phy: phy-mtk-dp: Add driver for DP phy

This is a new driver that supports the integrated DisplayPort phy for
mediatek SoCs, especially the mt8195. The phy is integrated into the
DisplayPort controller and will be created by the mtk-dp driver. This
driver expects a struct regmap to be able to work on the same registers
as the DisplayPort controller. It sets the device data to be the struct
phy so that the DisplayPort controller can easily work with it.

The driver does not have any devicetree bindings because the datasheet
does not list the controller and the phy as distinct units.

The interaction with the controller can be covered by the configure
callback of the phy framework and its displayport parameters.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
[Bo-Chen: Modify reviewers' comments.]
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220624062725.4095-1-rex-bc.chen@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

3 files changed, 211 insertions, 0 deletions

diff --git a/drivers/phy/mediatek/Kconfig b/drivers/phy/mediatek/Kconfig
index dfb18b490d07..3125ecb5d119 100644
--- a/drivers/phy/mediatek/Kconfig
+++ b/drivers/phy/mediatek/Kconfig
@@ -66,3 +66,11 @@ config PHY_MTK_MIPI_DSI
 	select GENERIC_PHY
 	help
 	  Support MIPI DSI for Mediatek SoCs.
+
+config PHY_MTK_DP
+	tristate "MediaTek DP-PHY Driver"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	depends on OF
+	select GENERIC_PHY
+	help
+	  Support DisplayPort PHY for MediaTek SoCs.
diff --git a/drivers/phy/mediatek/Makefile b/drivers/phy/mediatek/Makefile
index 445b23728a61..fb1f8edaffa7 100644
--- a/drivers/phy/mediatek/Makefile
+++ b/drivers/phy/mediatek/Makefile
@@ -3,6 +3,7 @@
 # Makefile for the phy drivers.
 #
 
