freq(st, this_attr->address, val);
-       mutex_unlock(&indio_dev->mlock);
+       iio_device_release_direct_mode(indio_dev);
 
        return ret ? ret : len;
 }
@@ -364,7 +369,7 @@ static ssize_t ad5933_show(struct device *dev,
        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
        int ret = 0, len = 0;
 
-       mutex_lock(&indio_dev->mlock);
+       mutex_lock(&st->lock);
        switch ((u32)this_attr->address) {
        case AD5933_OUT_RANGE:
                len = sprintf(buf, "%u\n",
@@ -393,7 +398,7 @@ static ssize_t ad5933_show(struct device *dev,
                ret = -EINVAL;
        }
 
-       mutex_unlock(&indio_dev->mlock);
+       mutex_unlock(&st->lock);
        return ret ? ret : len;
 }
 
@@ -415,7 +420,10 @@ static ssize_t ad5933_store(struct device *dev,
                        return ret;
        }
 
-       mutex_lock(&indio_dev->mlock);
+       ret = iio_device_claim_direct_mode(indio_dev);
+       if (ret)
+               return ret;
+       mutex_lock(&st->lock);
        switch ((u32)this_attr->address) {
        case AD5933_OUT_RANGE:
                ret = -EINVAL;
@@ -465,7 +473,8 @@ static ssize_t ad5933_store(struct device *dev,
                ret = -EINVAL;
        }
 
-       mutex_unlock(&indio_dev->mlock);
+       mutex_unlock(&st->lock);
+       iio_device_release_direct_mode(indio_dev);
        return ret ? ret : len;
 }
 
@@ -532,11 +541,9 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
 
        switch (m) {
        case IIO_CHAN_INFO_RAW:
-               mutex_lock(&indio_dev->mlock);
-               if (iio_buffer_enabled(indio_dev)) {
-                       ret = -EBUSY;
-                       goto out;
-               }
+               ret = iio_device_claim_direct_mode(indio_dev);
+               if (ret)
+                       return ret;
                ret = ad5933_cmd(st, AD5933_CTRL_MEASURE_TEMP);
                if (ret < 0)
                        goto out;
@@ -549,7 +556,7 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
                                      2, (u8 *)&dat);
                if (ret < 0)
                        goto out;
-               mutex_unlock(&indio_dev->mlock);
+               iio_device_release_direct_mode(indio_dev);
                *val = sign_extend32(be16_to_cpu(dat), 13);
 
                return IIO_VAL_INT;
@@ -561,7 +568,7 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
 
        return -EINVAL;
 out:
-       mutex_unlock(&indio_dev->mlock);
+       iio_device_release_direct_mode(indio_dev);
        return ret;
 }
 
@@ -657,18 +664,17 @@ static void ad5933_work(struct work_struct *work)
        unsigned char status;
        int ret;
 
-       mutex_lock(&indio_dev->mlock);
        if (st->state == AD5933_CTRL_INIT_START_FREQ) {
                /* start sweep */
                ad5933_cmd(st, AD5933_CTRL_START_SWEEP);
                st->state = AD5933_CTRL_START_SWEEP;
                schedule_delayed_work(&st->work, st->poll_time_jiffies);
-               goto out;
+               return;
        }
 
        ret = ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
        if (ret)
-               goto out;
+               return;
 
        if (status & AD5933_STAT_DATA_VALID) {
                int scan_count = bitmap_weight(indio_dev->active_scan_mask,
@@ -678,7 +684,7 @@ static void ad5933_work(struct work_struct *work)
                                AD5933_REG_REAL_DATA : AD5933_REG_IMAG_DATA,
                                scan_count * 2, (u8 *)buf);
                if (ret)
-                       goto out;
+                       return;
 
                if (scan_count == 2) {
                        val[0] = be16_to_cpu(buf[0]);
@@ -690,7 +696,7 @@ static void ad5933_work(struct work_struct *work)
        } else {
                /* no data available - try again later */
                schedule_delayed_work(&st->work, st->poll_time_jiffies);
-               goto out;
+               return;
        }
 
        if (status & AD5933_STAT_SWEEP_DONE) {
@@ -703,8 +709,6 @@ static void ad5933_work(struct work_struct *work)
                ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
                schedule_delayed_work(&st->work, st->poll_time_jiffies);
        }
-out:
-       mutex_unlock(&indio_dev->mlock);
 }
 
 static int ad5933_probe(struct i2c_client *client,
@@ -723,6 +727,8 @@ static int ad5933_probe(struct i2c_client *client,
        i2c_set_clientdata(client, indio_dev);
        st->client = client;
 
+       mutex_init(&st->lock);
+
        if (!pdata)
                pdata = &ad5933_default_pdata;