[PATCH v2 0/3] Add the dwmac driver support for T-HEAD TH1520 SoC

[Drew Fustini]

This patch series is based on linux-next which contains the TH1520 clk
dts patches in my v6.12 pull request:

 https://lore.kernel.org/linux-riscv/ZsWs8QiVruMXjzPc@x1/

This patch also depends on this TH1520 pinctrl series:

 https://lore.kernel.org/linux-riscv/20240914-th1520-pinctrl-v2-0-3ba67dde882c@tenstorrent.com/

I have a branch with this series and the dependencies:

 https://github.com/pdp7/linux/tree/b4/th1520-dwmac

Regarding clocks, the gmac nodes in th1520.dtsi have the "stmmac_clk"
clock set to CLK_GMAC_AXI in the AP_SUBSYS clock controller. This
corresponds to the enable bit for the GMAC axi4_clk gate which is
handled by the clk-th1520-ap driver. thead_dwmac_fix_speed() does not
modify anything in the AP_SUBSYS clock controller. It only writes to
GMAC APB registers. It seems unnecessary to create a new clock driver
just for the GMAC APB registers. Refer to section 1.6.2 in the TH1520
Peripheral Interface User Manual [1].

Regarding rx and tx internal delays, that same section in the manual
doesn't specify what unit is represented by the delay_ctrl bit field in
GMAC_RXCLK_DELAY_CTRL and GMAC_TXCLK_DELAY_CTRL. It is only 5 bits and
a max value of 31 seems too small to represent picoseconds. The vendor
kernel [2] uses properties named "rx-clk-delay" and "tx-clk-delay" but
doesn't indicate any units. I see ti,dp83867.yaml adds vendor specific
rx and tx delay properties so that is what I've now done in this series.
Note: the hardware default value of 0 for delay_ctrl works okay for the
TH1520 hardware that I have.

There was a question in my v1 series about if the phy required a delay
after reset in the BeagleV Ahead device tree. The board has the Realtek
RTL8211F-CG phy [3]. According to this datasheet I found [4], the reset
pin must be asserted low for at least 10ms for the internal regulator.
Software must wait least 50ms before accessing the phy registers. I've
now added reset-delay-us and reset-post-delay-us with those values.

[1] https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/tree/main/docs
[2] https://github.com/revyos/thead-kernel/blob/lpi4a/drivers/net/ethernet/stmicro/stmmac/dwmac-thead.c
[3] https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/blob/main/BeagleV-Ahead_SCH.pdf
[4] https://www.lcsc.com/datasheet/lcsc_datasheet_1912111437_Realtek-Semicon-RTL8211F-CG_C187932.pdf

Changes since v1:
 - Drop the first patch as it is no longer needed due to upstream commit
   d01e0e98de31 ("dt-bindings: net: dwmac: Validate PBL for all IP-cores")
 - Rename compatible from "thead,th1520-dwmac" to "thead,th1520-gmac"
 - Add thead,rx-internal-delay and thead,tx-internal-delay properties
   and check that it does not exceed the maximum value
 - Convert from stmmac_dvr_probe() to devm_stmmac_pltfr_probe() and
   delete the .remove_new hook as it is no longer needed
 - Handle return value of regmap_write() in case it fails
 - Add phy reset delay properties to the BeagleV Ahead device tree
 - Link: https://lore.kernel.org/all/20240713-thead-dwmac-v1-0-81f04480cd31@tenstorrent.com/

Changes since Jisheng v2:
 - remove thead,gmacapb that references syscon for APB registers
 - add a second memory region to gmac nodes for the APB registers
 - Link: https://lore.kernel.org/all/20230827091710.1483-1-jszhang@kernel.org/

Changes since Jisheng v1:
 - rebase on the lastest net-next
 - collect Reviewed-by tag
 - address Krzysztof's comment of the dt binding
 - fix "div is not initialised" issue pointed out by Simon
 - Link: https://lore.kernel.org/all/20230820120213.2054-1-jszhang@kernel.org/

---
Emil Renner Berthing (1):
      riscv: dts: thead: Add TH1520 ethernet nodes

Jisheng Zhang (2):
      dt-bindings: net: Add T-HEAD dwmac support
      net: stmmac: Add glue layer for T-HEAD TH1520 SoC

 .../devicetree/bindings/net/snps,dwmac.yaml        |   1 +
 .../devicetree/bindings/net/thead,th1520-gmac.yaml | 109 +++++++
 MAINTAINERS                                        |   2 +
 arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts |  91 ++++++
 .../boot/dts/thead/th1520-lichee-module-4a.dtsi    | 135 +++++++++
 arch/riscv/boot/dts/thead/th1520.dtsi              |  50 ++++
 drivers/net/ethernet/stmicro/stmmac/Kconfig        |  11 +
 drivers/net/ethernet/stmicro/stmmac/Makefile       |   1 +
 drivers/net/ethernet/stmicro/stmmac/dwmac-thead.c  | 319 +++++++++++++++++++++
 9 files changed, 719 insertions(+)
---
base-commit: eb9913a02c55913317dcb4797026f958ce2c97d5
change-id: 20240923-th1520-dwmac-55a320ae01a6

Best regards,
-- 
Drew Fustini <dfustini at tenstorrent.com>