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@xxxxxxxxxxxxxxx>
> Reviewed-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Tested-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
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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> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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