linux-kernel - Re: [PATCH 1/1] aspeed: i2c: add manual clock setup feature

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Date:   Tue, 31 May 2022 22:21:18 +0800
From:   Potin Lai <potin.lai.pt@...il.com>
To:     Patrick Williams <patrick@...cx.xyz>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Porin Lai <potin.lai@...ntatw.com>, linux-i2c@...r.kernel.org,
        openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] aspeed: i2c: add manual clock setup feature


Patrick Williams 於 31/05/2022 9:47 pm 寫道:
> On Mon, May 30, 2022 at 07:40:56PM +0800, Potin Lai wrote:
>> From: Porin Lai <potin.lai.pt@...il.com>
>>
>> Add properties for manual tuning i2c clock timing register.
>>
>> * aspeed,i2c-manual-clk: Enable aspeed i2c clock manual setup
>> * aspeed,i2c-base-clk-div: Base Clock divisor (tBaseClk)
>> * aspeed,i2c-clk-high-cycle: Cycles of clock-high pulse (tClkHigh)
>> * aspeed,i2c-clk-low-cycle: Cycles of clock-low pulse (tClkLow)
> Do we need to add these to
> Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml ?

Sorry, I wasn't notice the yaml file, I will update the documentation in next version.

Potin

>> Signed-off-by: Potin Lai <potin.lai.pt@...il.com>
>> ---
>>  drivers/i2c/busses/i2c-aspeed.c | 55 ++++++++++++++++++++++++++++++++-
>>  1 file changed, 54 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index 67e8b97c0c95..1f4b5c4b5bf4 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -898,6 +898,56 @@ static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
>>  	return 0;
>>  }
>>  
>> +/* precondition: bus.lock has been acquired. */
>> +static int aspeed_i2c_manual_clk_setup(struct aspeed_i2c_bus *bus)
>> +{
>> +	u32 divisor, clk_high, clk_low, clk_reg_val;
>> +
>> +	if (device_property_read_u32(bus->dev, "aspeed,i2c-base-clk-div",
>> +				     &divisor) != 0) {
>> +		dev_err(bus->dev, "Could not read aspeed,i2c-base-clk-div\n");
>> +		return -EINVAL;
>> +	} else if (divisor > ASPEED_I2CD_TIME_BASE_DIVISOR_MASK) {
>> +		dev_err(bus->dev, "Invalid aspeed,i2c-base-clk-div: %u\n",
>> +			divisor);
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (device_property_read_u32(bus->dev, "aspeed,i2c-clk-high-cycle",
>> +				     &clk_high) != 0) {
>> +		dev_err(bus->dev, "Could not read aspeed,i2c-clk-high-cycle\n");
>> +		return -EINVAL;
>> +	} else if (clk_high > ASPEED_I2CD_TIME_SCL_REG_MAX) {
>> +		dev_err(bus->dev, "Invalid aspeed,i2c-clk-high-cycle: %u\n",
>> +			clk_high);
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (device_property_read_u32(bus->dev, "aspeed,i2c-clk-low-cycle",
>> +				     &clk_low) != 0) {
>> +		dev_err(bus->dev, "Could not read aspeed,i2c-clk-low-cycle\n");
>> +		return -EINVAL;
>> +	} else if (clk_low > ASPEED_I2CD_TIME_SCL_REG_MAX) {
>> +		dev_err(bus->dev, "Invalid aspeed,i2c-clk-low-cycle: %u\n",
>> +			clk_low);
>> +		return -EINVAL;
>> +	}
>> +
>> +	clk_reg_val = readl(bus->base + ASPEED_I2C_AC_TIMING_REG1);
>> +	clk_reg_val &= (ASPEED_I2CD_TIME_TBUF_MASK |
>> +			ASPEED_I2CD_TIME_THDSTA_MASK |
>> +			ASPEED_I2CD_TIME_TACST_MASK);
>> +	clk_reg_val |= (divisor & ASPEED_I2CD_TIME_BASE_DIVISOR_MASK)
>> +			| ((clk_high << ASPEED_I2CD_TIME_SCL_HIGH_SHIFT)
>> +			   & ASPEED_I2CD_TIME_SCL_HIGH_MASK)
>> +			| ((clk_low << ASPEED_I2CD_TIME_SCL_LOW_SHIFT)
>> +			   & ASPEED_I2CD_TIME_SCL_LOW_MASK);
>> +	writel(clk_reg_val, bus->base + ASPEED_I2C_AC_TIMING_REG1);
>> +	writel(ASPEED_NO_TIMEOUT_CTRL, bus->base + ASPEED_I2C_AC_TIMING_REG2);
>> +
>> +	return 0;
>> +}
>> +
>>  /* precondition: bus.lock has been acquired. */
>>  static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
>>  			     struct platform_device *pdev)
>> @@ -908,7 +958,10 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
>>  	/* Disable everything. */
>>  	writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
>>  
>> -	ret = aspeed_i2c_init_clk(bus);
>> +	if (of_property_read_bool(pdev->dev.of_node, "aspeed,i2c-manual-clk"))
>> +		ret = aspeed_i2c_manual_clk_setup(bus);
>> +	else
>> +		ret = aspeed_i2c_init_clk(bus);
>>  	if (ret < 0)
>>  		return ret;
>>  
>> -- 
>> 2.17.1
>>