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>

diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index df443b908ca305694c43d9665859c9cca11f3dde..533ccfe770945581597efd04051672a64fca8491 100644 (file)
--- 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;
 }