Re: [PATCH V7 13/15] phy: tegra: Add PCIe PIPE2UPHY support

From: Vidya Sagar
Date: Tue May 21 2019 - 15:40:37 EST

On 5/21/2019 4:30 PM, Thierry Reding wrote:
On Fri, May 17, 2019 at 06:08:44PM +0530, Vidya Sagar wrote:
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>
---
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/pcie-p2u-tegra194.c | 109 ++++++++++++++++++++++++++
3 files changed, 117 insertions(+)
create mode 100644 drivers/phy/tegra/pcie-p2u-tegra194.c

diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
index a3b1de953fb7..06d423fa85b4 100644
--- a/drivers/phy/tegra/Kconfig
+++ b/drivers/phy/tegra/Kconfig
@@ -6,3 +6,10 @@ 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_PCIE_P2U
+ tristate "NVIDIA Tegra P2U PHY Driver"

The Kconfig symbol and driver are named inconsistently. That's not
inherently wrong, but I think it unnecessarily complicates things. Why
not just do something like:

config PHY_TEGRA194_P2U

and name the driver...
Ok. Done.


+ depends on ARCH_TEGRA || 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 a93cd9a499b2..1aaca794f40c 100644
--- a/drivers/phy/tegra/Makefile
+++ b/drivers/phy/tegra/Makefile
@@ -5,3 +5,4 @@ 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_PCIE_P2U) += pcie-p2u-tegra194.o

... phy-tegra194-p2u here? Or perhaps even leave away the 194 and make
it just phy-tegra-p2u. That would make it consistent with the
phy-tegra-xusb driver.
I'll go with phy-tegra194-p2u here as P2U is present only starting from T194.


Looks good otherwise.

Thierry

diff --git a/drivers/phy/tegra/pcie-p2u-tegra194.c b/drivers/phy/tegra/pcie-p2u-tegra194.c
new file mode 100644
index 000000000000..fae2afe1a1aa
--- /dev/null
+++ b/drivers/phy/tegra/pcie-p2u-tegra194.c
@@ -0,0 +1,109 @@
+// 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 int tegra_p2u_power_on(struct phy *x)
+{
+ struct tegra_p2u *phy = phy_get_drvdata(x);
+ u32 val;
+
+ val = readl(phy->base + 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;
+ writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN3);
+
+ val = readl(phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
+ val |= P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN;
+ writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
+
+ val = readl(phy->base + P2U_RX_DEBOUNCE_TIME);
+ val &= ~P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK;
+ val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
+ writel(val, phy->base + 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_OR_ZERO(phy->base);
+
+ platform_set_drvdata(pdev, phy);
+
+ generic_phy = devm_phy_create(dev, NULL, &ops);
+ if (IS_ERR(generic_phy))
+ return PTR_ERR_OR_ZERO(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_OR_ZERO(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 Tegra PIPE2UPHY PHY driver");
+MODULE_LICENSE("GPL v2");
--
2.17.1