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

Add htm setup support to htmdump module. To use the
HTM (Hardware Trace Macro), HTM buffer has to be allocated.
Support setup of HTM buffers via debugfs interface. Under
debugfs folder, "/sys/kernel/debug/powerpc/htmdump", add file
"htmsetup". The interface allows setup of HTM buffer by writing
size of HTM buffer in power of 2 to the "htmsetup" file

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

arch/powerpc/platforms/pseries/htmdump.c

···
 static u32 htmtype;
 static u32 htmconfigure;
 static u32 htmstart;
+static u32 htmsetup;
+
 static struct dentry *htmdump_debugfs_dir;
 #define	HTM_ENABLE	1
 #define	HTM_DISABLE	0
···
 	.open   = simple_open,
 };
 
+static int  htmsetup_set(void *data, u64 val)
+{
+	long rc, ret;
+
+	/*
+	 * Input value: HTM buffer size in the power of 2
+	 * example: hex value 0x21 ( decimal: 33 ) is for
+	 * 8GB
+	 * Invoke H_HTM call with:
+	 * - operation as htm start (H_HTM_OP_SETUP)
+	 * - parameter 1 set to input value.
+	 * - last two values are unused, hence set to zero
+	 */
+	rc = htm_hcall_wrapper(nodeindex, nodalchipindex, coreindexonchip,
+			htmtype, H_HTM_OP_SETUP, val, 0, 0);
+
+	ret = htm_return_check(rc);
+	if (ret <= 0) {
+		pr_debug("H_HTM hcall failed for op: H_HTM_OP_SETUP, returning %ld\n", ret);
+		return ret;
+	}
+
+	/* Set htmsetup if H_HTM_OP_SETUP operation succeeds */
+	htmsetup = val;
+
+	return 0;
+}
+
+static int htmsetup_get(void *data, u64 *val)
+{
+	*val = htmsetup;
+	return 0;
+}
+
 DEFINE_SIMPLE_ATTRIBUTE(htmconfigure_fops, htmconfigure_get, htmconfigure_set, "%llu\n");
 DEFINE_SIMPLE_ATTRIBUTE(htmstart_fops, htmstart_get, htmstart_set, "%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(htmsetup_fops, htmsetup_get, htmsetup_set, "%llu\n");
 
 static int htmdump_init_debugfs(void)
 {
···
 	 */
 	debugfs_create_file("htmconfigure", 0600, htmdump_debugfs_dir, NULL, &htmconfigure_fops);
 	debugfs_create_file("htmstart", 0600, htmdump_debugfs_dir, NULL, &htmstart_fops);
+	debugfs_create_file("htmsetup", 0600, htmdump_debugfs_dir, NULL, &htmsetup_fops);
 
 	/* Debugfs interface file to present status of HTM */
 	htm_status_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);