From 4ff037c13c1e7ab16362d39a59ebb8fffb929f99 Mon Sep 17 00:00:00 2001
From: Shawn Lin <shawn.lin@rock-chips.com>
Date: Wed, 15 Apr 2020 09:19:09 +0800
Subject: [PATCH] mmc: dw_mmc-rockchip: add v2 tuning support

v2 tuning will inherit pre-stage loader's phase
settings for the first time, and do re-tune if
necessary. Re-tune will still try the rough degrees,
for instance, 90, 180, 270, 360 but continue to do the
fine tuning if sample window isn't good enough.

Change-Id: I593384ee381d09df5b9adfc29a18eb22517b2764
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
---
 drivers/mmc/host/dw_mmc-rockchip.c | 48 ++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -35,6 +35,8 @@ struct dw_mci_rockchip_priv_data {
 	int			default_sample_phase;
 	int			num_phases;
 	bool			internal_phase;
+	int			last_degree;
+	bool			use_v2_tuning;
 };
 
 /*
@@ -279,6 +281,58 @@ static void dw_mci_rk3288_set_ios(struct
 #define TUNING_ITERATION_TO_PHASE(i, num_phases) \
 		(DIV_ROUND_UP((i) * 360, num_phases))
 
+static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
+{
+	struct dw_mci *host = slot->host;
+	struct dw_mci_rockchip_priv_data *priv = host->priv;
+	struct mmc_host *mmc = slot->mmc;
+	u32 degrees[4] = {0, 90, 180, 270}, degree;
+	int i;
+	static bool inherit = true;
+
+	if (inherit) {
+		inherit = false;
+		i = clk_get_phase(priv->sample_clk) / 90;
+		degree = degrees[i];
+		goto done;
+	}
+
+	/*
+	 * v2 only support 4 degrees in theory.
+	 * First we inherit sample phases from firmware, which should
+	 * be able work fine, at least in the first place.
+	 * If retune is needed, we search forward to pick the last
+	 * one phase from degree list and loop around until we get one.
+	 * It's impossible all 4 fixed phase won't be able to work.
+	 */
+	for (i = 0; i < ARRAY_SIZE(degrees); i++) {
+		degree = degrees[i] + priv->last_degree + 90;
+		degree = degree % 360;
+		clk_set_phase(priv->sample_clk, degree);
+		if (mmc_send_tuning(mmc, opcode, NULL)) {
+			/*
+			 * Tuning error, the phase is a bad phase,
+			 * then try using the calculated best phase.
+			 */
+			dev_info(host->dev, "V2 tuned phase to %d error, try the best phase\n", degree);
+			degree = (degree + 180) % 360;
+			clk_set_phase(priv->sample_clk, degree);
+			if (!mmc_send_tuning(mmc, opcode, NULL))
+				break;
+		}
+	}
+
+	if (i == ARRAY_SIZE(degrees)) {
+		dev_warn(host->dev, "V2 All phases bad!");
+		return -EIO;
+	}
+
+done:
+	dev_info(host->dev, "V2 Successfully tuned phase to %d\n", degree);
+	priv->last_degree = degree;
+	return 0;
+}
+
 static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
 {
 	struct dw_mci *host = slot->host;
@@ -303,6 +357,12 @@ static int dw_mci_rk3288_execute_tuning(
 		return -EIO;
 	}
 
+	if (priv->use_v2_tuning) {
+		if (!dw_mci_v2_execute_tuning(slot, opcode))
+			return 0;
+		/* Otherwise we continue using fine tuning */
+	}
+
 	ranges = kmalloc_array(priv->num_phases / 2 + 1,
 			       sizeof(*ranges), GFP_KERNEL);
 	if (!ranges)
@@ -431,6 +491,7 @@ static int dw_mci_common_parse_dt(struct
 
 static int dw_mci_rk3288_parse_dt(struct dw_mci *host)
 {
+	struct device_node *np = host->dev->of_node;
 	struct dw_mci_rockchip_priv_data *priv;
 	int err;
 
@@ -440,6 +501,9 @@ static int dw_mci_rk3288_parse_dt(struct
 
 	priv = host->priv;
 
+	if (of_property_read_bool(np, "rockchip,use-v2-tuning"))
+		priv->use_v2_tuning = true;
+
 	priv->drv_clk = devm_clk_get(host->dev, "ciu-drive");
 	if (IS_ERR(priv->drv_clk))
 		dev_dbg(host->dev, "ciu-drive not available\n");