Hi,
On Saturday, 22 February 2020 17:16:26 CET Mr. Smith wrote:
> Currently ipq806x soc use generic bitbang driver to
> comunicate with the gmac ethernet interface.
> Add a dedicated driver created by chunkeey to fix this.
Ok, I'm officially a bit "out-of-the-loop" here (was looking for
a changelog, but I guess I missed that mail). So please excuse me,
if I say something that was already stated. Instead kindly reply
with a text extract (preferably with the link to the mail as I'm not
a regular linux-net subscriber) to that discussion.
> Co-developed-by: Christian Lamparter <chunkeey@xxxxxxxxx>
Ahh, I see that
"docs: Clarify the usage and sign-off requirements for Co-developed-by"
did away with the "original author" wording in the submitting-patches doc.
So keeping the original "From:" doesn't matter as such anymore.
Still, for reference (historical digs or if someone wants to take a peek):
Most of this patch comes from a patch named:
700-net-mdio-add-ipq8064-mdio-driver.patch
which is part of a bigger "ipq8064: ipq8064-mdio + dsa test" commit.
This is currently in a staging tree hosted on <git.openwrt.org>.
Here's a direct link: [0] (sadly, this is not self-updating).
Background: This driver was mainly written to make and test the qca8k
patches I posted to the linux-net ML last year. The Idea was that I
didn't have to deal with the odd random timing issues on the slow debug
kernels, when I was perfing/hammering the device.
(The IPQ8064 has/had various scaling problems so, this might be already
fixed by some of Mr. Smith's other work for the abandoned IPQ8064).
>From what I know, this patch mostly helps/fixes a problem with the
out-of-tree OpenWrt swconfig-based ar8216/ar8236 driver for the
used QCA8337 switch.
This driver really needs the faster, more efficient reads due to having
a statistics worker which is just gobbing cycles because of all the
exclusive-access bit-banging taking place.
(Remember, the worker could read all the phy-counters for each of the 7
ports over gpio-mdio (there have been attempts to make it less hoggy
in the mean time though). While the IPQ8064 SoC has a beefy dual-core
Cortex-A15 with up to 1.4GHz*, this bitbanging will result in a
considerable load on at least one of the cores.)
Mr. Smith knows more about this though, as he has the hardware and
is the upcoming IPQ8064 expert on this.
>From my POV, I never anticipated this hack was up to standards of linux-net.
As there is this ugly dependency on having the "master" MAC (handled by the
sttmac/dwmac-ipq806x.c) part up and operational all the time (that's why
the "master" property is needed for some devices at least).
I had hopes to do this properly and integrate it into
dwmac-ipq806x.c, but this requires much more work and ultimately
"virtual-mdio" was "just good enough™️" for standard, production kernels.
>From what I remember the Qualcomm devs themselves never bothered in their
abandoned posts with the DeviceTree for the qcom-ipq8064.dts to include a
standalone mdio driver. Instead the dev went straight to "virtual-mdio".
(but this was too long ago to really remember the details and it's getting late)
But Ok, if linux-net is content with the standalone mdio-ipq8064 approach,
then: Sure!
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 9dabe03a668c..ec2a5493a7e8 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -157,6 +157,14 @@ config MDIO_I2C
>
> This is library mode.
