linux-kernel - Re: [RFC PATCH v3 2/3] regmap-irq: Add support for POLARITY_HI and POLARITY

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Date:   Mon, 15 Mar 2021 13:33:37 -0700
From:   Guru Das Srinagesh <gurus@...eaurora.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Markus Elfring <Markus.Elfring@....de>,
        Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Joe Perches <joe@...ches.com>,
        Subbaraman Narayanamurthy <subbaram@...eaurora.org>,
        David Collins <collinsd@...eaurora.org>,
        Anirudh Ghayal <aghayal@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [RFC PATCH v3 2/3] regmap-irq: Add support for POLARITY_HI and
 POLARITY_LO config regs

On Fri, Mar 12, 2021 at 12:19:16PM +0000, Mark Brown wrote:
> On Wed, Mar 10, 2021 at 04:39:53PM -0800, Guru Das Srinagesh wrote:
> > If an interrupt is already configured as either edge- or
> > level-triggered, setting the corresponding bit for it in the POLARITY_HI
> > register further configures it as rising-edge or level-high triggered
> > (as the case may be), while setting the same bit in POLARITY_LO further
> > configures it as falling-edge or level-low triggered.
> 
> I think you probably need to bring these three fields together into a
> single virtual field and then map the values within that field using
> the existing type stuff.

Sure, how about this scheme then, for patches 2 and 3 in this series?
(Patch 1 will remain the same, pending your review of it.)

Since I do need to write to two extra registers, I'll need two
register_base's and two buffers to hold their data. This can be
generalized to "extra config registers" in the framework as follows:

- Add these two fields to `struct regmap_irq_chip`:

	unsigned int *extra_config_base; /* Points to array of extra regs */
	int num_extra_config_regs;	 /* = ARRAY_SIZE(array above) */

- Add this field to `struct regmap_irq_chip_data`:

	unsigned int **extra_config_buf;
  	/* Will be dynamically allocated to size of:
  	 * [chip->num_extra_config_regs][chip->num_regs]
  	 */

- Add a new function callback in `struct regmap_irq_chip`:

	int (*configure_extra_regs)(void *irq_drv_data, unsigned int
	type)

  This callback will be called at the end of regmap_irq_set_type():
  	
  	if (d->chip->configure_extra_regs)
		d->chip->configure_extra_regs();

  The callback, defined in the client driver, will specifically address
  the changes to regmap_irq_set_type() made in patches 2 and 3 of this
  series, viz. overriding how type_buf is to be handled, plus the
  populating of polarity_*_buf's (rechristened as extra_config_bufs in
  this proposed new scheme).

This new scheme thus makes v2 more generic. I thought I'd discuss this
with you before implementing it as v3 RFC. Could you please let me know
your thoughts?

Thank you.

Guru Das.