cpts: specify the input clock frequency via DT

This patch adds a way to configure the CPTS input clock scaling factors
via the device tree.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/cpsw.txt

@@ -24,6 +24,8 @@ Required properties:
 			  for the specific platform
 - slaves		: Specifies number for slaves
 - cpts_active_slave	: Specifies the slave to use for time stamping
+- cpts_clock_mult	: Numerator to convert input clock ticks into nanoseconds
+- cpts_clock_shift	: Denominator to convert input clock ticks into nanoseconds
 - slave_reg_ofs		: Specifies slave register offset
 - sliver_reg_ofs	: Specifies slave sliver register offset
 - phy_id		: Specifies slave phy id
@@ -62,6 +64,8 @@ Examples:
 		mac_control = <0x20>;
 		slaves = <2>;
 		cpts_active_slave = <0>;
+		cpts_clock_mult = <0x80000000>;
+		cpts_clock_shift = <29>;
 		cpsw_emac0: slave@0 {
 			slave_reg_ofs = <0x200>;
 			sliver_reg_ofs = <0xd80>;
@@ -98,6 +102,8 @@ Examples:
 		mac_control = <0x20>;
 		slaves = <2>;
 		cpts_active_slave = <0>;
+		cpts_clock_mult = <0x80000000>;
+		cpts_clock_shift = <29>;
 		cpsw_emac0: slave@0 {
 			slave_reg_ofs = <0x200>;
 			sliver_reg_ofs = <0xd80>;

drivers/net/ethernet/ti/cpsw.c

@@ -854,6 +854,20 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
 	}
 	data->cpts_active_slave = prop;
 
+	if (of_property_read_u32(node, "cpts_clock_mult", &prop)) {
+		pr_err("Missing cpts_clock_mult property in the DT.\n");
+		ret = -EINVAL;
+		goto error_ret;
+	}
+	data->cpts_clock_mult = prop;
+
+	if (of_property_read_u32(node, "cpts_clock_shift", &prop)) {
+		pr_err("Missing cpts_clock_shift property in the DT.\n");
+		ret = -EINVAL;
+		goto error_ret;
+	}
+	data->cpts_clock_shift = prop;
+
 	data->slave_data = kzalloc(sizeof(struct cpsw_slave_data) *
 				   data->slaves, GFP_KERNEL);
 	if (!data->slave_data) {

include/linux/platform_data/cpsw.h

@@ -34,6 +34,8 @@ struct cpsw_platform_data {
 	u32	slaves;		/* number of slave cpgmac ports */
 	struct cpsw_slave_data	*slave_data;
 	u32	cpts_active_slave; /* time stamping slave */
+	u32	cpts_clock_mult;  /* convert input clock ticks to nanoseconds */
+	u32	cpts_clock_shift; /* convert input clock ticks to nanoseconds */
 
 	u32	ale_reg_ofs;	/* address lookup engine reg offset */
 	u32	ale_entries;	/* ale table size */