linux-kernel - Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave

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Message-ID: <3eba7d01-2507-17c6-2b27-7f1a7e286413@os.amperecomputing.com>
Date:   Thu, 20 May 2021 21:10:21 +0700
From:   Quan Nguyen <quan@...amperecomputing.com>
To:     Ryan Chen <ryan_chen@...eedtech.com>,
        Corey Minyard <minyard@....org>,
        Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Wolfram Sang <wsa@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "openipmi-developer@...ts.sourceforge.net" 
        <openipmi-developer@...ts.sourceforge.net>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Cc:     Open Source Submission <patches@...erecomputing.com>,
        "Thang Q . Nguyen" <thang@...amperecomputing.com>,
        Phong Vo <phong@...amperecomputing.com>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()

On 20/05/2021 18:06, Ryan Chen wrote:
>> -----Original Message-----
>> From: openbmc
>> <openbmc-bounces+ryan_chen=aspeedtech.com@...ts.ozlabs.org> On Behalf
>> Of Quan Nguyen
>> Sent: Wednesday, May 19, 2021 3:50 PM
>> To: Corey Minyard <minyard@....org>; Rob Herring <robh+dt@...nel.org>;
>> Joel Stanley <joel@....id.au>; Andrew Jeffery <andrew@...id.au>; Brendan
>> Higgins <brendanhiggins@...gle.com>; Benjamin Herrenschmidt
>> <benh@...nel.crashing.org>; Wolfram Sang <wsa@...nel.org>; Philipp Zabel
>> <p.zabel@...gutronix.de>; openipmi-developer@...ts.sourceforge.net;
>> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
>> linux-aspeed@...ts.ozlabs.org; linux-kernel@...r.kernel.org;
>> linux-i2c@...r.kernel.org
>> Cc: Open Source Submission <patches@...erecomputing.com>; Thang Q .
>> Nguyen <thang@...amperecomputing.com>; Phong Vo
>> <phong@...amperecomputing.com>; openbmc@...ts.ozlabs.org
>> 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@...amperecomputing.com>
>> ---
>> 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