diff mbox

[v11,07/10] OF: Introduce helper function for getting PCI domain_nr

Message ID 1411003825-21521-8-git-send-email-Liviu.Dudau@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Liviu Dudau Sept. 18, 2014, 1:30 a.m. UTC
Add of_pci_get_domain_nr() to retrieve the PCI domain number
of a given device from DT. If the information is not present,
the function can be requested to allocate a new domain number.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/of/of_pci.c    | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_pci.h |  7 ++++++
 2 files changed, 69 insertions(+)

Comments

Bjorn Helgaas Sept. 19, 2014, 9:03 p.m. UTC | #1
On Thu, Sep 18, 2014 at 02:30:22AM +0100, Liviu Dudau wrote:
> Add of_pci_get_domain_nr() to retrieve the PCI domain number
> of a given device from DT. If the information is not present,
> the function can be requested to allocate a new domain number.

Is of_pci_get_domain_nr() used somewhere?  If the use is in some future
series, please mention it explicitly.  I'm just trying to avoid merging
unused code.

Bjorn
Arnd Bergmann Sept. 20, 2014, 2:24 a.m. UTC | #2
On Thursday 18 September 2014, Liviu Dudau wrote:
> 
> Add of_pci_get_domain_nr() to retrieve the PCI domain number
> of a given device from DT. If the information is not present,
> the function can be requested to allocate a new domain number.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Grant Likely <grant.likely@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

This is more elaborate than I remember it, and while the simpler
version (which potentially resulted in a conflict for inconsistent
DTs) was fine, this one also seems ok.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Rob Herring Sept. 20, 2014, 5:52 p.m. UTC | #3
On 09/17/2014 08:30 PM, Liviu Dudau wrote:
> Add of_pci_get_domain_nr() to retrieve the PCI domain number
> of a given device from DT. If the information is not present,
> the function can be requested to allocate a new domain number.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Grant Likely <grant.likely@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> ---

[...]

> +/**
> + * This function will try to obtain the host bridge domain number by
> + * using of_alias_get_id() call with "pci-domain" as a stem. If that
> + * fails, a local allocator will be used. The local allocator can
> + * be requested to return a new domain_nr if the information is missing
> + * from the device tree.
> + *
> + * @node: device tree node with the domain information
> + * @allocate_if_missing: if DT lacks information about the domain nr,
> + * allocate a new number.
> + *
> + * Returns the associated domain number from DT, or a new domain number
> + * if DT information is missing and @allocate_if_missing is true. If
> + * @allocate_if_missing is false then the last allocated domain number
> + * will be returned.
> + */
> +int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
> +{
> +	int domain;
> +
> +	domain = atomic_read(&of_domain_nr);
> +	if (domain == -1) {
> +		/* first run, get max defined domain nr in device tree */
> +		domain = of_get_max_pci_domain_nr();
> +		/* then set the start value for allocator to be max + 1 */
> +		atomic_set(&of_domain_nr, domain + 1);

atomic_read followed by atomic_set is not an atomic operation.

As I previously said, I don't like how this function is a mixture of
data retrieval and domian # allocation. I think we need 2 functions.

> +	}
> +	domain = of_alias_get_id(node, "pci-domain");

I still do not like using aliases here. Just put pci-domain or
linux,pci-domain into the PCI node.

I think we should assume all PCI root buses either have a domain
property or they don't and a mixture is an error. I'm not sure if that
simplifies the code or not though.

In the interest of merging, I think you should just do a simple
allocation and add the DT domain handling as a second step. You will
also need to document the DT part.

Rob
Liviu Dudau Sept. 22, 2014, 11:05 a.m. UTC | #4
On Fri, Sep 19, 2014 at 10:03:13PM +0100, Bjorn Helgaas wrote:
> On Thu, Sep 18, 2014 at 02:30:22AM +0100, Liviu Dudau wrote:
> > Add of_pci_get_domain_nr() to retrieve the PCI domain number
> > of a given device from DT. If the information is not present,
> > the function can be requested to allocate a new domain number.
> 
> Is of_pci_get_domain_nr() used somewhere?  If the use is in some future
> series, please mention it explicitly.  I'm just trying to avoid merging
> unused code.

