stmmac: ptp: fix the reference clock

The PTP reference clock, used for setting the addend in the Timestamp Addend
Register, was erroneously hard-coded (as reported in the databook just as
example).

The patch removes the macro named: STMMAC_SYSCLOCK and allows to use a
reference clock (clk_ptp_ref_i) that can be passed from the platform.

If not passed, the main driver clock will be used as default; note that
this can be fine on some platforms.

Note that, prior this patch, using the old STMMAC_SYSCLOCK on some platforms,
as side effect, the ptp clock can move faster/slower than the system clock.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index 9b03c57..e45ac3f 100644 (file)
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -39,6 +39,10 @@ Optional properties:
   further clocks may be specified in derived bindings.
 - clock-names: One name for each entry in the clocks property, the
   first one should be "stmmaceth".
+- clk_ptp_ref: this is the PTP reference clock; in case of the PTP is
+  available this clock is used for programming the Timestamp Addend Register.
+  If not passed then the system clock will be used and this is fine on some
+  platforms.
 
 Examples:
 

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index ca01035..128a0b7 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -105,6 +105,8 @@ struct stmmac_priv {
        struct ptp_clock *ptp_clock;
        struct ptp_clock_info ptp_clock_ops;
        unsigned int default_addend;
+       struct clk *clk_ptp_ref;
+       unsigned int clk_ptp_rate;
        u32 adv_ts;
        int use_riwt;
        int irq_wake;

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 51a89d4..0365289 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -603,16 +603,16 @@ static int stmmac_hwtstamp_ioctl(struct net_device *dev, struct ifreq *ifr)
                /* calculate default added value:
                 * formula is :
                 * addend = (2^32)/freq_div_ratio;
-                * where, freq_div_ratio = STMMAC_SYSCLOCK/50MHz
-                * hence, addend = ((2^32) * 50MHz)/STMMAC_SYSCLOCK;
-                * NOTE: STMMAC_SYSCLOCK should be >= 50MHz to
+                * where, freq_div_ratio = clk_ptp_ref_i/50MHz
+                * hence, addend = ((2^32) * 50MHz)/clk_ptp_ref_i;
+                * NOTE: clk_ptp_ref_i should be >= 50MHz to
                 *       achive 20ns accuracy.
                 *
                 * 2^x * y == (y << x), hence
                 * 2^32 * 50000000 ==> (50000000 << 32)
                 */
                temp = (u64) (50000000ULL << 32);
-               priv->default_addend = div_u64(temp, STMMAC_SYSCLOCK);
+               priv->default_addend = div_u64(temp, priv->clk_ptp_rate);
                priv->hw->ptp->config_addend(priv->ioaddr,
                                             priv->default_addend);
 
@@ -638,6 +638,16 @@ static int stmmac_init_ptp(struct stmmac_priv *priv)
        if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp))
                return -EOPNOTSUPP;
 
+       /* Fall-back to main clock in case of no PTP ref is passed */
+       priv->clk_ptp_ref = devm_clk_get(priv->device, "clk_ptp_ref");
+       if (IS_ERR(priv->clk_ptp_ref)) {
+               priv->clk_ptp_rate = clk_get_rate(priv->stmmac_clk);
+               priv->clk_ptp_ref = NULL;
+       } else {
+               clk_prepare_enable(priv->clk_ptp_ref);
+               priv->clk_ptp_rate = clk_get_rate(priv->clk_ptp_ref);
+       }
+
        priv->adv_ts = 0;
        if (priv->dma_cap.atime_stamp && priv->extend_desc)
                priv->adv_ts = 1;
@@ -657,6 +667,8 @@ static int stmmac_init_ptp(struct stmmac_priv *priv)
 
 static void stmmac_release_ptp(struct stmmac_priv *priv)
 {
+       if (priv->clk_ptp_ref)
+               clk_disable_unprepare(priv->clk_ptp_ref);
        stmmac_ptp_unregister(priv);
 }
 

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
index 3dbc047..4535df3 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
@@ -25,8 +25,6 @@
 #ifndef __STMMAC_PTP_H__
 #define __STMMAC_PTP_H__
 
-#define STMMAC_SYSCLOCK 62500000
-
 /* IEEE 1588 PTP register offsets */
 #define PTP_TCR                0x0700  /* Timestamp Control Reg */
 #define PTP_SSIR       0x0704  /* Sub-Second Increment Reg */