[PATCH v4 6/7] phy: rockchip-samsung-dcphy: Add a second PHY for the receiver

[Jason Yang via B4 Relay <devnull+jason98166.gmail.com@kernel.org>]

From: Jason Yang <jason98166@gmail.com>

Give the receiver a struct phy of its own, with its own phy_ops and its
own samsung_mipi_phy for the state the two do not share.

of_xlate() takes the second cell, PHY_TYPE_DSI selecting the transmitter
and PHY_TYPE_CSI the receiver, and falls back to the transmitter for a
single-cell provider, so existing device trees keep working. It now
rejects an unknown value in either cell, and a mix of D-PHY and C-PHY
consumers, which the TRM does not support [1].

The receiver's callbacks return -EOPNOTSUPP until its bring-up is added
in the next change.

[1] RK3588 TRM: section 22.1 (overview)

Assisted-by: Claude:claude-fable-5
Signed-off-by: Jason Yang <jason98166@gmail.com>
---
 drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c | 69 +++++++++++++++++++++--
 1 file changed, 63 insertions(+), 6 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c b/drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c
index 5d9d44a1d6a2..d27a5916bd40 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c
@@ -296,6 +296,8 @@ struct samsung_mipi_dcphy {
 	struct reset_control *apb_rst;
 	struct reset_control *grf_apb_rst;
 	struct samsung_mipi_phy tx;
+	struct samsung_mipi_phy rx;
+	/* PHY mode, PHY_TYPE_DPHY or PHY_TYPE_CPHY. */
 	u8 type;
 
 	const struct samsung_mipi_dcphy_plat_data *pdata;
@@ -1508,6 +1510,22 @@ static int samsung_mipi_dcphy_exit(struct phy *phy)
 	return 0;
 }
 
+static int samsung_mipi_dcphy_rx_configure(struct phy *phy,
+					   union phy_configure_opts *opts)
+{
+	return -EOPNOTSUPP;
+}
+
+static int samsung_mipi_dcphy_rx_power_on(struct phy *phy)
+{
+	return -EOPNOTSUPP;
+}
+
+static int samsung_mipi_dcphy_rx_power_off(struct phy *phy)
+{
+	return -EOPNOTSUPP;
+}
+
 static const struct phy_ops samsung_mipi_dcphy_tx_ops = {
 	.configure = samsung_mipi_dcphy_tx_configure,
 	.power_on  = samsung_mipi_dcphy_tx_power_on,
@@ -1517,6 +1535,15 @@ static const struct phy_ops samsung_mipi_dcphy_tx_ops = {
 	.owner	   = THIS_MODULE,
 };
 
+static const struct phy_ops samsung_mipi_dcphy_rx_ops = {
+	.configure = samsung_mipi_dcphy_rx_configure,
+	.power_on  = samsung_mipi_dcphy_rx_power_on,
+	.power_off = samsung_mipi_dcphy_rx_power_off,
+	.init = samsung_mipi_dcphy_init,
+	.exit = samsung_mipi_dcphy_exit,
+	.owner	   = THIS_MODULE,
+};
+
 static const struct regmap_config samsung_mipi_dcphy_regmap_config = {
 	.name = "dcphy",
 	.reg_bits = 32,
@@ -1529,19 +1556,42 @@ static struct phy *samsung_mipi_dcphy_xlate(struct device *dev,
 					    const struct of_phandle_args *args)
 {
 	struct samsung_mipi_dcphy *samsung = dev_get_drvdata(dev);
+	/* Device trees without the second cell describe the transmitter. */
+	u32 protocol = PHY_TYPE_DSI;
+	u32 type;
 
-	if (args->args_count != 1) {
+	if (args->args_count < 1 || args->args_count > 2) {
 		dev_err(dev, "invalid number of arguments\n");
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (samsung->type != PHY_NONE && samsung->type != args->args[0])
-		dev_warn(dev, "phy type select %d overwriting type %d\n",
-			 args->args[0], samsung->type);
+	type = args->args[0];
+	if (type != PHY_TYPE_DPHY && type != PHY_TYPE_CPHY) {
+		dev_err(dev, "invalid phy type %u\n", type);
+		return ERR_PTR(-EINVAL);
+	}
 
-	samsung->type = args->args[0];
+	if (args->args_count == 2)
+		protocol = args->args[1];
 
-	return samsung->tx.phy;
+	if (protocol != PHY_TYPE_DSI && protocol != PHY_TYPE_CSI) {
+		dev_err(dev, "invalid protocol %u\n", protocol);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * The TRM (section 22.1) does not support the transmitter and the
+	 * receiver running in different modes, so the mode belongs to the
+	 * block.
+	 */
+	if (samsung->type != PHY_NONE && samsung->type != type) {
+		dev_err(dev, "phy type %u conflicts with type %u already selected\n",
+			type, samsung->type);
+		return ERR_PTR(-EINVAL);
+	}
+	samsung->type = type;
+
+	return protocol == PHY_TYPE_CSI ? samsung->rx.phy : samsung->tx.phy;
 }
 
 static int samsung_mipi_dcphy_probe(struct platform_device *pdev)
@@ -1617,6 +1667,13 @@ static int samsung_mipi_dcphy_probe(struct platform_device *pdev)
 
 	phy_set_drvdata(samsung->tx.phy, samsung);
 
+	samsung->rx.phy = devm_phy_create(dev, NULL, &samsung_mipi_dcphy_rx_ops);
+	if (IS_ERR(samsung->rx.phy))
+		return dev_err_probe(dev, PTR_ERR(samsung->rx.phy),
+				     "Failed to create MIPI DC-PHY receiver\n");
+
+	phy_set_drvdata(samsung->rx.phy, samsung);
+
 	phy_provider = devm_of_phy_provider_register(dev, samsung_mipi_dcphy_xlate);
 	if (IS_ERR(phy_provider))
 		return dev_err_probe(dev, PTR_ERR(phy_provider),

-- 
2.43.0