It is used in the arm64 specific patch that I have dropped out of my
pull request. After discussions with Catalin I will add the patch back
into the tree that you've pulled from as he is OK with your tree carrying
the whole package.

I need to ask for some guidance here: for addressing some of your comments
and Rob's I can add more patches in my v11 branch and you can pull them
when you think they are ready. But one of your comments was requesting
splitting a patch into two blocks - one that moves of_pci_range_to_resource()
into drivers/of/address.c and one that fixes it's behaviour - and I don't
know how you would like that handled. Should I revert the original patch
and add the new ones, or should I rebase the whole series into a different
branch that you can pull from?

Best regards,
Liviu

> 
> Bjorn
>
Liviu Dudau Sept. 22, 2014, 3:20 p.m. UTC | #5
On Sat, Sep 20, 2014 at 03:24:20AM +0100, Arnd Bergmann wrote:
> On Thursday 18 September 2014, Liviu Dudau wrote:
> > 
> > Add of_pci_get_domain_nr() to retrieve the PCI domain number
> > of a given device from DT. If the information is not present,
> > the function can be requested to allocate a new domain number.
> > 
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Grant Likely <grant.likely@linaro.org>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> 
> This is more elaborate than I remember it, and while the simpler
> version (which potentially resulted in a conflict for inconsistent
> DTs) was fine, this one also seems ok.
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>

Thanks Arnd!

Best regards,
Liviu

> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
Bjorn Helgaas Sept. 22, 2014, 3:25 p.m. UTC | #6
On Mon, Sep 22, 2014 at 5:05 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> On Fri, Sep 19, 2014 at 10:03:13PM +0100, Bjorn Helgaas wrote:
>> On Thu, Sep 18, 2014 at 02:30:22AM +0100, Liviu Dudau wrote:
>> > Add of_pci_get_domain_nr() to retrieve the PCI domain number
>> > of a given device from DT. If the information is not present,
>> > the function can be requested to allocate a new domain number.
>>
>> Is of_pci_get_domain_nr() used somewhere?  If the use is in some future
>> series, please mention it explicitly.  I'm just trying to avoid merging
>> unused code.
>
> It is used in the arm64 specific patch that I have dropped out of my
> pull request. After discussions with Catalin I will add the patch back
> into the tree that you've pulled from as he is OK with your tree carrying
> the whole package.
>
> I need to ask for some guidance here: for addressing some of your comments
> and Rob's I can add more patches in my v11 branch and you can pull them
> when you think they are ready. But one of your comments was requesting
> splitting a patch into two blocks - one that moves of_pci_range_to_resource()
> into drivers/of/address.c and one that fixes it's behaviour - and I don't
> know how you would like that handled. Should I revert the original patch
> and add the new ones, or should I rebase the whole series into a different
> branch that you can pull from?

I guess the easiest thing is probably just to send a v12 series.  I
was hoping we were close enough for me to just hand-integrate minor
tweaks into my branch, but I think that will just create more
confusion.