>
> +config MDIO_IPQ8064
> + tristate "Qualcomm IPQ8064 MDIO interface support"
> + depends on HAS_IOMEM && OF_MDIO
> + depends on MFD_SYSCON
> + help
> + This driver supports the MDIO interface found in the network
> + interface units of the IPQ8064 SoC
> +
> config MDIO_MOXART
> tristate "MOXA ART MDIO interface support"
> depends on ARCH_MOXART || COMPILE_TEST
> diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
> index fe5badf13b65..8f02bd2089f3 100644
> --- a/drivers/net/phy/Makefile
> +++ b/drivers/net/phy/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_MDIO_CAVIUM) += mdio-cavium.o
> obj-$(CONFIG_MDIO_GPIO) += mdio-gpio.o
> obj-$(CONFIG_MDIO_HISI_FEMAC) += mdio-hisi-femac.o
> obj-$(CONFIG_MDIO_I2C) += mdio-i2c.o
> +obj-$(CONFIG_MDIO_IPQ8064) += mdio-ipq8064.o
> obj-$(CONFIG_MDIO_MOXART) += mdio-moxart.o
> obj-$(CONFIG_MDIO_MSCC_MIIM) += mdio-mscc-miim.o
> obj-$(CONFIG_MDIO_OCTEON) += mdio-octeon.o
> diff --git a/drivers/net/phy/mdio-ipq8064.c b/drivers/net/phy/mdio-ipq8064.c
> new file mode 100644
> index 000000000000..74d6b92a6f48
> --- /dev/null
> +++ b/drivers/net/phy/mdio-ipq8064.c
> @@ -0,0 +1,166 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Qualcomm IPQ8064 MDIO interface driver
> +//
> +// Copyright (C) 2019 Christian Lamparter <chunkeey@xxxxxxxxx>
> +
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/of_mdio.h>
> +#include <linux/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/syscon.h>
> +
> +/* MII address register definitions */
> +#define MII_ADDR_REG_ADDR 0x10
> +#define MII_BUSY BIT(0)
> +#define MII_WRITE BIT(1)
> +#define MII_CLKRANGE_60_100M (0 << 2)
> +#define MII_CLKRANGE_100_150M (1 << 2)
> +#define MII_CLKRANGE_20_35M (2 << 2)
> +#define MII_CLKRANGE_35_60M (3 << 2)
> +#define MII_CLKRANGE_150_250M (4 << 2)
> +#define MII_CLKRANGE_250_300M (5 << 2)
> +#define MII_CLKRANGE_MASK GENMASK(4, 2)
> +#define MII_REG_SHIFT 6
> +#define MII_REG_MASK GENMASK(10, 6)
> +#define MII_ADDR_SHIFT 11
> +#define MII_ADDR_MASK GENMASK(15, 11)
Is it just me, or is something weird going on with tabs vs. spaces here
(and below in ipq8064_mdio_wait_busy() )?
> +
> +#define MII_DATA_REG_ADDR 0x14
> +
> +#define MII_MDIO_DELAY_USEC (1000)
> +#define MII_MDIO_RETRY_MSEC (10)
> +
> +struct ipq8064_mdio {
> + struct regmap *base; /* NSS_GMAC0_BASE */
> +};
> +
> +static int
> +ipq8064_mdio_wait_busy(struct ipq8064_mdio *priv)
> +{
> + u32 busy;
> +
> + return regmap_read_poll_timeout(priv->base, MII_ADDR_REG_ADDR, busy,
> + !(busy & MII_BUSY), MII_MDIO_DELAY_USEC,
> + MII_MDIO_RETRY_MSEC * USEC_PER_MSEC);
Didn't know this macro existed. This look much nicer.
> +}
> +
> +static int
> +ipq8064_mdio_read(struct mii_bus *bus, int phy_addr, int reg_offset)
> +{
> + struct ipq8064_mdio *priv = bus->priv;
> + u32 miiaddr = MII_BUSY | MII_CLKRANGE_250_300M;
> + u32 ret_val;
> + int err;
> +
> + /* Reject clause 45 */
> + if (reg_offset & MII_ADDR_C45)
> + return -EOPNOTSUPP;
Heh, C45 on IPQ806X? Ok, anyone know the hardware or is this some fancy
forward-thinking future-proofing?
(So it this will not break in the future. Not that the SoC of the
ipq8064 could more than 1GBit/s per port from what I know.)
> +
> + miiaddr |= ((phy_addr << MII_ADDR_SHIFT) & MII_ADDR_MASK) |
> + ((reg_offset << MII_REG_SHIFT) & MII_REG_MASK);
> +
> + regmap_write(priv->base, MII_ADDR_REG_ADDR, miiaddr);
> + usleep_range(10, 20);
Yeeah, this looks a bit different. I did measure with a for-loop how many
udelay(1); a operation took. I can't remember the exact values (I think it
was "8", so the "
SLEEPING FOR "A FEW" USECS ( < ~10us? ):
* Use udelay" from the timers-howto.txt applies, right?
