[PATCH net-next v4 0/5] Add PCS support for Qualcomm IPQ9574 SoC

[PATCH net-next v4 0/5] Add PCS support for Qualcomm IPQ9574 SoC

[Lei Wei]

The 'UNIPHY' PCS block in the Qualcomm IPQ9574 SoC provides Ethernet
PCS and SerDes functions. It supports 1Gbps mode PCS and 10-Gigabit
mode PCS (XPCS) functions, and supports various interface modes for
the connectivity between the Ethernet MAC and the external PHYs/Switch.
There are three UNIPHY (PCS) instances in IPQ9574, supporting the six
Ethernet ports.

This patch series adds base driver support for initializing the PCS,
and PCS phylink ops for managing the PCS modes/states. Support for
SGMII/QSGMII (PCS) and USXGMII (XPCS) modes is being added initially.

The Ethernet driver which handles the MAC operations will create the
PCS instances and phylink for the MAC, by utilizing the API exported
by this driver.

While support is being added initially for IPQ9574, the driver is
expected to be easily extendable later for other SoCs in the IPQ
family such as IPQ5332.

Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
Changes in v4:
- Add "COMMON_CLK" to the Kconfig dependency option.
- Optimize to avoid indentation in "ipq_pcs_config_usxgmii".
- Remove the PCS config lock.
- Add the "pcs_inband_caps" method.
- Link to v3: https://lore.kernel.org/r/20241216-ipq_pcs_6-13_rc1-v3-0-3abefda0fc48@quicinc.com

Changes in v3:
- Remove the clk enabled check in "pcs_disable" method.
- Add "pcs_validate" method to validate supported interface mode and
  duplex mode.
- Use regmap_set_bits()/regmap_clear_bits() API where appropriate.
- Collect Reviewed-by tag for dtbindings.
- Link to v2: https://lore.kernel.org/r/20241204-ipq_pcs_rc1-v2-0-26155f5364a1@quicinc.com

Changes in v2:
- dtbindings updates
  a.) Rename dt-binding header file to match binding file name.
  b.) Drop unused labels and the redundant examples.
  c.) Rename "mii_rx"/"mii_tx" clock names to "rx"/"tx".
- Rename "PCS_QCOM_IPQ" with specific name "PCS_QCOM_IPQ9574" in
  Kconfig.
- Remove interface mode check for the PCS lock.
- Use Cisco SGMII AN mode as default SGMII/QSGMII AN mode.
- Instantiate MII PCS instances in probe and export "ipq_pcs_get" and
  "ipq_pcs_put" APIs.
- Move MII RX and TX clock enable and disable to "pcs_enable" and
  "pcs_disable" methods.
- Change "dev_dbg" to "dev_dbg_ratelimited" in "pcs_get_state" method.
- Link to v1: https://lore.kernel.org/r/20241101-ipq_pcs_rc1-v1-0-fdef575620cf@quicinc.com

---
Lei Wei (5):
      dt-bindings: net: pcs: Add Ethernet PCS for Qualcomm IPQ9574 SoC
      net: pcs: Add PCS driver for Qualcomm IPQ9574 SoC
      net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations
      net: pcs: qcom-ipq9574: Add USXGMII interface mode support
      MAINTAINERS: Add maintainer for Qualcomm IPQ9574 PCS driver

 .../bindings/net/pcs/qcom,ipq9574-pcs.yaml         | 190 +++++
 MAINTAINERS                                        |   9 +
 drivers/net/pcs/Kconfig                            |   9 +
 drivers/net/pcs/Makefile                           |   1 +
 drivers/net/pcs/pcs-qcom-ipq9574.c                 | 877 +++++++++++++++++++++
 include/dt-bindings/net/qcom,ipq9574-pcs.h         |  15 +
 include/linux/pcs/pcs-qcom-ipq9574.h               |  15 +
 7 files changed, 1116 insertions(+)
---
base-commit: 3e5908172c05ab1511f2a6719b806d6eda6e1715
change-id: 20250107-ipq_pcs_net-next-cfd5ca91311c

Best regards,
-- 
Lei Wei <quic_leiwei@quicinc.com>

[PATCH net-next v4 1/5] dt-bindings: net: pcs: Add Ethernet PCS for Qualcomm IPQ9574 SoC

[Lei Wei]

The 'UNIPHY' PCS block in the IPQ9574 SoC includes PCS and SerDes
functions. It supports different interface modes to enable Ethernet
MAC connections to different types of external PHYs/switch. It includes
PCS functions for 1Gbps and 2.5Gbps interface modes and XPCS functions
for 10Gbps interface modes. There are three UNIPHY (PCS) instances
in IPQ9574 SoC which provide PCS/XPCS functions to the six Ethernet
ports.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
 .../bindings/net/pcs/qcom,ipq9574-pcs.yaml         | 190 +++++++++++++++++++++
 include/dt-bindings/net/qcom,ipq9574-pcs.h         |  15 ++
 2 files changed, 205 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/pcs/qcom,ipq9574-pcs.yaml b/Documentation/devicetree/bindings/net/pcs/qcom,ipq9574-pcs.yaml
new file mode 100644
index 000000000000..74573c28d6fe
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/pcs/qcom,ipq9574-pcs.yaml
@@ -0,0 +1,190 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/pcs/qcom,ipq9574-pcs.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Ethernet PCS for Qualcomm IPQ9574 SoC
+
+maintainers:
+  - Lei Wei <quic_leiwei@quicinc.com>
+
+description:
+  The UNIPHY hardware blocks in the Qualcomm IPQ SoC include PCS and SerDes
+  functions. They enable connectivity between the Ethernet MAC inside the
+  PPE (packet processing engine) and external Ethernet PHY/switch. There are
+  three UNIPHY instances in IPQ9574 SoC which provide PCS functions to the
+  six Ethernet ports.
+
+  For SGMII (1Gbps PHY) or 2500BASE-X (2.5Gbps PHY) interface modes, the PCS
+  function is enabled by using the PCS block inside UNIPHY. For USXGMII (10Gbps
+  PHY), the XPCS block in UNIPHY is used.
+
+  The SerDes provides 125M (1Gbps mode) or 312.5M (2.5Gbps and 10Gbps modes)
+  RX and TX clocks to the NSSCC (Networking Sub System Clock Controller). The
+  NSSCC divides these clocks and generates the MII RX and TX clocks to each
+  of the MII interfaces between the PCS and MAC, as per the link speeds and
+  interface modes.
+
+  Different IPQ SoC may support different number of UNIPHYs (PCSes) since the
+  number of ports and their capabilities can be different between these SoCs
+
+  Below diagram depicts the UNIPHY (PCS) connections for an IPQ9574 SoC based
+  board. In this example, the PCS0 has four GMIIs/XGMIIs, which can connect
+  with four MACs to support QSGMII (4 x 1Gbps) or 10G_QXGMII (4 x 2.5Gbps)
+  interface modes.
+
+  -           +-------+ +---------+  +-------------------------+
+    +---------+CMN PLL| |  GCC    |  |   NSSCC (Divider)       |
+    |         +----+--+ +----+----+  +--+-------+--------------+
+    |              |         |          ^       |
+    |       31.25M |  SYS/AHB|clk  RX/TX|clk    +------------+
+    |       ref clk|         |          |       |            |
+    |              |         v          | MII RX|TX clk   MAC| RX/TX clk
+    |25/50M     +--+---------+----------+-------+---+      +-+---------+
+    |ref clk    |  |   +----------------+       |   |      | |     PPE |
+    v           |  |   |     UNIPHY0            V   |      | V         |
+  +-------+     |  v   |       +-----------+ (X)GMII|      |           |
+  |       |     |  +---+---+   |           |--------|------|-- MAC0    |
+  |       |     |  |       |   |           | (X)GMII|      |           |
+  |  Quad |     |  |SerDes |   | PCS/XPCS  |--------|------|-- MAC1    |
+  |       +<----+  |       |   |           | (X)GMII|      |           |
+  |(X)GPHY|     |  |       |   |           |--------|------|-- MAC2    |
+  |       |     |  |       |   |           | (X)GMII|      |           |
+  |       |     |  +-------+   |           |--------|------|-- MAC3    |
+  +-------+     |              |           |        |      |           |
+                |              +-----------+        |      |           |
+                +-----------------------------------+      |           |
+                +--+---------+----------+-------+---+      |           |
+  +-------+     |            UNIPHY1                |      |           |
+  |       |     |              +-----------+        |      |           |
+  |(X)GPHY|     | +-------+    |           | (X)GMII|      |           |
+  |       +<----+ |SerDes |    | PCS/XPCS  |--------|------|- MAC4     |
+  |       |     | |       |    |           |        |      |           |
+  +-------+     | +-------+    |           |        |      |           |
+                |              +-----------+        |      |           |
+                +-----------------------------------+      |           |
+                +--+---------+----------+-------+---+      |           |
+  +-------+     |           UNIPHY2                 |      |           |
+  |       |     |              +-----------+        |      |           |
+  |(X)GPHY|     | +-------+    |           | (X)GMII|      |           |
+  |       +<----+ |SerDes |    | PCS/XPCS  |--------|------|- MAC5     |
+  |       |     | |       |    |           |        |      |           |
+  +-------+     | +-------+    |           |        |      |           |
+                |              +-----------+        |      |           |
+                +-----------------------------------+      +-----------+
+
+properties:
+  compatible:
+    enum:
+      - qcom,ipq9574-pcs
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  clocks:
+    items:
+      - description: System clock
+      - description: AHB clock needed for register interface access
+
+  clock-names:
+    items:
+      - const: sys
+      - const: ahb
+
+  '#clock-cells':
+    const: 1
+    description: See include/dt-bindings/net/qcom,ipq9574-pcs.h for constants
+
+patternProperties:
+  '^pcs-mii@[0-4]$':
+    type: object
+    description: PCS MII interface.
+
+    properties:
+      reg:
+        minimum: 0
+        maximum: 4
+        description: MII index
+
+      clocks:
+        items:
+          - description: PCS MII RX clock
+          - description: PCS MII TX clock
+
+      clock-names:
+        items:
+          - const: rx
+          - const: tx
+
+    required:
+      - reg
+      - clocks
+      - clock-names
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - '#address-cells'
+  - '#size-cells'
+  - clocks
+  - clock-names
+  - '#clock-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,ipq9574-gcc.h>
+
+    ethernet-pcs@7a00000 {
+        compatible = "qcom,ipq9574-pcs";
+        reg = <0x7a00000 0x10000>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        clocks = <&gcc GCC_UNIPHY0_SYS_CLK>,
+                 <&gcc GCC_UNIPHY0_AHB_CLK>;
+        clock-names = "sys",
+                      "ahb";
+        #clock-cells = <1>;
+
+        pcs-mii@0 {
+            reg = <0>;
+            clocks = <&nsscc 116>,
+                     <&nsscc 117>;
+            clock-names = "rx",
+                          "tx";
+        };
+
+        pcs-mii@1 {
+            reg = <1>;
+            clocks = <&nsscc 118>,
+                     <&nsscc 119>;
+            clock-names = "rx",
+                          "tx";
+        };
+
+        pcs-mii@2 {
+            reg = <2>;
+            clocks = <&nsscc 120>,
+                     <&nsscc 121>;
+            clock-names = "rx",
+                          "tx";
+        };
+
+        pcs-mii@3 {
+            reg = <3>;
+            clocks = <&nsscc 122>,
+                     <&nsscc 123>;
+            clock-names = "rx",
+                          "tx";
+        };
+    };
diff --git a/include/dt-bindings/net/qcom,ipq9574-pcs.h b/include/dt-bindings/net/qcom,ipq9574-pcs.h
new file mode 100644
index 000000000000..96bd036aaa70
--- /dev/null
+++ b/include/dt-bindings/net/qcom,ipq9574-pcs.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ *
+ * Device Tree constants for the Qualcomm IPQ9574 PCS
+ */
+
+#ifndef _DT_BINDINGS_PCS_QCOM_IPQ9574_H
+#define _DT_BINDINGS_PCS_QCOM_IPQ9574_H
+
+/* The RX and TX clocks which are provided from the SerDes to NSSCC. */
+#define PCS_RX_CLK		0
+#define PCS_TX_CLK		1
+
+#endif /* _DT_BINDINGS_PCS_QCOM_IPQ9574_H */