Bjorn
Liviu Dudau Sept. 22, 2014, 3:33 p.m. UTC | #7
On Mon, Sep 22, 2014 at 04:25:13PM +0100, Bjorn Helgaas wrote:
> On Mon, Sep 22, 2014 at 5:05 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> > On Fri, Sep 19, 2014 at 10:03:13PM +0100, Bjorn Helgaas wrote:
> >> On Thu, Sep 18, 2014 at 02:30:22AM +0100, Liviu Dudau wrote:
> >> > Add of_pci_get_domain_nr() to retrieve the PCI domain number
> >> > of a given device from DT. If the information is not present,
> >> > the function can be requested to allocate a new domain number.
> >>
> >> Is of_pci_get_domain_nr() used somewhere?  If the use is in some future
> >> series, please mention it explicitly.  I'm just trying to avoid merging
> >> unused code.
> >
> > It is used in the arm64 specific patch that I have dropped out of my
> > pull request. After discussions with Catalin I will add the patch back
> > into the tree that you've pulled from as he is OK with your tree carrying
> > the whole package.
> >
> > I need to ask for some guidance here: for addressing some of your comments
> > and Rob's I can add more patches in my v11 branch and you can pull them
> > when you think they are ready. But one of your comments was requesting
> > splitting a patch into two blocks - one that moves of_pci_range_to_resource()
> > into drivers/of/address.c and one that fixes it's behaviour - and I don't
> > know how you would like that handled. Should I revert the original patch
> > and add the new ones, or should I rebase the whole series into a different
> > branch that you can pull from?
> 
> I guess the easiest thing is probably just to send a v12 series.  I
> was hoping we were close enough for me to just hand-integrate minor
> tweaks into my branch, but I think that will just create more
> confusion.

OK, I will send v12 then with all the acquired ACKs and fixes.

Best regards,
Liviu

> 
> Bjorn
>
diff mbox

Patch

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 8481996..7eaeac2 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -3,6 +3,8 @@ 
 #include <linux/of.h>
 #include <linux/of_pci.h>
 
+#include "of_private.h"
+
 static inline int __of_pci_pci_compare(struct device_node *node,
 				       unsigned int data)
 {
@@ -89,6 +91,66 @@  int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
 }
 EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
 
+static atomic_t of_domain_nr = ATOMIC_INIT(-1);
+
+/*
+ * Get the maximum value for a domain number from the device tree
+ */
+static int of_get_max_pci_domain_nr(void)
+{
+	struct alias_prop *app;
+	int max_domain = -1;
+
+	mutex_lock(&of_mutex);
+	list_for_each_entry(app, &aliases_lookup, link) {
+		if (strncmp(app->stem, "pci-domain", 10) != 0)
+			continue;
+
+		max_domain = max(max_domain, app->id);
+	}
+	mutex_unlock(&of_mutex);
+
+	return max_domain;
+}
+
+/**
+ * This function will try to obtain the host bridge domain number by
+ * using of_alias_get_id() call with "pci-domain" as a stem. If that
+ * fails, a local allocator will be used. The local allocator can
+ * be requested to return a new domain_nr if the information is missing
+ * from the device tree.
+ *
+ * @node: device tree node with the domain information
+ * @allocate_if_missing: if DT lacks information about the domain nr,
+ * allocate a new number.
+ *
+ * Returns the associated domain number from DT, or a new domain number
+ * if DT information is missing and @allocate_if_missing is true. If
+ * @allocate_if_missing is false then the last allocated domain number
+ * will be returned.
+ */
+int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
+{
+	int domain;
+
+	domain = atomic_read(&of_domain_nr);
+	if (domain == -1) {
+		/* first run, get max defined domain nr in device tree */
+		domain = of_get_max_pci_domain_nr();
+		/* then set the start value for allocator to be max + 1 */
+		atomic_set(&of_domain_nr, domain + 1);
+	}
+	domain = of_alias_get_id(node, "pci-domain");
+	if (domain == -ENODEV) {
+		domain = atomic_read(&of_domain_nr);
+		if (allocate_if_missing)
+			atomic_inc(&of_domain_nr);
+	}
+
+	return domain;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_domain_nr);
+
 #ifdef CONFIG_PCI_MSI
 
 static LIST_HEAD(of_pci_msi_chip_list);
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index dde3a4a..3a3824c 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -15,6 +15,7 @@  struct device_node *of_pci_find_child_device(struct device_node *parent,
 int of_pci_get_devfn(struct device_node *np);
 int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
 int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
+int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing);
 #else
 static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
 {
@@ -43,6 +44,12 @@  of_pci_parse_bus_range(struct device_node *node, struct resource *res)
 {
 	return -EINVAL;
 }
+
+static inline int
+of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
+{
+	return -1;
+}
 #endif
 
 #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)