[PATCH V12 11/12] phy: tegra: Add PCIe PIPE2UPHY support

[Vidya Sagar]

Synopsys DesignWare core based PCIe controllers in Tegra 194 SoC interface
with Universal PHY (UPHY) module through a PIPE2UPHY (P2U) module.
For each PCIe lane of a controller, there is a P2U unit instantiated at
hardware level. This driver provides support for the programming required
for each P2U that is going to be used for a PCIe controller.

Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
Acked-by: Kishon Vijay Abraham I <kishon@xxxxxx>
---
Changes since [v11]:
* None

Changes since [v10]:
* Replaced PTR_ERR_OR_ZERO() with PTR_ERR() as the check for zero is already
  present in the code.

Changes since [v9]:
* Used _relaxed() versions of readl() & writel()

Changes since [v8]:
* Made it dependent on ARCH_TEGRA_194_SOC directly instead of ARCH_TEGRA

Changes since [v7]:
* Changed P2U driver file name from pcie-p2u-tegra194.c to phy-tegra194-p2u.c

Changes since [v6]:
* None

Changes since [v5]:
* Addressed review comments from Thierry

Changes since [v4]:
* None

Changes since [v3]:
* Rebased on top of linux-next top of the tree

Changes since [v2]:
* Replaced spaces with tabs in Kconfig file
* Sorted header file inclusion alphabetically

Changes since [v1]:
* Added COMPILE_TEST in Kconfig
* Removed empty phy_ops implementations
* Modified code according to DT documentation file modifications

 drivers/phy/tegra/Kconfig            |   7 ++
 drivers/phy/tegra/Makefile           |   1 +
 drivers/phy/tegra/phy-tegra194-p2u.c | 120 +++++++++++++++++++++++++++
 3 files changed, 128 insertions(+)
 create mode 100644 drivers/phy/tegra/phy-tegra194-p2u.c

diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
index e516967d695b..f9817c3ae85f 100644
--- a/drivers/phy/tegra/Kconfig
+++ b/drivers/phy/tegra/Kconfig
@@ -7,3 +7,10 @@ config PHY_TEGRA_XUSB
 
 	  To compile this driver as a module, choose M here: the module will
 	  be called phy-tegra-xusb.
+
+config PHY_TEGRA194_P2U
+	tristate "NVIDIA Tegra194 PIPE2UPHY PHY driver"
+	depends on ARCH_TEGRA_194_SOC || COMPILE_TEST
+	select GENERIC_PHY
+	help
+	  Enable this to support the P2U (PIPE to UPHY) that is part of Tegra 19x SOCs.
diff --git a/drivers/phy/tegra/Makefile b/drivers/phy/tegra/Makefile
index 64ccaeacb631..320dd389f34d 100644
--- a/drivers/phy/tegra/Makefile
+++ b/drivers/phy/tegra/Makefile
@@ -6,3 +6,4 @@ phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_124_SOC) += xusb-tegra124.o
 phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_132_SOC) += xusb-tegra124.o
 phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_210_SOC) += xusb-tegra210.o
 phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_186_SOC) += xusb-tegra186.o
+obj-$(CONFIG_PHY_TEGRA194_P2U) += phy-tegra194-p2u.o
diff --git a/drivers/phy/tegra/phy-tegra194-p2u.c b/drivers/phy/tegra/phy-tegra194-p2u.c
new file mode 100644
index 000000000000..7042bed9feaa
--- /dev/null
+++ b/drivers/phy/tegra/phy-tegra194-p2u.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * P2U (PIPE to UPHY) driver for Tegra T194 SoC
+ *
+ * Copyright (C) 2019 NVIDIA Corporation.
+ *
+ * Author: Vidya Sagar <vidyas@xxxxxxxxxx>
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+
+#define P2U_PERIODIC_EQ_CTRL_GEN3	0xc0
+#define P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN		BIT(0)
+#define P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
+#define P2U_PERIODIC_EQ_CTRL_GEN4	0xc4
+#define P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
+
+#define P2U_RX_DEBOUNCE_TIME				0xa4
+#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK	0xffff
+#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL		160
+
+struct tegra_p2u {
+	void __iomem *base;
+};
+
+static inline void p2u_writel(struct tegra_p2u *phy, const u32 value,
+			      const u32 reg)
+{
+	writel_relaxed(value, phy->base + reg);
+}
+
+static inline u32 p2u_readl(struct tegra_p2u *phy, const u32 reg)
+{
+	return readl_relaxed(phy->base + reg);
+}
+
+static int tegra_p2u_power_on(struct phy *x)
+{
+	struct tegra_p2u *phy = phy_get_drvdata(x);
+	u32 val;
+
+	val = p2u_readl(phy, P2U_PERIODIC_EQ_CTRL_GEN3);
+	val &= ~P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN;
+	val |= P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN;
+	p2u_writel(phy, val, P2U_PERIODIC_EQ_CTRL_GEN3);
+
+	val = p2u_readl(phy, P2U_PERIODIC_EQ_CTRL_GEN4);
+	val |= P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN;
+	p2u_writel(phy, val, P2U_PERIODIC_EQ_CTRL_GEN4);
+
+	val = p2u_readl(phy, P2U_RX_DEBOUNCE_TIME);
+	val &= ~P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK;
+	val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
+	p2u_writel(phy, val, P2U_RX_DEBOUNCE_TIME);
+
+	return 0;
+}
+
+static const struct phy_ops ops = {
+	.power_on = tegra_p2u_power_on,
+	.owner = THIS_MODULE,
+};
+
+static int tegra_p2u_probe(struct platform_device *pdev)
+{
+	struct phy_provider *phy_provider;
+	struct device *dev = &pdev->dev;
+	struct phy *generic_phy;
+	struct tegra_p2u *phy;
+	struct resource *res;
+
+	phy = devm_kzalloc(dev, sizeof(*phy), GFP_KERNEL);
+	if (!phy)
+		return -ENOMEM;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ctl");
+	phy->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(phy->base))
+		return PTR_ERR(phy->base);
+
+	platform_set_drvdata(pdev, phy);
+
+	generic_phy = devm_phy_create(dev, NULL, &ops);
+	if (IS_ERR(generic_phy))
+		return PTR_ERR(generic_phy);
+
+	phy_set_drvdata(generic_phy, phy);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	if (IS_ERR(phy_provider))
+		return PTR_ERR(phy_provider);
+
+	return 0;
+}
+
+static const struct of_device_id tegra_p2u_id_table[] = {
+	{
+		.compatible = "nvidia,tegra194-p2u",
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, tegra_p2u_id_table);
+
+static struct platform_driver tegra_p2u_driver = {
+	.probe = tegra_p2u_probe,
+	.driver = {
+		.name = "tegra194-p2u",
+		.of_match_table = tegra_p2u_id_table,
+	},
+};
+module_platform_driver(tegra_p2u_driver);
+
+MODULE_AUTHOR("Vidya Sagar <vidyas@xxxxxxxxxx>");
+MODULE_DESCRIPTION("NVIDIA Tegra194 PIPE2UPHY PHY driver");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1