Re: [PATCH 2/2] net, thunder, bgx: Add support for ACPI binding.

[David Daney <ddaney@xxxxxxxxxxxxxxxxxx>]

On 08/07/2015 07:54 AM, Graeme Gregory wrote:
> On Thu, Aug 06, 2015 at 05:33:10PM -0700, David Daney wrote:
> > From: David Daney <david.daney@xxxxxxxxxx>
> >
> > Find out which PHYs belong to which BGX instance in the ACPI way.
> >
> > Set the MAC address of the device as provided by ACPI tables. This is
> > similar to the implementation for devicetree in
> > of_get_mac_address(). The table is searched for the device property
> > entries "mac-address", "local-mac-address" and "address" in that
> > order. The address is provided in a u64 variable and must contain a
> > valid 6 bytes-len mac addr.
> >
> > Based on code from: Narinder Dhillon <ndhillon@xxxxxxxxxx>
> >                      Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> >                      Robert Richter <rrichter@xxxxxxxxxx>
> >
> > Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> > Signed-off-by: Robert Richter <rrichter@xxxxxxxxxx>
> > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 137 +++++++++++++++++++++-
> >   1 file changed, 135 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> > index 615b2af..2056583 100644
> > --- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> > +++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
[...]
> > +
> > +static int acpi_get_mac_address(struct acpi_device *adev, u8 *dst)
> > +{
> > +	const union acpi_object *prop;
> > +	u64 mac_val;
> > +	u8 mac[ETH_ALEN];
> > +	int i, j;
> > +	int ret;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(addr_propnames); i++) {
> > +		ret = acpi_dev_get_property(adev, addr_propnames[i],
> > +					    ACPI_TYPE_INTEGER, &prop);
>
> Shouldn't this be trying to use device_property_read_* API and making
> the DT/ACPI path the same where possible?

Ideally, something like you suggest would be possible.  However, there 
are a couple of problems trying to do it in the kernel as it exists today:

1) There is no 'struct device *' here, so device_property_read_* is not 
applicable.

2) There is no standard ACPI binding for MAC addresses, so it is 
impossible to create a hypothetical fw_get_mac_address(), which would be 
analogous to of_get_mac_address().

Other e-mail threads have suggested that the path to an elegant solution 
is to inter-mix a bunch of calls to acpi_dev_get_property*() and 
fwnode_property_read*() as to use these more generic 
fwnode_property_read*() functions whereever possible.  I rejected this 
approach as it seems cleaner to me to consistently use a single set of APIs.

Thanks,
David Daney



> Graeme
>
> > +		if (ret)
> > +			continue;
> > +
> > +		mac_val = prop->integer.value;
> > +
> > +		if (mac_val & (~0ULL << 48))
> > +			continue;	/* more than 6 bytes */
> > +
> > +		for (j = 0; j < ARRAY_SIZE(mac); j++)
> > +			mac[j] = (u8)(mac_val >> (8 * j));
> > +		if (!is_valid_ether_addr(mac))
> > +			continue;
> > +
> > +		memcpy(dst, mac, ETH_ALEN);
> > +
> > +		return 0;
> > +	}
> > +
> > +	return ret ? ret : -EINVAL;
> > +}
> > +
> > +static acpi_status bgx_acpi_register_phy(acpi_handle handle,
> > +					 u32 lvl, void *context, void **rv)
> > +{
> > +	struct acpi_reference_args args;
> > +	const union acpi_object *prop;
> > +	struct bgx *bgx = context;
> > +	struct acpi_device *adev;
> > +	struct device *phy_dev;
> > +	u32 phy_id;
> > +
> > +	if (acpi_bus_get_device(handle, &adev))
> > +		goto out;
> > +
> > +	SET_NETDEV_DEV(&bgx->lmac[bgx->lmac_count].netdev, &bgx->pdev->dev);
> > +
> > +	acpi_get_mac_address(adev, bgx->lmac[bgx->lmac_count].mac);
> > +
> > +	bgx->lmac[bgx->lmac_count].lmacid = bgx->lmac_count;
> > +
> > +	if (acpi_dev_get_property_reference(adev, "phy-handle", 0, &args))
> > +		goto out;
> > +
> > +	if (acpi_dev_get_property(args.adev, "phy-channel", ACPI_TYPE_INTEGER, &prop))
> > +		goto out;
> > +
> > +	phy_id = prop->integer.value;
> > +
> > +	phy_dev = bus_find_device(&mdio_bus_type, NULL, (void *)&phy_id,
> > +				  bgx_match_phy_id);
> > +	if (!phy_dev)
> > +		goto out;
> > +
> > +	bgx->lmac[bgx->lmac_count].phydev = to_phy_device(phy_dev);
> > +out:
> > +	bgx->lmac_count++;
> > +	return AE_OK;
> > +}
> > +
> > +static acpi_status bgx_acpi_match_id(acpi_handle handle, u32 lvl,
> > +				     void *context, void **ret_val)
> > +{
> > +	struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
> > +	struct bgx *bgx = context;
> > +	char bgx_sel[5];
> > +
> > +	snprintf(bgx_sel, 5, "BGX%d", bgx->bgx_id);
> > +	if (ACPI_FAILURE(acpi_get_name(handle, ACPI_SINGLE_NAME, &string))) {
> > +		pr_warn("Invalid link device\n");
> > +		return AE_OK;
> > +	}
> > +
> > +	if (strncmp(string.pointer, bgx_sel, 4))
> > +		return AE_OK;
> > +
> > +	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> > +			    bgx_acpi_register_phy, NULL, bgx, NULL);
> > +
> > +	kfree(string.pointer);
> > +	return AE_CTRL_TERMINATE;
> > +}
> > +
> > +static int bgx_init_acpi_phy(struct bgx *bgx)
> > +{
> > +	acpi_get_devices(NULL, bgx_acpi_match_id, bgx, (void **)NULL);
> > +	return 0;
> > +}
> > +
> > +#else
> > +
> > +static int bgx_init_acpi_phy(struct bgx *bgx)
> > +{
> > +	return -ENODEV;
> > +}
> > +
> > +#endif /* CONFIG_ACPI */
> > +
> >   #if IS_ENABLED(CONFIG_OF_MDIO)
> >
> >   static int bgx_init_of_phy(struct bgx *bgx)
> > @@ -882,7 +1010,12 @@ static int bgx_init_of_phy(struct bgx *bgx)
> >
> >   static int bgx_init_phy(struct bgx *bgx)
> >   {
> > -	return bgx_init_of_phy(bgx);
> > +	int err = bgx_init_of_phy(bgx);
> > +
> > +	if (err != -ENODEV)
> > +		return err;
> > +
> > +	return bgx_init_acpi_phy(bgx);
> >   }
> >
> >   static int bgx_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> > --
> > 1.9.1
> >
> > --
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