Re: [PATCH 2/2] acpi: support IBM SMBus CMI devices

[Jean Delvare <khali@linux-fr.org>]

Hi Darrick,

On Fri, 23 Oct 2009 10:03:11 -0700, Darrick J. Wong wrote:
> On some old IBM workstations and desktop computers, the BIOS presents in the
> DSDT an SMBus object that is missing the HID identifier that the i2c-scmi
> driver looks for.  Modify the ACPI device scan code to insert the missing HID
> if it finds an IBM system with such an object.  This patch requires Crane Cai's
> update to i2c-scmi to work around incorrectly named methods within the SMBus
> control object.
> 
> Affected machines: IntelliStation Z20/Z30.  Note that the i2c-i801 driver no
> longer works on these machines because of ACPI resource conflicts.
> 
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> ---
> 
>  drivers/acpi/scan.c           |   38 ++++++++++++++++++++++++++++++++++++++
>  drivers/i2c/busses/i2c-scmi.c |    2 +-
>  include/acpi/acpi_drivers.h   |    2 ++
>  3 files changed, 41 insertions(+), 1 deletions(-)
> 
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 14a7481..89f8992 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -8,6 +8,7 @@
>  #include <linux/acpi.h>
>  #include <linux/signal.h>
>  #include <linux/kthread.h>
> +#include <linux/dmi.h>
>  
>  #include <acpi/acpi_drivers.h>
>  
> @@ -1014,6 +1015,41 @@ static void acpi_add_id(struct acpi_device *device, const char *dev_id)
>  	list_add_tail(&id->list, &device->pnp.ids);
>  }
>  
> +/*
> + * Old IBM workstations have a DSDT bug wherein the SMBus object
> + * lacks the SMBUS01 HID and the methods do not have the necessary "_"
> + * prefix.  Work around this.
> + */
> +static int probe_ibm_smbus_device(struct acpi_device *device)
> +{
> +	acpi_handle h_dummy;
> +	struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
> +	int result;
> +
> +	if (!dmi_name_in_vendors("IBM"))
> +		return -ENODEV;
> +
> +	/* Look for SMBS object */
> +	result = acpi_get_name(device->handle, ACPI_SINGLE_NAME, &path);
> +	if (result)
> +		return result;
> +
> +	if (strcmp("SMBS", path.pointer)) {
> +		result = -ENODEV;
> +		goto out;
> +	}
> +
> +	/* Does it have the necessary (but misnamed) methods? */
> +	result = -ENODEV;
> +	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "SBI", &h_dummy)) &&
> +	    ACPI_SUCCESS(acpi_get_handle(device->handle, "SBR", &h_dummy)) &&
> +	    ACPI_SUCCESS(acpi_get_handle(device->handle, "SBW", &h_dummy)))
> +		result = 0;
> +out:
> +	kfree(path.pointer);
> +	return result;
> +}
> +
>  static void acpi_device_set_id(struct acpi_device *device)
>  {
>  	acpi_status status;
> @@ -1064,6 +1100,8 @@ static void acpi_device_set_id(struct acpi_device *device)
>  			acpi_add_id(device, ACPI_BAY_HID);
>  		else if (ACPI_SUCCESS(acpi_dock_match(device)))
>  			acpi_add_id(device, ACPI_DOCK_HID);
> +		else if (!probe_ibm_smbus_device(device))
> +			acpi_add_id(device, ACPI_SMBUS_IBM_HID);

I am not responsible for the ACPI code, but... wouldn't it make sense
to rename probe_ibm_smbus_device() to acpi_ibm_smbus_match() and have
it follow the same convention as acpi_dock_match() and
acpi_bay_match()? To make the code more consistent.

>  
>  		break;
>  	case ACPI_BUS_TYPE_POWER:
> diff --git a/drivers/i2c/busses/i2c-scmi.c b/drivers/i2c/busses/i2c-scmi.c
> index a15aaf4..22c26c2 100644
> --- a/drivers/i2c/busses/i2c-scmi.c
> +++ b/drivers/i2c/busses/i2c-scmi.c
> @@ -51,7 +51,7 @@ static const struct smbus_methods_t ibm_smbus_methods = {
>  
>  static const struct acpi_device_id acpi_smbus_cmi_ids[] = {
>  	{"SMBUS01", (kernel_ulong_t)&smbus_methods},
> -	{"SMBUSIBM", (kernel_ulong_t)&ibm_smbus_methods},
> +	{ACPI_SMBUS_IBM_HID, (kernel_ulong_t)&ibm_smbus_methods},

As both patches depend on each other and one is useless without the
other, you might as well sequence them the other way around, so that
you touch this line only once.

>  	{"", 0}
>  };
>  
> diff --git a/include/acpi/acpi_drivers.h b/include/acpi/acpi_drivers.h
> index f4906f6..83a2960 100644
> --- a/include/acpi/acpi_drivers.h
> +++ b/include/acpi/acpi_drivers.h
> @@ -65,6 +65,8 @@
>  #define ACPI_VIDEO_HID			"LNXVIDEO"
>  #define ACPI_BAY_HID			"LNXIOBAY"
>  #define ACPI_DOCK_HID			"LNXDOCK"
> +/* Quirk for broken IBM BIOSes */
> +#define ACPI_SMBUS_IBM_HID		"SMBUSIBM"
>  
>  /*
>   * For fixed hardware buttons, we fabricate acpi_devices with HID

Other that these details, I like the patch. If this helps with ACPI
resource conflicts, even better :)

-- 
Jean Delvare