-- 
2.34.1

[PATCH net-next v4 2/5] net: pcs: Add PCS driver for Qualcomm IPQ9574 SoC

[Lei Wei]

The 'UNIPHY' PCS hardware block in Qualcomm's IPQ SoC supports
different interface modes to enable Ethernet MAC connections
for different types of external PHYs/switch. Each UNIPHY block
includes a SerDes and PCS/XPCS blocks, and can operate in either
PCS or XPCS modes. It supports 1Gbps and 2.5Gbps interface modes
(Ex: SGMII) using the PCS, and 10Gbps interface modes (Ex: USXGMII)
using the XPCS. There are three UNIPHY (PCS) instances in IPQ9574
SoC which support the six Ethernet ports in the SoC.

This patch adds support for the platform driver, probe and clock
registrations for the PCS driver. The platform driver creates an
'ipq_pcs' instance for each of the UNIPHY used on the given board.

Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
 drivers/net/pcs/Kconfig            |   9 ++
 drivers/net/pcs/Makefile           |   1 +
 drivers/net/pcs/pcs-qcom-ipq9574.c | 245 +++++++++++++++++++++++++++++++++++++
 3 files changed, 255 insertions(+)

diff --git a/drivers/net/pcs/Kconfig b/drivers/net/pcs/Kconfig
index f6aa437473de..f1f5669f501a 100644
--- a/drivers/net/pcs/Kconfig
+++ b/drivers/net/pcs/Kconfig
@@ -25,6 +25,15 @@ config PCS_MTK_LYNXI
 	  This module provides helpers to phylink for managing the LynxI PCS
 	  which is part of MediaTek's SoC and Ethernet switch ICs.
 
