i2c: piix4: Fix SB800 locking

We need a single mutex for all 4 shared SMBus ports on the SB800. A
per-port mutex doesn't protect us from concurrent access.

In theory the mutex should be per PCI device, however in practice we
know that there's only ever a single instance of the device in a given
system so we can use a global.

Also take the mutex during initialization, as first port may be already
in use when second port is initialized.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Tested-by: Christian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: made mutex static]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index e045985950737c429c3c3253620559f55be1244e..5fd7505b90182be067623e12a5cfb7ae18e7f734 100644 (file)
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -137,6 +137,7 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
 };
 
 /* SB800 globals */
+static DEFINE_MUTEX(piix4_mutex_sb800);
 static const char *piix4_main_port_names_sb800[PIIX4_MAX_ADAPTERS] = {
        "SDA0", "SDA2", "SDA3", "SDA4"
 };
@@ -148,7 +149,6 @@ struct i2c_piix4_adapdata {
        /* SB800 */
        bool sb800_main;
        unsigned short port;
-       struct mutex *mutex;
 };
 
 static int piix4_setup(struct pci_dev *PIIX4_dev,
@@ -275,10 +275,12 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
        else
                smb_en = (aux) ? 0x28 : 0x2c;
 
+       mutex_lock(&piix4_mutex_sb800);
        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);
 
        if (!smb_en) {
                smb_en_status = smba_en_lo & 0x10;
@@ -559,7 +561,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
        u8 port;
        int retval;
 
-       mutex_lock(adapdata->mutex);
+       mutex_lock(&piix4_mutex_sb800);
 
        outb_p(SB800_PIIX4_PORT_IDX, SB800_PIIX4_SMB_IDX);
        smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
@@ -574,7 +576,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
 
        outb_p(smba_en_lo, SB800_PIIX4_SMB_IDX + 1);
 
-       mutex_unlock(adapdata->mutex);
+       mutex_unlock(&piix4_mutex_sb800);
 
        return retval;
 }
@@ -673,17 +675,10 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
 
 static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
 {
-       struct mutex *mutex;
        struct i2c_piix4_adapdata *adapdata;
        int port;
        int retval;
 
-       mutex = kzalloc(sizeof(*mutex), GFP_KERNEL);
-       if (mutex == NULL)
-               return -ENOMEM;
-
-       mutex_init(mutex);
-
        for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
                retval = piix4_add_adapter(dev, smba,
                                           piix4_main_port_names_sb800[port],
@@ -696,7 +691,6 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
                adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
                adapdata->sb800_main = true;
                adapdata->port = port;
-               adapdata->mutex = mutex;
        }
 
        return retval;
@@ -714,8 +708,6 @@ error:
                }
        }
 
-       kfree(mutex);
-
        return retval;
 }
 
@@ -798,10 +790,8 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
                i2c_del_adapter(adap);
                if (adapdata->port == 0) {
                        release_region(adapdata->smba, SMBIOSIZE);
-                       if (adapdata->sb800_main) {
-                               kfree(adapdata->mutex);
+                       if (adapdata->sb800_main)
                                release_region(SB800_PIIX4_SMB_IDX, 2);
-                       }
                }
                kfree(adapdata);
                kfree(adap);