But I know that "8" (again, 8 is the stand-in value) would seemed
too bike-sheddy... And looks like it was since this got changed.
> +
> + err = ipq8064_mdio_wait_busy(priv);
> + if (err)
> + return err;
> +
> + regmap_read(priv->base, MII_DATA_REG_ADDR, &ret_val);
> + return (int)ret_val;
> +}
> +
> +static int
> +ipq8064_mdio_write(struct mii_bus *bus, int phy_addr, int reg_offset, u16 data)
> +{
> + struct ipq8064_mdio *priv = bus->priv;
> + u32 miiaddr = MII_WRITE | MII_BUSY | MII_CLKRANGE_250_300M;
> +
> + /* Reject clause 45 */
> + if (reg_offset & MII_ADDR_C45)
> + return -EOPNOTSUPP;
> +
> + regmap_write(priv->base, MII_DATA_REG_ADDR, data);
> +
> + miiaddr |= ((phy_addr << MII_ADDR_SHIFT) & MII_ADDR_MASK) |
> + ((reg_offset << MII_REG_SHIFT) & MII_REG_MASK);
> +
> + regmap_write(priv->base, MII_ADDR_REG_ADDR, miiaddr);
> + usleep_range(10, 20);
> +
> + return ipq8064_mdio_wait_busy(priv);
> +}
> +
> +static int
> +ipq8064_mdio_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct ipq8064_mdio *priv;
> + struct mii_bus *bus;
> + int ret;
> +
> + bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*priv));
> + if (!bus)
> + return -ENOMEM;
> +
> + bus->name = "ipq8064_mdio_bus";
> + bus->read = ipq8064_mdio_read;
> + bus->write = ipq8064_mdio_write;
> + snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii", dev_name(&pdev->dev));
> + bus->parent = &pdev->dev;
> +
> + priv = bus->priv;
> + priv->base = syscon_node_to_regmap(np);
> + if (IS_ERR(priv->base) && priv->base != ERR_PTR(-EPROBE_DEFER))
> + priv->base = syscon_regmap_lookup_by_phandle(np, "master");
> +
> + if (priv->base == ERR_PTR(-EPROBE_DEFER)) {
> + return -EPROBE_DEFER;
> + } else if (IS_ERR(priv->base)) {
> + dev_err(&pdev->dev, "error getting syscon regmap, error=%pe\n",
> + priv->base);
> + return PTR_ERR(priv->base);
> + }
> +
> + ret = of_mdiobus_register(bus, np);
> + if (ret)
> + return ret;
> +
> + platform_set_drvdata(pdev, bus);
> + return 0;
> +}
> +
> +static int
> +ipq8064_mdio_remove(struct platform_device *pdev)
> +{
> + struct mii_bus *bus = platform_get_drvdata(pdev);
> +
> + mdiobus_unregister(bus);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id ipq8064_mdio_dt_ids[] = {
> + { .compatible = "qcom,ipq8064-mdio" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, ipq8064_mdio_dt_ids);
> +
> +static struct platform_driver ipq8064_mdio_driver = {
> + .probe = ipq8064_mdio_probe,
> + .remove = ipq8064_mdio_remove,
> + .driver = {
> + .name = "ipq8064-mdio",
> + .of_match_table = ipq8064_mdio_dt_ids,
> + },
> +};
> +
> +module_platform_driver(ipq8064_mdio_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm IPQ8064 MDIO interface driver");
> +MODULE_AUTHOR("Christian Lamparter <chunkeey@xxxxxxxxx>");
@Mr. Smith: Don't you want to add yourself there (and in the boilerplate)
as well then?
> +MODULE_LICENSE("GPL");
>
Cheers and good night,
Christian
---
[0] <https://git.openwrt.org/?p=openwrt/staging/chunkeey.git;a=blob;f=target/linux/ipq806x/patches-4.19/700-net-mdio-add-ipq8064-mdio-driver.patch;h=6f25b895cacb34b7fcf3e275c15ab26e25252fa8;hb=1034741b8735608b022d55b08df34d4cff423b46>
