linux-kernel - Re: [PATCH 2/4] bus: ti-sysc: Add support for PRUSS SYSC type

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Date:   Mon, 4 Feb 2019 10:00:31 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Roger Quadros <rogerq@...com>
Cc:     s-anna@...com, nsekhar@...com, linux-omap@...r.kernel.org,
        t-kristo@...com, nsaulnier@...com, jreeder@...com,
        m-karicheri2@...com, david@...hnology.com,
        woods.technical@...il.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] bus: ti-sysc: Add support for PRUSS SYSC type

* Roger Quadros <rogerq@...com> [190204 15:54]:
> +static int sysc_enable_pruss(struct sysc *sysc)
> +{
> +	int i;
> +	u32 reg;
> +	bool ready;
> +
> +	/* configure for Smart Idle & Smart Standby */
> +	reg = sysc_read(sysc, sysc->offsets[SYSC_SYSCONFIG]);
> +	reg &= ~(SYSC_PRUSS_STANDBY_MASK | SYSC_PRUSS_IDLE_MASK);
> +	reg |= SYSC_PRUSS_STANDBY_SMART | SYSC_IDLE_SMART;
> +	sysc_write(sysc, sysc->offsets[SYSC_SYSCONFIG], reg);

I think you can get rid of the SYSC_PRUSS_ defines here
if you define the bits for it in struct sysc_regbits. The
idle modes are SYSC_IDLE_* defines we already have in
include/dt-bindings/bus/ti-sysc.h.

My guess is these will just become generic sysc_enable()
and sysc_disable() functions :)

If you need module specific handling, you could add function
pointers for enable and disable to struct sysc_capabilities.

> @@ -649,6 +693,9 @@ static int __maybe_unused sysc_runtime_suspend(struct device *dev)
>  		goto idled;
>  	}
>  
> +	if (ddata->cap->type == TI_SYSC_PRUSS)
> +		sysc_disable_pruss(ddata);
> +
>  	for (i = 0; i < ddata->nr_clocks; i++) {
>  		if (IS_ERR_OR_NULL(ddata->clocks[i]))
>  			continue;

Ideally this would be just unconditional call to generic
sysc_disable() here for non-legacy mode. Then if module
specific enable and disable are there, sysc_enable() and
disable() can call them.

> +static const struct sysc_regbits sysc_regbits_pruss = {
> +	.midle_shift = -ENODEV,
> +	.clkact_shift = -ENODEV,
> +	.sidle_shift = -ENODEV,
> +	.enwkup_shift = -ENODEV,
> +	.srst_shift = -ENODEV,
> +	.autoidle_shift = -ENODEV,
> +	.dmadisable_shift = -ENODEV,
> +	.emufree_shift = -ENODEV,
> +};

So it seems you should populate at least midle_shift and sidle_shift
bits here as in PRUSS_SYSCFG. I think STANDBY_MODE offset should go
into the .midle_shift as it mentions initiator in TRM, and IDLE_MODE
offset should go into .sidle_shift. So this might be really just using
sysc_regbits_omap4_simple except it has an additional STANDBY_INIT
bit which you could add for struct sysc_regbits if we don't have
something similar already.

> @@ -1702,6 +1772,10 @@ static int sysc_probe(struct platform_device *pdev)
>  
>  	INIT_DELAYED_WORK(&ddata->idle_work, ti_sysc_idle);
>  
> +	/* FIXME: how to ensure PRUSS stays enabled? */
> +	if (ddata->cap->type == TI_SYSC_PRUSS)
> +		goto skip_pm_put;
> +
>  	/* At least earlycon won't survive without deferred idle */
>  	if (ddata->cfg.quirks & (SYSC_QUIRK_NO_IDLE_ON_INIT |
>  				 SYSC_QUIRK_NO_RESET_ON_INIT)) {

Hmm so do you need to specify ti,no-idle-on-init or what's
the logic needed here?

> diff --git a/include/dt-bindings/bus/ti-sysc.h b/include/dt-bindings/bus/ti-sysc.h
> index 8ec78e8..7138384 100644
> --- a/include/dt-bindings/bus/ti-sysc.h
> +++ b/include/dt-bindings/bus/ti-sysc.h
> @@ -17,17 +17,6 @@
>  
>  #define SYSC_DRA7_MCAN_ENAWAKEUP	(1 << 4)
>  
> -/* SYSCONFIG specific to PRUSS */
> -#define SYSC_PRUSS_SUB_MWAIT		(1 << 5)
> -#define SYSC_PRUSS_STANDBY_INIT		(1 << 4)
> -
> -#define SYSC_PRUSS_STANDBY_FORCE	(0 << 2)
> -#define SYSC_PRUSS_STANDBY_NO		(1 << 2)
> -#define SYSC_PRUSS_STANDBY_SMART	(2 << 2)
> -#define SYSC_PRUSS_STANDBY_MASK		(3 << 2)
> -
> -#define SYSC_PRUSS_IDLE_MASK		3
> -
>  /* SYSCONFIG STANDBYMODE/MIDLEMODE/SIDLEMODE supported by hardware */
>  #define SYSC_IDLE_FORCE			0
>  #define SYSC_IDLE_NO			1

I suggest you make this series independent of the
rest of the PRUSS patches as we can add this
separately. So no need to define these bits at all
AFAIK.

Regards,

Tony