+config PCS_QCOM_IPQ9574
+	tristate "Qualcomm IPQ9574 PCS"
+	depends on OF && (ARCH_QCOM || COMPILE_TEST)
+	depends on HAS_IOMEM && COMMON_CLK
+	help
+	  This module provides driver for UNIPHY PCS available on Qualcomm
+	  IPQ9574 SoC. The UNIPHY PCS supports both PCS and XPCS functions
+	  to support different interface modes for MAC to PHY connections.
+
 config PCS_RZN1_MIIC
 	tristate "Renesas RZ/N1 MII converter"
 	depends on OF && (ARCH_RZN1 || COMPILE_TEST)
diff --git a/drivers/net/pcs/Makefile b/drivers/net/pcs/Makefile
index 4f7920618b90..2fa3faf8a5db 100644
--- a/drivers/net/pcs/Makefile
+++ b/drivers/net/pcs/Makefile
@@ -7,4 +7,5 @@ pcs_xpcs-$(CONFIG_PCS_XPCS)	:= pcs-xpcs.o pcs-xpcs-plat.o \
 obj-$(CONFIG_PCS_XPCS)		+= pcs_xpcs.o
 obj-$(CONFIG_PCS_LYNX)		+= pcs-lynx.o
 obj-$(CONFIG_PCS_MTK_LYNXI)	+= pcs-mtk-lynxi.o
+obj-$(CONFIG_PCS_QCOM_IPQ9574)	+= pcs-qcom-ipq9574.o
 obj-$(CONFIG_PCS_RZN1_MIIC)	+= pcs-rzn1-miic.o
diff --git a/drivers/net/pcs/pcs-qcom-ipq9574.c b/drivers/net/pcs/pcs-qcom-ipq9574.c
new file mode 100644
index 000000000000..ea90c1902b61
--- /dev/null
+++ b/drivers/net/pcs/pcs-qcom-ipq9574.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/net/qcom,ipq9574-pcs.h>
+
+#define XPCS_INDIRECT_ADDR		0x8000
+#define XPCS_INDIRECT_AHB_ADDR		0x83fc
+#define XPCS_INDIRECT_ADDR_H		GENMASK(20, 8)
+#define XPCS_INDIRECT_ADDR_L		GENMASK(7, 0)
+#define XPCS_INDIRECT_DATA_ADDR(reg)	(FIELD_PREP(GENMASK(15, 10), 0x20) | \
+					 FIELD_PREP(GENMASK(9, 2), \
+					 FIELD_GET(XPCS_INDIRECT_ADDR_L, reg)))
+
+/* PCS private data */
+struct ipq_pcs {
+	struct device *dev;
+	void __iomem *base;
+	struct regmap *regmap;
+	phy_interface_t interface;
+
+	/* RX clock supplied to NSSCC */
+	struct clk_hw rx_hw;
+	/* TX clock supplied to NSSCC */
+	struct clk_hw tx_hw;
+};
+
+static unsigned long ipq_pcs_clk_rate_get(struct ipq_pcs *qpcs)
+{
+	switch (qpcs->interface) {
+	case PHY_INTERFACE_MODE_USXGMII:
+		return 312500000;
+	default:
+		return 125000000;
+	}
+}
+
+/* Return clock rate for the RX clock supplied to NSSCC
+ * as per the interface mode.
+ */
+static unsigned long ipq_pcs_rx_clk_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct ipq_pcs *qpcs = container_of(hw, struct ipq_pcs, rx_hw);
+
+	return ipq_pcs_clk_rate_get(qpcs);
+}
+
+/* Return clock rate for the TX clock supplied to NSSCC
+ * as per the interface mode.
+ */
+static unsigned long ipq_pcs_tx_clk_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct ipq_pcs *qpcs = container_of(hw, struct ipq_pcs, tx_hw);
+
+	return ipq_pcs_clk_rate_get(qpcs);
+}
+
+static int ipq_pcs_clk_determine_rate(struct clk_hw *hw,
+				      struct clk_rate_request *req)
+{
+	switch (req->rate) {
+	case 125000000:
+	case 312500000:
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+/* Clock ops for the RX clock supplied to NSSCC */
+static const struct clk_ops ipq_pcs_rx_clk_ops = {
+	.determine_rate = ipq_pcs_clk_determine_rate,
+	.recalc_rate = ipq_pcs_rx_clk_recalc_rate,
+};
+
+/* Clock ops for the TX clock supplied to NSSCC */
+static const struct clk_ops ipq_pcs_tx_clk_ops = {
+	.determine_rate = ipq_pcs_clk_determine_rate,
+	.recalc_rate = ipq_pcs_tx_clk_recalc_rate,
+};
+
+static struct clk_hw *ipq_pcs_clk_hw_get(struct of_phandle_args *clkspec,
+					 void *data)
+{
+	struct ipq_pcs *qpcs = data;
+
+	switch (clkspec->args[0]) {
+	case PCS_RX_CLK:
+		return &qpcs->rx_hw;
+	case PCS_TX_CLK:
+		return &qpcs->tx_hw;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+/* Register the RX and TX clock which are output from SerDes to
+ * the NSSCC. The NSSCC driver assigns the RX and TX clock as
+ * parent, divides them to generate the MII RX and TX clock to
+ * each MII interface of the PCS as per the link speeds and
+ * interface modes.
+ */
+static int ipq_pcs_clk_register(struct ipq_pcs *qpcs)
+{
+	struct clk_init_data init = { };
+	int ret;
+
+	init.ops = &ipq_pcs_rx_clk_ops;
+	init.name = devm_kasprintf(qpcs->dev, GFP_KERNEL, "%s::rx_clk",
+				   dev_name(qpcs->dev));
+	if (!init.name)
+		return -ENOMEM;
+
+	qpcs->rx_hw.init = &init;
+	ret = devm_clk_hw_register(qpcs->dev, &qpcs->rx_hw);
+	if (ret)
+		return ret;
+
+	init.ops = &ipq_pcs_tx_clk_ops;
+	init.name = devm_kasprintf(qpcs->dev, GFP_KERNEL, "%s::tx_clk",
+				   dev_name(qpcs->dev));
+	if (!init.name)
+		return -ENOMEM;
+
+	qpcs->tx_hw.init = &init;
+	ret = devm_clk_hw_register(qpcs->dev, &qpcs->tx_hw);
+	if (ret)
+		return ret;
+
+	return devm_of_clk_add_hw_provider(qpcs->dev, ipq_pcs_clk_hw_get, qpcs);
+}
+
+static int ipq_pcs_regmap_read(void *context, unsigned int reg,
+			       unsigned int *val)
+{
+	struct ipq_pcs *qpcs = context;
+
+	/* PCS uses direct AHB access while XPCS uses indirect AHB access */
+	if (reg >= XPCS_INDIRECT_ADDR) {
+		writel(FIELD_GET(XPCS_INDIRECT_ADDR_H, reg),
+		       qpcs->base + XPCS_INDIRECT_AHB_ADDR);
+		*val = readl(qpcs->base + XPCS_INDIRECT_DATA_ADDR(reg));
+	} else {
+		*val = readl(qpcs->base + reg);
+	}
+
+	return 0;
+}
+
+static int ipq_pcs_regmap_write(void *context, unsigned int reg,
+				unsigned int val)
+{
+	struct ipq_pcs *qpcs = context;
+
+	/* PCS uses direct AHB access while XPCS uses indirect AHB access */
+	if (reg >= XPCS_INDIRECT_ADDR) {
+		writel(FIELD_GET(XPCS_INDIRECT_ADDR_H, reg),
+		       qpcs->base + XPCS_INDIRECT_AHB_ADDR);
+		writel(val, qpcs->base + XPCS_INDIRECT_DATA_ADDR(reg));
+	} else {
+		writel(val, qpcs->base + reg);
+	}
+
+	return 0;
+}
+
+static const struct regmap_config ipq_pcs_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_read = ipq_pcs_regmap_read,
+	.reg_write = ipq_pcs_regmap_write,
+	.fast_io = true,
+};
+
+static int ipq9574_pcs_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ipq_pcs *qpcs;
+	struct clk *clk;
+	int ret;
+
+	qpcs = devm_kzalloc(dev, sizeof(*qpcs), GFP_KERNEL);
+	if (!qpcs)
+		return -ENOMEM;
+
+	qpcs->dev = dev;
+
+	qpcs->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(qpcs->base))
+		return dev_err_probe(dev, PTR_ERR(qpcs->base),
+				     "Failed to ioremap resource\n");
+
+	qpcs->regmap = devm_regmap_init(dev, NULL, qpcs, &ipq_pcs_regmap_cfg);
+	if (IS_ERR(qpcs->regmap))
+		return dev_err_probe(dev, PTR_ERR(qpcs->regmap),
+				     "Failed to allocate register map\n");
+
+	clk = devm_clk_get_enabled(dev, "sys");
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "Failed to enable SYS clock\n");
+
+	clk = devm_clk_get_enabled(dev, "ahb");
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "Failed to enable AHB clock\n");
+
+	ret = ipq_pcs_clk_register(qpcs);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, qpcs);
+
+	return 0;
+}
+
+static const struct of_device_id ipq9574_pcs_of_mtable[] = {
+	{ .compatible = "qcom,ipq9574-pcs" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ipq9574_pcs_of_mtable);
+
+static struct platform_driver ipq9574_pcs_driver = {
+	.driver = {
+		.name = "ipq9574_pcs",
+		.suppress_bind_attrs = true,
+		.of_match_table = ipq9574_pcs_of_mtable,
+	},
+	.probe = ipq9574_pcs_probe,
+};
+module_platform_driver(ipq9574_pcs_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Qualcomm IPQ9574 PCS driver");
+MODULE_AUTHOR("Lei Wei <quic_leiwei@quicinc.com>");

-- 
2.34.1

[PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Lei Wei]

This patch adds the following PCS functionality for the PCS driver
for IPQ9574 SoC:

a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
b.) Exports PCS instance get and put APIs. The network driver calls
the PCS get API to get and associate the PCS instance with the port
MAC.
c.) PCS phylink operations for SGMII/QSGMII interface modes.

Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
 drivers/net/pcs/pcs-qcom-ipq9574.c   | 462 +++++++++++++++++++++++++++++++++++
 include/linux/pcs/pcs-qcom-ipq9574.h |  15 ++
 2 files changed, 477 insertions(+)

diff --git a/drivers/net/pcs/pcs-qcom-ipq9574.c b/drivers/net/pcs/pcs-qcom-ipq9574.c
index ea90c1902b61..a34f6d708a56 100644
--- a/drivers/net/pcs/pcs-qcom-ipq9574.c
+++ b/drivers/net/pcs/pcs-qcom-ipq9574.c
@@ -6,12 +6,46 @@
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/device.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pcs/pcs-qcom-ipq9574.h>
 #include <linux/phy.h>
+#include <linux/phylink.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 
 #include <dt-bindings/net/qcom,ipq9574-pcs.h>
 
+/* Maximum number of MIIs per PCS instance. There are 5 MIIs for PSGMII. */
+#define PCS_MAX_MII_NRS			5
+
+#define PCS_CALIBRATION			0x1e0
+#define PCS_CALIBRATION_DONE		BIT(7)
+
+#define PCS_MODE_CTRL			0x46c
+#define PCS_MODE_SEL_MASK		GENMASK(12, 8)
+#define PCS_MODE_SGMII			FIELD_PREP(PCS_MODE_SEL_MASK, 0x4)
+#define PCS_MODE_QSGMII			FIELD_PREP(PCS_MODE_SEL_MASK, 0x1)
+
+#define PCS_MII_CTRL(x)			(0x480 + 0x18 * (x))
+#define PCS_MII_ADPT_RESET		BIT(11)
+#define PCS_MII_FORCE_MODE		BIT(3)
+#define PCS_MII_SPEED_MASK		GENMASK(2, 1)
+#define PCS_MII_SPEED_1000		FIELD_PREP(PCS_MII_SPEED_MASK, 0x2)
+#define PCS_MII_SPEED_100		FIELD_PREP(PCS_MII_SPEED_MASK, 0x1)
+#define PCS_MII_SPEED_10		FIELD_PREP(PCS_MII_SPEED_MASK, 0x0)
+
+#define PCS_MII_STS(x)			(0x488 + 0x18 * (x))
+#define PCS_MII_LINK_STS		BIT(7)
+#define PCS_MII_STS_DUPLEX_FULL		BIT(6)
+#define PCS_MII_STS_SPEED_MASK		GENMASK(5, 4)
+#define PCS_MII_STS_SPEED_10		0
+#define PCS_MII_STS_SPEED_100		1
+#define PCS_MII_STS_SPEED_1000		2
+
+#define PCS_PLL_RESET			0x780
+#define PCS_ANA_SW_RESET		BIT(6)
+
 #define XPCS_INDIRECT_ADDR		0x8000
 #define XPCS_INDIRECT_AHB_ADDR		0x83fc
 #define XPCS_INDIRECT_ADDR_H		GENMASK(20, 8)
@@ -20,6 +54,18 @@
 					 FIELD_PREP(GENMASK(9, 2), \
 					 FIELD_GET(XPCS_INDIRECT_ADDR_L, reg)))
 
+/* Per PCS MII private data */
+struct ipq_pcs_mii {
+	struct ipq_pcs *qpcs;
+	struct phylink_pcs pcs;
+	int index;
+
+	/* RX clock from NSSCC to PCS MII */
+	struct clk *rx_clk;
+	/* TX clock from NSSCC to PCS MII */
+	struct clk *tx_clk;
+};
+
 /* PCS private data */
 struct ipq_pcs {
 	struct device *dev;
@@ -31,8 +77,420 @@ struct ipq_pcs {
 	struct clk_hw rx_hw;
 	/* TX clock supplied to NSSCC */
 	struct clk_hw tx_hw;
+
+	struct ipq_pcs_mii *qpcs_mii[PCS_MAX_MII_NRS];
+};
+
+#define phylink_pcs_to_qpcs_mii(_pcs)	\
+	container_of(_pcs, struct ipq_pcs_mii, pcs)
+
+static void ipq_pcs_get_state_sgmii(struct ipq_pcs *qpcs,
+				    int index,
+				    struct phylink_link_state *state)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(qpcs->regmap, PCS_MII_STS(index), &val);
+	if (ret) {
+		state->link = 0;
+		return;
+	}
+
+	state->link = !!(val & PCS_MII_LINK_STS);
+
+	if (!state->link)
+		return;
+
+	switch (FIELD_GET(PCS_MII_STS_SPEED_MASK, val)) {
+	case PCS_MII_STS_SPEED_1000:
+		state->speed = SPEED_1000;
+		break;
+	case PCS_MII_STS_SPEED_100:
+		state->speed = SPEED_100;
+		break;
+	case PCS_MII_STS_SPEED_10:
+		state->speed = SPEED_10;
+		break;
+	default:
+		state->link = false;
+		return;
+	}
+
+	if (val & PCS_MII_STS_DUPLEX_FULL)
+		state->duplex = DUPLEX_FULL;
+	else
+		state->duplex = DUPLEX_HALF;
+}
+
+static int ipq_pcs_config_mode(struct ipq_pcs *qpcs,
+			       phy_interface_t interface)
+{
+	unsigned int val;
+	int ret;
+
+	/* Configure PCS interface mode */
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+		val = PCS_MODE_SGMII;
+		break;
+	case PHY_INTERFACE_MODE_QSGMII:
+		val = PCS_MODE_QSGMII;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	ret = regmap_update_bits(qpcs->regmap, PCS_MODE_CTRL,
+				 PCS_MODE_SEL_MASK, val);
+	if (ret)
+		return ret;
+
+	/* PCS PLL reset */
+	ret = regmap_clear_bits(qpcs->regmap, PCS_PLL_RESET, PCS_ANA_SW_RESET);
+	if (ret)
+		return ret;
+
+	fsleep(1000);
+	ret = regmap_set_bits(qpcs->regmap, PCS_PLL_RESET, PCS_ANA_SW_RESET);
+	if (ret)
+		return ret;
+
+	/* Wait for calibration completion */
+	ret = regmap_read_poll_timeout(qpcs->regmap, PCS_CALIBRATION,
+				       val, val & PCS_CALIBRATION_DONE,
+				       1000, 100000);
+	if (ret) {
+		dev_err(qpcs->dev, "PCS calibration timed-out\n");
+		return ret;
+	}
+
+	qpcs->interface = interface;
+
+	return 0;
+}
+
+static int ipq_pcs_config_sgmii(struct ipq_pcs *qpcs,
+				int index,
+				unsigned int neg_mode,
+				phy_interface_t interface)
+{
+	int ret;
+
+	/* Configure the PCS mode if required */
+	if (qpcs->interface != interface) {
+		ret = ipq_pcs_config_mode(qpcs, interface);
+		if (ret)
+			return ret;
+	}
+
+	/* Nothing to do here as in-band autoneg mode is enabled
+	 * by default for each PCS MII port.
+	 */
+	if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED)
+		return 0;
+
+	/* Set force speed mode */
+	return regmap_set_bits(qpcs->regmap,
+			       PCS_MII_CTRL(index), PCS_MII_FORCE_MODE);
+}
+
+static int ipq_pcs_link_up_config_sgmii(struct ipq_pcs *qpcs,
+					int index,
+					unsigned int neg_mode,
+					int speed)
+{
+	unsigned int val;
+	int ret;
+
+	/* PCS speed need not be configured if in-band autoneg is enabled */
+	if (neg_mode != PHYLINK_PCS_NEG_INBAND_ENABLED) {
+		/* PCS speed set for force mode */
+		switch (speed) {
+		case SPEED_1000:
+			val = PCS_MII_SPEED_1000;
+			break;
+		case SPEED_100:
+			val = PCS_MII_SPEED_100;
+			break;
+		case SPEED_10:
+			val = PCS_MII_SPEED_10;
+			break;
+		default:
+			dev_err(qpcs->dev, "Invalid SGMII speed %d\n", speed);
+			return -EINVAL;
+		}
+
+		ret = regmap_update_bits(qpcs->regmap, PCS_MII_CTRL(index),
+					 PCS_MII_SPEED_MASK, val);
+		if (ret)
+			return ret;
+	}
+
+	/* PCS adapter reset */
+	ret = regmap_clear_bits(qpcs->regmap,
+				PCS_MII_CTRL(index), PCS_MII_ADPT_RESET);
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(qpcs->regmap,
+			       PCS_MII_CTRL(index), PCS_MII_ADPT_RESET);
+}
+
+static int ipq_pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
+			    const struct phylink_link_state *state)
+{
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static unsigned int ipq_pcs_inband_caps(struct phylink_pcs *pcs,
+					phy_interface_t interface)
+{
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
+	default:
+		return 0;
+	}
+}
+
+static int ipq_pcs_enable(struct phylink_pcs *pcs)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
+	int index = qpcs_mii->index;
+	int ret;
+
+	ret = clk_prepare_enable(qpcs_mii->rx_clk);
+	if (ret) {
+		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(qpcs_mii->tx_clk);
+	if (ret) {
+		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ipq_pcs_disable(struct phylink_pcs *pcs)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+
+	clk_disable_unprepare(qpcs_mii->rx_clk);
+	clk_disable_unprepare(qpcs_mii->tx_clk);
+}
+
+static void ipq_pcs_get_state(struct phylink_pcs *pcs,
+			      struct phylink_link_state *state)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
+	int index = qpcs_mii->index;
+
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		ipq_pcs_get_state_sgmii(qpcs, index, state);
+		break;
+	default:
+		break;
+	}
+
+	dev_dbg_ratelimited(qpcs->dev,
+			    "mode=%s/%s/%s link=%u\n",
+			    phy_modes(state->interface),
+			    phy_speed_to_str(state->speed),
+			    phy_duplex_to_str(state->duplex),
+			    state->link);
+}
+
+static int ipq_pcs_config(struct phylink_pcs *pcs,
+			  unsigned int neg_mode,
+			  phy_interface_t interface,
+			  const unsigned long *advertising,
+			  bool permit)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
+	int index = qpcs_mii->index;
+
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		return ipq_pcs_config_sgmii(qpcs, index, neg_mode, interface);
+	default:
+		return -EOPNOTSUPP;
+	};
+}
+
+static void ipq_pcs_link_up(struct phylink_pcs *pcs,
+			    unsigned int neg_mode,
+			    phy_interface_t interface,
+			    int speed, int duplex)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
+	int index = qpcs_mii->index;
+	int ret;
+
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		ret = ipq_pcs_link_up_config_sgmii(qpcs, index,
+						   neg_mode, speed);
+		break;
+	default:
+		return;
+	}
+
+	if (ret)
+		dev_err(qpcs->dev, "PCS link up fail for interface %s\n",
+			phy_modes(interface));
+}
+
+static const struct phylink_pcs_ops ipq_pcs_phylink_ops = {
+	.pcs_validate = ipq_pcs_validate,
+	.pcs_inband_caps = ipq_pcs_inband_caps,
+	.pcs_enable = ipq_pcs_enable,
+	.pcs_disable = ipq_pcs_disable,
+	.pcs_get_state = ipq_pcs_get_state,
+	.pcs_config = ipq_pcs_config,
+	.pcs_link_up = ipq_pcs_link_up,
 };
 
