MDIO clock needs to be initialized in u-boot code for SoCs
having FMAN-v3(v3H or v3L) controller due to below reasons
-On SoCs that have FMAN-v3H like B4860, default value of
MDIO_CLK_DIV bits in mdio_stat(mdio_cfg) register generates
mdio clock too high (much higher than 2.5MHz), violating the
IEEE specs.
-On SOCs that have FMAN-v3L like T1040, default value of
MDIO_CLK_DIV bits is zero, so MDIO clock is disabled.
So, for proper functioninig of MDIO, MDIO_CLK_DIV bits needs to
be properly initialized.
Also this type of initialization is generally done in
PBI(pre-bootloader) phase using rcw.But for chips like T1040
which support deep-sleep, such type of initialization cannot be
done in PBI phase due to the limitation that during deep-sleep
resume, FMAN (MDIO) registers are not accessible in PBI phase.
So, mdio clock initailization must be done as part of u-boot.
This initialization code is implemented in memac_phy.c which
gets compiled only for SoCs having FMANv3, so no extra compilation
flag is required.
Signed-off-by: Priyanka Jain <priyanka.j...@freescale.com>
---
Changes for v2: Corrected Signed-off footer
drivers/net/fm/memac_phy.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/drivers/net/fm/memac_phy.c b/drivers/net/fm/memac_phy.c
index 140e59b..2f4bc11 100644
--- a/drivers/net/fm/memac_phy.c
+++ b/drivers/net/fm/memac_phy.c
@@ -133,5 +133,17 @@ int fm_memac_mdio_init(bd_t *bis, struct memac_mdio_info
*info)
bus->priv = info->regs;
+ /*
+ * On some platforms like B4860, default value of MDIO_CLK_DIV bits
+ * in mdio_stat(mdio_cfg) register generates MDIO clock too high
+ * (much higher than 2.5MHz), violating the IEEE specs.
+ * On other platforms like T1040, default value of MDIO_CLK_DIV bits
+ * is zero, so MDIO clock is disabled.
+ * So, for proper functioning of MDIO, MDIO_CLK_DIV bits needs to
+ * be properly initialized.
+ */
+ setbits_be32(&((struct memac_mdio_controller *)info->regs)->mdio_stat,
+ MDIO_STAT_CLKDIV(258));
+
return mdio_register(bus);
}
--
1.7.4.1
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