net: ethernet: ti: cpts: add support for ext rftclk selection

Some CPTS instances, which can be found on KeyStone 2 1G Ethernet Switch
Subsystems, can control an external multiplexer that selects one of up to
32 clocks as time sync reference (RFTCLK) clock. This feature can be
configured through CPTS_RFTCLK_SEL register (offset: x08) in CPTS module
and can be represented as multiplexer clock.

Hence, introduce support for optional cpts-refclk-mux clock, which, once
defined will allow to select required CPTS RFTCLK by using
assigned-clock-parents DT property in board files.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpts.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
  *
  */
+#include <linux/clk-provider.h>
 #include <linux/err.h>
 #include <linux/if.h>
 #include <linux/hrtimer.h>
@@ -532,6 +533,82 @@ static void cpts_calc_mult_shift(struct cpts *cpts)
 		 freq, cpts->cc.mult, cpts->cc.shift, (ns - NSEC_PER_SEC));
 }
 
+static int cpts_of_mux_clk_setup(struct cpts *cpts, struct device_node *node)
+{
+	struct device_node *refclk_np;
+	const char **parent_names;
+	unsigned int num_parents;
+	struct clk_hw *clk_hw;
+	int ret = -EINVAL;
+	u32 *mux_table;
+
+	refclk_np = of_get_child_by_name(node, "cpts-refclk-mux");
+	if (!refclk_np)
+		/* refclk selection supported not for all SoCs */
+		return 0;
+
+	num_parents = of_clk_get_parent_count(refclk_np);
+	if (num_parents < 1) {
+		dev_err(cpts->dev, "mux-clock %s must have parents\n",
+			refclk_np->name);
+		goto mux_fail;
+	}
+
+	parent_names = devm_kzalloc(cpts->dev, (sizeof(char *) * num_parents),
+				    GFP_KERNEL);
+
+	mux_table = devm_kzalloc(cpts->dev, sizeof(*mux_table) * num_parents,
+				 GFP_KERNEL);
+	if (!mux_table || !parent_names) {
+		ret = -ENOMEM;
+		goto mux_fail;
+	}
+
+	of_clk_parent_fill(refclk_np, parent_names, num_parents);
+
+	ret = of_property_read_variable_u32_array(refclk_np, "ti,mux-tbl",
+						  mux_table,
+						  num_parents, num_parents);
+	if (ret < 0)
+		goto mux_fail;
+
+	clk_hw = clk_hw_register_mux_table(cpts->dev, refclk_np->name,
+					   parent_names, num_parents,
+					   0,
+					   &cpts->reg->rftclk_sel, 0, 0x1F,
+					   0, mux_table, NULL);
+	if (IS_ERR(clk_hw)) {
+		ret = PTR_ERR(clk_hw);
+		goto mux_fail;
+	}
+
+	ret = devm_add_action_or_reset(cpts->dev,
+				       (void(*)(void *))clk_hw_unregister_mux,
+				       clk_hw);
+	if (ret) {
+		dev_err(cpts->dev, "add clkmux unreg action %d", ret);
+		goto mux_fail;
+	}
+
+	ret = of_clk_add_hw_provider(refclk_np, of_clk_hw_simple_get, clk_hw);
+	if (ret)
+		goto mux_fail;
+
+	ret = devm_add_action_or_reset(cpts->dev,
+				       (void(*)(void *))of_clk_del_provider,
+				       refclk_np);
+	if (ret) {
+		dev_err(cpts->dev, "add clkmux provider unreg action %d", ret);
+		goto mux_fail;
+	}
+
+	return ret;
+
+mux_fail:
+	of_node_put(refclk_np);
+	return ret;
+}
+
 static int cpts_of_parse(struct cpts *cpts, struct device_node *node)
 {
 	int ret = -EINVAL;
@@ -547,7 +624,7 @@ static int cpts_of_parse(struct cpts *cpts, struct device_node *node)
 	    (!cpts->cc.mult && cpts->cc.shift))
 		goto of_error;
 
-	return 0;
+	return cpts_of_mux_clk_setup(cpts, node);
 
 of_error:
 	dev_err(cpts->dev, "CPTS: Missing property in the DT.\n");

drivers/net/ethernet/ti/cpts.h

@@ -24,7 +24,7 @@
 struct cpsw_cpts {
 	u32 idver;                /* Identification and version */
 	u32 control;              /* Time sync control */
-	u32 res1;
+	u32 rftclk_sel;		  /* Reference Clock Select Register */
 	u32 ts_push;              /* Time stamp event push */
 	u32 ts_load_val;          /* Time stamp load value */
 	u32 ts_load_en;           /* Time stamp load enable */