[v8] i2c: imx: support slave mode for imx I2C driver

[Biwen Li (OSS)]

> > +/*
> > + * Enable bus idle interrupts
> > + * Note: IBIC register will be cleared after disabled i2c module.
> > + */
> > +static void i2c_imx_enable_bus_idle(struct imx_i2c_struct *i2c_imx) {
> > +	unsigned int temp;
> > +
> > +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_IBIC);
> > +	temp |= IBIC_BIIE;
> > +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_IBIC); }
> > +
> > +static void i2c_imx_clr_if_bit(unsigned int status, struct
> > +imx_i2c_struct *i2c_imx) {
> > +	status &= ~I2SR_IIF;
> > +	status |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
> > +	imx_i2c_write_reg(status, i2c_imx, IMX_I2C_I2SR); }
> > +
> > +/* Clear arbitration lost bit */
> > +static void i2c_imx_clr_al_bit(unsigned int status, struct
> > +imx_i2c_struct *i2c_imx) {
> > +	status &= ~I2SR_IAL;
> > +	status |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IAL);
> > +	imx_i2c_write_reg(status, i2c_imx, IMX_I2C_I2SR); }
> > +
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> 
> Last year (to be more precise Date: Fri, 6 Dec 2019 08:38:20 +0100), Sascha
> asked you to make I2C_SLAVE support not optional.
> In the V7 of this patch you even tried to do so...
> Please, patch drivers/i2c/busses/Kconfig and add "select I2C_SLAVE" to the
> I2C_IMX node.
Sure, np. Will add it in v4.
> 
> > +static irqreturn_t i2c_imx_slave_isr(struct imx_i2c_struct *i2c_imx,
> > +				     unsigned int status, unsigned int ctl) {
> > +	u8 value;
> > +
> > +	if (status & I2SR_IAL) { /* Arbitration lost */
> > +		i2c_imx_clr_al_bit(status | I2SR_IIF, i2c_imx);
> > +	} else if (status & I2SR_IAAS) { /* Addressed as a slave */
> > +		if (status & I2SR_SRW) { /* Master wants to read from us*/
> > +			dev_dbg(&i2c_imx->adapter.dev, "read requested");
> > +			i2c_slave_event(i2c_imx->slave, I2C_SLAVE_READ_REQUESTED,
> &value);
> > +