Message-ID: <20121113141642.GJ31759@intel.com>
Date:	Tue, 13 Nov 2012 16:16:42 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	mathias.nyman@...ux.intel.com, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, lenb@...nel.org,
	rafael.j.wysocki@...el.com, broonie@...nsource.wolfsonmicro.com,
	grant.likely@...retlab.ca, linus.walleij@...aro.org,
	khali@...ux-fr.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	"Moore, Robert" <robert.moore@...el.com>
Subject: Re: [Replacement][PATCH 3/3]

On Tue, Nov 13, 2012 at 01:06:59PM +0100, Rafael J. Wysocki wrote:
> > I don't know any better option.
> 
> Well, a better option would be to convince ACPICA to provide us different
> interfaces. :-)

Heh, indeed.

> We might actually try to do that in the future, but for now we still need
> _CRS to be evaluated centrally rather than by every interested party in
> isolation.  So below is a replacement for my original [3/3] patch that
> approaches the problem from a different angle (on top of [1/3] and
> updated [2/3] sent yesterday).  Please let me know what you think.
> 
> Thanks,
> Rafael
> 
> 
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: ACPI: Centralized processing of ACPI device resources
> 
> Currently, whoever wants to use ACPI device resources has to call
> acpi_walk_resources() to browse the buffer returned by the _CRS
> method for the given device and create filters passed to that
> routine to apply to the individual resource items.  This generally
> is cumbersome, time-consuming and inefficient.  Moreover, it may
> be problematic if resource conflicts need to be resolved, because
> the different users of _CRS will need to do that in a consistent
> way.  However, if there are resource conflicts, the ACPI core
> should be able to resolve them centrally instead of relying on
> various users of acpi_walk_resources() to handle them correctly
> together.
> 
> For this reason, introduce a new function, acpi_dev_get_resources(),
> that can be used by subsystems to obtain a list of struct resource
> objects corresponding to the ACPI device resources returned by
> _CRS and, if necessary, to apply additional preprocessing routine
> to the ACPI resources before converting them to the struct resource
> format.
> 
> Make the ACPI code that creates platform device objects use
> acpi_dev_get_resources() for resource processing instead of executing
> acpi_walk_resources() twice by itself, which causes it to be much
> more straightforward and easier to follow.
> 
> In the future, acpi_dev_get_resources() can be extended to meet
> the needs of the ACPI PNP subsystem and other users of _CRS in
> the kernel.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

I found one problem which resulted failure (see below) but once that was
fixed devices were enumerated correctly. I tested this also with modified
SPI/I2C/GPIO patches and they also work as expected on my test machine.

Nice work, thanks.

> ---
>  drivers/acpi/acpi_platform.c |   94 +++++-------------------------
>  drivers/acpi/resource.c      |  132 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/acpi.h         |   10 +++
>  3 files changed, 159 insertions(+), 77 deletions(-)
> 
> Index: linux/include/linux/acpi.h
> ===================================================================
> --- linux.orig/include/linux/acpi.h
> +++ linux/include/linux/acpi.h
> @@ -261,6 +261,16 @@ unsigned long acpi_dev_irq_flags(u8 trig
>  bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
>  				 struct resource *res);
>  
> +struct resource_list_entry {
> +	struct list_head node;
> +	struct resource res;
> +};
> +
> +void acpi_dev_free_resource_list(struct list_head *list);
> +int acpi_dev_get_resources(struct acpi_device *adev, struct list_head *list,
> +			   int (*preproc)(struct acpi_resource *, void *),
> +			   void *preproc_data);
> +
>  int acpi_check_resource_conflict(const struct resource *res);
>  
>  int acpi_check_region(resource_size_t start, resource_size_t n,
> Index: linux/drivers/acpi/resource.c
> ===================================================================
> --- linux.orig/drivers/acpi/resource.c
> +++ linux/drivers/acpi/resource.c
> @@ -26,6 +26,7 @@
>  #include <linux/device.h>
>  #include <linux/export.h>
>  #include <linux/ioport.h>
> +#include <linux/slab.h>
>  
>  #ifdef CONFIG_X86
>  #define valid_IRQ(i) (((i) != 0) && ((i) != 2))
> @@ -391,3 +392,134 @@ bool acpi_dev_resource_interrupt(struct
>  	return true;
>  }
>  EXPORT_SYMBOL_GPL(acpi_dev_resource_interrupt);
> +
> +/**
> + * acpi_dev_free_resource_list - Free resource from %acpi_dev_get_resources().
> + * @list: The head of the resource list to free.
> + */
> +void acpi_dev_free_resource_list(struct list_head *list)
> +{
> +	struct resource_list_entry *rentry, *re;
> +
> +	list_for_each_entry_safe(rentry, re, list, node) {
> +		list_del(&rentry->node);
> +		kfree(rentry);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_free_resource_list);
> +
> +struct res_proc_context {
> +	struct list_head *list;
> +	int (*preproc)(struct acpi_resource *, void *);
> +	void *preproc_data;
> +	int count;
> +	int error;
> +};
> +
> +static acpi_status acpi_dev_new_resource_entry(struct resource *r,
> +					       struct res_proc_context *c)
> +{
> +	struct resource_list_entry *rentry;
> +
> +	rentry = kmalloc(sizeof(*rentry), GFP_KERNEL);
> +	if (!rentry) {
> +		c->error = -ENOMEM;
> +		return AE_NO_MEMORY;
> +	}
> +	INIT_LIST_HEAD(&rentry->node);
> +	rentry->res = *r;
> +	list_add_tail(&rentry->node, c->list);
> +	c->count++;
> +	return AE_OK;
> +}
> +
> +static acpi_status acpi_dev_process_resource(struct acpi_resource *ares,
> +					     void *context)
> +{
> +	struct res_proc_context *c = context;
> +	struct resource r;

