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Date:      Wed, 16 Oct 2013 19:36:50 +0000 (UTC)
From:      Adrian Chadd <adrian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r256648 - head/sys/mips/atheros
Message-ID:  <201310161936.r9GJao3G026937@svn.freebsd.org>
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Author: adrian
Date: Wed Oct 16 19:36:50 2013
New Revision: 256648
URL: http://svnweb.freebsd.org/changeset/base/256648

Log:
  Allow the MDIO bus frequency to be selected.
  
  The MDIO bus frequency is configured as a divisor off of the MDIO bus
  reference clock.  For the AR9344 and later, the MDIO bus frequency can
  be faster than normal (ie, up to 100MHz) and thus a static divisor may
  not be very applicable.
  
  So, for those boards that may require an actual frequency to be selected
  regardless of what crazy stuff the vendor throws in uboot, one can now
  set the MDIO bus frequency.  It uses the MDIO frequency and the target
  frequency to choose a divisor that doesn't exceed the target frequency.
  
  By default it will choose:
  
  * DIV_28 on everything; except
  * DIV_58 on the AR9344 to be conservative.
  
  Whilst I'm here, add some comments about the defaults being not quite
  right.  For the other internal switch devices (like the AR933x, AR724x)
  the divisor can be higher - it's internal and the reference MDIO clock
  is much lower than 100MHz.
  
  The divisor tables and loop code is inspired from Linux/OpenWRT.  It's very
  simple; I didn't feel that reimplementing it would yield a substantially
  different solution.
  
  Tested:
  
  * AR9331 (mips24k)
  * AR9344 (mips74k)
  
  Obtained from:	Linux/OpenWRT

Modified:
  head/sys/mips/atheros/if_arge.c
  head/sys/mips/atheros/if_argevar.h

Modified: head/sys/mips/atheros/if_arge.c
==============================================================================
--- head/sys/mips/atheros/if_arge.c	Wed Oct 16 19:06:44 2013	(r256647)
+++ head/sys/mips/atheros/if_arge.c	Wed Oct 16 19:36:50 2013	(r256648)
@@ -345,10 +345,101 @@ arge_reset_mac(struct arge_softc *sc)
 }
 
