Re: [PATCH 4/8] soc: ti: omap-prm: add support for denying idle for reset clockdomain

[Tero Kristo <t-kristo@xxxxxx>]

On 20.8.2019 2.16, Suman Anna wrote:
> Hi Tero,
>
> On 8/7/19 2:48 AM, Tero Kristo wrote:
> > TI SoCs hardware reset signals require the parent clockdomain to be
> > in force wakeup mode while de-asserting the reset, otherwise it may
> > never complete. To support this, add pdata hooks to control the
> > clockdomain directly.
> >
> > Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
> > ---
> >   drivers/soc/ti/omap_prm.c            | 32 ++++++++++++++++++++++++++++----
> >   include/linux/platform_data/ti-prm.h | 21 +++++++++++++++++++++
> >   2 files changed, 49 insertions(+), 4 deletions(-)
> >   create mode 100644 include/linux/platform_data/ti-prm.h
> >
> > diff --git a/drivers/soc/ti/omap_prm.c b/drivers/soc/ti/omap_prm.c
> > index d412af3..870515e3 100644
> > --- a/drivers/soc/ti/omap_prm.c
> > +++ b/drivers/soc/ti/omap_prm.c
> > @@ -16,6 +16,8 @@
> >   #include <linux/reset-controller.h>
> >   #include <linux/delay.h>
> >   
> > +#include <linux/platform_data/ti-prm.h>
> > +
> >   struct omap_rst_map {
> >   	s8 rst;
> >   	s8 st;
> > @@ -24,6 +26,7 @@ struct omap_rst_map {
> >   struct omap_prm_data {
> >   	u32 base;
> >   	const char *name;
> > +	const char *clkdm_name;
> >   	u16 pwstctrl;
> >   	u16 pwstst;
> >   	u16 rstctl;
> > @@ -40,6 +43,8 @@ struct omap_prm {
> >   struct omap_reset_data {
> >   	struct reset_controller_dev rcdev;
> >   	struct omap_prm *prm;
> > +	struct clockdomain *clkdm;
> > +	struct device *dev;
> >   };
> >   
> >   #define to_omap_reset_data(p) container_of((p), struct omap_reset_data, rcdev)
> > @@ -108,6 +113,8 @@ static int omap_reset_deassert(struct reset_controller_dev *rcdev,
> >   	int st_bit = id;
> >   	bool has_rstst;
> >   	int timeout = 0;
> > +	struct ti_prm_platform_data *pdata = dev_get_platdata(reset->dev);
> > +	int ret = 0;
> >   
> >   	/* check the current status to avoid de-asserting the line twice */
> >   	v = readl_relaxed(reset->prm->base + reset->prm->data->rstctl);
> > @@ -125,13 +132,16 @@ static int omap_reset_deassert(struct reset_controller_dev *rcdev,
> >   		writel_relaxed(v, reset->prm->base + reset->prm->data->rstst);
> >   	}
> >   
> > +	if (pdata->clkdm_deny_idle && reset->clkdm)
> > +		pdata->clkdm_deny_idle(reset->clkdm);
> > +
> >   	/* de-assert the reset control line */
> >   	v = readl_relaxed(reset->prm->base + reset->prm->data->rstctl);
> >   	v &= ~(1 << id);
> >   	writel_relaxed(v, reset->prm->base + reset->prm->data->rstctl);
> >   
> >   	if (!has_rstst)
> > -		return 0;
> > +		goto exit;
> >   
> >   	/* wait for the status to be set */
> >   	while (1) {
> > @@ -140,13 +150,19 @@ static int omap_reset_deassert(struct reset_controller_dev *rcdev,
> >   		if (v)
> >   			break;
> >   		timeout++;
> > -		if (timeout > OMAP_RESET_MAX_WAIT)
> > -			return -EBUSY;
> > +		if (timeout > OMAP_RESET_MAX_WAIT) {
> > +			ret = -EBUSY;
> > +			goto exit;
> > +		}
> >   
> >   		udelay(1);
> >   	}
> >   
> > -	return 0;
> > +exit:
> > +	if (pdata->clkdm_allow_idle && reset->clkdm)
> > +		pdata->clkdm_allow_idle(reset->clkdm);
> > +
> > +	return ret;
> >   }
> >   
> >   static const struct reset_control_ops omap_reset_ops = {
> > @@ -159,6 +175,8 @@ static int omap_prm_reset_probe(struct platform_device *pdev,
> >   				struct omap_prm *prm)
> >   {
> >   	struct omap_reset_data *reset;
> > +	struct ti_prm_platform_data *pdata = dev_get_platdata(&pdev->dev);
>
> Please add checks for NULL callbacks. I don't think these are optional
> right, so better to check in init rather than during runtime. Granted
> you will probably not run into this after patch 8, but would be good to
> check and print an error in case pdata quirks is missed out.

Hmm ok, this would get rid of the runtime checks which would be slightly 
cleaner.

> > +	char buf[32];
> >   
> >   	/*
> >   	 * Check if we have resets. If either rstctl or rstst is
> > @@ -177,9 +195,15 @@ static int omap_prm_reset_probe(struct platform_device *pdev,
> >   	reset->rcdev.ops = &omap_reset_ops;
> >   	reset->rcdev.of_node = pdev->dev.of_node;
> >   	reset->rcdev.nr_resets = OMAP_MAX_RESETS;
> > +	reset->dev = &pdev->dev;
> >   
> >   	reset->prm = prm;
> >   
> > +	sprintf(buf, "%s_clkdm", prm->data->clkdm_name ? prm->data->clkdm_name :
> > +		prm->data->name);
> > +
> > +	reset->clkdm = pdata->clkdm_lookup(buf);
>
> Not checking return status?

clkdm will just end up being NULL in failure, which is fine for rest of 
the code. I don't think it can be ever NULL though, so I can add a check 
here for sanity.

-Tero

> regards
> Suman
>
> > +
> >   	return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
> >   }
> >   
> > diff --git a/include/linux/platform_data/ti-prm.h b/include/linux/platform_data/ti-prm.h
> > new file mode 100644
> > index 0000000..28154c3
> > --- /dev/null
> > +++ b/include/linux/platform_data/ti-prm.h
> > @@ -0,0 +1,21 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * TI PRM (Power & Reset Manager) platform data
> > + *
> > + * Copyright (C) 2019 Texas Instruments, Inc.
> > + *
> > + * Tero Kristo <t-kristo@xxxxxx>
> > + */
> > +
> > +#ifndef _LINUX_PLATFORM_DATA_TI_PRM_H
> > +#define _LINUX_PLATFORM_DATA_TI_PRM_H
> > +
> > +struct clockdomain;
> > +
> > +struct ti_prm_platform_data {
> > +	void (*clkdm_deny_idle)(struct clockdomain *clkdm);
> > +	void (*clkdm_allow_idle)(struct clockdomain *clkdm);
> > +	struct clockdomain * (*clkdm_lookup)(const char *name);
> > +};
> > +
> > +#endif /* _LINUX_PLATFORM_DATA_TI_PRM_H */

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