linux-kernel - Re: [PATCH v3 4/6] bus: ti-sysc: Add support for software reset

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Message-ID: <20180608062158.GI5738@atomide.com>
Date:   Thu, 7 Jun 2018 23:21:58 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Faiz Abbas <faiz_abbas@...com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org, mark.rutland@....com, paul@...an.com,
        t-kristo@...com, robh+dt@...nel.org, bcousson@...libre.com
Subject: Re: [PATCH v3 4/6] bus: ti-sysc: Add support for software reset

* Faiz Abbas <faiz_abbas@...com> [180607 10:24]:
> Hi,
> 
> On Thursday 07 June 2018 01:05 PM, Tony Lindgren wrote:
> > * Faiz Abbas <faiz_abbas@...com> [180606 06:14]:
> >> +static int sysc_reset(struct sysc *ddata)
> >> +{
> >> +	int offset = ddata->offsets[SYSC_SYSCONFIG];
> >> +	int val = sysc_read(ddata, offset);
> >> +
> >> +	val |= (0x1 << ddata->cap->regbits->srst_shift);
> >> +	sysc_write(ddata, offset, val);
> >> +
> >> +	/* Poll on reset status */
> >> +	if (ddata->cfg.quirks & SYSC_QUIRK_RESET_STATUS) {
> >> +		offset = ddata->offsets[SYSC_SYSSTATUS];
> >> +
> >> +		return readl_poll_timeout(ddata->module_va + offset, val,
> >> +				(val & ddata->cfg.syss_mask) == 0x0,
> >> +				100, MAX_MODULE_SOFTRESET_WAIT);
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> > 
> > I wonder if we should also add SYSS_QUIRK_RESET_STATUS in
> > addition to SYSC_QUIRK_RESET status to make it easy to
> > read the right register?
> 
> I assumed SYSC_QUIRK is the prefix to indicate the ti-sysc driver not
> the register. Are there layouts in which the reset status bit is in the
> sysconfig register rather than the sysstatus register?

Yes we can have reset status bit in either syss or syssconfig register.
We detect that in sysc_init_syss_mask() but we should also set something
at that point to make it clear which reset to use. But as we don't need
the quirk flag, it's probably set a function pointer after the detection.
So how about let's have two functions sysc_reset() and sysc_syss_reset()
and then we can implement sysc_syss_reset() in a separate patch after
testing it when we have a non-platform data using example for
sysc_syss_reset().

Regards,

Tony