Re: [PATCH V10 13/15] phy: tegra: Add PCIe PIPE2UPHY support

From: Vidya Sagar
Date: Sat Jun 22 2019 - 13:56:25 EST

On 6/21/2019 4:53 AM, Dmitry Osipenko wrote:
20.06.2019 10:24, Kishon Vijay Abraham I ÐÐÑÐÑ:


On 12/06/19 3:23 PM, 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.

One minor comment below. With that fixed

Acked-by: Kishon Vijay Abraham I <kishon@xxxxxx>

Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
---
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..df009abd2482
--- /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_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;

Just make this..
phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
return PTR_ERR_OR_ZERO(phy_provider);

There is a need to s/PTR_ERR_OR_ZERO/PTR_ERR/ for all of the occurrences
in this patch because it is impossible to get ZERO if we already know
that pointer is a error.
Agree with this point.


Secondly, it is always cleaner to return 0 explicitly on success and
PTR_ERR_OR_ZERO(phy_provider) is a much less readable form than a simple
return 0. So I'm suggesting to keep that part as-is.

yes, true that. I'll address these in the next series