 /*
+ * These values map to the divisor values programmed into
+ * AR71XX_MAC_MII_CFG.
+ *
+ * The index of each value corresponds to the divisor section
+ * value in AR71XX_MAC_MII_CFG (ie, table[0] means '0' in
+ * AR71XX_MAC_MII_CFG, table[1] means '1', etc.)
+ */
+static const uint32_t ar71xx_mdio_div_table[] = {
+	4, 4, 6, 8, 10, 14, 20, 28,
+};
+
+static const uint32_t ar7240_mdio_div_table[] = {
+	2, 2, 4, 6, 8, 12, 18, 26, 32, 40, 48, 56, 62, 70, 78, 96,
+};
+
+static const uint32_t ar933x_mdio_div_table[] = {
+	4, 4, 6, 8, 10, 14, 20, 28, 34, 42, 50, 58, 66, 74, 82, 98,
+};
+
+/*
+ * Lookup the divisor to use based on the given frequency.
+ *
+ * Returns the divisor to use, or -ve on error.
+ */
+static int
+arge_mdio_get_divider(struct arge_softc *sc, unsigned long mdio_clock)
+{
+	unsigned long ref_clock, t;
+	const uint32_t *table;
+	int ndivs;
+	int i;
+
+	/*
+	 * This is the base MDIO frequency on the SoC.
+	 * The dividers .. well, divide. Duh.
+	 */
+	ref_clock = ar71xx_mdio_freq();
+
+	/*
+	 * If either clock is undefined, just tell the
+	 * caller to fall through to the defaults.
+	 */
+	if (ref_clock == 0 || mdio_clock == 0)
+		return (-EINVAL);
+
+	/*
+	 * Pick the correct table!
+	 */
+	switch (ar71xx_soc) {
+	case AR71XX_SOC_AR9330:
+	case AR71XX_SOC_AR9331:
+	case AR71XX_SOC_AR9341:
+	case AR71XX_SOC_AR9342:
+	case AR71XX_SOC_AR9344:
+		table = ar933x_mdio_div_table;
+		ndivs = nitems(ar933x_mdio_div_table);
+		break;
+
+	case AR71XX_SOC_AR7240:
+	case AR71XX_SOC_AR7241:
+	case AR71XX_SOC_AR7242:
+		table = ar7240_mdio_div_table;
+		ndivs = nitems(ar7240_mdio_div_table);
+		break;
+
+	default:
+		table = ar71xx_mdio_div_table;
+		ndivs = nitems(ar71xx_mdio_div_table);
+	}
+
+	/*
+	 * Now, walk through the list and find the first divisor
+	 * that falls under the target MDIO frequency.
+	 *
+	 * The divisors go up, but the corresponding frequencies
+	 * are actually decreasing.
+	 */
+	for (i = 0; i < ndivs; i++) {
+		t = ref_clock / table[i];
+		if (t <= mdio_clock) {
+			return (i);
+		}
+	}
+
+	ARGEDEBUG(sc, ARGE_DBG_RESET,
+	    "No divider found; MDIO=%lu Hz; target=%lu Hz\n",
+		ref_clock, mdio_clock);
+	return (-ENOENT);
+}
+
+/*
  * Fetch the MDIO bus clock rate.
  *
  * For now, the default is DIV_28 for everything
- * bar AR934x, which will be DIV_42.
+ * bar AR934x, which will be DIV_58.
  *
  * It will definitely need updating to take into account
  * the MDIO bus core clock rate and the target clock
@@ -357,12 +448,48 @@ arge_reset_mac(struct arge_softc *sc)
 static uint32_t
 arge_fetch_mdiobus_clock_rate(struct arge_softc *sc)
 {
+	int mdio_freq, div;
+
+	/*
+	 * Is the MDIO frequency defined? If so, find a divisor that
+	 * makes reasonable sense.  Don't overshoot the frequency.
+	 */
+	if (resource_int_value(device_get_name(sc->arge_dev),
+	    device_get_unit(sc->arge_dev),
+	    "mdio_freq",
+	    &mdio_freq) == 0) {
+		sc->arge_mdiofreq = mdio_freq;
+		div = arge_mdio_get_divider(sc, sc->arge_mdiofreq);
+		if (bootverbose)
+			device_printf(sc->arge_dev,
+			    "%s: mdio ref freq=%llu Hz, target freq=%llu Hz,"
+			    " divisor index=%d\n",
+			    __func__,
+			    (unsigned long long) ar71xx_mdio_freq(),
+			    (unsigned long long) mdio_freq,
+			    div);
+		if (div >= 0)
+			return (div);
+	}
 
+	/*
+	 * Default value(s).
+	 *
+	 * XXX obviously these need .. fixing.
+	 *
+	 * From Linux/OpenWRT:
+	 *
+	 * + 7240? DIV_6
+	 * + Builtin-switch port and not 934x? DIV_10
+	 * + Not built-in switch port and 934x? DIV_58
+	 * + .. else DIV_28.
+	 */
 	switch (ar71xx_soc) {
 	case AR71XX_SOC_AR9341:
 	case AR71XX_SOC_AR9342:
 	case AR71XX_SOC_AR9344:
-		return (MAC_MII_CFG_CLOCK_DIV_42);
+		return (MAC_MII_CFG_CLOCK_DIV_58);
+		break;
 	default:
 		return (MAC_MII_CFG_CLOCK_DIV_28);
 	}

Modified: head/sys/mips/atheros/if_argevar.h
==============================================================================
--- head/sys/mips/atheros/if_argevar.h	Wed Oct 16 19:06:44 2013	(r256647)
+++ head/sys/mips/atheros/if_argevar.h	Wed Oct 16 19:36:50 2013	(r256648)
@@ -169,6 +169,7 @@ struct arge_softc {
 	int			arge_mac_unit;
 	int			arge_if_flags;
 	uint32_t		arge_debug;
+	uint32_t		arge_mdiofreq;
 	struct {
 		uint32_t	tx_pkts_unaligned;
 		uint32_t	tx_pkts_aligned;

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