linux-kernel - Re: [PATCH v4 3/9] i2c: piix4: Move port I/O region request/release code into functions

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Date:   Tue, 8 Feb 2022 15:45:24 +0100
From:   Jean Delvare <jdelvare@...e.de>
To:     Terry Bowman <terry.bowman@....com>
Cc:     <linux@...ck-us.net>, <linux-watchdog@...r.kernel.org>,
        <jdelvare@...e.com>, <linux-i2c@...r.kernel.org>, <wsa@...nel.org>,
        <andy.shevchenko@...il.com>, <rafael.j.wysocki@...el.com>,
        <linux-kernel@...r.kernel.org>, <wim@...ux-watchdog.org>,
        <rrichter@....com>, <thomas.lendacky@....com>,
        <sudheesh.mavila@....com>, <Nehal-bakulchandra.Shah@....com>,
        <Basavaraj.Natikar@....com>, <Shyam-sundar.S-k@....com>,
        <Mario.Limonciello@....com>
Subject: Re: [PATCH v4 3/9] i2c: piix4: Move port I/O region request/release
 code into functions

Hi Terry,

On Sun, 30 Jan 2022 12:41:24 -0600, Terry Bowman wrote:
> Move duplicated region request and release code into a function. Move is
> in preparation for following MMIO changes.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> ---
>  drivers/i2c/busses/i2c-piix4.c | 39 +++++++++++++++++++++++-----------
>  1 file changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 3ff68967034e..5a98970ac60a 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -165,6 +165,24 @@ struct i2c_piix4_adapdata {
>  	u8 port;		/* Port number, shifted */
>  };
>  
> +static int piix4_sb800_region_request(struct device *dev)
> +{
> +	if (!request_muxed_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE,
> +				  "sb800_piix4_smb")) {
> +		dev_err(dev,
> +			"SMBus base address index region 0x%x already in use.\n",
> +			SB800_PIIX4_SMB_IDX);
> +		return -EBUSY;
> +	}
> +
> +	return 0;
> +}
> +
> +static void piix4_sb800_region_release(struct device *dev)
> +{
> +	release_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE);
> +}
> +
>  static int piix4_setup(struct pci_dev *PIIX4_dev,
>  		       const struct pci_device_id *id)
>  {
> @@ -270,6 +288,7 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>  	unsigned short piix4_smba;
>  	u8 smba_en_lo, smba_en_hi, smb_en, smb_en_status, port_sel;
>  	u8 i2ccfg, i2ccfg_offset = 0x10;
> +	int retval;
>  
>  	/* SB800 and later SMBus does not support forcing address */
>  	if (force || force_addr) {
> @@ -291,20 +310,16 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>  	else
>  		smb_en = (aux) ? 0x28 : 0x2c;
>  
> -	if (!request_muxed_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE,
> -				  "sb800_piix4_smb")) {
> -		dev_err(&PIIX4_dev->dev,
> -			"SMB base address index region 0x%x already in use.\n",
> -			SB800_PIIX4_SMB_IDX);
> -		return -EBUSY;
> -	}
> +	retval = piix4_sb800_region_request(&PIIX4_dev->dev);
> +	if (retval)
> +		return retval;
>  
>  	outb_p(smb_en, SB800_PIIX4_SMB_IDX);
>  	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
>  	outb_p(smb_en + 1, SB800_PIIX4_SMB_IDX);
>  	smba_en_hi = inb_p(SB800_PIIX4_SMB_IDX + 1);
>  
> -	release_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE);
> +	piix4_sb800_region_release(&PIIX4_dev->dev);
>  
>  	if (!smb_en) {
>  		smb_en_status = smba_en_lo & 0x10;
> @@ -685,9 +700,9 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>  	u8 port;
>  	int retval;
>  
> -	if (!request_muxed_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE,
> -				  "sb800_piix4_smb"))
> -		return -EBUSY;
> +	retval = piix4_sb800_region_request(&adap->dev);
> +	if (retval)
> +		return retval;
>  
>  	/* Request the SMBUS semaphore, avoid conflicts with the IMC */
>  	smbslvcnt  = inb_p(SMBSLVCNT);
> @@ -762,7 +777,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>  		piix4_imc_wakeup();
>  
>  release:
> -	release_region(SB800_PIIX4_SMB_IDX, SB800_PIIX4_SMB_MAP_SIZE);
> +	piix4_sb800_region_release(&adap->dev);
>  	return retval;
>  }
>  

There's a third occurrence of request_muxed_region(SB800_PIIX4_SMB_IDX,
...) / release_region(SB800_PIIX4_SMB_IDX, ...) in function
piix4_setup_sb800. Any reason why you don't make use of the new helper
functions there as well?

OK, I see that this part of the code is specific to the original (ATI)
SB800, so it can't use MMIO, therefore you don't *have* to call the
helper functions. But for consistency, wouldn't it still make sense to
use them?

-- 
Jean Delvare
SUSE L3 Support