Re: [PATCH 2/2] soc: bcm: iproc: Add Broadcom iProc IDM driver

[Ray Jui]

On 12/5/19 4:22 PM, Florian Fainelli wrote:
> On 12/2/19 3:31 PM, Ray Jui wrote:
> > Add Broadcom iProc IDM driver that controls that IDM devices available
> > on various iProc based SoCs for bus transaction timeout monitoring and
> > error logging.
> >
> > Signed-off-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
> > Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@xxxxxxxxxxxx>
> > ---
>
> Looks good to me, just a few suggestions below
>
> [snip]
>
> > --- /dev/null
> > +++ b/drivers/soc/bcm/iproc/Kconfig
> > @@ -0,0 +1,6 @@
>
> You would want an
>
> if SOC_BRCM_IPROC
>
> > +config IPROC_IDM
> > +	bool "Broadcom iProc IDM driver"
> > +	depends on (ARCH_BCM_IPROC || COMPILE_TEST) && OF
> > +	default ARCH_BCM_IPROC
> > +	help
> > +	  Enables support for iProc Interconnect and Device Management (IDM) control and monitoring
>
> and endif here to make this a nice menu.

Sure I'll add SOC_BRCM_IPROC at one layer higher and use the if here.

> [snip]
>
> > +
> > +static int iproc_idm_dev_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct device_node *np = dev->of_node;
> > +	struct platform_device *elog_pdev;
> > +	struct device_node *elog_np;
> > +	struct iproc_idm *idm;
> > +	const char *name;
> > +	int ret;
> > +	u32 val;
> > +
> > +	idm = devm_kzalloc(dev, sizeof(*idm), GFP_KERNEL);
> > +	if (!idm)
> > +		return -ENOMEM;
> > +
> > +	ret = of_property_read_string(np, "brcm,iproc-idm-bus", &name);
> > +	if (ret) {
> > +		dev_err(dev, "Unable to parse IDM bus name\n");
> > +		return ret;
> > +	}
> > +	idm->name = name;
> > +
> > +	platform_set_drvdata(pdev, idm);
> > +	idm->dev = dev;
> > +
> > +	idm->base = of_iomap(np, 0);
> > +	if (!idm->base) {
> > +		dev_err(dev, "Unable to map I/O\n");
> > +		ret = -ENOMEM;
> > +		goto err_exit;
> > +	}
> > +
> > +	ret = of_irq_get(np, 0);
> > +	if (ret <= 0) {
> > +		dev_err(dev, "Unable to find IRQ number. ret=%d\n", ret);
> > +		goto err_iounmap;
> > +	}
>
> Since this is a standard platform device, you can use the standard
> platform_get_resource() and platform_get_irq(). If you ever needed to
> support ACPI in the future, that would make it transparent and almost
> already ready.

Will do, thanks!

> > +
> > +	ret = devm_request_irq(dev, ret, iproc_idm_irq_handler, IRQF_SHARED,
> > +			       idm->name, idm);
> > +	if (ret < 0) {
> > +		dev_err(dev, "Unable to request irq. ret=%d\n", ret);
> > +		goto err_iounmap;
> > +	}
> > +
> > +	/*
> > +	 * ELOG phandle is optional. If ELOG phandle is specified, it indicates
> > +	 * ELOG logging needs to be enabled
> > +	 */
> > +	elog_np = of_parse_phandle(dev->of_node, ELOG_IDM_COMPAT_STR, 0);
> > +	if (elog_np) {
> > +		elog_pdev = of_find_device_by_node(elog_np);
> > +		if (!elog_pdev) {
> > +			dev_err(dev, "Unable to find IDM ELOG device\n");
> > +			ret = -ENODEV;
> > +			goto err_iounmap;
> > +		}
> > +
> > +		idm->elog = platform_get_drvdata(elog_pdev);
> > +		if (!idm->elog) {
> > +			dev_err(dev, "Unable to get IDM ELOG driver data\n");
> > +			ret = -EINVAL;
> > +			goto err_iounmap;
> > +		}
> > +	}
> > +
> > +	/* enable IDM timeout and its interrupt */
> > +	val = readl(idm->base + IDM_CTRL_OFFSET);
> > +	val |= IDM_CTRL_TIMEOUT_EXP_MASK | IDM_CTRL_TIMEOUT_ENABLE |
> > +	       IDM_CTRL_TIMEOUT_IRQ;
> > +	writel(val, idm->base + IDM_CTRL_OFFSET);
> > +
> > +	ret = device_create_file(dev, &dev_attr_no_panic);
> > +	if (ret < 0)
> > +		goto err_iounmap;
> > +
> > +	of_node_put(np);
>
> Did not you intend to drop the reference count on elog_np here?

Sorry, I'm not following this comment. Could you please help to clarify 
for me a bit more? Thanks!

> [snip]
>
> > +static struct platform_driver iproc_idm_driver = {
> > +	.probe = iproc_idm_probe,
>
> Do not you need a remove function in order to unregister the sysfs file
> that you created in iproc_idm_dev_probe() to avoid bind/unbind (or
> rmmod/modprobe) to spit out an existing sysfs entry warning?

This driver should never be compiled as a module. It's meant to be 
always there to capture IDM bus timeouts.

But you are right that I cannot prevent user from trying to unbind it 
for whatever reason. I'll add a remove routine to take care of this.

Thanks!

Ray