[PATCH linux-phy v2 3/4] phy: marvell: phy-mvebu-a3700-comphy: Support changing tx amplitude for ethernet
From: Marek Behún
Date: Wed Aug 17 2022 - 16:04:02 EST
Add support to set SerDes transmit amplitude if specified via the
'tx-p2p-microvolt' and 'tx-p2p-microvolt-names' device-tree properties.
This support is currently only for ethernet mode.
Signed-off-by: Marek Behún <kabel@xxxxxxxxxx>
---
drivers/phy/marvell/phy-mvebu-a3700-comphy.c | 109 ++++++++++++++++++-
1 file changed, 108 insertions(+), 1 deletion(-)
diff --git a/drivers/phy/marvell/phy-mvebu-a3700-comphy.c b/drivers/phy/marvell/phy-mvebu-a3700-comphy.c
index a4d7d9bd100d..7fabd959ae0f 100644
--- a/drivers/phy/marvell/phy-mvebu-a3700-comphy.c
+++ b/drivers/phy/marvell/phy-mvebu-a3700-comphy.c
@@ -68,6 +68,16 @@
#define SPEED_PLL_MASK GENMASK(7, 2)
#define SPEED_PLL_VALUE_16 FIELD_PREP(SPEED_PLL_MASK, 0x10)
+#define COMPHY_GEN1_SET0 0x0d
+#define COMPHY_GEN2_SET0 0x0f
+#define COMPHY_GEN3_SET0 0x11
+#define COMPHY_GEN4_SET0 0x13
+#define COMPHY_GENx_SET0(x) (0x0d + (((x) & 3) - 1) * 2)
+#define Gx_TX_AMP_MASK GENMASK(5, 1)
+#define Gx_TX_AMP_VALUE(x) FIELD_PREP(Gx_TX_AMP_MASK, x)
+#define Gx_TX_AMP_ADJ BIT(6)
+#define Gx_TX_AMP_1025MV (Gx_TX_AMP_VALUE(0x12) | Gx_TX_AMP_ADJ)
+
#define COMPHY_DIG_LOOPBACK_EN 0x23
#define SEL_DATA_WIDTH_MASK GENMASK(11, 10)
#define DATA_WIDTH_10BIT FIELD_PREP(SEL_DATA_WIDTH_MASK, 0x0)
@@ -269,6 +279,7 @@ struct mvebu_a3700_comphy_priv {
struct mvebu_a3700_comphy_lane {
struct mvebu_a3700_comphy_priv *priv;
struct device *dev;
+ struct phy *phy;
unsigned int id;
enum phy_mode mode;
int submode;
@@ -385,6 +396,15 @@ static inline void comphy_reg_set16(void __iomem *addr, u16 data, u16 mask)
}
/* Used for accessing lane 2 registers (SATA/USB3 PHY) */
+static u16 comphy_get_indirect(struct mvebu_a3700_comphy_priv *priv, u32 offset)
+{
+ writel(offset,
+ priv->lane2_phy_indirect + COMPHY_LANE2_INDIR_ADDR);
+
+ /* We need to read the register with 32-bit read */
+ return readl(priv->lane2_phy_indirect + COMPHY_LANE2_INDIR_DATA);
+}
+
static void comphy_set_indirect(struct mvebu_a3700_comphy_priv *priv,
u32 offset, u16 data, u16 mask)
{
@@ -394,6 +414,21 @@ static void comphy_set_indirect(struct mvebu_a3700_comphy_priv *priv,
data, mask);
}
+static u16 comphy_lane_reg_get(struct mvebu_a3700_comphy_lane *lane, u16 reg)
+{
+ if (lane->id == 2) {
+ /* lane 2 PHY registers are accessed indirectly */
+ return comphy_get_indirect(lane->priv,
+ reg + COMPHY_LANE2_REGS_BASE);
+ } else {
+ void __iomem *base = lane->id == 1 ?
