net: phy: Add support to configure clock in Broadcom iProc mdio mux

Add support to configure the internal rate adjust register based on the
core clock supplied through device tree in the Broadcom iProc mdio mux.

The operating frequency of the mdio mux block is 11MHz. This is derrived
by dividing the clock to the mdio mux with the rate adjust register.

In some SoC's the default values of the rate adjust register do not yield
11MHz. These SoC's are required to specify the clock via the device tree
for proper operation.

Signed-off-by: Arun Parameswaran <arun.parameswaran@broadcom.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/mdio-mux-bcm-iproc.c b/drivers/net/phy/mdio-mux-bcm-iproc.c
index e6146b439b455067a42e5eb25a21f6d089b4307e..c5aae5e3f20f57a6ca981c467b7a66e69f6bd90f 100644 (file)
--- a/drivers/net/phy/mdio-mux-bcm-iproc.c
+++ b/drivers/net/phy/mdio-mux-bcm-iproc.c
@@ -13,7 +13,7 @@
  * You should have received a copy of the GNU General Public License
  * version 2 (GPLv2) along with this source code.
  */
-
+#include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/device.h>
 #include <linux/of_mdio.h>
@@ -22,6 +22,10 @@
 #include <linux/mdio-mux.h>
 #include <linux/delay.h>
 
+#define MDIO_RATE_ADJ_EXT_OFFSET       0x000
+#define MDIO_RATE_ADJ_INT_OFFSET       0x004
+#define MDIO_RATE_ADJ_DIVIDENT_SHIFT   16
+
 #define MDIO_SCAN_CTRL_OFFSET          0x008
 #define MDIO_SCAN_CTRL_OVRIDE_EXT_MSTR 28
 
@@ -49,21 +53,38 @@
 
 #define MDIO_REG_ADDR_SPACE_SIZE       0x250
 
+#define MDIO_OPERATING_FREQUENCY       11000000
+#define MDIO_RATE_ADJ_DIVIDENT         1
+
 struct iproc_mdiomux_desc {
        void *mux_handle;
        void __iomem *base;
        struct device *dev;
        struct mii_bus *mii_bus;
+       struct clk *core_clk;
 };
 
 static void mdio_mux_iproc_config(struct iproc_mdiomux_desc *md)
 {
+       u32 divisor;
        u32 val;
 
        /* Disable external mdio master access */
        val = readl(md->base + MDIO_SCAN_CTRL_OFFSET);
        val |= BIT(MDIO_SCAN_CTRL_OVRIDE_EXT_MSTR);
        writel(val, md->base + MDIO_SCAN_CTRL_OFFSET);
+
+       if (md->core_clk) {
+               /* use rate adjust regs to derrive the mdio's operating
+                * frequency from the specified core clock
+                */
+               divisor = clk_get_rate(md->core_clk) / MDIO_OPERATING_FREQUENCY;
+               divisor = divisor / (MDIO_RATE_ADJ_DIVIDENT + 1);
+               val = divisor;
+               val |= MDIO_RATE_ADJ_DIVIDENT << MDIO_RATE_ADJ_DIVIDENT_SHIFT;
+               writel(val, md->base + MDIO_RATE_ADJ_EXT_OFFSET);
+               writel(val, md->base + MDIO_RATE_ADJ_INT_OFFSET);
+       }
 }
 
 static int iproc_mdio_wait_for_idle(void __iomem *base, bool result)
@@ -204,6 +225,19 @@ static int mdio_mux_iproc_probe(struct platform_device *pdev)
                return -ENOMEM;
        }
 
+       md->core_clk = devm_clk_get(&pdev->dev, NULL);
+       if (md->core_clk == ERR_PTR(-ENOENT) ||
+           md->core_clk == ERR_PTR(-EINVAL))
+               md->core_clk = NULL;
+       else if (IS_ERR(md->core_clk))
+               return PTR_ERR(md->core_clk);
+
+       rc = clk_prepare_enable(md->core_clk);
+       if (rc) {
+               dev_err(&pdev->dev, "failed to enable core clk\n");
+               return rc;
+       }
+
        bus = md->mii_bus;
        bus->priv = md;
        bus->name = "iProc MDIO mux bus";
@@ -217,7 +251,7 @@ static int mdio_mux_iproc_probe(struct platform_device *pdev)
        rc = mdiobus_register(bus);
        if (rc) {
                dev_err(&pdev->dev, "mdiomux registration failed\n");
-               return rc;
+               goto out_clk;
        }
 
        platform_set_drvdata(pdev, md);
@@ -236,6 +270,8 @@ static int mdio_mux_iproc_probe(struct platform_device *pdev)
 
 out_register:
        mdiobus_unregister(bus);
+out_clk:
+       clk_disable_unprepare(md->core_clk);
        return rc;
 }
 
@@ -245,6 +281,7 @@ static int mdio_mux_iproc_remove(struct platform_device *pdev)
 
        mdio_mux_uninit(md->mux_handle);
        mdiobus_unregister(md->mii_bus);
+       clk_disable_unprepare(md->core_clk);
 
        return 0;
 }