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

From: David Daney
Date: Fri Aug 07 2015 - 14:15:02 EST

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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