[PATCH v2] dt: platform driver: Fill the resources before probe and defer if needed

[Ludovic Desroches]

On Fri, Feb 21, 2014 at 02:18:40PM +0100, Jean-Jacques Hiblot wrote:
> The goal of this patch is to allow drivers to be probed even if at the time of
> the DT parsing some of their ressources are not available yet.
> 
> In the current situation, the resource of a platform device are filled from the
> DT at the time the device is created (of_device_alloc()). The drawbackof this
> is that a device sitting close to the top of the DT (ahb for example) but
> depending on ressources that are initialized later (IRQ domain dynamically
> created for example)  will fail to probe because the ressources don't exist
> at this time.
> 
> This patch fills the resource structure only before the device is probed and
> will defer the probe if the resource are not available yet.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at traphandler.com>
> Reviewed-by: Gregory CLEMENT <gregory.clement at free-electrons.com>

Tested-by: Ludovic Desroches <ludovic.desroches at atmel.com>

I wanted to add support for the external ethernet controller on
at91sam9n12ek board and I was facing an issue because the irq domain
doesn't exist yet (gpio controller as parent interrupt).

This patch solves this trouble.

> ---
> 
> Hi Grant,
> 
> I reworked the patch as you proposed. To keep the overhead minimum, nirq and
> nreg are computed only the first time.
> In this implementation, only the missing IRQ ressources are re-tried for. It could
> easily be changed to re-parse all the IRQs though (replace if (!res->flags)
> with if ((!res->flags) || (res->flags & IORESOURCE_IRQ)).
> 
> drivers/base/platform.c     |   5 +++
>  drivers/of/platform.c       | 100 +++++++++++++++++++++++++++++++++-----------
>  include/linux/of_platform.h |  10 +++++
>  3 files changed, 90 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index bc78848..cee9b8d 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -481,6 +481,10 @@ static int platform_drv_probe(struct device *_dev)
>  	struct platform_device *dev = to_platform_device(_dev);
>  	int ret;
>  
> +	ret = of_platform_device_prepare(dev);
> +	if (ret)
> +		goto error;
> +
>  	if (ACPI_HANDLE(_dev))
>  		acpi_dev_pm_attach(_dev, true);
>  
> @@ -488,6 +492,7 @@ static int platform_drv_probe(struct device *_dev)
>  	if (ret && ACPI_HANDLE(_dev))
>  		acpi_dev_pm_detach(_dev, true);
>  
> +error:
>  	if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
>  		dev_warn(_dev, "probe deferral not supported\n");
>  		ret = -ENXIO;
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 404d1da..a4e2602 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -141,36 +141,11 @@ struct platform_device *of_device_alloc(struct device_node *np,
>  				  struct device *parent)
>  {
>  	struct platform_device *dev;
> -	int rc, i, num_reg = 0, num_irq;
> -	struct resource *res, temp_res;
>  
>  	dev = platform_device_alloc("", -1);
>  	if (!dev)
>  		return NULL;
>  
> -	/* count the io and irq resources */
> -	if (of_can_translate_address(np))
> -		while (of_address_to_resource(np, num_reg, &temp_res) == 0)
> -			num_reg++;
> -	num_irq = of_irq_count(np);
> -
> -	/* Populate the resource table */
> -	if (num_irq || num_reg) {
> -		res = kzalloc(sizeof(*res) * (num_irq + num_reg), GFP_KERNEL);
> -		if (!res) {
> -			platform_device_put(dev);
> -			return NULL;
> -		}
> -
> -		dev->num_resources = num_reg + num_irq;
> -		dev->resource = res;
> -		for (i = 0; i < num_reg; i++, res++) {
> -			rc = of_address_to_resource(np, i, res);
> -			WARN_ON(rc);
> -		}
> -		WARN_ON(of_irq_to_resource_table(np, res, num_irq) != num_irq);
> -	}
> -
>  	dev->dev.of_node = of_node_get(np);
>  #if defined(CONFIG_MICROBLAZE)
>  	dev->dev.dma_mask = &dev->archdata.dma_mask;
> @@ -233,6 +208,81 @@ static struct platform_device *of_platform_device_create_pdata(
>  	return dev;
>  }
>  
> +static int of_reg_count(struct device_node *np)
> +{
> +	int nreg = 0;
> +	if (of_can_translate_address(np)) {
> +		struct resource temp_res;
> +		while (of_address_to_resource(np, nreg, &temp_res) == 0)
> +			nreg++;
> +	}
> +	return nreg;
> +}
> +
> +int of_platform_device_prepare(struct platform_device *dev)
> +{
> +	struct device_node *np;
> +	int i, irq_index;
> +	struct resource *res;
> +
> +	/*
> +	 * This function applies only devices described in the DT.
> +	 * Other platform devices have their ressources already populated.
> +	 */
> +	np = dev->dev.of_node;
> +	if (!np)
> +		return 0;
> +
> +	/* Populate the resource table */
> +	if (!dev->resource) {
> +		int rc, nreg = 0, nirq;
> +		/* count the io and irq resources */
> +		nreg = of_reg_count(np);
> +		nirq = of_irq_count(np);
> +
> +		if (!nirq && !nreg)
> +			return 0;
> +
> +		res = kzalloc(sizeof(*res) * (nirq + nreg), GFP_KERNEL);
> +		if (!res)
> +			return -ENOMEM;
> +
> +		dev->resource = res;
> +		dev->num_resources = nreg + nirq;
> +
> +		for (i = 0; i < nreg; i++, res++) {
> +			rc = of_address_to_resource(np, i, res);
> +			if (WARN_ON(rc)) {
> +				/* THIS IS BAD; don't try to defer probing */
> +				dev->num_resources = 0;
> +				dev->resource = NULL;
> +				kfree(res);
> +				return rc;
> +			}
> +		}
> +
> +		if (!rc && of_irq_to_resource_table(np, res, nirq) != nirq) {
> +			/* IRQ controller is yet available. defer probing */
> +			return -EPROBE_DEFER;
> +		}
> +
> +		return 0;
> +	}
> +
> +	/* See which IRQ resources need to be redone */
> +	irq_index = 0;
> +	for (i = 0, res = dev->resource; i < dev->num_resources; i++, res++) {
> +		if (!res->flags) {
> +			if (!of_irq_to_resource(np, irq_index, res))
> +				return -EPROBE_DEFER;
> +			irq_index++;
> +		} else if (res->flags & IORESOURCE_IRQ)
> +			irq_index++;
> +	}
> +	return 0;
> +}
> +EXPORT_SYMBOL(of_platform_device_prepare);
> +
>  /**
>   * of_platform_device_create - Alloc, initialize and register an of_device
>   * @np: pointer to node to create device for
> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
> index 05cb4a9..4e487ff 100644
> --- a/include/linux/of_platform.h
> +++ b/include/linux/of_platform.h
> @@ -53,6 +53,16 @@ struct of_dev_auxdata {
>  
>  extern const struct of_device_id of_default_bus_match_table[];
>  
> +/* Populate the resource for a platform device */
> +#ifdef CONFIG_OF
> +int of_platform_device_prepare(struct platform_device *dev);
> +#else
> +static inline int of_platform_device_prepare(
> +	struct platform_device *dev)
> +{
> +	return 0;
> +}
> +#endif
>  /* Platform drivers register/unregister */
>  extern struct platform_device *of_device_alloc(struct device_node *np,
>  					 const char *bus_id,
> -- 
> 1.9.0
> 
> 
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