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iio: temperature: mcp9600: Fix temperature reading for negative values

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commit 827dca3129708a8465bde90c86c2e3c38e62dd4f upstream.

Temperature is stored as 16bit value in two's complement format. Current
implementation ignores the sign bit. Make it aware of the sign bit by
using sign_extend32.

Fixes: 3f6b9598b6df ("iio: temperature: Add MCP9600 thermocouple EMF converter")
Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Tested-by: Andrew Hepp <andrew.hepp@ahepp.dev>
Link: https://lore.kernel.org/r/20240424185913.1177127-1-dima.fedrau@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dimitri Fedrau 2024-04-24 20:59:10 +02:00 committed by Greg Kroah-Hartman
parent 6f0cfe3b8d
commit c70cc82c80
1 changed files with 2 additions and 1 deletions
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3
drivers/iio/temperature/mcp9600.c
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@ -52,7 +52,8 @@ static int mcp9600_read(struct mcp9600_data *data,
if (ret < 0)
return ret;
*val = ret;
*val = sign_extend32(ret, 15);
return 0;
}