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i2c: i801: Allow ACPI SystemIO OpRegion to conflict with PCI BAR
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Many Intel systems the BIOS declares a SystemIO OpRegion below the SMBus
PCI device as can be seen in ACPI DSDT table from Lenovo Yoga 900:

  Device (SBUS)
  {
      OperationRegion (SMBI, SystemIO, (SBAR << 0x05), 0x10)
      Field (SMBI, ByteAcc, NoLock, Preserve)
      {
          HSTS,   8,
          Offset (0x02),
          HCON,   8,
          HCOM,   8,
          TXSA,   8,
          DAT0,   8,
          DAT1,   8,
          HBDR,   8,
          PECR,   8,
          RXSA,   8,
          SDAT,   16
      }

There are also bunch of AML methods that that the BIOS can use to access
these fields. Most of the systems in question AML methods accessing the
SMBI OpRegion are never used.

Now, because of this SMBI OpRegion many systems fail to load the SMBus
driver with an error looking like one below:

  ACPI Warning: SystemIO range 0x0000000000003040-0x000000000000305F
       conflicts with OpRegion 0x0000000000003040-0x000000000000304F
       (\_SB.PCI0.SBUS.SMBI) (20160108/utaddress-255)
  ACPI: If an ACPI driver is available for this device, you should use
       it instead of the native driver

The reason is that this SMBI OpRegion conflicts with the PCI BAR used by
the SMBus driver.

It turns out that we can install a custom SystemIO address space handler
for the SMBus device to intercept all accesses through that OpRegion. This
allows us to share the PCI BAR with the AML code if it for some reason is
using it. We do not expect that this OpRegion handler will ever be called
but if it is we print a warning and prevent all access from the SMBus
driver itself.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=110041
Reported-by: Andy Lutomirski <luto@kernel.org>
Reported-by: Pali Rohár <pali.rohar@gmail.com>
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@vger.kernel.org
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@westeri
westeri authored and Wolfram Sang committed Jun 9, 2016
1 parent af8c34c commit a7ae819
Showing 1 changed file with 96 additions and 3 deletions.
99 changes: 96 additions & 3 deletions drivers/i2c/busses/i2c-i801.c
View file
Expand Up @@ -245,6 +245,13 @@ struct i801_priv {
struct platform_device *mux_pdev;
#endif
struct platform_device *tco_pdev;

/*
* If set to true the host controller registers are reserved for
* ACPI AML use. Protected by acpi_lock.
*/
bool acpi_reserved;
struct mutex acpi_lock;
};

#define FEATURE_SMBUS_PEC (1 << 0)
Expand Down Expand Up @@ -718,6 +725,12 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
int ret = 0, xact = 0;
struct i801_priv *priv = i2c_get_adapdata(adap);

mutex_lock(&priv->acpi_lock);
if (priv->acpi_reserved) {
mutex_unlock(&priv->acpi_lock);
return -EBUSY;
}

pm_runtime_get_sync(&priv->pci_dev->dev);

hwpec = (priv->features & FEATURE_SMBUS_PEC) && (flags & I2C_CLIENT_PEC)
Expand Down Expand Up @@ -820,6 +833,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
out:
pm_runtime_mark_last_busy(&priv->pci_dev->dev);
pm_runtime_put_autosuspend(&priv->pci_dev->dev);
mutex_unlock(&priv->acpi_lock);
return ret;
}

Expand Down Expand Up @@ -1257,6 +1271,83 @@ static void i801_add_tco(struct i801_priv *priv)
priv->tco_pdev = pdev;
}

#ifdef CONFIG_ACPI
static acpi_status
i801_acpi_io_handler(u32 function, acpi_physical_address address, u32 bits,
u64 *value, void *handler_context, void *region_context)
{
struct i801_priv *priv = handler_context;
struct pci_dev *pdev = priv->pci_dev;
acpi_status status;

/*
* Once BIOS AML code touches the OpRegion we warn and inhibit any
* further access from the driver itself. This device is now owned
* by the system firmware.
*/
mutex_lock(&priv->acpi_lock);

if (!priv->acpi_reserved) {
priv->acpi_reserved = true;

dev_warn(&pdev->dev, "BIOS is accessing SMBus registers\n");
dev_warn(&pdev->dev, "Driver SMBus register access inhibited\n");

/*
* BIOS is accessing the host controller so prevent it from
* suspending automatically from now on.
*/
pm_runtime_get_sync(&pdev->dev);
}

if ((function & ACPI_IO_MASK) == ACPI_READ)
status = acpi_os_read_port(address, (u32 *)value, bits);
else
status = acpi_os_write_port(address, (u32)*value, bits);

mutex_unlock(&priv->acpi_lock);

return status;
}

static int i801_acpi_probe(struct i801_priv *priv)
{
struct acpi_device *adev;
acpi_status status;

adev = ACPI_COMPANION(&priv->pci_dev->dev);
if (adev) {
status = acpi_install_address_space_handler(adev->handle,
ACPI_ADR_SPACE_SYSTEM_IO, i801_acpi_io_handler,
NULL, priv);
if (ACPI_SUCCESS(status))
return 0;
}

return acpi_check_resource_conflict(&priv->pci_dev->resource[SMBBAR]);
}

static void i801_acpi_remove(struct i801_priv *priv)
{
struct acpi_device *adev;

adev = ACPI_COMPANION(&priv->pci_dev->dev);
if (!adev)
return;

acpi_remove_address_space_handler(adev->handle,
ACPI_ADR_SPACE_SYSTEM_IO, i801_acpi_io_handler);

mutex_lock(&priv->acpi_lock);
if (priv->acpi_reserved)
pm_runtime_put(&priv->pci_dev->dev);
mutex_unlock(&priv->acpi_lock);
}
#else
static inline int i801_acpi_probe(struct i801_priv *priv) { return 0; }
static inline void i801_acpi_remove(struct i801_priv *priv) { }
#endif

static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
unsigned char temp;
Expand All @@ -1274,6 +1365,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
priv->adapter.dev.parent = &dev->dev;
ACPI_COMPANION_SET(&priv->adapter.dev, ACPI_COMPANION(&dev->dev));
priv->adapter.retries = 3;
mutex_init(&priv->acpi_lock);

priv->pci_dev = dev;
switch (dev->device) {
Expand Down Expand Up @@ -1336,10 +1428,8 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
return -ENODEV;
}

err = acpi_check_resource_conflict(&dev->resource[SMBBAR]);
if (err) {
if (i801_acpi_probe(priv))
return -ENODEV;
}

err = pcim_iomap_regions(dev, 1 << SMBBAR,
dev_driver_string(&dev->dev));
Expand All @@ -1348,6 +1438,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
"Failed to request SMBus region 0x%lx-0x%Lx\n",
priv->smba,
(unsigned long long)pci_resource_end(dev, SMBBAR));
i801_acpi_remove(priv);
return err;
}

Expand Down Expand Up @@ -1412,6 +1503,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
err = i2c_add_adapter(&priv->adapter);
if (err) {
dev_err(&dev->dev, "Failed to add SMBus adapter\n");
i801_acpi_remove(priv);
return err;
}

Expand All @@ -1438,6 +1530,7 @@ static void i801_remove(struct pci_dev *dev)

i801_del_mux(priv);
i2c_del_adapter(&priv->adapter);
i801_acpi_remove(priv);
pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);

platform_device_unregister(priv->tco_pdev);
Expand Down

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