+ lane->priv->lane1_phy_regs :
+ lane->priv->lane0_phy_regs;
+
+ return readw(base + COMPHY_LANE_REG_DIRECT(reg));
+ }
+}
+
static void comphy_lane_reg_set(struct mvebu_a3700_comphy_lane *lane,
u16 reg, u16 data, u16 mask)
{
@@ -624,10 +659,53 @@ static void comphy_gbe_phy_init(struct mvebu_a3700_comphy_lane *lane,
}
}
+static u8 comphy_find_best_tx_amp(bool full_swing, u32 amp, u32 *true_amp)
+{
+ static const u32 half_swing_table[32] = {
+ 250, 270, 290, 310, 330, 345, 365, 380,
+ 400, 420, 435, 455, 470, 490, 505, 525,
+ 485, 520, 555, 590, 625, 660, 695, 730,
+ 765, 800, 830, 865, 900, 930, 965, 1000,
+ };
+ static const u32 full_swing_table[22] = {
+ 470, 505, 540, 575, 610, 645, 680, 715,
+ 750, 785, 820, 850, 885, 915, 950, 980,
+ 900, 965, 1025, 1095, 1160, 1220,
+ };
+ u32 diff, min_diff;
+ const u32 *table;
+ size_t len;
+ u8 res;
+
+ if (full_swing) {
+ table = full_swing_table;
+ len = ARRAY_SIZE(full_swing_table);
+ } else {
+ table = half_swing_table;
+ len = ARRAY_SIZE(half_swing_table);
+ }
+
+ res = 0;
+ min_diff = abs(amp - table[0]);
+
+ for (size_t i = 1; i < len; ++i) {
+ diff = abs(amp - table[i]);
+ if (diff < min_diff) {
+ min_diff = diff;
+ res = i;
+ }
+ }
+
+ if (true_amp)
+ *true_amp = table[res];
+
+ return res;
+}
+
static int
mvebu_a3700_comphy_ethernet_power_on(struct mvebu_a3700_comphy_lane *lane)
{
- u32 mask, data, speed_sel;
+ u32 mask, data, speed_sel, tx_amp_uv;
int ret;
/* Set selector */
@@ -746,6 +824,34 @@ mvebu_a3700_comphy_ethernet_power_on(struct mvebu_a3700_comphy_lane *lane)
comphy_gbe_phy_init(lane,
lane->submode != PHY_INTERFACE_MODE_2500BASEX);
+ /*
+ * Change transmit amplitude if specified in device-tree.
+ */
+ if (!device_get_tx_p2p_amplitude(&lane->phy->dev,
+ phy_modes(lane->submode),
+ &tx_amp_uv)) {
+ u32 tx_amp_mv, true_tx_amp_mv;
+ bool full_swing;
+ u8 tx_amp;
+ u16 reg;
+
+ reg = COMPHY_GENx_SET0(speed_sel + 1);
+
+ data = comphy_lane_reg_get(lane, reg);
+ full_swing = data & Gx_TX_AMP_ADJ;
+ tx_amp_mv = DIV_ROUND_CLOSEST(tx_amp_uv, 1000);
+ tx_amp = comphy_find_best_tx_amp(full_swing, tx_amp_mv,
+ &true_tx_amp_mv);
+
+ data = Gx_TX_AMP_VALUE(tx_amp);
+ mask = Gx_TX_AMP_MASK;
+ comphy_lane_reg_set(lane, reg, data, mask);
+
+ dev_dbg(lane->dev,
+ "changed tx amplitude to %u mV (requested %u mV) on lane %d\n",
+ true_tx_amp_mv, tx_amp_mv, lane->id);
+ }
+
/*
* 14. Check the PHY Polarity invert bit
*/
@@ -1382,6 +1488,7 @@ static int mvebu_a3700_comphy_probe(struct platform_device *pdev)
lane->priv = priv;
lane->dev = &pdev->dev;
+ lane->phy = phy;
lane->mode = PHY_MODE_INVALID;
lane->submode = PHY_INTERFACE_MODE_NA;
lane->id = lane_id;
--
2.35.1