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Date:   Tue, 19 Dec 2017 18:15:10 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Zoltan Boszormenyi <zboszor@...hu>, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-i2c@...r.kernel.org
Cc:     Paul Menzel <paulepanter@...rs.sourceforge.net>,
        Christian Fetzer <fetzer.ch@...il.com>,
        Jean Delvare <jdelvare@...e.com>,
        Nehal Shah <nehal-bakulchandra.shah@....com>,
        Tim Small <tim@...ss.co.uk>, kernel@...ss.net, wim@...ana.be,
        jlayton@...chiereds.net, marc.2377@...il.com,
        cshorler@...glemail.com, wsa@...-dreams.de,
        regressions@...mhuis.info,
        Alex Williamson <alex.williamson@...hat.com>, lyude@...hat.com,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Toshi Kani <toshi.kani@....com>,
        Jiang Liu <jiang.liu@...ux.intel.com>,
        Jakub Sitnicki <jsitnicki@...il.com>,
        Thierry Reding <treding@...dia.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Simon Guinot <simon.guinot@...uanux.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Mike Travis <travis@....com>,
        Daeseok Youn <daeseok.youn@...il.com>,
        Huang Rui <ray.huang@....com>, Andiry Xu <andiry.xu@....com>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        David Howells <dhowells@...hat.com>,
        Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
        Alexandre Desnoyers <alex@...c.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wan ZongShun <Vincent.Wan@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Lucas Stach <dev@...xeye.de>,
        Denis Turischev <denis.turischev@...pulab.co.il>
Subject: Re: [PATCH 4/5 v5] i2c: i2c-piix4: Use
 request_declared_muxed_region()

On 12/18/2017 12:48 AM, Zoltan Boszormenyi wrote:
> From: Böszörményi Zoltán <zboszor@...hu>
> 
> Use the new request_declared_muxed_region() macro to
> synchronize access to the I/O port pair 0xcd6 / 0xcd7.
> 
> At the same time, remove the long lifetime request_region()
> call to reserve these I/O ports, so the sp5100_tco watchdog
> driver can also load.
> 
> This fixes an old regression in Linux 4.4-rc4, caused by
> commit 2fee61d22e60 ("i2c: piix4: Add support for multiplexed
> main adapter in SB800")
> 
> v1: Started with a common mutex in a C source file.
> 
> v2: Referenced to common mutex from drivers/usb/host/pci-quirks.c
> 
> v3: Switched to using the new request_declared_muxed_region
>      macro.
> 
> v4: Fixed checkpatch.pl warnings and use the new
>      release_declared_region() macro.
> 
> v5: Rebased for 4.15-rc4
>      Use struct i2c_algorithm pointer directly instead of
>      a bool to select the proper algo.

This change makes sense, but it should be a separate patch.

