linux-kernel - Re: [PATCH RFC v3 3/4] spmi: pmic-arb: Make core resources acquiring a version operation

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Date: Wed, 14 Feb 2024 23:36:29 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Stephen Boyd <sboyd@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Bjorn Andersson <andersson@...nel.org>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Srini Kandagatla <srinivas.kandagatla@...aro.org>,
	Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH RFC v3 3/4] spmi: pmic-arb: Make core resources acquiring
 a version operation

On 24-02-14 22:18:33, Konrad Dybcio wrote:
> On 14.02.2024 22:13, Abel Vesa wrote:
> > Rather than setting up the core, obsrv and chnls in probe by using
> > version specific conditionals, add a dedicated "get_core_resources"
> > version specific op and move the acquiring in there.
> > 
> > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> > ---
> >  drivers/spmi/spmi-pmic-arb.c | 111 ++++++++++++++++++++++++++++++-------------
> >  1 file changed, 78 insertions(+), 33 deletions(-)
> > 
> > diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
> > index 23939c0d225f..489556467a4c 100644
> > --- a/drivers/spmi/spmi-pmic-arb.c
> > +++ b/drivers/spmi/spmi-pmic-arb.c
> > @@ -203,6 +203,7 @@ struct spmi_pmic_arb {
> >   */
> >  struct pmic_arb_ver_ops {
> >  	const char *ver_str;
> > +	int (*get_core_resources)(struct platform_device *pdev, void __iomem *core);
> >  	int (*init_apid)(struct spmi_pmic_arb *pmic_arb, int index);
> >  	int (*ppid_to_apid)(struct spmi_pmic_arb *pmic_arb, u16 ppid);
> >  	/* spmi commands (read_cmd, write_cmd, cmd) functionality */
> > @@ -956,6 +957,19 @@ static int pmic_arb_init_apid_min_max(struct spmi_pmic_arb *pmic_arb)
> >  	return 0;
> >  }
> >  
> > +static int pmic_arb_get_core_resources_v1(struct platform_device *pdev,
> > +					  void __iomem *core)
> > +{
> > +	struct spmi_pmic_arb *pmic_arb = platform_get_drvdata(pdev);
> > +
> > +	pmic_arb->wr_base = core;
> > +	pmic_arb->rd_base = core;
> > +
> > +	pmic_arb->max_periphs = PMIC_ARB_MAX_PERIPHS;
> > +
> > +	return 0;
> > +}
> > +
> >  static int pmic_arb_init_apid_v1(struct spmi_pmic_arb *pmic_arb, int index)
> >  {
> >  	u32 *mapping_table;
> > @@ -1063,6 +1077,41 @@ static u16 pmic_arb_find_apid(struct spmi_pmic_arb *pmic_arb, u16 ppid)
> >  	return apid;
> >  }
> >  
> > +static int pmic_arb_get_obsrvr_chnls_v2(struct platform_device *pdev)
> > +{
> > +	struct spmi_pmic_arb *pmic_arb = platform_get_drvdata(pdev);
> > +	struct device *dev = &pdev->dev;
> > +	struct resource *res;
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> 
> It's no longer indented to deep, no need to keep such aggressive wrapping
> 

The pmic_arb_get_obsrvr_chnls_v2 is used by both:
pmic_arb_get_core_resources_v2
pmic_arb_get_core_resources_v7

> > +					   "obsrvr");
> > +	pmic_arb->rd_base = devm_ioremap(dev, res->start,
> > +					 resource_size(res));
> > +	if (IS_ERR(pmic_arb->rd_base))
> > +		return PTR_ERR(pmic_arb->rd_base);
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > +					   "chnls");
> > +	pmic_arb->wr_base = devm_ioremap(dev, res->start,
> > +					 resource_size(res));
> > +	if (IS_ERR(pmic_arb->wr_base))
> > +		return PTR_ERR(pmic_arb->wr_base);
> 
> Could probably make it "devm_platform_get_and_ioremap_resource "

The reason this needs to stay as is is because of reason explained by
the following comment found in probe:

/*                                                                           
 * Please don't replace this with devm_platform_ioremap_resource() or        
 * devm_ioremap_resource().  These both result in a call to                  
 * devm_request_mem_region() which prevents multiple mappings of this        
 * register address range.  SoCs with PMIC arbiter v7 may define two         
 * arbiter devices, for the two physical SPMI interfaces, which  share       
 * some register address ranges (i.e. "core", "obsrvr", and "chnls").        
 * Ensure that both devices probe successfully by calling devm_ioremap()     
 * which does not result in a devm_request_mem_region() call.                
 */                                                                          

Even though, AFAICT, there is no platform that adds a second node for
the second bus, currently, in mainline, we should probably allow the
"legacy" approach to still work.

> 
> Konrad