[ARM] Convert AMBA PL010 driver to use the clk infrastructure

Convert the AMBA PL010 serial driver to use the clock infrastructure
to allow EP93xx platforms to properly gate the clock to the UARTs.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 42 insertions, 2 deletions

diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
index f174d1a3b11c..9d7515c36bff 100644
--- a/arch/arm/mach-ep93xx/clock.c
+++ b/arch/arm/mach-ep93xx/clock.c
@@ -27,6 +27,10 @@ struct clk {
         u32             enable_mask;
 };
 
+static struct clk clk_uart = {
+        .name           = "UARTCLK",
+        .rate           = 14745600,
+};
 static struct clk clk_pll1 = {
         .name           = "pll1",
 };
@@ -50,6 +54,7 @@ static struct clk clk_usb_host = {
 
 
 static struct clk *clocks[] = {
+        &clk_uart,
         &clk_pll1,
         &clk_f,
         &clk_h,
diff --git a/drivers/serial/amba-pl010.c b/drivers/serial/amba-pl010.c
index ea49aafd66bf..1a9a24b82636 100644
--- a/drivers/serial/amba-pl010.c
+++ b/drivers/serial/amba-pl010.c
@@ -48,6 +48,7 @@
 #include <linux/serial.h>
 #include <linux/amba/bus.h>
 #include <linux/amba/serial.h>
+#include <linux/clk.h>
 
 #include <asm/io.h>
 
@@ -70,6 +71,7 @@
  */
 struct uart_amba_port {
         struct uart_port        port;
+        struct clk              *clk;
         struct amba_device      *dev;
         struct amba_pl010_data  *data;
         unsigned int            old_status;
@@ -313,11 +315,20 @@ static int pl010_startup(struct uart_port *port)
         int retval;
 
         /*
+         * Try to enable the clock producer.
+         */
+        retval = clk_enable(uap->clk);
+        if (retval)
+                goto out;
+
+        uap->port.uartclk = clk_get_rate(uap->clk);
+
+        /*
          * Allocate the IRQ
          */
         retval = request_irq(uap->port.irq, pl010_int, 0, "uart-pl010", uap);
         if (retval)
-                return retval;
+                goto clk_dis;
 
         /*
          * initialise the old status of the modem signals
@@ -331,6 +342,11 @@ static int pl010_startup(struct uart_port *port)
                uap->port.membase + UART010_CR);
 
         return 0;
+
+ clk_dis:
+        clk_disable(uap->clk);
+ out:
+        return retval;
 }
 
 static void pl010_shutdown(struct uart_port *port)
@@ -351,6 +367,11 @@ static void pl010_shutdown(struct uart_port *port)
         writel(readb(uap->port.membase + UART010_LCRH) &
                 ~(UART01x_LCRH_BRK | UART01x_LCRH_FEN),
                uap->port.membase + UART010_LCRH);
+
+        /*
+         * Shut down the clock producer
+         */
+        clk_disable(uap->clk);
 }
 
 static void
@@ -540,6 +561,8 @@ pl010_console_write(struct console *co, const char *s, unsigned int count)
         struct uart_amba_port *uap = amba_ports[co->index];
         unsigned int status, old_cr;
 
+        clk_enable(uap->clk);
+
         /*
          *      First save the CR then disable the interrupts
          */
@@ -557,6 +580,8 @@ pl010_console_write(struct console *co, const char *s, unsigned int count)
                 barrier();
         } while (status & UART01x_FR_BUSY);
         writel(old_cr, uap->port.membase + UART010_CR);
+
+        clk_disable(uap->clk);
 }
 
 static void __init
@@ -605,6 +630,8 @@ static int __init pl010_console_setup(struct console *co, char *options)
         if (!uap)
                 return -ENODEV;
 
+        uap->port.uartclk = clk_get_rate(uap->clk);
+
         if (options)
                 uart_parse_options(options, &baud, &parity, &bits, &flow);
         else
@@ -666,12 +693,17 @@ static int pl010_probe(struct amba_device *dev, void *id)
                 goto free;
         }
 
+        uap->clk = clk_get(&dev->dev, "UARTCLK");
+        if (IS_ERR(uap->clk)) {
+                ret = PTR_ERR(uap->clk);
+                goto unmap;
+        }
+
         uap->port.dev = &dev->dev;
         uap->port.mapbase = dev->res.start;
         uap->port.membase = base;
         uap->port.iotype = UPIO_MEM;
         uap->port.irq = dev->irq[0];
-        uap->port.uartclk = 14745600;
         uap->port.fifosize = 16;
         uap->port.ops = &amba_pl010_pops;
         uap->port.flags = UPF_BOOT_AUTOCONF;
@@ -686,6 +718,8 @@ static int pl010_probe(struct amba_device *dev, void *id)
         if (ret) {
                 amba_set_drvdata(dev, NULL);
                 amba_ports[i] = NULL;
+                clk_put(uap->clk);
+ unmap:
                 iounmap(base);
  free:
                 kfree(uap);
@@ -708,6 +742,7 @@ static int pl010_remove(struct amba_device *dev)
                         amba_ports[i] = NULL;
 
         iounmap(uap->port.membase);
+        clk_put(uap->clk);
         kfree(uap);
         return 0;
 }