+/**
+ * ipq_pcs_get() - Get the IPQ PCS MII instance
+ * @np: Device tree node to the PCS MII
+ *
+ * Description: Get the phylink PCS instance for the given PCS MII node @np.
+ * This instance is associated with the specific MII of the PCS and the
+ * corresponding Ethernet netdevice.
+ *
+ * Return: A pointer to the phylink PCS instance or an error-pointer value.
+ */
+struct phylink_pcs *ipq_pcs_get(struct device_node *np)
+{
+	struct platform_device *pdev;
+	struct ipq_pcs_mii *qpcs_mii;
+	struct ipq_pcs *qpcs;
+	u32 index;
+
+	if (of_property_read_u32(np, "reg", &index))
+		return ERR_PTR(-EINVAL);
+
+	if (index >= PCS_MAX_MII_NRS)
+		return ERR_PTR(-EINVAL);
+
+	/* Get the parent device */
+	pdev = of_find_device_by_node(np->parent);
+	if (!pdev)
+		return ERR_PTR(-ENODEV);
+
+	qpcs = platform_get_drvdata(pdev);
+	if (!qpcs) {
+		put_device(&pdev->dev);
+
+		/* If probe is not yet completed, return DEFER to
+		 * the dependent driver.
+		 */
+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	qpcs_mii = qpcs->qpcs_mii[index];
+	if (!qpcs_mii) {
+		put_device(&pdev->dev);
+		return ERR_PTR(-ENOENT);
+	}
+
+	return &qpcs_mii->pcs;
+}
+EXPORT_SYMBOL(ipq_pcs_get);
+
+/**
+ * ipq_pcs_put() - Release the IPQ PCS MII instance
+ * @pcs: PCS instance
+ *
+ * Description: Release a phylink PCS instance.
+ */
+void ipq_pcs_put(struct phylink_pcs *pcs)
+{
+	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
+
+	/* Put reference taken by of_find_device_by_node() in
+	 * ipq_pcs_get().
+	 */
+	put_device(qpcs_mii->qpcs->dev);
+}
+EXPORT_SYMBOL(ipq_pcs_put);
+
+/* Parse the PCS MII DT nodes which are child nodes of the PCS node,
+ * and instantiate each MII PCS instance.
+ */
+static int ipq_pcs_create_miis(struct ipq_pcs *qpcs)
+{
+	struct device *dev = qpcs->dev;
+	struct ipq_pcs_mii *qpcs_mii;
+	struct device_node *mii_np;
+	u32 index;
+	int ret;
+
+	for_each_available_child_of_node(dev->of_node, mii_np) {
+		ret = of_property_read_u32(mii_np, "reg", &index);
+		if (ret) {
+			dev_err(dev, "Failed to read MII index\n");
+			of_node_put(mii_np);
+			return ret;
+		}
+
+		if (index >= PCS_MAX_MII_NRS) {
+			dev_err(dev, "Invalid MII index\n");
+			of_node_put(mii_np);
+			return -EINVAL;
+		}
+
+		qpcs_mii = devm_kzalloc(dev, sizeof(*qpcs_mii), GFP_KERNEL);
+		if (!qpcs_mii) {
+			of_node_put(mii_np);
+			return -ENOMEM;
+		}
+
+		qpcs_mii->qpcs = qpcs;
+		qpcs_mii->index = index;
+		qpcs_mii->pcs.ops = &ipq_pcs_phylink_ops;
+		qpcs_mii->pcs.neg_mode = true;
+		qpcs_mii->pcs.poll = true;
+
+		qpcs_mii->rx_clk = devm_get_clk_from_child(dev, mii_np, "rx");
+		if (IS_ERR(qpcs_mii->rx_clk)) {
+			of_node_put(mii_np);
+			return dev_err_probe(dev, PTR_ERR(qpcs_mii->rx_clk),
+					     "Failed to get MII %d RX clock\n", index);
+		}
+
+		qpcs_mii->tx_clk = devm_get_clk_from_child(dev, mii_np, "tx");
+		if (IS_ERR(qpcs_mii->tx_clk)) {
+			of_node_put(mii_np);
+			return dev_err_probe(dev, PTR_ERR(qpcs_mii->tx_clk),
+					     "Failed to get MII %d TX clock\n", index);
+		}
+
+		qpcs->qpcs_mii[index] = qpcs_mii;
+	}
+
+	return 0;
+}
+
 static unsigned long ipq_pcs_clk_rate_get(struct ipq_pcs *qpcs)
 {
 	switch (qpcs->interface) {
@@ -219,6 +677,10 @@ static int ipq9574_pcs_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ret = ipq_pcs_create_miis(qpcs);
+	if (ret)
+		return ret;
+
 	platform_set_drvdata(pdev, qpcs);
 
 	return 0;
diff --git a/include/linux/pcs/pcs-qcom-ipq9574.h b/include/linux/pcs/pcs-qcom-ipq9574.h
new file mode 100644
index 000000000000..8daff8fa5a00
--- /dev/null
+++ b/include/linux/pcs/pcs-qcom-ipq9574.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#ifndef __LINUX_PCS_QCOM_IPQ9574_H
+#define __LINUX_PCS_QCOM_IPQ9574_H
+
+struct device_node;
+struct phylink_pcs;
+
+struct phylink_pcs *ipq_pcs_get(struct device_node *np);
+void ipq_pcs_put(struct phylink_pcs *pcs);
+
+#endif /* __LINUX_PCS_QCOM_IPQ9574_H */

-- 
2.34.1

[PATCH net-next v4 4/5] net: pcs: qcom-ipq9574: Add USXGMII interface mode support

[Lei Wei]

USXGMII mode is enabled by PCS when 10Gbps PHYs are connected, such as
Aquantia 10Gbps PHY.

Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
 drivers/net/pcs/pcs-qcom-ipq9574.c | 170 +++++++++++++++++++++++++++++++++++++
 1 file changed, 170 insertions(+)

diff --git a/drivers/net/pcs/pcs-qcom-ipq9574.c b/drivers/net/pcs/pcs-qcom-ipq9574.c
index a34f6d708a56..1c17adbd03d5 100644
--- a/drivers/net/pcs/pcs-qcom-ipq9574.c
+++ b/drivers/net/pcs/pcs-qcom-ipq9574.c
@@ -26,6 +26,7 @@
 #define PCS_MODE_SEL_MASK		GENMASK(12, 8)
 #define PCS_MODE_SGMII			FIELD_PREP(PCS_MODE_SEL_MASK, 0x4)
 #define PCS_MODE_QSGMII			FIELD_PREP(PCS_MODE_SEL_MASK, 0x1)
+#define PCS_MODE_XPCS			FIELD_PREP(PCS_MODE_SEL_MASK, 0x10)
 
 #define PCS_MII_CTRL(x)			(0x480 + 0x18 * (x))
 #define PCS_MII_ADPT_RESET		BIT(11)
@@ -54,6 +55,34 @@
 					 FIELD_PREP(GENMASK(9, 2), \
 					 FIELD_GET(XPCS_INDIRECT_ADDR_L, reg)))
 
+#define XPCS_DIG_CTRL			0x38000
+#define XPCS_USXG_ADPT_RESET		BIT(10)
+#define XPCS_USXG_EN			BIT(9)
+
+#define XPCS_MII_CTRL			0x1f0000
+#define XPCS_MII_AN_EN			BIT(12)
+#define XPCS_DUPLEX_FULL		BIT(8)
+#define XPCS_SPEED_MASK			(BIT(13) | BIT(6) | BIT(5))
+#define XPCS_SPEED_10000		(BIT(13) | BIT(6))
+#define XPCS_SPEED_5000			(BIT(13) | BIT(5))
+#define XPCS_SPEED_2500			BIT(5)
+#define XPCS_SPEED_1000			BIT(6)
+#define XPCS_SPEED_100			BIT(13)
+#define XPCS_SPEED_10			0
+
+#define XPCS_MII_AN_CTRL		0x1f8001
+#define XPCS_MII_AN_8BIT		BIT(8)
+
+#define XPCS_MII_AN_INTR_STS		0x1f8002
+#define XPCS_USXG_AN_LINK_STS		BIT(14)
+#define XPCS_USXG_AN_SPEED_MASK		GENMASK(12, 10)
+#define XPCS_USXG_AN_SPEED_10		0
+#define XPCS_USXG_AN_SPEED_100		1
+#define XPCS_USXG_AN_SPEED_1000		2
+#define XPCS_USXG_AN_SPEED_2500		4
+#define XPCS_USXG_AN_SPEED_5000		5
+#define XPCS_USXG_AN_SPEED_10000	3
+
 /* Per PCS MII private data */
 struct ipq_pcs_mii {
 	struct ipq_pcs *qpcs;
@@ -123,9 +152,54 @@ static void ipq_pcs_get_state_sgmii(struct ipq_pcs *qpcs,
 		state->duplex = DUPLEX_HALF;
 }
 
+static void ipq_pcs_get_state_usxgmii(struct ipq_pcs *qpcs,
+				      struct phylink_link_state *state)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(qpcs->regmap, XPCS_MII_AN_INTR_STS, &val);
+	if (ret) {
+		state->link = 0;
+		return;
+	}
+
+	state->link = !!(val & XPCS_USXG_AN_LINK_STS);
+
+	if (!state->link)
+		return;
+
+	switch (FIELD_GET(XPCS_USXG_AN_SPEED_MASK, val)) {
+	case XPCS_USXG_AN_SPEED_10000:
+		state->speed = SPEED_10000;
+		break;
+	case XPCS_USXG_AN_SPEED_5000:
+		state->speed = SPEED_5000;
+		break;
+	case XPCS_USXG_AN_SPEED_2500:
+		state->speed = SPEED_2500;
+		break;
+	case XPCS_USXG_AN_SPEED_1000:
+		state->speed = SPEED_1000;
+		break;
+	case XPCS_USXG_AN_SPEED_100:
+		state->speed = SPEED_100;
+		break;
+	case XPCS_USXG_AN_SPEED_10:
+		state->speed = SPEED_10;
+		break;
+	default:
+		state->link = false;
+		return;
+	}
+
+	state->duplex = DUPLEX_FULL;
+}
+
 static int ipq_pcs_config_mode(struct ipq_pcs *qpcs,
 			       phy_interface_t interface)
 {
+	unsigned long rate = 125000000;
 	unsigned int val;
 	int ret;
 
@@ -137,6 +211,10 @@ static int ipq_pcs_config_mode(struct ipq_pcs *qpcs,
 	case PHY_INTERFACE_MODE_QSGMII:
 		val = PCS_MODE_QSGMII;
 		break;
+	case PHY_INTERFACE_MODE_USXGMII:
+		val = PCS_MODE_XPCS;
+		rate = 312500000;
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -167,6 +245,21 @@ static int ipq_pcs_config_mode(struct ipq_pcs *qpcs,
 
 	qpcs->interface = interface;
 
+	/* Configure the RX and TX clock to NSSCC as 125M or 312.5M based
+	 * on current interface mode.
+	 */
+	ret = clk_set_rate(qpcs->rx_hw.clk, rate);
+	if (ret) {
+		dev_err(qpcs->dev, "Failed to set RX clock rate\n");
+		return ret;
+	}
+
+	ret = clk_set_rate(qpcs->tx_hw.clk, rate);
+	if (ret) {
+		dev_err(qpcs->dev, "Failed to set TX clock rate\n");
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -195,6 +288,29 @@ static int ipq_pcs_config_sgmii(struct ipq_pcs *qpcs,
 			       PCS_MII_CTRL(index), PCS_MII_FORCE_MODE);
 }
 
+static int ipq_pcs_config_usxgmii(struct ipq_pcs *qpcs)
+{
+	int ret;
+
+	/* Configure the XPCS for USXGMII mode if required */
+	if (qpcs->interface == PHY_INTERFACE_MODE_USXGMII)
+		return 0;
+
+	ret = ipq_pcs_config_mode(qpcs, PHY_INTERFACE_MODE_USXGMII);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(qpcs->regmap, XPCS_DIG_CTRL, XPCS_USXG_EN);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(qpcs->regmap, XPCS_MII_AN_CTRL, XPCS_MII_AN_8BIT);
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(qpcs->regmap, XPCS_MII_CTRL, XPCS_MII_AN_EN);
+}
+
 static int ipq_pcs_link_up_config_sgmii(struct ipq_pcs *qpcs,
 					int index,
 					unsigned int neg_mode,
@@ -237,6 +353,46 @@ static int ipq_pcs_link_up_config_sgmii(struct ipq_pcs *qpcs,
 			       PCS_MII_CTRL(index), PCS_MII_ADPT_RESET);
 }
 
