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Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation
From: |
Marek Vasut |
Subject: |
Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation |
Date: |
Tue, 16 Aug 2016 18:48:08 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.2.0 |
On 08/15/2016 01:39 PM, Dmitry Osipenko wrote:
[...]
>>> Also, ptimer now supports "on the fly mode switch":
>>>
>>> https://github.com/qemu/qemu/commit/869e92b5c392eb6b2c7b398b878c435442b8e9dd
>>>
>>> ptimer_run(t->ptimer, !(value & CONTROL_CONT)) could be used here and
>>> "manual"
>>> re-run dropped from the timer_hit() handler.
>>
>> So who will re-run the timer if it's configured in the continuous mode
>> if it's not re-run in the timer_hit() ?
>>
>
> Ptimer will, timer_hit() will only have to assert IRQ and set ptimer count to
> the limit tvalue if timer is in the oneshot mode.
>
> Something like:
>
> static void timer_hit(void *opaque)
> {
> AlteraTimer *t = opaque;
> const uint64_t tvalue = (t->regs[R_PERIODH] << 16) | t->regs[R_PERIODL];
>
> t->regs[R_STATUS] |= STATUS_TO;
>
> if (!(t->regs[R_CONTROL] & CONTROL_CONT)) {
> t->regs[R_STATUS] &= ~STATUS_RUN;
There should probably be } else { statement here , no ?
> ptimer_set_count(t->ptimer, tvalue);
> }
>
> qemu_set_irq(t->irq, timer_irq_state(t));
> }
Thanks for the draft.
[...]
>>>>>> +static void timer_hit(void *opaque)
>>>>>> +{
>>>>>> + AlteraTimer *t = opaque;
>>>>>> + const uint64_t tvalue = (t->regs[R_PERIODH] << 16) |
>>>>>> t->regs[R_PERIODL];
>>>
>>> ptimer_get_limit() could be used here.
>>
>> You probably want to use the value in the register instead of the value
>> in the ptimer state in case someone rewrote those registers, no ?
>>
>
> In case someone rewrote the registers, the ptimer limit would be also updated.
> So this could be changed to:
>
> uint64_t tvalue = ptimer_get_limit(t->ptimer) - 1;
>
> Actually, R_PERIODL and R_PERIODH regs aren't really needed and could be
> removed
> from the AlteraTimer state, since ptimer stores the same limit value + 1. The
> timer_read/write() would need to be changed accordingly.
Ha, so we're getting to something like the following code (based on your
example + the else bit) ?
static void timer_hit(void *opaque)
{
AlteraTimer *t = opaque;
const uint64_t tvalue = ptimer_get_limit(t->ptimer) - 1;
t->regs[R_STATUS] |= STATUS_TO;
if (!(t->regs[R_CONTROL] & CONTROL_CONT)) {
t->regs[R_STATUS] &= ~STATUS_RUN;
} else {
ptimer_set_count(t->ptimer, tvalue);
}
qemu_set_irq(t->irq, timer_irq_state(t));
}
[...]
>> For the timer, that reset would look like this?
>>
>> 197 static void altera_timer_reset(DeviceState *dev)
>> 198 {
>> 199 AlteraTimer *t = ALTERA_TIMER(dev);
>> 200
>> 201 ptimer_stop(t->ptimer);
>> 202 memset(t->regs, 0, ARRAY_SIZE(t->regs));
>> 203 }
>>
>
> Yes, and move ptimer_set_limit(t->ptimer, 0xffffffff, 1) here from the
> altera_timer_realize().
Got it, thanks.
>> +static Property altera_timer_properties[] = {
>> + DEFINE_PROP_UINT32("clock-frequency", AlteraTimer, freq_hz, 0),
>> + DEFINE_PROP_END_OF_LIST(),
>> +};
>
> Why not to have some sane "clock-frequency" by default?
Well what is sane clock frequency for hardware which can have arbitrary
frequency configured in ?
>> For the IIC, I wonder what that'd look like -- probably
>> qemu_set_irq(parent, 0); ?
>>
>
> No, IRQ's would be "deasserted" by resetting CPUClass state, of which QEMU
> takes
> care itself. No action needed by the IIC.
I see, thanks :)
btw any chance someone can look at the other patches too ?
--
Best regards,
Marek Vasut
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/07
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/10
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/10
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/12
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/15
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation,
Marek Vasut <=
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/16
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/16
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/16
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/17
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Peter Maydell, 2016/08/17
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/17
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/18
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/18
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Dmitry Osipenko, 2016/08/19
- Re: [Qemu-devel] [PATCH 5/7] nios2: Add periodic timer emulation, Marek Vasut, 2016/08/19