Fix potential overflow problem when calculating pwm_duty.
1. Ensure p->cmr and p->cnr to be from [0,65535], according to the
hardware specification.
2. Changed duty to uint32_t. However, since MAX_DUTY * (p->cmr+1)
can excceed UINT32_MAX, we convert them to uint64_t in computation
and converted them back to uint32_t.
(duty is guaranteed to be <= MAX_DUTY so it won't overflow.)
Fixes: CID 1442342
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Doug Evans <dje@google.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Message-id: 20210127011142.2122790-1-wuhaotsh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The PWM module is part of NPCM7XX module. Each NPCM7XX module has two
identical PWM modules. Each module contains 4 PWM entries. Each PWM has
two outputs: frequency and duty_cycle. Both are computed using inputs
from software side.
This module does not model detail pulse signals since it is expensive.
It also does not model interrupts and watchdogs that are dependant on
the detail models. The interfaces for these are left in the module so
that anyone in need for these functionalities can implement on their
own.
The user can read the duty cycle and frequency using qom-get command.
Reviewed-by: Havard Skinnemoen <hskinnemoen@google.com>
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Message-id: 20210108190945.949196-5-wuhaotsh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
