iio: adc: max1363: Use a small fixed size buffer to replace dynamic allocation

Drop the recurrent allocation of the data buffer from the trigger
handler and put it in the iio_priv(). This way, the maximum amount of
channels is always allocated in favor of simpler code and drop
of usage of the internal private variable "scan_timestamp" of the
struct iio_dev.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20241214191421.94172-3-vassilisamir@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c
index 9a0baea08ab6162b024932f3f65c8a68d156672d..e8d731bc34e0f479d594100d8750665412f0bd07 100644 (file)
--- a/drivers/iio/adc/max1363.c
+++ b/drivers/iio/adc/max1363.c
@@ -161,6 +161,7 @@ struct max1363_chip_info {
  * @vref_uv:           Actual (external or internal) reference voltage
  * @send:              function used to send data to the chip
  * @recv:              function used to receive data from the chip
+ * @data:              buffer to store channel data and timestamp
  */
 struct max1363_state {
        struct i2c_client               *client;
@@ -186,6 +187,10 @@ struct max1363_state {
                                                const char *buf, int count);
        int                             (*recv)(const struct i2c_client *client,
                                                char *buf, int count);
+       struct {
+               u8 buf[MAX1363_MAX_CHANNELS * 2];
+               aligned_s64 ts;
+       } data;
 };
 
 #define MAX1363_MODE_SINGLE(_num, _mask) {                             \
@@ -1462,22 +1467,10 @@ static irqreturn_t max1363_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct max1363_state *st = iio_priv(indio_dev);
-       __u8 *rxbuf;
        int b_sent;
-       size_t d_size;
        unsigned long numvals = bitmap_weight(st->current_mode->modemask,
                                              MAX1363_MAX_CHANNELS);
 
-       /* Ensure the timestamp is 8 byte aligned */
-       if (st->chip_info->bits != 8)
-               d_size = numvals*2;
-       else
-               d_size = numvals;
-       if (indio_dev->scan_timestamp) {
-               d_size += sizeof(s64);
-               if (d_size % sizeof(s64))
-                       d_size += sizeof(s64) - (d_size % sizeof(s64));
-       }
        /* Monitor mode prevents reading. Whilst not currently implemented
         * might as well have this test in here in the meantime as it does
         * no harm.
@@ -1485,21 +1478,16 @@ static irqreturn_t max1363_trigger_handler(int irq, void *p)
        if (numvals == 0)
                goto done;
 
-       rxbuf = kmalloc(d_size, GFP_KERNEL);
-       if (rxbuf == NULL)
-               goto done;
        if (st->chip_info->bits != 8)
-               b_sent = st->recv(st->client, rxbuf, numvals * 2);
+               b_sent = st->recv(st->client, st->data.buf, numvals * 2);
        else
-               b_sent = st->recv(st->client, rxbuf, numvals);
+               b_sent = st->recv(st->client, st->data.buf, numvals);
        if (b_sent < 0)
-               goto done_free;
+               goto done;
 
-       iio_push_to_buffers_with_timestamp(indio_dev, rxbuf,
+       iio_push_to_buffers_with_timestamp(indio_dev, &st->data,
                                           iio_get_time_ns(indio_dev));
 
-done_free:
-       kfree(rxbuf);
 done:
        iio_trigger_notify_done(indio_dev->trig);