tools/power/x86/intel-speed-select: Helpful warning for missing kernel interface

When the device file "/dev/isst_interface" is not present, instead of
failing on access, check at the start and print a helpful warning.

Here CLX platform is an exception, which doesn't depend on the device
file. So continue for CLX platform.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/tools/power/x86/intel-speed-select/isst-config.c b/tools/power/x86/intel-speed-select/isst-config.c
index 4773970..9bf461e 100644 (file)
--- a/tools/power/x86/intel-speed-select/isst-config.c
+++ b/tools/power/x86/intel-speed-select/isst-config.c
@@ -2408,6 +2408,8 @@ static void print_version(void)
 
 static void cmdline(int argc, char **argv)
 {
+       const char *pathname = "/dev/isst_interface";
+       FILE *fp;
        int opt;
        int option_index = 0;
        int ret;
@@ -2423,6 +2425,28 @@ static void cmdline(int argc, char **argv)
                { 0, 0, 0, 0 }
        };
 
+       if (geteuid() != 0) {
+               fprintf(stderr, "Must run as root\n");
+               exit(0);
+       }
+
+       ret = update_cpu_model();
+       if (ret)
+               err(-1, "Invalid CPU model (%d)\n", cpu_model);
+       printf("Intel(R) Speed Select Technology\n");
+       printf("Executing on CPU model:%d[0x%x]\n", cpu_model, cpu_model);
+
+       if (!is_clx_n_platform()) {
+               fp = fopen(pathname, "rb");
+               if (!fp) {
+                       fprintf(stderr, "Intel speed select drivers are not loaded on this system.\n");
+                       fprintf(stderr, "Verify that kernel config includes CONFIG_INTEL_SPEED_SELECT_INTERFACE.\n");
+                       fprintf(stderr, "If the config is included then this is not a supported platform.\n");
+                       exit(0);
+               }
+               fclose(fp);
+       }
+
        progname = argv[0];
        while ((opt = getopt_long_only(argc, argv, "+c:df:hio:v", long_options,
                                       &option_index)) != -1) {
@@ -2457,20 +2481,10 @@ static void cmdline(int argc, char **argv)
                }
        }
 
-       if (geteuid() != 0) {
-               fprintf(stderr, "Must run as root\n");
-               exit(0);
-       }
-
        if (optind > (argc - 2)) {
                fprintf(stderr, "Feature name and|or command not specified\n");
                exit(0);
        }
-       ret = update_cpu_model();
-       if (ret)
-               err(-1, "Invalid CPU model (%d)\n", cpu_model);
-       printf("Intel(R) Speed Select Technology\n");
-       printf("Executing on CPU model:%d[0x%x]\n", cpu_model, cpu_model);
        set_max_cpu_num();
        store_cpu_topology();
        set_cpu_present_cpu_mask();