linux-kernel - Re: [PATCH v7 5/9] misc: smpro-misc: Add Ampere's Altra SMpro misc driver

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Date:   Mon, 21 Mar 2022 16:46:50 +0700
From:   Quan Nguyen <quan@...amperecomputing.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>,
        Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Arnd Bergmann <arnd@...db.de>,
        Thu Nguyen <thu@...amperecomputing.com>,
        Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "open list:HARDWARE MONITORING" <linux-hwmon@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Open Source Submission <patches@...erecomputing.com>,
        Phong Vo <phong@...amperecomputing.com>,
        "Thang Q . Nguyen" <thang@...amperecomputing.com>
Subject: Re: [PATCH v7 5/9] misc: smpro-misc: Add Ampere's Altra SMpro misc
 driver



On 21/03/2022 15:21, Greg Kroah-Hartman wrote:
> On Mon, Mar 21, 2022 at 03:13:51PM +0700, Quan Nguyen wrote:
>> This commit adds driver support for accessing various information
>> reported by Ampere's SMpro co-processor such as Boot Progress and
>> other miscellaneous data.
>>
>> Signed-off-by: Quan Nguyen <quan@...amperecomputing.com>
> 
> No Documentation/ABI/ entries for your sysfs file?
> 

Thank you, Greg, for a very quick review.
I have put this file in other patch.

>> +static ssize_t boot_progress_show(struct device *dev, struct device_attribute *da, char *buf)
>> +{
>> +	struct smpro_misc *misc = dev_get_drvdata(dev);
>> +	u32 boot_progress;
>> +	u8 current_stage;
>> +	u8 boot_status;
>> +	u8 boot_stage;
>> +	u32 select;
>> +	u32 reg_lo;
>> +	u32 reg;
>> +	int ret;
>> +
>> +	/* Read current boot stage */
>> +	ret = regmap_read(misc->regmap, BOOTSTAGE_CUR_STAGE, &reg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	current_stage = reg & 0xff;
>> +
>> +	/* Read the boot progress */
>> +	ret = regmap_read(misc->regmap, BOOTSTAGE_SELECT, &select);
>> +	if (ret)
>> +		return ret;
>> +
>> +	boot_stage = (select >> 8) & 0xff;
>> +	boot_status = select & 0xff;
>> +
>> +	if (boot_stage > current_stage)
>> +		return -EINVAL;
>> +
>> +	ret = regmap_read(misc->regmap,	BOOTSTAGE_STATUS_LO, &reg_lo);
>> +	if (!ret)
>> +		ret = regmap_read(misc->regmap, BOOTSTAGE_STATUS_HI, &reg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	boot_progress = swab16(reg) << 16 | swab16(reg_lo);
>> +
>> +	/* Tell firmware to provide next boot stage next time */
>> +	if (boot_stage < current_stage) {
>> +		ret = regmap_write(misc->regmap, BOOTSTAGE_SELECT, ((select & 0xff00) | 0x1));
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	return snprintf(buf, PAGE_SIZE, "0x%02x 0x%02x 0x%08x\n",
>> +			boot_stage, boot_status, boot_progress);
> 
> sysfs_emit() please.
> 
Thanks, Greg.

Will switch to sysfs_emit() in my next version.

> Also, this is 3 different things, put all of these in different sysfs
> files.
> 
> thanks,
> 
> greg k-h

Actually, no. It is single value of boot stage.

Let me explain:
The boot progress consists of three things together: boot_stage, 
boot_status and boot_progress and they have no meaning if reported them 
as three separate values:
+ boot_stage is to indicate the boot stage
+ boot_status is to report the result of that boot_stage: started, 
complete or error.
+ boot_progress is to report more extra information for the stage other 
than the boot_stage/boot_status.

There is more information in the Documentation/ABI/testing sysfs patch.

- Quan