stmmac: MDC clock dynamically based on the csr clock input

If a specific clk_csr value is passed from the platform
this means that the CSR Clock Range selection cannot be
changed at run-time and it is fixed (as reported in the driver
documentation). Viceversa the driver will try to set the MDC
clock dynamically according to the actual clock input.

Signed-off-by: Deepak Sikri <deepak.sikri@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Reviewed-by: Francesco Virlinzi <francesco.virlinzi@st.com>
Reviewed-by: David Laight <david.laight@aculab.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 53 insertions, 2 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index b14829f8085d..9e42b5d32cff 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -97,6 +97,16 @@ struct stmmac_extra_stats {
         unsigned long normal_irq_n;
 };
 
+/* CSR Frequency Access Defines*/
+#define CSR_F_35M       35000000
+#define CSR_F_60M       60000000
+#define CSR_F_100M      100000000
+#define CSR_F_150M      150000000
+#define CSR_F_250M      250000000
+#define CSR_F_300M      300000000
+
+#define MAC_CSR_H_FRQ_MASK      0x20
+
 #define HASH_TABLE_SIZE 64
 #define PAUSE_TIME 0x200
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 7182f159c2c9..ddd07691cef1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -84,6 +84,7 @@ struct stmmac_priv {
 #ifdef CONFIG_HAVE_CLK
         struct clk *stmmac_clk;
 #endif
+        int clk_csr;
 };
 
 extern int phyaddr;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ddb47e147f70..90d5c4c75d25 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -163,6 +163,35 @@ static void stmmac_verify_args(void)
                 pause = PAUSE_TIME;
 }
 
+static void stmmac_clk_csr_set(struct stmmac_priv *priv)
+{
+#ifdef CONFIG_HAVE_CLK
+        u32 clk_rate;
+
+        clk_rate = clk_get_rate(priv->stmmac_clk);
+
+        /* Platform provided default clk_csr would be assumed valid
+         * for all other cases except for the below mentioned ones. */
+        if (!(priv->clk_csr & MAC_CSR_H_FRQ_MASK)) {
+                if (clk_rate < CSR_F_35M)
+                        priv->clk_csr = STMMAC_CSR_20_35M;
+                else if ((clk_rate >= CSR_F_35M) && (clk_rate < CSR_F_60M))
+                        priv->clk_csr = STMMAC_CSR_35_60M;
+                else if ((clk_rate >= CSR_F_60M) && (clk_rate < CSR_F_100M))
+                        priv->clk_csr = STMMAC_CSR_60_100M;
+                else if ((clk_rate >= CSR_F_100M) && (clk_rate < CSR_F_150M))
+                        priv->clk_csr = STMMAC_CSR_100_150M;
+                else if ((clk_rate >= CSR_F_150M) && (clk_rate < CSR_F_250M))
+                        priv->clk_csr = STMMAC_CSR_150_250M;
+                else if ((clk_rate >= CSR_F_250M) && (clk_rate < CSR_F_300M))
+                        priv->clk_csr = STMMAC_CSR_250_300M;
+        } /* For values higher than the IEEE 802.3 specified frequency
+           * we can not estimate the proper divider as it is not known
+           * the frequency of clk_csr_i. So we do not change the default
+           * divider. */
+#endif
+}
+
 #if defined(STMMAC_XMIT_DEBUG) || defined(STMMAC_RX_DEBUG)
 static void print_pkt(unsigned char *buf, int len)
 {
@@ -1890,6 +1919,17 @@ struct stmmac_priv *stmmac_dvr_probe(struct device *device,
         if (stmmac_clk_get(priv))
                 goto error;
 
+        /* If a specific clk_csr value is passed from the platform
+         * this means that the CSR Clock Range selection cannot be
+         * changed at run-time and it is fixed. Viceversa the driver'll try to
+         * set the MDC clock dynamically according to the csr actual
+         * clock input.
+         */
+        if (!priv->plat->clk_csr)
+                stmmac_clk_csr_set(priv);
+        else
+                priv->clk_csr = priv->plat->clk_csr;
+
         return priv;
 
 error:
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index 1a420142f6ac..ade108232048 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -70,7 +70,7 @@ static int stmmac_mdio_read(struct mii_bus *bus, int phyaddr, int phyreg)
         int data;
         u16 regValue = (((phyaddr << 11) & (0x0000F800)) |
                         ((phyreg << 6) & (0x000007C0)));
-        regValue |= MII_BUSY | ((priv->plat->clk_csr & 0xF) << 2);
+        regValue |= MII_BUSY | ((priv->clk_csr & 0xF) << 2);
 
         if (stmmac_mdio_busy_wait(priv->ioaddr, mii_address))
                 return -EBUSY;
@@ -106,7 +106,7 @@ static int stmmac_mdio_write(struct mii_bus *bus, int phyaddr, int phyreg,
             (((phyaddr << 11) & (0x0000F800)) | ((phyreg << 6) & (0x000007C0)))
             | MII_WRITE;
 
-        value |= MII_BUSY | ((priv->plat->clk_csr & 0xF) << 2);
+        value |= MII_BUSY | ((priv->clk_csr & 0xF) << 2);
 
         /* Wait until any existing MII operation is complete */
         if (stmmac_mdio_busy_wait(priv->ioaddr, mii_address))