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Eliav Farber 7055f29780 hwmon: (mr75203) fix voltage equation for negative source input 
[ Upstream commit 227a3a2fc3 ]

According to Moortec Embedded Voltage Monitor (MEVM) series 3 data
sheet, the minimum input signal is -100mv and maximum input signal
is +1000mv.

The equation used to convert the digital word to voltage uses mixed
types (*val signed and n unsigned), and on 64 bit machines also has
different size, since sizeof(u32) = 4 and sizeof(long) = 8.

So when measuring a negative input, n will be small enough, such that
PVT_N_CONST * n < PVT_R_CONST, and the result of
(PVT_N_CONST * n - PVT_R_CONST) will overflow to a very big positive
32 bit number. Then when storing the result in *val it will be the same
value just in 64 bit (instead of it representing a negative number which
will what happen when sizeof(long) = 4).

When -1023 <= (PVT_N_CONST * n - PVT_R_CONST) <= -1
dividing the number by 1024 should result of in 0, but because ">> 10"
is used, and the sign bit is used to fill the vacated bit positions, it
results in -1 (0xf...fffff) which is wrong.

This change fixes the sign problem and supports negative values by
casting n to long and replacing the shift right with div operation.

Fixes: 9d823351a3 ("hwmon: Add hardware monitoring driver for Moortec MR75203 PVT controller")
Signed-off-by: Eliav Farber <farbere@amazon.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220908152449.35457-5-farbere@amazon.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2022-09-15 10:47:19 +02:00
arch s390/boot: fix absolute zero lowcore corruption on boot 2022-09-15 10:47:19 +02:00
block block: don't add partitions if GD_SUPPRESS_PART_SCAN is set 2022-09-15 10:47:15 +02:00
certs certs: make system keyring depend on x509 parser 2022-07-24 12:53:55 -07:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-17 15:16:17 +02:00
Documentation arm64: errata: add detection for AMEVCNTR01 incrementing incorrectly 2022-09-15 10:47:08 +02:00
drivers hwmon: (mr75203) fix voltage equation for negative source input 2022-09-15 10:47:19 +02:00
fs btrfs: fix the max chunk size and stripe length calculation 2022-09-15 10:47:16 +02:00
include time64.h: consolidate uses of PSEC_PER_NSEC 2022-09-15 10:47:19 +02:00
init arm64: fix rodata=full 2022-08-31 17:18:19 +02:00
io_uring lsm,io_uring: add LSM hooks for the new uring_cmd file op 2022-09-15 10:47:18 +02:00
ipc ipc: Free mq_sysctls if ipc namespace creation failed 2022-06-22 17:47:41 -05:00
kernel swiotlb: avoid potential left shift overflow 2022-09-15 10:47:18 +02:00
lib crypto: lib - remove unneeded selection of XOR_BLOCKS 2022-09-05 10:31:26 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()" 2022-09-15 10:47:07 +02:00
net time64.h: consolidate uses of PSEC_PER_NSEC 2022-09-15 10:47:19 +02:00
samples sample: bpf: xdp_router_ipv4: Allow the kernel to send arp requests 2022-08-17 15:14:25 +02:00
scripts kbuild: dummy-tools: avoid tmpdir leak in dummy gcc 2022-08-29 11:07:58 +02:00
security Smack: Provide read control for io_uring_cmd 2022-09-15 10:47:18 +02:00
sound ASoC: mchp-spdiftx: Fix clang -Wbitfield-constant-conversion 2022-09-15 10:47:18 +02:00
tools perf record: Fix synthesis failure warnings 2022-09-15 10:47:18 +02:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Unconditionally get a ref to /dev/kvm module when creating a VM 2022-08-25 11:45:05 +02:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap ARM: SoC fixes for 5.19, part 4 2022-07-27 09:43:07 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan 2022-07-07 15:17:00 +02:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS io_uring: move to separate directory 2022-08-17 15:14:20 +02:00
Makefile kbuild: disable header exports for UML in a straightforward way 2022-09-15 10:47:18 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.