clk: do not disable clock if it is critical

Do not disable clock if it is a critical one.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/clk_ccf.c b/test/dm/clk_ccf.c
index 1ce28d7..e4ebb93 100644
--- a/test/dm/clk_ccf.c
+++ b/test/dm/clk_ccf.c
@@ -24,7 +24,7 @@
 	int ret;
 #if CONFIG_IS_ENABLED(CLK_CCF)
 	const char *clkname;
-	int clkid;
+	int clkid, i;
 #endif
 
 	/* Get the device using the clk device */
@@ -157,6 +157,36 @@
 	pclk = clk_get_parent(clk);
 	ut_assertok_ptr(pclk);
 	ut_asserteq_str(clkname, pclk->dev->name);
+
+	/* Test disabling critical clock. */
+	ret = clk_get_by_id(SANDBOX_CLK_I2C_ROOT, &clk);
+	ut_assertok(ret);
+	ut_asserteq_str("i2c_root", clk->dev->name);
+
+	/* Disable it, if any. */
+	ret = sandbox_clk_enable_count(clk);
+	for (i = 0; i < ret; i++) {
+		ret = clk_disable(clk);
+		ut_assertok(ret);
+	}
+
+	ret = sandbox_clk_enable_count(clk);
+	ut_asserteq(ret, 0);
+
+	clk->flags = CLK_IS_CRITICAL;
+	ret = clk_enable(clk);
+	ut_assertok(ret);
+
+	ret = clk_disable(clk);
+	ut_assertok(ret);
+	ret = sandbox_clk_enable_count(clk);
+	ut_asserteq(ret, 1);
+	clk->flags &= ~CLK_IS_CRITICAL;
+
+	ret = clk_disable(clk);
+	ut_assertok(ret);
+	ret = sandbox_clk_enable_count(clk);
+	ut_asserteq(ret, 0);
 #endif
 
 	return 1;