stm class: Make dummy's master/channel ranges configurable

To allow for more flexible testing of the stm class, make it possible
to specify the ranges of masters and channels that the dummy_stm devices
cover. This is done via module parameters.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

2 files changed, 25 insertions, 3 deletions

diff --git a/drivers/hwtracing/stm/dummy_stm.c b/drivers/hwtracing/stm/dummy_stm.c
index 63288020ea5b..38528ffdc0b3 100644
--- a/drivers/hwtracing/stm/dummy_stm.c
+++ b/drivers/hwtracing/stm/dummy_stm.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/stm.h>
+#include <uapi/linux/stm.h>
 
 static ssize_t notrace
 dummy_stm_packet(struct stm_data *stm_data, unsigned int master,
@@ -44,6 +45,18 @@ static unsigned int fail_mode;
 
 module_param(fail_mode, int, 0600);
 
+static unsigned int master_min;
+
+module_param(master_min, int, 0400);
+
+static unsigned int master_max = STP_MASTER_MAX;
+
+module_param(master_max, int, 0400);
+
+static unsigned int nr_channels = STP_CHANNEL_MAX;
+
+module_param(nr_channels, int, 0400);
+
 static int dummy_stm_link(struct stm_data *data, unsigned int master,
                           unsigned int channel)
 {
@@ -60,14 +73,19 @@ static int dummy_stm_init(void)
         if (nr_dummies < 0 || nr_dummies > DUMMY_STM_MAX)
                 return -EINVAL;
 
+        if (master_min > master_max ||
+            master_max > STP_MASTER_MAX ||
+            nr_channels > STP_CHANNEL_MAX)
+                return -EINVAL;
+
         for (i = 0; i < nr_dummies; i++) {
                 dummy_stm[i].name = kasprintf(GFP_KERNEL, "dummy_stm.%d", i);
                 if (!dummy_stm[i].name)
                         goto fail_unregister;
 
-                dummy_stm[i].sw_start           = 0x0000;
-                dummy_stm[i].sw_end             = 0xffff;
-                dummy_stm[i].sw_nchannels       = 0xffff;
+                dummy_stm[i].sw_start           = master_min;
+                dummy_stm[i].sw_end             = master_max;
+                dummy_stm[i].sw_nchannels       = nr_channels;
                 dummy_stm[i].packet             = dummy_stm_packet;
                 dummy_stm[i].link               = dummy_stm_link;
 
diff --git a/include/uapi/linux/stm.h b/include/uapi/linux/stm.h
index 29c89be72275..7bac318b4440 100644
--- a/include/uapi/linux/stm.h
+++ b/include/uapi/linux/stm.h
@@ -12,6 +12,10 @@
 
 #include <linux/types.h>
 
+/* Maximum allowed master and channel values */
+#define STP_MASTER_MAX  0xffff
+#define STP_CHANNEL_MAX 0xffff
+
 /**
  * struct stp_policy_id - identification for the STP policy
  * @size:       size of the structure including real id[] length