Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()

[Quan Nguyen]

On 20/05/2021 18:06, Ryan Chen wrote:
> > -----Original Message-----
> > From: openbmc
> > <openbmc-bounces+ryan_chen=aspeedtech.com@xxxxxxxxxxxxxxxx> On Behalf
> > Of Quan Nguyen
> > Sent: Wednesday, May 19, 2021 3:50 PM
> > To: Corey Minyard <minyard@xxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>;
> > Joel Stanley <joel@xxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>; Brendan
> > Higgins <brendanhiggins@xxxxxxxxxx>; Benjamin Herrenschmidt
> > <benh@xxxxxxxxxxxxxxxxxxx>; Wolfram Sang <wsa@xxxxxxxxxx>; Philipp Zabel
> > <p.zabel@xxxxxxxxxxxxxx>; openipmi-developer@xxxxxxxxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux-aspeed@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linux-i2c@xxxxxxxxxxxxxxx
> > Cc: Open Source Submission <patches@xxxxxxxxxxxxxxxxxxx>; Thang Q .
> > Nguyen <thang@xxxxxxxxxxxxxxxxxxxxxx>; Phong Vo
> > <phong@xxxxxxxxxxxxxxxxxxxxxx>; openbmc@xxxxxxxxxxxxxxxx
> > Subject: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()
> >
> > Slave i2c device on AST2500 received a lot of slave irq while it is busy
> > processing the response. To handle this case, adds and exports
> > aspeed_set_slave_busy() for controller to temporary stop slave irq while slave
> > is handling the response, and re-enable them again when the response is ready.
> >
> > Signed-off-by: Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> > v3:
> >    + First introduce in v3 [Quan]
> >
> >   drivers/i2c/busses/i2c-aspeed.c | 20 ++++++++++++++++++++
> >   1 file changed, 20 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> > index b2e9c8f0ddf7..9926d04831a2 100644
> > --- a/drivers/i2c/busses/i2c-aspeed.c
> > +++ b/drivers/i2c/busses/i2c-aspeed.c
> > @@ -944,6 +944,26 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus
> > *bus,
> >   	return 0;
> >   }
> >
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > +void aspeed_set_slave_busy(struct i2c_adapter *adap, bool busy) {
> > +	struct aspeed_i2c_bus *bus = i2c_get_adapdata(adap);
> > +	unsigned long current_mask, flags;
> > +
> > +	spin_lock_irqsave(&bus->lock, flags);
> > +
> > +	current_mask = readl(bus->base + ASPEED_I2C_INTR_CTRL_REG);
> > +	if (busy)
> > +		current_mask &= ~(ASPEED_I2CD_INTR_RX_DONE |
> > ASPEED_I2CD_INTR_SLAVE_MATCH);
> > +	else
> > +		current_mask |= ASPEED_I2CD_INTR_RX_DONE |
> > ASPEED_I2CD_INTR_SLAVE_MATCH;
> > +	writel(current_mask, bus->base + ASPEED_I2C_INTR_CTRL_REG);
> > +
> > +	spin_unlock_irqrestore(&bus->lock, flags); }
> > +EXPORT_SYMBOL_GPL(aspeed_set_slave_busy);
> > +#endif
> > +
> >   static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus)  {
> >   	struct platform_device *pdev = to_platform_device(bus->dev);
> > --
> > 2.28.0
>
> Hello,
> 	The better idea is use disable i2c slave mode.
> 	Due to if i2c controller running in slave will get slave match, and latch the SCL.
> 	Until cpu clear interrupt status.
> Ryan
Thanks Ryan,

Do you mean to enable/disable slave function as per example code below ?

        /* Turn on slave mode. */
        func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
        func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
        writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);

Will try this idea.
- Quan