+obj-$(CONFIG_PHY_MTK_DP)		+= phy-mtk-dp.o
 obj-$(CONFIG_PHY_MTK_PCIE)		+= phy-mtk-pcie.o
 obj-$(CONFIG_PHY_MTK_TPHY)		+= phy-mtk-tphy.o
 obj-$(CONFIG_PHY_MTK_UFS)		+= phy-mtk-ufs.o
diff --git a/drivers/phy/mediatek/phy-mtk-dp.c b/drivers/phy/mediatek/phy-mtk-dp.c
new file mode 100644
index 000000000000..715bd2336c17
--- /dev/null
+++ b/drivers/phy/mediatek/phy-mtk-dp.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MediaTek DisplayPort PHY driver
+ *
+ * Copyright (c) 2022, BayLibre Inc.
+ * Copyright (c) 2022, MediaTek Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define PHY_OFFSET			0x1000
+
+#define MTK_DP_PHY_DIG_PLL_CTL_1	(PHY_OFFSET + 0x14)
+#define TPLL_SSC_EN			BIT(3)
+
+#define MTK_DP_PHY_DIG_BIT_RATE		(PHY_OFFSET + 0x3C)
+#define BIT_RATE_RBR			0
+#define BIT_RATE_HBR			1
+#define BIT_RATE_HBR2			2
+#define BIT_RATE_HBR3			3
+
+#define MTK_DP_PHY_DIG_SW_RST		(PHY_OFFSET + 0x38)
+#define DP_GLB_SW_RST_PHYD		BIT(0)
+
+#define MTK_DP_LANE0_DRIVING_PARAM_3		(PHY_OFFSET + 0x138)
+#define MTK_DP_LANE1_DRIVING_PARAM_3		(PHY_OFFSET + 0x238)
+#define MTK_DP_LANE2_DRIVING_PARAM_3		(PHY_OFFSET + 0x338)
+#define MTK_DP_LANE3_DRIVING_PARAM_3		(PHY_OFFSET + 0x438)
+#define XTP_LN_TX_LCTXC0_SW0_PRE0_DEFAULT	BIT(4)
+#define XTP_LN_TX_LCTXC0_SW0_PRE1_DEFAULT	(BIT(10) | BIT(12))
+#define XTP_LN_TX_LCTXC0_SW0_PRE2_DEFAULT	GENMASK(20, 19)
+#define XTP_LN_TX_LCTXC0_SW0_PRE3_DEFAULT	GENMASK(29, 29)
+#define DRIVING_PARAM_3_DEFAULT	(XTP_LN_TX_LCTXC0_SW0_PRE0_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW0_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW0_PRE2_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW0_PRE3_DEFAULT)
+
+#define XTP_LN_TX_LCTXC0_SW1_PRE0_DEFAULT	GENMASK(4, 3)
+#define XTP_LN_TX_LCTXC0_SW1_PRE1_DEFAULT	GENMASK(12, 9)
+#define XTP_LN_TX_LCTXC0_SW1_PRE2_DEFAULT	(BIT(18) | BIT(21))
+#define XTP_LN_TX_LCTXC0_SW2_PRE0_DEFAULT	GENMASK(29, 29)
+#define DRIVING_PARAM_4_DEFAULT	(XTP_LN_TX_LCTXC0_SW1_PRE0_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW1_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW1_PRE2_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW2_PRE0_DEFAULT)
+
+#define XTP_LN_TX_LCTXC0_SW2_PRE1_DEFAULT	(BIT(3) | BIT(5))
+#define XTP_LN_TX_LCTXC0_SW3_PRE0_DEFAULT	GENMASK(13, 12)
+#define DRIVING_PARAM_5_DEFAULT	(XTP_LN_TX_LCTXC0_SW2_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXC0_SW3_PRE0_DEFAULT)
+
+#define XTP_LN_TX_LCTXCP1_SW0_PRE0_DEFAULT	0
+#define XTP_LN_TX_LCTXCP1_SW0_PRE1_DEFAULT	GENMASK(10, 10)
+#define XTP_LN_TX_LCTXCP1_SW0_PRE2_DEFAULT	GENMASK(19, 19)
+#define XTP_LN_TX_LCTXCP1_SW0_PRE3_DEFAULT	GENMASK(28, 28)
+#define DRIVING_PARAM_6_DEFAULT	(XTP_LN_TX_LCTXCP1_SW0_PRE0_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW0_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW0_PRE2_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW0_PRE3_DEFAULT)
+
+#define XTP_LN_TX_LCTXCP1_SW1_PRE0_DEFAULT	0
+#define XTP_LN_TX_LCTXCP1_SW1_PRE1_DEFAULT	GENMASK(10, 9)
+#define XTP_LN_TX_LCTXCP1_SW1_PRE2_DEFAULT	GENMASK(19, 18)
+#define XTP_LN_TX_LCTXCP1_SW2_PRE0_DEFAULT	0
+#define DRIVING_PARAM_7_DEFAULT	(XTP_LN_TX_LCTXCP1_SW1_PRE0_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW1_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW1_PRE2_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW2_PRE0_DEFAULT)
