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 2fee61d22e606fc99ade9079fda15fdee83ec33e
Author: Christian Fetzer <fetzer...@gmail.com>
Date:   Thu Nov 19 20:13:48 2015 +0100

    i2c: piix4: Add support for multiplexed main adapter in SB800

Signed-off-by: Zoltán Böszörményi <zbos...@pr.hu>
---
 drivers/i2c/busses/i2c-piix4.c | 42 +++++++++++++-----------------------------
 1 file changed, 13 insertions(+), 29 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 0ecdb47..010daa8 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -144,10 +144,7 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
 
 /*
  * SB800 globals
- * piix4_mutex_sb800 protects piix4_port_sel_sb800 and the pair
- * of I/O ports at SB800_PIIX4_SMB_IDX.
  */
-static DEFINE_MUTEX(piix4_mutex_sb800);
 static u8 piix4_port_sel_sb800;
 static const char *piix4_main_port_names_sb800[PIIX4_MAX_ADAPTERS] = {
        " port 0", " port 2", " port 3", " port 4"
@@ -158,7 +155,6 @@ struct i2c_piix4_adapdata {
        unsigned short smba;
 
        /* SB800 */
-       bool sb800_main;
        u8 port;                /* Port number, shifted */
 };
 
@@ -264,6 +260,7 @@ static int piix4_setup(struct pci_dev *PIIX4_dev,
 static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
                             const struct pci_device_id *id, u8 aux)
 {
+       struct resource res = DEFINE_RES_IO_NAMED(SB800_PIIX4_SMB_IDX, 2, 
"i2c-piix4");
        unsigned short piix4_smba;
        u8 smba_en_lo, smba_en_hi, smb_en, smb_en_status, port_sel;
        u8 i2ccfg, i2ccfg_offset = 0x10;
@@ -286,12 +283,12 @@ 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(&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_region(SB800_PIIX4_SMB_IDX, 2);
 
        if (!smb_en) {
                smb_en_status = smba_en_lo & 0x10;
@@ -349,13 +346,14 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
        if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD) {
                piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_ALT;
        } else {
-               mutex_lock(&piix4_mutex_sb800);
+               struct resource res = DEFINE_RES_IO_NAMED(SB800_PIIX4_SMB_IDX, 
2, "i2c-piix4");
+               request_declared_muxed_region(&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) ?
                                       SB800_PIIX4_PORT_IDX_ALT :
                                       SB800_PIIX4_PORT_IDX;
-               mutex_unlock(&piix4_mutex_sb800);
+               release_region(SB800_PIIX4_SMB_IDX, 2);
        }
 
        dev_info(&PIIX4_dev->dev,
@@ -584,6 +582,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 
addr,
                 unsigned short flags, char read_write,
                 u8 command, int size, union i2c_smbus_data *data)
 {
+       struct resource res = DEFINE_RES_IO_NAMED(SB800_PIIX4_SMB_IDX, 2, 
"i2c-piix4");
        struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
        unsigned short piix4_smba = adapdata->smba;
        int retries = MAX_TIMEOUT;
@@ -592,7 +591,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 
addr,
        u8 port;
        int retval;
 
-       mutex_lock(&piix4_mutex_sb800);
+       request_declared_muxed_region(&res);
 
        /* Request the SMBUS semaphore, avoid conflicts with the IMC */
        smbslvcnt  = inb_p(SMBSLVCNT);
@@ -608,7 +607,7 @@ 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_region(SB800_PIIX4_SMB_IDX, 2);
                return -EBUSY;
        }
 
@@ -628,7 +627,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 
addr,
        /* Release the semaphore */
        outb_p(smbslvcnt | 0x20, SMBSLVCNT);
 
-       mutex_unlock(&piix4_mutex_sb800);
+       release_region(SB800_PIIX4_SMB_IDX, 2);
 
        return retval;
 }
@@ -705,7 +704,6 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned 
short smba,
        }
 
        adapdata->smba = smba;
-       adapdata->sb800_main = sb800_main;
        adapdata->port = port << 1;
 
        /* set up the sysfs linkage to our parent device */
@@ -771,29 +769,18 @@ static int piix4_probe(struct pci_dev *dev, const struct 
pci_device_id *id)
            dev->vendor == PCI_VENDOR_ID_AMD) {
                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;
-               }
-
                /* 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);
-               if (retval < 0) {
-                       release_region(SB800_PIIX4_SMB_IDX, 2);
+               if (retval < 0)
                        return retval;
-               }
        } else {
                retval = piix4_setup(dev, id);
                if (retval < 0)
@@ -841,11 +828,8 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 
        if (adapdata->smba) {
                i2c_del_adapter(adap);
-               if (adapdata->port == (0 << 1)) {
+               if (adapdata->port == (0 << 1))
                        release_region(adapdata->smba, SMBIOSIZE);
-                       if (adapdata->sb800_main)
-                               release_region(SB800_PIIX4_SMB_IDX, 2);
-               }
                kfree(adapdata);
                kfree(adap);
        }
-- 
2.9.4

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