On 12/18/2017 12:48 AM, Zoltan Boszormenyi wrote:
From: Böszörményi Zoltán <zbos...@pr.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 <zbos...@pr.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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