cpm_uart: Add generic clock API support to set baudrates

This patch introduces baudrate setting support via the generic clock API.
When present the optional device tree clock property is used instead of
fsl-cpm-brg. Platforms can then define complex clock schemes, to output
the serial clock on an external pin for instance.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

2 files changed, 20 insertions, 7 deletions

diff --git a/drivers/serial/cpm_uart/cpm_uart.h b/drivers/serial/cpm_uart/cpm_uart.h
index 5999ef5ac78e..7274b527a3c1 100644
--- a/drivers/serial/cpm_uart/cpm_uart.h
+++ b/drivers/serial/cpm_uart/cpm_uart.h
@@ -77,6 +77,7 @@ struct uart_cpm_port {
         unsigned char           *rx_buf;
         u32                     flags;
         void                    (*set_lineif)(struct uart_cpm_port *);
+        struct clk              *clk;
         u8                      brg;
         uint                     dp_addr;
         void                    *mem_addr;
diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c
index 5e0c17f71653..25efca5a7a1f 100644
--- a/drivers/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/serial/cpm_uart/cpm_uart_core.c
@@ -45,6 +45,7 @@
 #include <linux/of_platform.h>
 #include <linux/gpio.h>
 #include <linux/of_gpio.h>
+#include <linux/clk.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -596,7 +597,10 @@ static void cpm_uart_set_termios(struct uart_port *port,
                 out_be16(&sccp->scc_psmr, (sbits << 12) | scval);
         }
 
-        cpm_set_brg(pinfo->brg - 1, baud);
+        if (pinfo->clk)
+                clk_set_rate(pinfo->clk, baud);
+        else
+                cpm_set_brg(pinfo->brg - 1, baud);
         spin_unlock_irqrestore(&port->lock, flags);
 }
 
@@ -1023,13 +1027,21 @@ static int cpm_uart_init_port(struct device_node *np,
         int ret;
         int i;
 
-        data = of_get_property(np, "fsl,cpm-brg", &len);
-        if (!data || len != 4) {
-                printk(KERN_ERR "CPM UART %s has no/invalid "
-                                "fsl,cpm-brg property.\n", np->name);
-                return -EINVAL;
+        data = of_get_property(np, "clock", NULL);
+        if (data) {
+                struct clk *clk = clk_get(NULL, (const char*)data);
+                if (!IS_ERR(clk))
+                        pinfo->clk = clk;
+        }
+        if (!pinfo->clk) {
+                data = of_get_property(np, "fsl,cpm-brg", &len);
+                if (!data || len != 4) {
+                        printk(KERN_ERR "CPM UART %s has no/invalid "
+                                        "fsl,cpm-brg property.\n", np->name);
+                        return -EINVAL;
+                }
+                pinfo->brg = *data;
         }
-        pinfo->brg = *data;
 
         data = of_get_property(np, "fsl,cpm-command", &len);
         if (!data || len != 4) {