clk: qcom: clk-debug: Add custom measure operators for mccc_clk

Since the generic way of using testclock to measure ddr mc clock
is not available, rely on reading the period of the current mc clock
frequency written to by DDRSS software. This does not provide the
physical rate at which the clock is running, but a snapshot of the
current configuration.

Change-Id: I37ce2927be7712adc2b722ed0a26c8eaf4596dd2
Signed-off-by: David Dai <daidavid1@codeaurora.org>

drivers/clk/qcom/clk-debug.c

@@ -297,15 +297,54 @@ exit:
 DEFINE_SIMPLE_ATTRIBUTE(clk_measure_fops, clk_debug_measure_get,
 							NULL, "%lld\n");
 
+static int clk_debug_read_period(void *data, u64 *val)
+{
+	struct clk_hw *hw = data;
+	struct clk_debug_mux *meas = to_clk_measure(measure);
+	int index;
+	int dbg_cc;
+	int ret = 0;
+	u32 regval;
+
+	mutex_lock(&clk_debug_lock);
+
+	ret = clk_set_parent(measure->clk, hw->clk);
+	if (!ret) {
+		index = clk_debug_mux_get_parent(measure);
+		dbg_cc = meas->parent[index].dbg_cc;
+
+		regmap_read(meas->regmap[dbg_cc], meas->period_offset, &regval);
+		if (!regval) {
+			pr_err("Error reading mccc period register, ret = %d\n",
+			       ret);
+			mutex_unlock(&clk_debug_lock);
+			return 0;
+		}
+		*val = 1000000000000UL;
+		do_div(*val, regval);
+	} else {
+		pr_err("Failed to set the debug mux's parent.\n");
+	}
+
+	mutex_unlock(&clk_debug_lock);
+	return ret;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(clk_read_period_fops, clk_debug_read_period,
+							NULL, "%lld\n");
+
 int clk_debug_measure_add(struct clk_hw *hw, struct dentry *dentry)
 {
 	int ret;
+	int index;
+	struct clk_debug_mux *meas;
 
 	if (IS_ERR_OR_NULL(measure)) {
 		pr_err_once("Please check if `measure` clk is registered.\n");
 		return 0;
 	}
 
+	meas = to_clk_measure(measure);
 	ret = clk_set_parent(measure->clk, hw->clk);
 	if (ret) {
 		pr_debug("Unable to set %s as %s's parent, ret=%d\n",
@@ -313,7 +352,12 @@ int clk_debug_measure_add(struct clk_hw *hw, struct dentry *dentry)
 		return 0;
 	}
 
-	debugfs_create_file("clk_measure", 0444, dentry, hw,
+	index = clk_debug_mux_get_parent(measure);
+	if (meas->parent[index].dbg_cc == MC_CC)
+		debugfs_create_file("clk_measure", 0444, dentry, hw,
+					&clk_read_period_fops);
+	else
+		debugfs_create_file("clk_measure", 0444, dentry, hw,
 					&clk_measure_fops);
 	return 0;
 }

drivers/clk/qcom/clk-debug.h

@@ -45,6 +45,7 @@ enum debug_cc {
 	GPU_CC,
 	VIDEO_CC,
 	CPU_CC,
+	MC_CC,
 	MAX_NUM_CC,
 };
 
@@ -111,6 +112,8 @@ struct clk_src {
 			mux.
  * @post_div_shift:	indicates the shift required for post divider
 			selection in primary mux.
+ * @period_offset:	offset of the period register used to read to determine
+			the mc clock period
  * @hw:			handle between common and hardware-specific interfaces.
  */
 struct clk_debug_mux {
@@ -126,6 +129,7 @@ struct clk_debug_mux {
 	u32 src_sel_shift;
 	u32 post_div_mask;
 	u32 post_div_shift;
+	u32 period_offset;
 	struct clk_hw hw;
 };