flexcan: Prefer device tree clock frequency if available.

If our CAN device's device tree node has a clock-frequency property,
then use that value for the can devices clock frequency.  If not, fall
back to asking the platform/mach code for the clock frequency associated
with the flexcan device.

Signed-off-by: Robin Holt <holt@sgi.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>,
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>,
Cc: U Bhaskar-B22300 <B22300@freescale.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: socketcan-core@lists.berlios.de,
Cc: netdev@vger.kernel.org,
Cc: PPC list <linuxppc-dev@lists.ozlabs.org>
Cc: devicetree-discuss@lists.ozlabs.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 9 deletions

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index cc1e0a7b554f..e02337953f41 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -33,6 +33,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 
 #define DRV_NAME                        "flexcan"
@@ -925,16 +926,29 @@ static int __devinit flexcan_probe(struct platform_device *pdev)
         struct net_device *dev;
         struct flexcan_priv *priv;
         struct resource *mem;
-        struct clk *clk;
+        struct clk *clk = NULL;
         void __iomem *base;
         resource_size_t mem_size;
         int err, irq;
+        u32 clock_freq = 0;
+
+        if (pdev->dev.of_node) {
+                const u32 *clock_freq_p;
 
-        clk = clk_get(&pdev->dev, NULL);
-        if (IS_ERR(clk)) {
-                dev_err(&pdev->dev, "no clock defined\n");
-                err = PTR_ERR(clk);
-                goto failed_clock;
+                clock_freq_p = of_get_property(pdev->dev.of_node,
+                                                "clock-frequency", NULL);
+                if (clock_freq_p)
+                        clock_freq = *clock_freq_p;
+        }
+
+        if (!clock_freq) {
+                clk = clk_get(&pdev->dev, NULL);
+                if (IS_ERR(clk)) {
+                        dev_err(&pdev->dev, "no clock defined\n");
+                        err = PTR_ERR(clk);
+                        goto failed_clock;
+                }
+                clock_freq = clk_get_rate(clk);
         }
 
         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -967,7 +981,7 @@ static int __devinit flexcan_probe(struct platform_device *pdev)
         dev->flags |= IFF_ECHO; /* we support local echo in hardware */
 
         priv = netdev_priv(dev);
-        priv->can.clock.freq = clk_get_rate(clk);
+        priv->can.clock.freq = clock_freq;
         priv->can.bittiming_const = &flexcan_bittiming_const;
         priv->can.do_set_mode = flexcan_set_mode;
         priv->can.do_get_berr_counter = flexcan_get_berr_counter;
@@ -1002,7 +1016,8 @@ static int __devinit flexcan_probe(struct platform_device *pdev)
  failed_map:
         release_mem_region(mem->start, mem_size);
  failed_get:
-        clk_put(clk);
+        if (clk)
+                clk_put(clk);
  failed_clock:
         return err;
 }
@@ -1020,7 +1035,8 @@ static int __devexit flexcan_remove(struct platform_device *pdev)
         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         release_mem_region(mem->start, resource_size(mem));
 
-        clk_put(priv->clk);
+        if (priv->clk)
+                clk_put(priv->clk);
 
         free_candev(dev);