+static int ipq_pcs_link_up_config_usxgmii(struct ipq_pcs *qpcs, int speed)
+{
+	unsigned int val;
+	int ret;
+
+	switch (speed) {
+	case SPEED_10000:
+		val = XPCS_SPEED_10000;
+		break;
+	case SPEED_5000:
+		val = XPCS_SPEED_5000;
+		break;
+	case SPEED_2500:
+		val = XPCS_SPEED_2500;
+		break;
+	case SPEED_1000:
+		val = XPCS_SPEED_1000;
+		break;
+	case SPEED_100:
+		val = XPCS_SPEED_100;
+		break;
+	case SPEED_10:
+		val = XPCS_SPEED_10;
+		break;
+	default:
+		dev_err(qpcs->dev, "Invalid USXGMII speed %d\n", speed);
+		return -EINVAL;
+	}
+
+	/* Configure XPCS speed */
+	ret = regmap_update_bits(qpcs->regmap, XPCS_MII_CTRL,
+				 XPCS_SPEED_MASK, val | XPCS_DUPLEX_FULL);
+	if (ret)
+		return ret;
+
+	/* XPCS adapter reset */
+	return regmap_set_bits(qpcs->regmap,
+			       XPCS_DIG_CTRL, XPCS_USXG_ADPT_RESET);
+}
+
 static int ipq_pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
 			    const struct phylink_link_state *state)
 {
@@ -244,6 +400,11 @@ static int ipq_pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
 	case PHY_INTERFACE_MODE_SGMII:
 	case PHY_INTERFACE_MODE_QSGMII:
 		return 0;
+	case PHY_INTERFACE_MODE_USXGMII:
+		/* USXGMII only supports full duplex mode */
+		phylink_clear(supported, 100baseT_Half);
+		phylink_clear(supported, 10baseT_Half);
+		return 0;
 	default:
 		return -EINVAL;
 	}
@@ -255,6 +416,7 @@ static unsigned int ipq_pcs_inband_caps(struct phylink_pcs *pcs,
 	switch (interface) {
 	case PHY_INTERFACE_MODE_SGMII:
 	case PHY_INTERFACE_MODE_QSGMII:
+	case PHY_INTERFACE_MODE_USXGMII:
 		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
 	default:
 		return 0;
@@ -303,6 +465,9 @@ static void ipq_pcs_get_state(struct phylink_pcs *pcs,
 	case PHY_INTERFACE_MODE_QSGMII:
 		ipq_pcs_get_state_sgmii(qpcs, index, state);
 		break;
+	case PHY_INTERFACE_MODE_USXGMII:
+		ipq_pcs_get_state_usxgmii(qpcs, state);
+		break;
 	default:
 		break;
 	}
@@ -329,6 +494,8 @@ static int ipq_pcs_config(struct phylink_pcs *pcs,
 	case PHY_INTERFACE_MODE_SGMII:
 	case PHY_INTERFACE_MODE_QSGMII:
 		return ipq_pcs_config_sgmii(qpcs, index, neg_mode, interface);
+	case PHY_INTERFACE_MODE_USXGMII:
+		return ipq_pcs_config_usxgmii(qpcs);
 	default:
 		return -EOPNOTSUPP;
 	};
@@ -350,6 +517,9 @@ static void ipq_pcs_link_up(struct phylink_pcs *pcs,
 		ret = ipq_pcs_link_up_config_sgmii(qpcs, index,
 						   neg_mode, speed);
 		break;
+	case PHY_INTERFACE_MODE_USXGMII:
+		ret = ipq_pcs_link_up_config_usxgmii(qpcs, speed);
+		break;
 	default:
 		return;
 	}

-- 
2.34.1

[PATCH net-next v4 5/5] MAINTAINERS: Add maintainer for Qualcomm IPQ9574 PCS driver

[Lei Wei]

Add maintainer for the Ethernet PCS driver supported for Qualcomm
IPQ9574 SoC.

Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
---
 MAINTAINERS | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index a685c551faf0..11325f6e3103 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19365,6 +19365,15 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/regulator/vqmmc-ipq4019-regulator.yaml
 F:	drivers/regulator/vqmmc-ipq4019-regulator.c
 
+QUALCOMM IPQ9574 Ethernet PCS DRIVER
+M:	Lei Wei <quic_leiwei@quicinc.com>
+L:	netdev@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/net/pcs/qcom,ipq9574-pcs.yaml
+F:	drivers/net/pcs/pcs-qcom-ipq9574.c
+F:	include/dt-bindings/net/qcom,ipq9574-pcs.h
+F:	include/linux/pcs/pcs-qcom-ipq9574.h
+
 QUALCOMM NAND CONTROLLER DRIVER
 M:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 L:	linux-mtd@lists.infradead.org

-- 
2.34.1

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Simon Horman]

On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
> This patch adds the following PCS functionality for the PCS driver
> for IPQ9574 SoC:
> 
> a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
> b.) Exports PCS instance get and put APIs. The network driver calls
> the PCS get API to get and associate the PCS instance with the port
> MAC.
> c.) PCS phylink operations for SGMII/QSGMII interface modes.
> 
> Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>

...

> +static int ipq_pcs_enable(struct phylink_pcs *pcs)
> +{
> +	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
> +	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
> +	int index = qpcs_mii->index;
> +	int ret;
> +
> +	ret = clk_prepare_enable(qpcs_mii->rx_clk);
> +	if (ret) {
> +		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(qpcs_mii->tx_clk);
> +	if (ret) {
> +		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
> +		return ret;

Hi Lei Wei,

I think you need something like the following to avoid leaking qpcs_mii->rx_clk.

		goto err_disable_unprepare_rx_clk;
	}

	return 0;

err_disable_unprepare_rx_clk:
	clk_disable_unprepare(qpcs_mii->rx_clk);
	return ret;
}

Flagged by Smatch.

> +	}
> +
> +	return 0;
> +}

...

-- 
pw-bot: changes-requested

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Lei Wei]

On 1/8/2025 6:03 PM, Simon Horman wrote:
> On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
>> This patch adds the following PCS functionality for the PCS driver
>> for IPQ9574 SoC:
>>
>> a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
>> b.) Exports PCS instance get and put APIs. The network driver calls
>> the PCS get API to get and associate the PCS instance with the port
>> MAC.
>> c.) PCS phylink operations for SGMII/QSGMII interface modes.
>>
>> Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
> 
> ...
> 
>> +static int ipq_pcs_enable(struct phylink_pcs *pcs)
>> +{
>> +	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
>> +	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
>> +	int index = qpcs_mii->index;
>> +	int ret;
>> +
>> +	ret = clk_prepare_enable(qpcs_mii->rx_clk);
>> +	if (ret) {
>> +		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
>> +		return ret;
>> +	}
>> +
>> +	ret = clk_prepare_enable(qpcs_mii->tx_clk);
>> +	if (ret) {
>> +		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
>> +		return ret;
> 
> Hi Lei Wei,
> 
> I think you need something like the following to avoid leaking qpcs_mii->rx_clk.
> 
> 		goto err_disable_unprepare_rx_clk;
> 	}
> 
> 	return 0;
> 
> err_disable_unprepare_rx_clk:
> 	clk_disable_unprepare(qpcs_mii->rx_clk);
> 	return ret;
> }
> 
> Flagged by Smatch.
> 

We had a conversation with Russell King in v2 that even if the phylink 
pcs enable sequence encounters an error, it does not unwind the steps it 
has already done. So we removed the call to unprepare in case of error 
here, since an error here is essentially fatal in this path with no 
unwind possibility.

https://lore.kernel.org/all/38d7191f-e4bf-4457-9898-bb2b186ec3c7@quicinc.com/

However to satisfy this smatch warning/error, we may need to revert back 
to the adding the unprepare call in case of error. Request Russel to 
comment as well if this is fine.

Is it possible to share the log/command-options of the smatch failure so 
that we can reproduce this? Thanks.


>> +	}
>> +
>> +	return 0;
>> +}
> 
> ...
> 

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Russell King (Oracle)]

On Thu, Jan 09, 2025 at 09:11:05PM +0800, Lei Wei wrote:
> 
> 
> On 1/8/2025 6:03 PM, Simon Horman wrote:
> > On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
> > > This patch adds the following PCS functionality for the PCS driver
> > > for IPQ9574 SoC:
> > > 
> > > a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
> > > b.) Exports PCS instance get and put APIs. The network driver calls
> > > the PCS get API to get and associate the PCS instance with the port
> > > MAC.
> > > c.) PCS phylink operations for SGMII/QSGMII interface modes.
> > > 
> > > Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
> > 
> > ...
> > 
> > > +static int ipq_pcs_enable(struct phylink_pcs *pcs)
> > > +{
> > > +	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
> > > +	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
> > > +	int index = qpcs_mii->index;
> > > +	int ret;
> > > +
> > > +	ret = clk_prepare_enable(qpcs_mii->rx_clk);
> > > +	if (ret) {
> > > +		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
> > > +		return ret;
> > > +	}
> > > +
> > > +	ret = clk_prepare_enable(qpcs_mii->tx_clk);
> > > +	if (ret) {
> > > +		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
> > > +		return ret;
> > 
> > Hi Lei Wei,
> > 
> > I think you need something like the following to avoid leaking qpcs_mii->rx_clk.
> > 
> > 		goto err_disable_unprepare_rx_clk;
> > 	}
> > 
> > 	return 0;
> > 
> > err_disable_unprepare_rx_clk:
> > 	clk_disable_unprepare(qpcs_mii->rx_clk);
> > 	return ret;
> > }
> > 
> > Flagged by Smatch.
> > 
> 
> We had a conversation with Russell King in v2 that even if the phylink pcs
> enable sequence encounters an error, it does not unwind the steps it has
> already done. So we removed the call to unprepare in case of error here,
> since an error here is essentially fatal in this path with no unwind
> possibility.
> 
> https://lore.kernel.org/all/38d7191f-e4bf-4457-9898-bb2b186ec3c7@quicinc.com/
> 
> However to satisfy this smatch warning/error, we may need to revert back to
> the adding the unprepare call in case of error. Request Russel to comment as
> well if this is fine.
> 
> Is it possible to share the log/command-options of the smatch failure so
> that we can reproduce this? Thanks.