We should initialize this to zero, otherwise insert_resource() will fail as
parent, sibling etc. pointers are garbage.

> +	int i;
> +
> +	if (c->preproc) {
> +		int ret;
> +
> +		ret = c->preproc(ares, c->preproc_data);
> +		if (ret < 0) {
> +			c->error = ret;
> +			return AE_ABORT_METHOD;
> +		} else if (ret > 0) {
> +			return AE_OK;
> +		}
> +	}
> +
> +	if (acpi_dev_resource_memory(ares, &r)
> +	    || acpi_dev_resource_io(ares, &r)
> +	    || acpi_dev_resource_address_space(ares, &r)
> +	    || acpi_dev_resource_ext_address_space(ares, &r))
> +		return acpi_dev_new_resource_entry(&r, c);
> +
> +	for (i = 0; acpi_dev_resource_interrupt(ares, i, &r); i++) {
> +		acpi_status status;
> +
> +		status = acpi_dev_new_resource_entry(&r, c);
> +		if (ACPI_FAILURE(status))
> +			return status;
> +	}
> +
> +	return AE_OK;
> +}
> +
> +/**
> + * acpi_dev_get_resources - Get current resources of a device.
> + * @adev: ACPI device node to get the resources for.
> + * @list: Head of the resultant list of resources (must be empty).
> + * @preproc: The caller's preprocessing routine.
> + * @preproc_data: Pointer passed to the caller's preprocessing routine.
> + *
> + * Evaluate the _CRS method for the given device node and process its output by
> + * (1) executing the @preproc() rountine provided by the caller, passing the
> + * resource pointer and @preproc_data to it as arguments, for each ACPI resource
> + * returned and (2) converting all of the returned ACPI resources into struct
> + * resource objects if possible.  If the return value of @preproc() in step (1)
> + * is different from 0, step (2) is not applied to the given ACPI resource and
> + * if that value is negative, the whole processing is aborted and that value is
> + * returned as the final error code.
> + *
> + * The resultant struct resource objects are put on the list pointed to by
> + * @list, that must be empty initially, as members of struct resource_list_entry
> + * objects.  Callers of this routine should use %acpi_dev_free_resource_list() to
> + * free that list.
> + *
> + * The number of resources in the output list is returned on success, an error
> + * code reflecting the error condition is returned otherwise.
> + */
> +int acpi_dev_get_resources(struct acpi_device *adev, struct list_head *list,
> +			   int (*preproc)(struct acpi_resource *, void *),
> +			   void *preproc_data)

Could we change this so that you can pass NULL list as well (provided that
the preproc is given)?

This is useful in case when we try to find the SPI/I2C device handle based
on the ACPI serial bus resource address. In that case we are not interested
in any other resources (and hence there is no need to allocate memory for
them etc.)
--
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