[PATCH 2/3] mmc: dw_mmc-rockchip: Add v2 tuning support

[Detlev Casanova <detlev.casanova@collabora.com>]

From: Shawn Lin <shawn.lin@rock-chips.com>

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.

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

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c b/drivers/mmc/host/dw_mmc-rockchip.c
index b07190ba4b7ac..c47b93d99a1b3 100644
--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -24,6 +24,8 @@ struct dw_mci_rockchip_priv_data {
 	struct clk		*sample_clk;
 	int			default_sample_phase;
 	int			num_phases;
+	bool			use_v2_tuning;
+	int			last_degree;
 };
 
 static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
@@ -134,6 +136,42 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
 #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] = {90, 180, 270, 360};
+	int i;
+	static bool inherit = true;
+
+	if (inherit) {
+		inherit = false;
+		i = clk_get_phase(priv->sample_clk) / 90 - 1;
+		goto done;
+	}
+
+	/* v2 only support 4 degrees in theory */
+	for (i = 0; i < ARRAY_SIZE(degrees); i++) {
+		if (degrees[i] == priv->last_degree)
+			continue;
+
+		clk_set_phase(priv->sample_clk, degrees[i]);
+		if (!mmc_send_tuning(mmc, opcode, NULL))
+			break;
+	}
+
+	if (i == ARRAY_SIZE(degrees)) {
+		dev_warn(host->dev, "All phases bad!");
+		return -EIO;
+	}
+
+done:
+	dev_info(host->dev, "Successfully tuned phase to %d\n", degrees[i]);
+	priv->last_degree = degrees[i];
+	return 0;
+}
+
 static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
 {
 	struct dw_mci *host = slot->host;
@@ -157,6 +195,13 @@ static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
 		return -EIO;
 	}
 
+	if (priv->use_v2_tuning) {
+		ret = dw_mci_v2_execute_tuning(slot, opcode);
+		if (!ret)
+			return 0;
+		/* Otherwise we continue using fine tuning */
+	}
+
 	ranges = kmalloc_array(priv->num_phases / 2 + 1,
 			       sizeof(*ranges), GFP_KERNEL);
 	if (!ranges)
@@ -277,6 +322,9 @@ static int dw_mci_rk3288_parse_dt(struct dw_mci *host)
 					&priv->default_sample_phase))
 		priv->default_sample_phase = 0;
 
+	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");
-- 
2.46.0