of serial port driver - add clk_get_rate() support

Currently this driver expects the clock-frequency attribute. This
patch allows getting clock-frequency through clk driver API
clk_get_rate() if clock-frequency attribute is not defined.

So in the device bindings for serial device, one can add clocks
phandle to refer to the clk device to get the rate.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 26 insertions, 6 deletions

diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index df443b908ca3..533ccfe77094 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -21,8 +21,10 @@
 #include <linux/of_serial.h>
 #include <linux/of_platform.h>
 #include <linux/nwpserial.h>
+#include <linux/clk.h>
 
 struct of_serial_info {
+        struct clk *clk;
         int type;
         int line;
 };
@@ -51,7 +53,8 @@ EXPORT_SYMBOL_GPL(tegra_serial_handle_break);
  * Fill a struct uart_port for a given device node
  */
 static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
-                                        int type, struct uart_port *port)
+                        int type, struct uart_port *port,
+                        struct of_serial_info *info)
 {
         struct resource resource;
         struct device_node *np = ofdev->dev.of_node;
@@ -60,8 +63,17 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
 
         memset(port, 0, sizeof *port);
         if (of_property_read_u32(np, "clock-frequency", &clk)) {
-                dev_warn(&ofdev->dev, "no clock-frequency property set\n");
-                return -ENODEV;
+
+                /* Get clk rate through clk driver if present */
+                info->clk = clk_get(&ofdev->dev, NULL);
+                if (info->clk == NULL) {
+                        dev_warn(&ofdev->dev,
+                                "clk or clock-frequency not defined\n");
+                        return -ENODEV;
+                }
+
+                clk_prepare_enable(info->clk);
+                clk = clk_get_rate(info->clk);
         }
         /* If current-speed was set, then try not to change it. */
         if (of_property_read_u32(np, "current-speed", &spd) == 0)
@@ -70,7 +82,7 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
         ret = of_address_to_resource(np, 0, &resource);
         if (ret) {
                 dev_warn(&ofdev->dev, "invalid address\n");
-                return ret;
+                goto out;
         }
 
         spin_lock_init(&port->lock);
@@ -97,7 +109,8 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
                 default:
                         dev_warn(&ofdev->dev, "unsupported reg-io-width (%d)\n",
                                  prop);
-                        return -EINVAL;
+                        ret = -EINVAL;
+                        goto out;
                 }
         }
 
@@ -115,6 +128,10 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
                 port->handle_break = tegra_serial_handle_break;
 
         return 0;
+out:
+        if (info->clk)
+                clk_disable_unprepare(info->clk);
+        return ret;
 }
 
 /*
@@ -141,7 +158,7 @@ static int __devinit of_platform_serial_probe(struct platform_device *ofdev)
                 return -ENOMEM;
 
         port_type = (unsigned long)match->data;
-        ret = of_platform_serial_setup(ofdev, port_type, &port);
+        ret = of_platform_serial_setup(ofdev, port_type, &port, info);
         if (ret)
                 goto out;
 
@@ -204,6 +221,9 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
                 /* need to add code for these */
                 break;
         }
+
+        if (info->clk)
+                clk_disable_unprepare(info->clk);
         kfree(info);
         return 0;
 }