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

[Quan Nguyen <quan@os.amperecomputing.com>]

On 25/05/2021 17:30, Ryan Chen wrote:
>> -----Original Message-----
>> From: Quan Nguyen <quan@os.amperecomputing.com>
>> Sent: Monday, May 24, 2021 6:49 PM
>> To: Ryan Chen <ryan_chen@aspeedtech.com>; Corey Minyard
>> <minyard@acm.org>; Rob Herring <robh+dt@kernel.org>; Joel Stanley
>> <joel@jms.id.au>; Andrew Jeffery <andrew@aj.id.au>; Brendan Higgins
>> <brendanhiggins@google.com>; Benjamin Herrenschmidt
>> <benh@kernel.crashing.org>; Wolfram Sang <wsa@kernel.org>; Philipp Zabel
>> <p.zabel@pengutronix.de>; openipmi-developer@lists.sourceforge.net;
>> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
>> linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org;
>> linux-i2c@vger.kernel.org
>> Cc: Open Source Submission <patches@amperecomputing.com>; Thang Q .
>> Nguyen <thang@os.amperecomputing.com>; Phong Vo
>> <phong@os.amperecomputing.com>; openbmc@lists.ozlabs.org
>> Subject: Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()
>>
>> On 24/05/2021 17:36, Ryan Chen wrote:
>>>> -----Original Message-----
>>>> From: Quan Nguyen <quan@os.amperecomputing.com>
>>>> Sent: Monday, May 24, 2021 6:20 PM
>>>> To: Ryan Chen <ryan_chen@aspeedtech.com>; Corey Minyard
>>>> <minyard@acm.org>; Rob Herring <robh+dt@kernel.org>; Joel Stanley
>>>> <joel@jms.id.au>; Andrew Jeffery <andrew@aj.id.au>; Brendan Higgins
>>>> <brendanhiggins@google.com>; Benjamin Herrenschmidt
>>>> <benh@kernel.crashing.org>; Wolfram Sang <wsa@kernel.org>; Philipp
>>>> Zabel <p.zabel@pengutronix.de>;
>>>> openipmi-developer@lists.sourceforge.net;
>>>> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
>>>> linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org;
>>>> linux-i2c@vger.kernel.org
>>>> Cc: Open Source Submission <patches@amperecomputing.com>; Thang Q .
>>>> Nguyen <thang@os.amperecomputing.com>; Phong Vo
>>>> <phong@os.amperecomputing.com>; openbmc@lists.ozlabs.org
>>>> Subject: Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()
>>>>
>>>> On 24/05/2021 17:06, Ryan Chen wrote:
>>>>>> -----Original Message-----
>>>>>> From: openbmc
>>>>>> <openbmc-bounces+ryan_chen=aspeedtech.com@lists.ozlabs.org> On
>>>> Behalf
>>>>>> Of Quan Nguyen
>>>>>> Sent: Wednesday, May 19, 2021 3:50 PM
>>>>>> To: Corey Minyard <minyard@acm.org>; Rob Herring
>>>>>> <robh+dt@kernel.org>; Joel Stanley <joel@jms.id.au>; Andrew Jeffery
>>>>>> <andrew@aj.id.au>; Brendan Higgins <brendanhiggins@google.com>;
>>>>>> Benjamin Herrenschmidt <benh@kernel.crashing.org>; Wolfram Sang
>>>>>> <wsa@kernel.org>; Philipp Zabel <p.zabel@pengutronix.de>;
>>>>>> openipmi-developer@lists.sourceforge.net;
>>>>>> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
>>>>>> linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org;
>>>>>> linux-i2c@vger.kernel.org
>>>>>> Cc: Open Source Submission <patches@amperecomputing.com>; Thang
>> Q .
>>>>>> Nguyen <thang@os.amperecomputing.com>; Phong Vo
>>>>>> <phong@os.amperecomputing.com>; openbmc@lists.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@os.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);
>>>>> Hello
>>>>> 	Where the bus->base to be remap?
>>>>>
>>>>
>>>> Hi Ryan,
>>>>
>>>> In "[PATCH v3 6/7] ipmi: ssif_bmc: Add Aspeed SSIF BMC driver", the
>>>> ->priv is retrieved by calling i2c_get_adapdata(client->adapter). And
>>>> ->in
>>>> aspeed_set_ssif_bmc_status(), call the exported
>>>> aspeed_set_slave_busy() using ->priv pointer as code below.
>>>>
>>> Yes, I see the probe function " ssif_bmc->priv =
>> i2c_get_adapdata(client->adapter);" to get priv.
>>> But my question I don’t see the bus->base address be assigned.
>>>
>> Hi Ryan,
>>
>> In drivers/i2c/busses/i2c-aspeed.c:
>> struct aspeed_i2c_bus {
>>           struct i2c_adapter              adap;
>>           struct device                   *dev;
>>           void __iomem                    *base;
>>           struct reset_control            *rst;
>>           /* Synchronizes I/O mem access to base. */
>>           spinlock_t                      lock;
>>
>> So when "struct aspeed_i2c_bus *bus = i2c_get_adapdata(adap);", the
>> bus->base should point to the base of the aspeed_i2c_bus, which is
>> already initialized by the aspeed i2c bus driver.
>>
>> Do I miss something?
> Hello Quan,
> 	After study. I think the ssif_bmc_aspeed.c assume the priv data is the same struct.
> 	That is trick.
> 	Do we have a better for slave enable/disable call back to implement this?
> 	If add call back in struct i2c_algorithm; is it workable?
>>

Hi Ryan,

I dont know which is better, ie: adding callback to struct i2c_algorithm 
or to struct i2c_adapter.
I have tried to add generic callback to struct i2c_adapter as below and 
it works.

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 4e7714c88f95..6e9abf2d6abb 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -713,6 +713,10 @@ struct i2c_adapter {
  	const struct i2c_adapter_quirks *quirks;

  	struct irq_domain *host_notify_domain;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	int (*slave_enable)(struct i2c_adapter *adap);
+	int (*slave_disable)(struct i2c_adapter *adap);
+#endif
  };
  #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)

>>>> +extern void aspeed_set_slave_busy(struct i2c_adapter *adap, bool busy);
>>>> +static void aspeed_set_ssif_bmc_status(struct ssif_bmc_ctx *ssif_bmc,
>>>> unsigned int status)
>>>> +{
>>>> +	if (status & SSIF_BMC_BUSY)
>>>> +		aspeed_set_slave_busy((struct i2c_adapter *)ssif_bmc->priv, true);
>>>> +	else if (status & SSIF_BMC_READY)
>>>> +		aspeed_set_slave_busy((struct i2c_adapter *)ssif_bmc->priv, false); }
>>>> +
>>>> +static int ssif_bmc_probe(struct i2c_client *client, const struct
>>>> i2c_device_id *id)
>>>> +{
>>>> +	struct ssif_bmc_ctx *ssif_bmc;
>>>> +
>>>> +	ssif_bmc = ssif_bmc_alloc(client, 0);
>>>> +	if (IS_ERR(ssif_bmc))
>>>> +		return PTR_ERR(ssif_bmc);
>>>> +
>>>> +	ssif_bmc->priv = i2c_get_adapdata(client->adapter);
>>>> +	ssif_bmc->set_ssif_bmc_status = aspeed_set_ssif_bmc_status;
>>>> +
>>>> +	return 0;
>>>> +}
>>>>
>>>> - Quan
>>>>
>>>>
>>>
>