platform/x86: ISST: Avoid some SkyLake server models

Some SkyLake server variants don't support any SST functionality. No use
of providing any SST related interfaces on them.

All supported SkyLake servers provide mailbox interface via MSR. So check
for the presence of MSR 0xB0 and 0xB1. If not present don't load common
module.

Move defines for MSR_OS_MAILBOX_INTERFACE and MSR_OS_MAILBOX_DATA to
common header file to avoid duplicating them.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20240531083554.1313110-3-srinivas.pandruvada@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

diff --git a/drivers/platform/x86/intel/speed_select_if/isst_if_common.c b/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
index 47f5f26e6c205e3ab503a20a49d6c152d813d02c..7ea058571ab5d21cd8875f65e0ad48f0666a970c 100644 (file)
--- a/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
+++ b/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
@@ -814,6 +814,7 @@ void isst_if_cdev_unregister(int device_type)
 EXPORT_SYMBOL_GPL(isst_if_cdev_unregister);
 
 #define SST_HPM_SUPPORTED      0x01
+#define SST_MBOX_SUPPORTED     0x02
 
 static const struct x86_cpu_id isst_cpu_ids[] = {
        X86_MATCH_VFM(INTEL_ATOM_CRESTMONT,     SST_HPM_SUPPORTED),
@@ -824,7 +825,7 @@ static const struct x86_cpu_id isst_cpu_ids[] = {
        X86_MATCH_VFM(INTEL_ICELAKE_D,          0),
        X86_MATCH_VFM(INTEL_ICELAKE_X,          0),
        X86_MATCH_VFM(INTEL_SAPPHIRERAPIDS_X,   0),
-       X86_MATCH_VFM(INTEL_SKYLAKE_X,          0),
+       X86_MATCH_VFM(INTEL_SKYLAKE_X,          SST_MBOX_SUPPORTED),
        {}
 };
 MODULE_DEVICE_TABLE(x86cpu, isst_cpu_ids);
@@ -837,8 +838,16 @@ static int __init isst_if_common_init(void)
        if (!id)
                return -ENODEV;
 
-       if (id->driver_data == SST_HPM_SUPPORTED)
+       if (id->driver_data == SST_HPM_SUPPORTED) {
                isst_hpm_support = true;
+       } else if (id->driver_data == SST_MBOX_SUPPORTED) {
+               u64 data;
+
+               /* Can fail only on some Skylake-X generations */
+               if (rdmsrl_safe(MSR_OS_MAILBOX_INTERFACE, &data) ||
+                   rdmsrl_safe(MSR_OS_MAILBOX_DATA, &data))
+                       return -ENODEV;
+       }
 
        return isst_misc_reg();
 }

diff --git a/drivers/platform/x86/intel/speed_select_if/isst_if_common.h b/drivers/platform/x86/intel/speed_select_if/isst_if_common.h
index 1004f2c9cca86bf2f47d24e13ddf55a6d80ad7d0..378055fe1d16faf1b4fb0fe822c933c6d6b6cb50 100644 (file)
--- a/drivers/platform/x86/intel/speed_select_if/isst_if_common.h
+++ b/drivers/platform/x86/intel/speed_select_if/isst_if_common.h
@@ -16,6 +16,9 @@
 #define PCI_DEVICE_ID_INTEL_RAPL_PRIO_DEVID_1  0x3251
 #define PCI_DEVICE_ID_INTEL_CFG_MBOX_DEVID_1   0x3259
 
+#define MSR_OS_MAILBOX_INTERFACE               0xB0
+#define MSR_OS_MAILBOX_DATA                    0xB1
+
 /*
  * Validate maximum commands in a single request.
  * This is enough to handle command to every core in one ioctl, or all

diff --git a/drivers/platform/x86/intel/speed_select_if/isst_if_mbox_msr.c b/drivers/platform/x86/intel/speed_select_if/isst_if_mbox_msr.c
index 1b6eab07106810cf1b77ec1348ce4fcb7f895c88..48b608eaca5f587b708c5dc5397c80cced1083d5 100644 (file)
--- a/drivers/platform/x86/intel/speed_select_if/isst_if_mbox_msr.c
+++ b/drivers/platform/x86/intel/speed_select_if/isst_if_mbox_msr.c
@@ -21,8 +21,6 @@
 
 #include "isst_if_common.h"
 
-#define MSR_OS_MAILBOX_INTERFACE       0xB0
-#define MSR_OS_MAILBOX_DATA            0xB1
 #define MSR_OS_MAILBOX_BUSY_BIT                31
 
 /*