hwmon: (it87) request only Environment Controller ports

The IT8705F and related parts are Super I/O controllers that contain
many separate devices.

Some BIOSes describe IT8705F I/O port usage under a motherboard device
(PNP0C02) with overlapping regions, e.g., 0x290-0x29f and 0x290-0x294.

The it87 driver supports only the Environment Controller, which requires
only two ISA ports, but it used to request an eight-port range.  If that
range exceeds a range reported by the BIOS, as 0x290-0x297 would, the
request fails, and the it87 driver cannot claim the device.

This patch makes the it87 driver request only the two ports used for the
Environment Controller device.

Systems where this problem has been reported:
    Gigabyte GA-K8N Ultra 9
    Gigabyte M56S-S3
    Gigabyte GA-965G-DS3

Kernel bug reports:
    http://bugzilla.kernel.org/show_bug.cgi?id=9514
    http://lkml.org/lkml/2007/12/4/466

Related change:
    http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=a7839e960675b549f06209d18283d5cee2ce9261

    The patch above increases the number of PNP port resources we support.
    Prior to this patch, we ignored some port resources, which masked the
    it87 problem.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>

1 files changed, 23 insertions, 9 deletions

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 6a182e14cf58..ad6c8a319903 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -2,6 +2,14 @@
     it87.c - Part of lm_sensors, Linux kernel modules for hardware
              monitoring.
 
+    The IT8705F is an LPC-based Super I/O part that contains UARTs, a
+    parallel port, an IR port, a MIDI port, a floppy controller, etc., in
+    addition to an Environment Controller (Enhanced Hardware Monitor and
+    Fan Controller)
+
+    This driver supports only the Environment Controller in the IT8705F and
+    similar parts.  The other devices are supported by different drivers.
+
     Supports: IT8705F  Super I/O chip w/LPC interface
               IT8712F  Super I/O chip w/LPC interface
               IT8716F  Super I/O chip w/LPC interface
@@ -118,9 +126,15 @@ static int fix_pwm_polarity;
 /* Length of ISA address segment */
 #define IT87_EXTENT 8
 
-/* Where are the ISA address/data registers relative to the base address */
-#define IT87_ADDR_REG_OFFSET 5
-#define IT87_DATA_REG_OFFSET 6
+/* Length of ISA address segment for Environmental Controller */
+#define IT87_EC_EXTENT 2
+
+/* Offset of EC registers from ISA base address */
+#define IT87_EC_OFFSET 5
+
+/* Where are the ISA address/data registers relative to the EC base address */
+#define IT87_ADDR_REG_OFFSET 0
+#define IT87_DATA_REG_OFFSET 1
 
 /*----- The IT87 registers -----*/
 
@@ -968,10 +982,10 @@ static int __devinit it87_probe(struct platform_device *pdev)
         };
 
         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
-        if (!request_region(res->start, IT87_EXTENT, DRVNAME)) {
+        if (!request_region(res->start, IT87_EC_EXTENT, DRVNAME)) {
                 dev_err(dev, "Failed to request region 0x%lx-0x%lx\n",
                         (unsigned long)res->start,
-                        (unsigned long)(res->start + IT87_EXTENT - 1));
+                        (unsigned long)(res->start + IT87_EC_EXTENT - 1));
                 err = -EBUSY;
                 goto ERROR0;
         }
@@ -1124,7 +1138,7 @@ ERROR2:
         platform_set_drvdata(pdev, NULL);
         kfree(data);
 ERROR1:
-        release_region(res->start, IT87_EXTENT);
+        release_region(res->start, IT87_EC_EXTENT);
 ERROR0:
         return err;
 }
@@ -1137,7 +1151,7 @@ static int __devexit it87_remove(struct platform_device *pdev)
         sysfs_remove_group(&pdev->dev.kobj, &it87_group);
         sysfs_remove_group(&pdev->dev.kobj, &it87_group_opt);
 
-        release_region(data->addr, IT87_EXTENT);
+        release_region(data->addr, IT87_EC_EXTENT);
         platform_set_drvdata(pdev, NULL);
         kfree(data);
 
@@ -1402,8 +1416,8 @@ static int __init it87_device_add(unsigned short address,
                                   const struct it87_sio_data *sio_data)
 {
         struct resource res = {
-                .start  = address ,
-                .end    = address + IT87_EXTENT - 1,
+                .start  = address + IT87_EC_OFFSET,
+                .end    = address + IT87_EC_OFFSET + IT87_EC_EXTENT - 1,
                 .name   = DRVNAME,
                 .flags  = IORESOURCE_IO,
         };