cpsw: add a DT field for the active time stamping port

Because time stamping on both external ports of the switch simultaneously
is positively useless from the application's point of view, this patch
provides a DT configuration method to choose the active port.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/net/cpsw.txt b/Documentation/devicetree/bindings/net/cpsw.txt
index dba014fc5e7b..9f61f2b51681 100644
--- a/Documentation/devicetree/bindings/net/cpsw.txt
+++ b/Documentation/devicetree/bindings/net/cpsw.txt
@@ -23,6 +23,7 @@ Required properties:
 - mac_control           : Specifies Default MAC control register content
                           for the specific platform
 - slaves                : Specifies number for slaves
+- cpts_active_slave     : Specifies the slave to use for time stamping
 - slave_reg_ofs         : Specifies slave register offset
 - sliver_reg_ofs        : Specifies slave sliver register offset
 - phy_id                : Specifies slave phy id
@@ -60,6 +61,7 @@ Examples:
                 rx_descs = <64>;
                 mac_control = <0x20>;
                 slaves = <2>;
+                cpts_active_slave = <0>;
                 cpsw_emac0: slave@0 {
                         slave_reg_ofs = <0x200>;
                         sliver_reg_ofs = <0xd80>;
@@ -95,6 +97,7 @@ Examples:
                 rx_descs = <64>;
                 mac_control = <0x20>;
                 slaves = <2>;
+                cpts_active_slave = <0>;
                 cpsw_emac0: slave@0 {
                         slave_reg_ofs = <0x200>;
                         sliver_reg_ofs = <0xd80>;
diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index f1af5e08cabb..f16579123c1b 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -847,6 +847,13 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
         }
         data->slaves = prop;
 
+        if (of_property_read_u32(node, "cpts_active_slave", &prop)) {
+                pr_err("Missing cpts_active_slave property in the DT.\n");
+                ret = -EINVAL;
+                goto error_ret;
+        }
+        data->cpts_active_slave = prop;
+
         data->slave_data = kzalloc(sizeof(struct cpsw_slave_data) *
                                    data->slaves, GFP_KERNEL);
         if (!data->slave_data) {
diff --git a/include/linux/platform_data/cpsw.h b/include/linux/platform_data/cpsw.h
index a052b1dca957..15a077eb0689 100644
--- a/include/linux/platform_data/cpsw.h
+++ b/include/linux/platform_data/cpsw.h
@@ -33,6 +33,7 @@ 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     ale_reg_ofs;    /* address lookup engine reg offset */
         u32     ale_entries;    /* ale table size */