[PATCH v2 v2 0/3] Extend dt bindings to support I2C on sifive devices and a fix broken IRQ in polling mode.

From: Sagar Shrikant Kadam
Date: Tue May 07 2019 - 11:16:22 EST

The patch is based on mainline v5.1 and extends DT-bindings for Opencore based I2C device in FU540
SoC, available on HiFive unleashed board (Rev A00), and also provides a workaround for broken IRQ
which affect I2C polling mode interface on FU540 chipsets.

The polling mode workaround patch fixes the CPU stall issue, when-ever i2c transfer are initiated.

This workaround checks if it's a FU540 chipset based on device tree information, and check's for open
core's IF(interrupt flag) and TIP flags to break from the polling loop upon completion of transfer.

To test the patch, a PMOD-AD2 sensor is connected to HiFive Unleashed board over J1 connector, and
appropriate device node is added into board specific device tree as per the information provided in
dt-bindings in Documentation/devicetree/bindings/i2c/i2c-sifive.txt.
Without this workaround, the CPU stall's infinitely.

Busybox i2c utilities used to verify workaround : i2cdetect, i2cdump, i2cset, i2cget

Patch History:

-Incorporate review comments from Andrew
-Extend dt bindings into i2c-ocores.txt instead of adding new file

-Update dt bindings for sifive i2c devices
-Fix broken IRQ affecting i2c polling mode interface.

Sagar Shrikant Kadam (3):
dt-bindings: i2c: extend existing opencore bindings.
i2c-ocore: sifive: add support for i2c device on FU540-c000 SoC.
i2c-ocores: sifive: add polling mode workaround for FU540-C000 SoC.

.../devicetree/bindings/i2c/i2c-ocores.txt | 20 +++++++++++++
drivers/i2c/busses/i2c-ocores.c | 33 +++++++++++++++++++---
2 files changed, 49 insertions(+), 4 deletions(-)


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