[PATCH RFC 5/6] phy: qcom: mipi-csi2: Add C-PHY settle calculation

[Nihal Kumar Gupta]

C-PHY settle timing is provided by the sensor and does not use the D-PHY
T_hs_settle calculation. Add a C-PHY settle count helper and select the
settle calculation from the configured PHY mode.

Use the sensor-provided t_prepare_ns and t_preamble_ns values to derive
the C-PHY settle count:

  settle_cnt = (t_prepare_ns + t_preamble_ns / 3) * timer_clk_rate
               / NSEC_PER_SEC

Signed-off-by: Nihal Kumar Gupta <nihal.gupta at oss.qualcomm.com>
---
 drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c | 54 ++++++++++++++++++----
 1 file changed, 44 insertions(+), 10 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c
index 30f7f39ba855a0a2921189050f0084dead207fbd..d93fd9845b50bd7e5623013aecd6db42dd491dca 100644
--- a/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c
+++ b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c
@@ -210,7 +210,7 @@ static void phy_qcom_mipi_csi2_reset(struct mipi_csi2phy_device *csi2phy)
 }
 
 /*
- * phy_qcom_mipi_csi2_settle_cnt_calc - Calculate settle count value
+ * phy_qcom_dphy_settle_cnt - Calculate settle count value
  *
  * Helper function to calculate settle count value. This is
  * based on the CSI2 T_hs_settle parameter which in turn
@@ -218,7 +218,7 @@ static void phy_qcom_mipi_csi2_reset(struct mipi_csi2phy_device *csi2phy)
  *
  * Return settle count.
  */
-static u8 phy_qcom_mipi_csi2_settle_cnt_calc(s64 link_freq, u32 timer_clk_rate)
+static u8 phy_qcom_dphy_settle_cnt(s64 link_freq, u32 timer_clk_rate)
 {
 	u32 t_hs_prepare_max_ps;
 	u32 timer_period_ps;
@@ -310,14 +310,44 @@ phy_qcom_mipi_csi2_gen2_config_lanes(struct mipi_csi2phy_device *csi2phy,
 	return 0;
 }
 
+static u8 phy_qcom_cphy_settle_cnt(struct mipi_csi2phy_stream_cfg *cfg,
+				   u32 timer_clk_rate)
+{
+	u64 settle_cnt;
+
+	settle_cnt = ((u64)cfg->t_prepare_ns +
+		      DIV_ROUND_CLOSEST(cfg->t_preamble_ns, 3)) * timer_clk_rate;
+	do_div(settle_cnt, NSEC_PER_SEC);
+
+	return settle_cnt;
+}
+
 static int phy_qcom_mipi_csi2_lanes_enable(struct mipi_csi2phy_device *csi2phy,
 					   struct mipi_csi2phy_stream_cfg *cfg)
 {
+	struct device *dev = csi2phy->dev;
 	const struct mipi_csi2phy_device_regs *regs = csi2phy_dev_to_regs(csi2phy);
 	struct mipi_csi2phy_lanes_cfg *lane_cfg = &cfg->lane_cfg;
 	u8 settle_cnt;
 	u8 val;
 	int i, ret;
+
+	if (cfg->link_freq <= 0)
+		return -EINVAL;
+
+	switch (csi2phy->phy_mode) {
+	case PHY_MODE_MIPI_CPHY:
+		settle_cnt = phy_qcom_cphy_settle_cnt(cfg,
+						 csi2phy->timer_clk_rate);
+		break;
+	case PHY_MODE_MIPI_DPHY:
+		settle_cnt = phy_qcom_dphy_settle_cnt(cfg->link_freq,
+						 csi2phy->timer_clk_rate);
+		break;
+	default:
+		dev_err(dev, "Unsupported PHY mode %u\n", csi2phy->phy_mode);
+		return -EINVAL;
+	}
 	if (!settle_cnt)
 		return -ENODEV;
 
@@ -334,17 +364,21 @@ static int phy_qcom_mipi_csi2_lanes_enable(struct mipi_csi2phy_device *csi2phy,
 	writel(val, csi2phy->base +
 	       CSIPHY_3PH_CMN_CSI_COMMON_CTRLn(regs->common_regs_offset, 5));
 
-	/* Lane configuration for polarity @ CSIPHY-base + CTRL9 */
-	for (i = 0; i < cfg->num_data_lanes; i++) {
-		if (lane_cfg->data[i].pol) {
-			u8 pos = lane_cfg->data[i].pos;
+	if (csi2phy->phy_mode == PHY_MODE_MIPI_DPHY) {
+		/* Lane configuration for polarity @ CSIPHY-base + CTRL9 */
+		for (i = 0; i < cfg->num_data_lanes; i++) {
+			if (lane_cfg->data[i].pol) {
+				u8 pos = lane_cfg->data[i].pos;
 
-			writel(BIT(2), csi2phy->base + CSIPHY_2PH_LN_CSI_2PHASE_CTRL9n(pos * 2));
+				writel(BIT(2), csi2phy->base +
+				       CSIPHY_2PH_LN_CSI_2PHASE_CTRL9n(pos * 2));
+			}
 		}
-	}
 
-	if (lane_cfg->clk.pol)
-		writel(BIT(2), csi2phy->base + CSIPHY_2PH_LN_CSI_2PHASE_CTRL9n(lane_cfg->clk.pos));
+		if (lane_cfg->clk.pol)
+			writel(BIT(2), csi2phy->base +
+			       CSIPHY_2PH_LN_CSI_2PHASE_CTRL9n(lane_cfg->clk.pos));
+	}
 
 	val = CSIPHY_3PH_CMN_CSI_COMMON_CTRL6_COMMON_PWRDN_B;
 	writel(val, csi2phy->base +

-- 
2.34.1