Guenter

> 
> Signed-off-by: Zoltán Böszörményi <zboszor@...hu>
> ---
>   drivers/i2c/busses/i2c-piix4.c | 51 +++++++++++++++---------------------------
>   1 file changed, 18 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 462948e2c535..1846d9ea7d27 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -153,10 +153,11 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
>   
>   /*
>    * SB800 globals
> - * piix4_mutex_sb800 protects piix4_port_sel_sb800 and the pair
> + * request_declared_muxed_region() protects piix4_port_sel_sb800 and the pair
>    * of I/O ports at SB800_PIIX4_SMB_IDX.
>    */
> -static DEFINE_MUTEX(piix4_mutex_sb800);
> +static struct resource sb800_res = DEFINE_RES_IO_NAMED(SB800_PIIX4_SMB_IDX, 2,
> +						 "i2c-piix4");
>   static u8 piix4_port_sel_sb800;
>   static u8 piix4_port_mask_sb800;
>   static u8 piix4_port_shift_sb800;
> @@ -169,7 +170,6 @@ struct i2c_piix4_adapdata {
>   	unsigned short smba;
>   
>   	/* SB800 */
> -	bool sb800_main;
>   	bool notify_imc;
>   	u8 port;		/* Port number, shifted */
>   };
> @@ -298,12 +298,12 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>   	else
>   		smb_en = (aux) ? 0x28 : 0x2c;
>   
> -	mutex_lock(&piix4_mutex_sb800);
> +	request_declared_muxed_region(&sb800_res);
>   	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);
> -	mutex_unlock(&piix4_mutex_sb800);
> +	release_declared_region(&sb800_res);
>   
>   	if (!smb_en) {
>   		smb_en_status = smba_en_lo & 0x10;
> @@ -373,7 +373,7 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>   			break;
>   		}
>   	} else {
> -		mutex_lock(&piix4_mutex_sb800);
> +		request_declared_muxed_region(&sb800_res);
>   		outb_p(SB800_PIIX4_PORT_IDX_SEL, SB800_PIIX4_SMB_IDX);
>   		port_sel = inb_p(SB800_PIIX4_SMB_IDX + 1);
>   		piix4_port_sel_sb800 = (port_sel & 0x01) ?
> @@ -381,7 +381,7 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>   				       SB800_PIIX4_PORT_IDX;
>   		piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK;
>   		piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT;
> -		mutex_unlock(&piix4_mutex_sb800);
> +		release_declared_region(&sb800_res);
>   	}
>   
>   	dev_info(&PIIX4_dev->dev,
> @@ -679,7 +679,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>   	u8 port;
>   	int retval;
>   
> -	mutex_lock(&piix4_mutex_sb800);
> +	request_declared_muxed_region(&sb800_res);
>   
>   	/* Request the SMBUS semaphore, avoid conflicts with the IMC */
>   	smbslvcnt  = inb_p(SMBSLVCNT);
> @@ -695,7 +695,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>   	} while (--retries);
>   	/* SMBus is still owned by the IMC, we give up */
>   	if (!retries) {
> -		mutex_unlock(&piix4_mutex_sb800);
> +		release_declared_region(&sb800_res);
>   		return -EBUSY;
>   	}
>   
> @@ -753,7 +753,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>   	if ((size == I2C_SMBUS_BLOCK_DATA) && adapdata->notify_imc)
>   		piix4_imc_wakeup();
>   
> -	mutex_unlock(&piix4_mutex_sb800);
> +	release_declared_region(&sb800_res);
>   
>   	return retval;
>   }
> @@ -804,7 +804,8 @@ static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
>   static struct i2c_adapter *piix4_aux_adapter;
>   
>   static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
> -			     bool sb800_main, u8 port, bool notify_imc,
> +			     struct i2c_algorithm *algo,
> +			     u8 port, bool notify_imc,
>   			     const char *name, struct i2c_adapter **padap)
>   {
>   	struct i2c_adapter *adap;
> @@ -819,8 +820,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
>   
>   	adap->owner = THIS_MODULE;
>   	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
> -	adap->algo = sb800_main ? &piix4_smbus_algorithm_sb800
> -				: &smbus_algorithm;
> +	adap->algo = algo;
>   
>   	adapdata = kzalloc(sizeof(*adapdata), GFP_KERNEL);
>   	if (adapdata == NULL) {
> @@ -830,7 +830,6 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
>   	}
>   
>   	adapdata->smba = smba;
> -	adapdata->sb800_main = sb800_main;
>   	adapdata->port = port << piix4_port_shift_sb800;
>   	adapdata->notify_imc = notify_imc;
>   
> @@ -862,7 +861,9 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
>   	int retval;
>   
>   	for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> -		retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
> +		retval = piix4_add_adapter(dev, smba,
> +					   &piix4_smbus_algorithm_sb800,
> +					   port, notify_imc,
>   					   piix4_main_port_names_sb800[port],
>   					   &piix4_main_adapters[port]);
>   		if (retval < 0)
> @@ -899,13 +900,6 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
>   		bool notify_imc = false;
>   		is_sb800 = true;
>   
> -		if (!request_region(SB800_PIIX4_SMB_IDX, 2, "smba_idx")) {
> -			dev_err(&dev->dev,
> -			"SMBus base address index region 0x%x already in use!\n",
> -			SB800_PIIX4_SMB_IDX);
> -			return -EBUSY;
> -		}
> -
>   		if (dev->vendor == PCI_VENDOR_ID_AMD &&
>   		    dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
>   			u8 imc;
> @@ -922,27 +916,24 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
>   
>   		/* base address location etc changed in SB800 */
>   		retval = piix4_setup_sb800(dev, id, 0);
> -		if (retval < 0) {
> -			release_region(SB800_PIIX4_SMB_IDX, 2);
> +		if (retval < 0)
>   			return retval;
> -		}
>   
>   		/*
>   		 * Try to register multiplexed main SMBus adapter,
>   		 * give up if we can't
>   		 */
>   		retval = piix4_add_adapters_sb800(dev, retval, notify_imc);
> -		if (retval < 0) {
> -			release_region(SB800_PIIX4_SMB_IDX, 2);
> +		if (retval < 0)
>   			return retval;
> -		}
>   	} else {
>   		retval = piix4_setup(dev, id);
>   		if (retval < 0)
>   			return retval;
>   
>   		/* Try to register main SMBus adapter, give up if we can't */
> -		retval = piix4_add_adapter(dev, retval, false, 0, false, "",
> +		retval = piix4_add_adapter(dev, retval,
> +					   &smbus_algorithm, 0, false, "",
>   					   &piix4_main_adapters[0]);
>   		if (retval < 0)
>   			return retval;
> @@ -983,11 +974,8 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
>   
>   	if (adapdata->smba) {
>   		i2c_del_adapter(adap);
> -		if (adapdata->port == (0 << piix4_port_shift_sb800)) {
> +		if (adapdata->port == (0 << piix4_port_shift_sb800))
>   			release_region(adapdata->smba, SMBIOSIZE);
> -			if (adapdata->sb800_main)
> -				release_region(SB800_PIIX4_SMB_IDX, 2);
> -		}
>   		kfree(adapdata);
>   		kfree(adap);
>   	}
> 

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