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Date: Mon, 08 Sep 2014 15:52:04 +0100
From: Grant Likely <grant.likely@...aro.org>
To: Stanimir Varbanov <svarbanov@...sol.com>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
Rob Herring <robherring2@...il.com>,
Rob Herring <rob.herring@...aro.org>,
Arnd Bergmann <arnd@...db.de>,
Lee Jones <lee.jones@...aro.org>,
Stephen Boyd <sboyd@...eaurora.org>,
Stanimir Varbanov <svarbanov@...sol.com>
Subject: Re: [PATCH] RFC: add function for localbus address
On Tue, 2 Sep 2014 18:45:00 +0300, Stanimir Varbanov <svarbanov@...sol.com> wrote:
> Hi Grant,
>
> I came down to this. Could you review? Is that
> implementation closer to the suggestion made by you.
>
> ---
> drivers/of/address.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
> drivers/of/platform.c | 20 ++++++++++++++---
> include/linux/of_address.h | 19 +++++++++++++++++
> 3 files changed, 84 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index e371825..86c2166 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -601,6 +601,32 @@ const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
> }
> EXPORT_SYMBOL(of_get_address);
>
> +const __be32 *of_get_localbus_address(struct device_node *np, int index,
> + u64 *size)
> +{
> + struct device_node *root, *parent;
> + const __be32 *ranges, *prop = NULL;
> +
> + parent = of_get_parent(np);
> + if (!parent)
> + return NULL;
> +
> + root = of_find_node_by_path("/");
> +
> + if (parent == root) {
> + of_node_put(parent);
> + return NULL;
> + }
> +
> + ranges = of_get_property(parent, "ranges", NULL);
> + of_node_put(parent);
> +
> + if (!ranges)
> + prop = of_get_address(np, index, size, NULL);
> +
> + return prop;
> +}
So, the above doesn't make much sense to me. It looks like the function
merely decodes the local address, and the below function will stuff it
into a resource structure, but the tests for if the parent is root or
the parent has a ranges property are nonsensical. That shouldn't matter
for the functionality (except for automatically decoding them.. more
below)
> +
> unsigned long __weak pci_address_to_pio(phys_addr_t address)
> {
> if (address > IO_SPACE_LIMIT)
> @@ -665,6 +691,29 @@ int of_address_to_resource(struct device_node *dev, int index,
> }
> EXPORT_SYMBOL_GPL(of_address_to_resource);
>
> +int of_localbus_address_to_resource(struct device_node *dev, int index,
> + struct resource *r)
> +{
> + const char *name = NULL;
> + const __be32 *addrp;
> + u64 size;
> +
> + addrp = of_get_localbus_address(dev, index, &size);
> + if (!addrp)
> + return -EINVAL;
> +
> + of_property_read_string_index(dev, "reg-names", index, &name);
> +
> + memset(r, 0, sizeof(*r));
> + r->start = be32_to_cpup(addrp);
> + r->end = r->start + size - 1;
> + r->flags = IORESOURCE_REG;
This is problematic. A resource is created, but there is absolutely no
indication that the resource represents a localbus address instead of a
CPU address. platform_device reg resources represent CPU addresses.
Trying to overload it will cause confusion in drivers.
> + r->name = name ? name : dev->full_name;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_localbus_address_to_resource);
> +
> struct device_node *of_find_matching_node_by_address(struct device_node *from,
> const struct of_device_id *matches,
> u64 base_address)
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 0197725..36dcbd7 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -106,8 +106,9 @@ 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;
> + int rc, i, num_reg = 0, num_localbus_reg = 0, num_irq;
> struct resource *res, temp_res;
> + int num_resources;
>
> dev = platform_device_alloc("", -1);
> if (!dev)
> @@ -116,22 +117,33 @@ struct platform_device *of_device_alloc(struct device_node *np,
> /* count the io and irq resources */
> while (of_address_to_resource(np, num_reg, &temp_res) == 0)
> num_reg++;
> +
> + while (of_localbus_address_to_resource(np,
> + num_localbus_reg, &temp_res) == 0)
> + num_localbus_reg++;
> +
No, I don't support doing this. The moment a platform_driver depends on
a local bus address it is doing something special. It needs to decode
its own address in that case, which it can easily do.
Any platform_driver that interprets a IORESOURCE_REG as a localbus
address instead of a CPU address is *BROKEN*. It should be changed to
either decode the address itself, of a new bus type should be created
that can make its own decisions about what address resources mean.
I realize that you want to reuse the platform populate functionality in
this case. We can refactor some of that code to make it usable for
customized platform_bus_type instances.
g.
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