+
+#define XTP_LN_TX_LCTXCP1_SW2_PRE1_DEFAULT	GENMASK(3, 3)
+#define XTP_LN_TX_LCTXCP1_SW3_PRE0_DEFAULT	0
+#define DRIVING_PARAM_8_DEFAULT	(XTP_LN_TX_LCTXCP1_SW2_PRE1_DEFAULT | \
+				 XTP_LN_TX_LCTXCP1_SW3_PRE0_DEFAULT)
+
+struct mtk_dp_phy {
+	struct regmap *regs;
+};
+
+static int mtk_dp_phy_init(struct phy *phy)
+{
+	struct mtk_dp_phy *dp_phy = phy_get_drvdata(phy);
+	u32 driving_params[] = {
+		DRIVING_PARAM_3_DEFAULT,
+		DRIVING_PARAM_4_DEFAULT,
+		DRIVING_PARAM_5_DEFAULT,
+		DRIVING_PARAM_6_DEFAULT,
+		DRIVING_PARAM_7_DEFAULT,
+		DRIVING_PARAM_8_DEFAULT
+	};
+
+	regmap_bulk_write(dp_phy->regs, MTK_DP_LANE0_DRIVING_PARAM_3,
+			  driving_params, ARRAY_SIZE(driving_params));
+	regmap_bulk_write(dp_phy->regs, MTK_DP_LANE1_DRIVING_PARAM_3,
+			  driving_params, ARRAY_SIZE(driving_params));
+	regmap_bulk_write(dp_phy->regs, MTK_DP_LANE2_DRIVING_PARAM_3,
+			  driving_params, ARRAY_SIZE(driving_params));
+	regmap_bulk_write(dp_phy->regs, MTK_DP_LANE3_DRIVING_PARAM_3,
+			  driving_params, ARRAY_SIZE(driving_params));
+
+	return 0;
+}
+
+static int mtk_dp_phy_configure(struct phy *phy, union phy_configure_opts *opts)
+{
+	struct mtk_dp_phy *dp_phy = phy_get_drvdata(phy);
+	u32 val;
+
+	if (opts->dp.set_rate) {
+		switch (opts->dp.link_rate) {
+		default:
+			dev_err(&phy->dev,
+				"Implementation error, unknown linkrate %x\n",
+				opts->dp.link_rate);
+			return -EINVAL;
+		case 1620:
+			val = BIT_RATE_RBR;
+			break;
+		case 2700:
+			val = BIT_RATE_HBR;
+			break;
+		case 5400:
+			val = BIT_RATE_HBR2;
+			break;
+		case 8100:
+			val = BIT_RATE_HBR3;
+			break;
+		}
+		regmap_write(dp_phy->regs, MTK_DP_PHY_DIG_BIT_RATE, val);
+	}
+
+	regmap_update_bits(dp_phy->regs, MTK_DP_PHY_DIG_PLL_CTL_1,
+			   TPLL_SSC_EN, opts->dp.ssc ? TPLL_SSC_EN : 0);
+
+	return 0;
+}
+
+static int mtk_dp_phy_reset(struct phy *phy)
+{
+	struct mtk_dp_phy *dp_phy = phy_get_drvdata(phy);
+
+	regmap_update_bits(dp_phy->regs, MTK_DP_PHY_DIG_SW_RST,
+			   DP_GLB_SW_RST_PHYD, 0);
+	usleep_range(50, 200);
+	regmap_update_bits(dp_phy->regs, MTK_DP_PHY_DIG_SW_RST,
+			   DP_GLB_SW_RST_PHYD, 1);
+
+	return 0;
+}
+
+static const struct phy_ops mtk_dp_phy_dev_ops = {
+	.init = mtk_dp_phy_init,
+	.configure = mtk_dp_phy_configure,
+	.reset = mtk_dp_phy_reset,
+	.owner = THIS_MODULE,
+};
+
+static int mtk_dp_phy_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mtk_dp_phy *dp_phy;
+	struct phy *phy;
+	struct regmap *regs;
+
+	regs = *(struct regmap **)dev->platform_data;
+	if (!regs)
+		return dev_err_probe(dev, EINVAL,
+				     "No data passed, requires struct regmap**\n");
+
+	dp_phy = devm_kzalloc(dev, sizeof(*dp_phy), GFP_KERNEL);
+	if (!dp_phy)
+		return -ENOMEM;
+
+	dp_phy->regs = regs;
+	phy = devm_phy_create(dev, NULL, &mtk_dp_phy_dev_ops);
+	if (IS_ERR(phy))
+		return dev_err_probe(dev, PTR_ERR(phy),
+				     "Failed to create DP PHY\n");
+
+	phy_set_drvdata(phy, dp_phy);
+	if (!dev->of_node)
+		phy_create_lookup(phy, "dp", dev_name(dev));
+
+	return 0;
+}
+
+struct platform_driver mtk_dp_phy_driver = {
+	.probe = mtk_dp_phy_probe,
+	.driver = {
+		.name = "mediatek-dp-phy",
+	},
+};
+module_platform_driver(mtk_dp_phy_driver);
+
+MODULE_AUTHOR("Markus Schneider-Pargmann <msp@baylibre.com>");
+MODULE_DESCRIPTION("MediaTek DP PHY Driver");
+MODULE_LICENSE("GPL");