powerpc/pseries/htmdump: Add htm configure support to htmdump module

Support configuring of Hardware Trace Macro (HTM) function
via debugfs interface. Under debugfs folder
"/sys/kernel/debug/powerpc/htmdump", add file "htmconfigure".
The interface allows configuring of htm via this file
by writing value "1". Allow deconfiguring of htm via this file
by writing value "0".  Any other value returns -EINVAL.

Signed-off-by: Athira Rajeev <[email protected]>
Tested-by: Venkat Rao Bagalkote <[email protected]>
Signed-off-by: Madhavan Srinivasan <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: Athira Rajeev

arch/powerpc/platforms/pseries/htmdump.c

@@ -16,7 +16,10 @@ static u32 nodeindex;
 static u32 nodalchipindex;
 static u32 coreindexonchip;
 static u32 htmtype;
+static u32 htmconfigure;
 static struct dentry *htmdump_debugfs_dir;
+#define	HTM_ENABLE	1
+#define	HTM_DISABLE	0
 
 /*
  * Check the return code for H_HTM hcall.
@@ -108,6 +111,54 @@ static const struct file_operations htmdump_fops = {
 	.open	= simple_open,
 };
 
+static int  htmconfigure_set(void *data, u64 val)
+{
+	long rc, ret;
+
+	/*
+	 * value as 1 : configure HTM.
+	 * value as 0 : deconfigure HTM. Return -EINVAL for
+	 * other values.
+	 */
+	if (val == HTM_ENABLE) {
+		/*
+		 * Invoke H_HTM call with:
+		 * - operation as htm configure (H_HTM_OP_CONFIGURE)
+		 * - last three values are unused, hence set to zero
+		 */
+		rc = htm_hcall_wrapper(nodeindex, nodalchipindex, coreindexonchip,
+			   htmtype, H_HTM_OP_CONFIGURE, 0, 0, 0);
+	} else if (val == HTM_DISABLE) {
+		/*
+		 * Invoke H_HTM call with:
+		 * - operation as htm deconfigure (H_HTM_OP_DECONFIGURE)
+		 * - last three values are unused, hence set to zero
+		 */
+		rc = htm_hcall_wrapper(nodeindex, nodalchipindex, coreindexonchip,
+				htmtype, H_HTM_OP_DECONFIGURE, 0, 0, 0);
+	} else
+		return -EINVAL;
+
+	ret = htm_return_check(rc);
+	if (ret <= 0) {
+		pr_debug("H_HTM hcall failed, returning %ld\n", ret);
+		return ret;
+	}
+
+	/* Set htmconfigure if operation succeeds */
+	htmconfigure = val;
+
+	return 0;
+}
+
+static int htmconfigure_get(void *data, u64 *val)
+{
+	*val = htmconfigure;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(htmconfigure_fops, htmconfigure_get, htmconfigure_set, "%llu\n");
+
 static int htmdump_init_debugfs(void)
 {
 	htm_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
@@ -129,6 +180,11 @@ static int htmdump_init_debugfs(void)
 			htmdump_debugfs_dir, &htmtype);
 	debugfs_create_file("trace", 0400, htmdump_debugfs_dir, htm_buf, &htmdump_fops);
 
+	/*
+	 * Debugfs interface files to control HTM operations:
+	 */
+	debugfs_create_file("htmconfigure", 0600, htmdump_debugfs_dir, NULL, &htmconfigure_fops);
+
 	return 0;
 }