arch/arm/ameba: add shared I2C master driver (RTL8721Dx + RTL8721F) - #19780
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arch/arm/ameba: add shared I2C master driver (RTL8721Dx + RTL8721F)#19780dcgong2917 wants to merge 2 commits into
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Add a shared NuttX I2C master lower-half for the Realtek Ameba I2C controllers (I2C0/I2C1) in arch/arm/src/common/ameba, driven through the SDK fwlib in polling mode. Per-chip wiring (controller count, register bases, clock masks, crossbar pad-mux codes and the fwlib I2C_InitTypeDef layout) lives in arch/arm/src/rtl8721dx/ameba_i2c_chip.h so a port to the other Ameba chips only supplies a same-named header. Each controller registers as /dev/i2cN from pke8721daf bring-up through the stock I2C character driver; a dedicated `i2c` defconfig drives the i2ctool for validation. Assisted-by: Claude <noreply@anthropic.com> Signed-off-by: dechao_gong <dechao_gong@realsil.com.cn>
Wire the shared Ameba I2C master lower-half (arch/arm/src/common/ ameba/ameba_i2c.c) into the RTL8721F (amebagreen2) build through a per-chip header (ameba_i2c_chip.h), and register the RTL8721F EVB buses at /dev/i2cN. Per-chip differences from the other Ameba SoCs (non-secure register bases, crossbar pinmux codes, APB clock masks and the fwlib I2C_InitTypeDef layout) are isolated in ameba_i2c_chip.h; no change to the shared driver is needed. Verified end-to-end on hardware against a second Ameba board acting as an I2C slave: address ACK, register write and read-back over repeated-START, and bus scan all pass on I2C0 (PA22/PA23). Assisted-by: Claude <noreply@anthropic.com> Signed-off-by: dechao_gong <dechao_gong@realsil.com.cn>
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August 11, 2026 01:59
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Summary
Adds a shared NuttX I2C master lower-half for the Realtek Ameba I2C
controllers (I2C0/I2C1) under arch/arm/src/common/ameba, driven through
the SDK fwlib DesignWare block in polling mode. Per-chip wiring
(controller count, non-secure register bases, APB clock masks, crossbar
pad-mux codes and the fwlib I2C_InitTypeDef layout) is isolated in a
per-chip ameba_i2c_chip.h, so each SoC only supplies a same-named header.
Two commits:
driver + RTL8721Dx chip header + pke8721daf board glue +
i2cdefconfig.driver into the RTL8721F (amebagreen2) build via its chip header + EVB
board glue +
i2cdefconfig (no change to the shared driver).Each controller registers at /dev/i2cN and is exercised with the
system/i2c i2ctool.
Impact
New optional feature (CONFIG_AMEBA_I2C, default n); no impact when
disabled. Touches only arch/arm/src/common/ameba, arch/arm/src/rtl8721dx,
arch/arm/src/rtl8721f, their boards, and one nxstyle whitelist entry.
Testing
Verified end-to-end on RTL8721F EVB hardware against a second Ameba board
acting as an I2C slave: 7-bit address ACK, register write and read-back
over repeated-START, and full bus scan all pass on I2C0 (PA22/PA23).
Also validated on RTL8721Dx (pke8721daf): SS/FS 100k/400k, 8/16-bit
register access, both I2C0 and I2C1. checkpatch (
tools/checkpatch.sh -g)passes clean on both commits.