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Message-ID: <5558D01E.2070809@tronnes.org>
Date: Sun, 17 May 2015 19:30:06 +0200
From: Noralf Trønnes <noralf@...nnes.org>
To: Eric Anholt <eric@...olt.net>, linux-arm-kernel@...ts.infradead.org
CC: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-rpi-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3 v2] ARM: bcm2835: Add the Raspberry Pi firmware driver
Den 13.05.2015 21:00, skrev Eric Anholt:
> This gives us a function for making mailbox property channel requests
> of the firmware, which is most notable in that it will let us get and
> set clock rates.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>
> v2: Drop power-domains stuff for now since we don't have the driver
> core support to make it useful. Move to drivers/firmware/.
> Capitalize the enums. De-global the firmware variable. Use the
> firmware device to allocate our DMA buffer, so that the dma-ranges
> DT property gets respected. Simplify the property tag transaction
> interface even more, leaving a multi-tag interface still
> available. For conciseness, rename "raspberrypi" to "rpi" on all
> functions/enums/structs, and the "firmware" variable to "fw".
> Print when the driver is probed successfully, since debugging
> -EPROBE_DEFER handling is such a big part of bcm2835 development.
> Drop -EBUSY mailbox handling since the mailbox core has been fixed
> to return -EPROBE_DEFER in -next.
>
> Note that I don't think I've done what srwarren wanted for
> -EPROBE_DEFER, because I'm not clear what he wants. I think he might
> just be asking for a function that does:
>
> /*
> * Returns 0 if the firmware device is probed and available, otherwise
> * -EPROBE_DEFER.
> */
> int rpi_firmware_get(struct device_node *firmware_node)
> {
> struct platform_device *pdev = of_find_device_by_node(of_node);
> if (!platform_get_drvdata(pdev))
> return -EPROBE_DEFER;
> return 0;
> }
> EXPORT_SYMBOL(rpi_firmware_get)
>
> If that's all, I'm happy to add it.
>
> Note that a client could currently do this:
>
> ret = rpi_firmware_property_list(firmware_node, NULL, 0);
>
> in exchange for a bit of overhead in the case that it's actually probed already.
>
[...]
> diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
[...]
> +int rpi_firmware_property_list(struct device_node *of_node,
> + void *data, size_t tag_size)
> +{
> + struct platform_device *pdev = of_find_device_by_node(of_node);
> + struct rpi_firmware *fw = platform_get_drvdata(pdev);
> + size_t size = tag_size + 12;
> + u32 *buf;
> + dma_addr_t bus_addr;
> + int ret = 0;
> +
> + if (!fw)
> + return -EPROBE_DEFER;
> +
> + /* Packets are processed a dword at a time. */
> + if (size & 3)
> + return -EINVAL;
> +
> + buf = dma_alloc_coherent(fw->cl.dev, PAGE_ALIGN(size), &bus_addr,
[...]
> + dma_free_coherent(NULL, PAGE_ALIGN(size), buf, bus_addr);
Should probably pass the device when freeing as well.
> +static int rpi_firmware_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + int ret = 0;
> + struct rpi_firmware *fw;
> +
> + fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
> + if (!fw)
> + return -ENOMEM;
> +
> + fw->cl.dev = dev;
> + fw->cl.rx_callback = response_callback;
> + fw->cl.tx_block = true;
> +
> + fw->chan = mbox_request_channel(&fw->cl, 0);
> + if (IS_ERR(fw->chan)) {
Definition of ret can be move here.
> + ret = PTR_ERR(fw->chan);
> + /* An -EBUSY from the core means it couldn't find our
> + * channel, because the mailbox driver hadn't
> + * registered yet.
> + */
You forgot to remove this comment.
> + if (ret != -EPROBE_DEFER)
> + dev_err(dev, "Failed to get mbox channel: %d\n", ret);
> + return ret;
> + }
Why not turn the comments into kernel-doc comments:
(Thunderbird converts my tabs into spaces, sorry about that)
/**
* struct rpi_firmware_property_tag_header - Firmware property tag header
* @tag: One of enum_mbox_property_tag.
* @buf_size: The number of bytes in the value buffer following this
struct.
* @req_resp_size: On submit, the length of the request (though it doesn't
* appear to be currently used by the firmware). On
return,
* the length of the response (always 4 byte aligned), with
* the low bit set.
*/
struct rpi_firmware_property_tag_header {
u32 tag;
u32 buf_size;
u32 req_resp_size;
};
/**
* rpi_firmware_property_list - Submit firmware property list
* @of_node: Pointer to the firmware Device Tree node.
* @data: Buffer holding tags.
* @tag_size: Size of tags buffer.
*
* Submits a set of concatenated tags to the VPU firmware through the
* mailbox property interface.
*
* The buffer header and the ending tag are added by this function and
* don't need to be supplied, just the actual tags for your operation.
* See struct rpi_firmware_property_tag_header for the per-tag
* structure.
*/
int rpi_firmware_property_list(struct device_node *of_node,
void *data, size_t tag_size)
/**
* rpi_firmware_property - Submit single firmware property
* @of_node: Pointer to the firmware Device Tree node.
* @tag: One of enum_mbox_property_tag.
* @tag_data: Tag data buffer.
* @buf_size: Buffer size.
*
* Submits a single tag to the VPU firmware through the mailbox
* property interface.
*
* This is a convenience wrapper around
* rpi_firmware_property_list() to avoid some of the
* boilerplate in property calls.
*/
int rpi_firmware_property(struct device_node *of_node,
u32 tag, void *tag_data, size_t buf_size)
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