hwmon: (k8temp) Warn about fam F rev F errata

Add warning about wrong CPU temperature readouts on all fam F rev F.

The allowed combinations of processors ensure that all processors
in a multisocket system have similar characteristics, e.g.

(1) provide temperature sensor interface (>=RevC && <RevF)
(2) are affected by erratum #141 (>=RevF)

Thus it is sufficient to check the revision of the boot CPU.

For "mixed silicon support" refer to
"Revision Guide for AMD Athlon 64 and AMD Opteron Processors" (RevA-E) and
"Revision Guide for AMD NPT Family 0Fh Processors" (RefF-G).

Cc: Rudolf Marek <r.marek@assembler.cz>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 22 insertions, 7 deletions

diff --git a/drivers/hwmon/k8temp.c b/drivers/hwmon/k8temp.c
index bd2bde0ef95e..ca56f2e26fd1 100644
--- a/drivers/hwmon/k8temp.c
+++ b/drivers/hwmon/k8temp.c
@@ -31,6 +31,7 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <asm/processor.h>
 
 #define TEMP_FROM_REG(val)      (((((val) >> 16) & 0xff) - 49) * 1000)
 #define REG_TEMP        0xe4
@@ -141,20 +142,34 @@ static int __devinit k8temp_probe(struct pci_dev *pdev,
         int err;
         u8 scfg;
         u32 temp;
+        u8 model, stepping;
         struct k8temp_data *data;
-        u32 cpuid = cpuid_eax(1);
-
-        /* this feature should be available since SH-C0 core */
-        if ((cpuid == 0xf40) || (cpuid == 0xf50) || (cpuid == 0xf51)) {
-                err = -ENODEV;
-                goto exit;
-        }
 
         if (!(data = kzalloc(sizeof(struct k8temp_data), GFP_KERNEL))) {
                 err = -ENOMEM;
                 goto exit;
         }
 
+        model = boot_cpu_data.x86_model;
+        stepping = boot_cpu_data.x86_mask;
+
+        switch (boot_cpu_data.x86) {
+        case 0xf:
+                /* feature available since SH-C0, exclude older revisions */
+                if (((model == 4) && (stepping == 0)) ||
+                    ((model == 5) && (stepping <= 1))) {
+                        err = -ENODEV;
+                        goto exit_free;
+                }
+
+                if (model >= 0x40) {
+                        dev_warn(&pdev->dev, "Temperature readouts might be "
+                                 "wrong - check erratum #141\n");
+                }
+
+                break;
+        }
+
         pci_read_config_byte(pdev, REG_TEMP, &scfg);
         scfg &= ~(SEL_PLACE | SEL_CORE);                /* Select sensor 0, core0 */
         pci_write_config_byte(pdev, REG_TEMP, scfg);