iio: temperature: ltc2983: make bulk write buffer DMA-safe

[ Upstream commit 5e0176213949724fbe9a8e4a39817edce337b8a0 ]

regmap_bulk_write() does not guarantee implicit DMA-safety,
even though the current implementation duplicates the given
buffer. Do not rely on it.

Fixes: f110f3188e56 ("iio: temperature: Add support for LTC2983")
Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com>
Link: https://lore.kernel.org/r/20221103130041.2153295-2-demonsingur@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
index 8306daa7790812e53602ca1cf6a75d0a97efabef..b2ae2d2c7eefc8df1860f9a18d571d3bdfffe3ca 100644 (file)
--- a/drivers/iio/temperature/ltc2983.c
+++ b/drivers/iio/temperature/ltc2983.c
@@ -205,6 +205,7 @@ struct ltc2983_data {
         * Holds the converted temperature
         */
        __be32 temp ____cacheline_aligned;
+       __be32 chan_val;
 };
 
 struct ltc2983_sensor {
@@ -309,19 +310,18 @@ static int __ltc2983_fault_handler(const struct ltc2983_data *st,
        return 0;
 }
 
-static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
+static int __ltc2983_chan_assign_common(struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor,
                                        u32 chan_val)
 {
        u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
-       __be32 __chan_val;
 
        chan_val |= LTC2983_CHAN_TYPE(sensor->type);
        dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
                chan_val);
-       __chan_val = cpu_to_be32(chan_val);
-       return regmap_bulk_write(st->regmap, reg, &__chan_val,
-                                sizeof(__chan_val));
+       st->chan_val = cpu_to_be32(chan_val);
+       return regmap_bulk_write(st->regmap, reg, &st->chan_val,
+                                sizeof(st->chan_val));
 }
 
 static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,