[PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties

[Ryan Chen]

> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
> 
> Hi Ryan,
> 
> > > Do you mean sysfs select support mode selection(byte, buffer, dma)
> > > Or just force byte mode?
> >
> > I would think that the best approach would be a mechanism to specify
> > the mode - either byte, buffer, or DMA - if DMA is indicated as
> > available to the controller.
> 
> ... with a sensible default mode (DMA if it is available, buffer if not).
> 
> But none of that logic relates to the binding, it's all driver implementation
> detail.

I will add new dma_available in struct ast2600_i2c_bus, align with dma property.
i2c_bus->dma_available = device_property_read_bool(dev, "aspeed,enable-dma");
And add sysfs for xfer_mode 
static ssize_t xfer_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
static ssize_t xfer_mode_store(struct device *dev,
			       struct device_attribute *attr,
			       const char *buf, size_t count)