From: Matti Vaittinen <mazziesaccount@gmail.com>
To: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: Stephen Boyd <sboyd@kernel.org>,
Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
broonie@kernel.org, lee.jones@linaro.org, lgirdwood@gmail.com,
mark.rutland@arm.com, mturquette@baylibre.com,
robh+dt@kernel.org, linux-clk@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
mikko.mutanen@fi.rohmeurope.com,
heikki.haikola@fi.rohmeurope.com
Subject: Re: [PATCH v5 4/4] clk: bd71837: Add driver for BD71837 PMIC clock
Date: Wed, 13 Jun 2018 16:03:38 +0300 [thread overview]
Message-ID: <20180613130338.GH20078@localhost.localdomain> (raw)
In-Reply-To: <20180612082354.GG20078@localhost.localdomain>
On Tue, Jun 12, 2018 at 11:23:54AM +0300, Matti Vaittinen wrote:
> Hello Stephen,
>
> Thanks again for the review. I'll do new patch which fixes these issues.
>
> On Tue, Jun 12, 2018 at 12:44:11AM -0700, Stephen Boyd wrote:
> > Quoting Matti Vaittinen (2018-06-04 06:19:13)
> > > +}
> > > +
> > > +static unsigned long bd71837_clk_recalc_rate(struct clk_hw *hw,
> > > + unsigned long parent_rate)
> > > +{
> > > + struct bd71837_clk *c = container_of(hw, struct bd71837_clk, hw);
> > > +
> > > + return c->rate;
> > > +}
> > > +
> > > +static const struct clk_ops bd71837_clk_ops = {
> > > + .recalc_rate = &bd71837_clk_recalc_rate,
> > > + .prepare = &bd71837_clk_enable,
> > > + .unprepare = &bd71837_clk_disable,
> > > + .is_prepared = &bd71837_clk_is_enabled,
> > > +};
> > > +
> > > +static int bd71837_clk_probe(struct platform_device *pdev)
> > > +{
> > > + struct bd71837_clk *c;
> > > + int rval = -ENOMEM;
> > > + struct bd71837 *mfd = dev_get_drvdata(pdev->dev.parent);
> > > + struct clk_init_data init = {
> > > + .name = "bd71837-32k-out",
> > > + .ops = &bd71837_clk_ops,
> > > + };
> > > +
> > > + c = devm_kzalloc(&pdev->dev, sizeof(*c), GFP_KERNEL);
> > > + if (!c)
> > > + goto err_out;
> > > +
> > > + c->reg = BD71837_REG_OUT32K;
> > > + c->mask = BD71837_OUT32K_EN;
> > > + c->rate = BD71837_CLK_RATE;
> >
> > The PMIC has an 'XIN' pin that would be the clk input for this chip, and
> > the output clk, this driver, would specify that xin clock as the parent.
> > The 'xin' clock would then be listed in DT as a fixed-rate clock. That
> > way this driver doesn't hardcode the frequency.
>
> I see. This makes sense. I need to verify from HW colleagues whether
> this chip has internal oscillator or not. I originally thought we have
> on-chip oscillator - but as you say, we do have XIN pin in documentation.
> So now I am not sure if the test board I have contains oscillator driving
> the clk on PMIC - or if the PMIC has internal oscillator. I'll clarify this.
It really turned out that the PMIC just acts as a clock buffer. So I do
as you suggested and add lookup for parent clock to the driver. I
planned to do it so that if no parent is found from DT - then we assume
the 32.768KHz clock (as described in documentation). Eg, something along
the lines:
init.parent_names = of_clk_get_parent_name(pdev->dev.parent->of_node, 0);
if (init.parent_names) {
init.num_parents = 1;
} else {
/* If parent is not given from DT we assume the typical use-case with
* 32.768 KHz oscillator for RTC (Maybe we could just error out here?)
*/
c->rate = BD71837_CLK_RATE;
bd71837_clk_ops.recalc_rate = &bd71837_clk_recalc_rate;
}
Does this make sense?
Br,
Matti Vaittinen
next prev parent reply other threads:[~2018-06-13 13:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-04 13:17 [PATCH v5 0/4] mfd/regulator/clk: bd71837: ROHM BD71837 PMIC driver Matti Vaittinen
2018-06-04 13:18 ` [PATCH v5 1/4] mfd: bd71837: mfd driver for ROHM BD71837 PMIC Matti Vaittinen
2018-06-05 7:57 ` Matti Vaittinen
2018-06-04 13:18 ` [PATCH v5 2/4] mfd: bd71837: Devicetree bindings " Matti Vaittinen
2018-06-05 15:47 ` Rob Herring
2018-06-06 5:14 ` Matti Vaittinen
2018-06-04 13:18 ` [PATCH v5 3/4] clk: " Matti Vaittinen
2018-06-05 15:49 ` Rob Herring
2018-06-06 5:10 ` Matti Vaittinen
2018-06-04 13:19 ` [PATCH v5 4/4] clk: bd71837: Add driver for BD71837 PMIC clock Matti Vaittinen
2018-06-12 7:44 ` Stephen Boyd
2018-06-12 8:23 ` Matti Vaittinen
2018-06-13 13:03 ` Matti Vaittinen [this message]
2018-06-25 23:46 ` Stephen Boyd
2018-06-27 8:40 ` Matti Vaittinen
2018-07-31 9:05 ` Matti Vaittinen
2018-06-25 23:44 ` Stephen Boyd
2018-06-26 8:13 ` Matti Vaittinen
2018-07-31 8:28 ` Matti Vaittinen
2018-08-03 8:09 ` Matti Vaittinen
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