As I previously stated, the problem is that an error in this path is
basically unrecoverable. Therefore, I don't see any point in trying to
clean up.

We could probably do a bit better in phylink, and report the error, so
something like this:

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 0ae96d1376b4..62385c46118f 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1401,11 +1401,21 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 
 	phylink_mac_config(pl, state);
 
-	if (pl->pcs)
-		phylink_pcs_post_config(pl->pcs, state->interface);
+	if (pl->pcs) {
+		err = phylink_pcs_post_config(pl->pcs, state->interface);
+		if (err < 0)
+			phylink_err(pl, "%s (%ps) failed: %pe\n",
+				    "pcs_post_config",
+				    pl->pcs->pcs_post_config, ERR_PTR(err));
+	}
 
-	if (pl->pcs_state == PCS_STATE_STARTING || pcs_changed)
-		phylink_pcs_enable(pl->pcs);
+	if (pl->pcs_state == PCS_STATE_STARTING || pcs_changed) {
+		err = phylink_pcs_enable(pl->pcs);
+		if (err < 0)
+			phylink_err(pl, "%s (%ps) failed: %pe\n",
+				    "pcs_enable",
+				    pl->pcs->pcs_enable, ERR_PTR(err));
+	}
 
 	neg_mode = pl->act_link_an_mode;
 	if (pl->pcs && pl->pcs->neg_mode)

but trying to unwind the state back to what it was previously on an
error doesn't make any sense.

For example, by this time, the PHY could have switched interface modes
on us because the media changed speed. If we fail to switch to the new
interface mode, then even if we _could_ restore the previous
confinguration, that would result in the PHY using a different
interface mode to the host, and there would still be no link.

If a major_config() operation ever fails, then the affected network
interface is basically dead.

So, is there any point in adding code to clean up after an error in
things like .pcs_enable() methods? Nice to have, but it doesn't solve
the problem that the network interface is still dead as a result of
the error.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Daniel Golle]

Hi Lei,

On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
> ...
> +/**
> + * ipq_pcs_get() - Get the IPQ PCS MII instance
> + * @np: Device tree node to the PCS MII
> + *
> + * Description: Get the phylink PCS instance for the given PCS MII node @np.
> + * This instance is associated with the specific MII of the PCS and the
> + * corresponding Ethernet netdevice.
> + *
> + * Return: A pointer to the phylink PCS instance or an error-pointer value.
> + */
> +struct phylink_pcs *ipq_pcs_get(struct device_node *np)
> +{
> +	struct platform_device *pdev;
> +	struct ipq_pcs_mii *qpcs_mii;
> +	struct ipq_pcs *qpcs;
> +	u32 index;
> +
> +	if (of_property_read_u32(np, "reg", &index))
> +		return ERR_PTR(-EINVAL);
> +
> +	if (index >= PCS_MAX_MII_NRS)
> +		return ERR_PTR(-EINVAL);
> +
> +	/* Get the parent device */
> +	pdev = of_find_device_by_node(np->parent);
> +	if (!pdev)
> +		return ERR_PTR(-ENODEV);
> +
> +	qpcs = platform_get_drvdata(pdev);

What if the node referenced belongs to another driver?

> +	if (!qpcs) {
> +		put_device(&pdev->dev);
> +
> +		/* If probe is not yet completed, return DEFER to
> +		 * the dependent driver.
> +		 */
> +		return ERR_PTR(-EPROBE_DEFER);
> +	}
> +
> +	qpcs_mii = qpcs->qpcs_mii[index];
> +	if (!qpcs_mii) {
> +		put_device(&pdev->dev);
> +		return ERR_PTR(-ENOENT);
> +	}
> +
> +	return &qpcs_mii->pcs;
> +}
> +EXPORT_SYMBOL(ipq_pcs_get);

All the above seems a bit fragile to me, and most of the comments
Russell King has made on my series implementing a PCS driver for the
MediaTek SoCs apply here as well, esp.:

"If we are going to have device drivers for PCS, then we need to
seriously think about how we look up PCS and return the phylink_pcs
pointer - and also how we handle the PCS device going away. None of that
should be coded into _any_ PCS driver."

It would hence be better to implement a generic way to get/put
phylink_pcs instances from a DT node, and take care of what happens
if the PCS device goes away.

See also
https://patchwork.kernel.org/comment/25625601/

I've since (unsucessfully) started to work on such infrastructure.
In order to avoid repeating the same debate and mistakes, you may want
to take a look at at:

https://patchwork.kernel.org/project/netdevbpf/patch/ba4e359584a6b3bc4b3470822c42186d5b0856f9.1721910728.git.daniel@makrotopia.org/


Cheers


Daniel

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Simon Horman]

On Thu, Jan 09, 2025 at 09:11:05PM +0800, Lei Wei wrote:
> 
> 
> On 1/8/2025 6:03 PM, Simon Horman wrote:
> > On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
> > > This patch adds the following PCS functionality for the PCS driver
> > > for IPQ9574 SoC:
> > > 
> > > a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
> > > b.) Exports PCS instance get and put APIs. The network driver calls
> > > the PCS get API to get and associate the PCS instance with the port
> > > MAC.
> > > c.) PCS phylink operations for SGMII/QSGMII interface modes.
> > > 
> > > Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
> > 
> > ...
> > 
> > > +static int ipq_pcs_enable(struct phylink_pcs *pcs)
> > > +{
> > > +	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
> > > +	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
> > > +	int index = qpcs_mii->index;
> > > +	int ret;
> > > +
> > > +	ret = clk_prepare_enable(qpcs_mii->rx_clk);
> > > +	if (ret) {
> > > +		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
> > > +		return ret;
> > > +	}
> > > +
> > > +	ret = clk_prepare_enable(qpcs_mii->tx_clk);
> > > +	if (ret) {
> > > +		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
> > > +		return ret;
> > 
> > Hi Lei Wei,
> > 
> > I think you need something like the following to avoid leaking qpcs_mii->rx_clk.
> > 
> > 		goto err_disable_unprepare_rx_clk;
> > 	}
> > 
> > 	return 0;
> > 
> > err_disable_unprepare_rx_clk:
> > 	clk_disable_unprepare(qpcs_mii->rx_clk);
> > 	return ret;
> > }
> > 
> > Flagged by Smatch.
> > 
> 
> We had a conversation with Russell King in v2 that even if the phylink pcs
> enable sequence encounters an error, it does not unwind the steps it has
> already done. So we removed the call to unprepare in case of error here,
> since an error here is essentially fatal in this path with no unwind
> possibility.
> 
> https://lore.kernel.org/all/38d7191f-e4bf-4457-9898-bb2b186ec3c7@quicinc.com/
> 
> However to satisfy this smatch warning/error, we may need to revert back to
> the adding the unprepare call in case of error. Request Russel to comment as
> well if this is fine.

Thanks, I had missed that.

I don't think there is a need to update the code just to make Smatch happy.
Only if there is a real problem. Which, with the discussion at the link
above in mind, does not seem to be the case here.

> Is it possible to share the log/command-options of the smatch failure so
> that we can reproduce this? Thanks.

Sure, I hope this answers your question.

Smatch can be found here https://github.com/error27/smatch/

And I invoked it like this:
$ PATH=".../smatch/bin:$PATH" .../smatch/smatch_scripts/kchecker drivers/net/pcs/pcs-qcom-ipq9574.o

Which yields the following warning:
drivers/net/pcs/pcs-qcom-ipq9574.c:283 ipq_pcs_enable() warn: 'qpcs_mii->rx_clk' from clk_prepare_enable() not released on lines: 280.

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Jakub Kicinski]

On Fri, 10 Jan 2025 10:52:52 +0000 Simon Horman wrote:
> I don't think there is a need to update the code just to make Smatch happy.
> Only if there is a real problem. Which, with the discussion at the link
> above in mind, does not seem to be the case here.

Maybe be good to add a one line comment in the code to make it clear
this is intentional. Chances are we'll get a semi-automated "fixes"
for this before long.

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Lei Wei]

On 1/10/2025 6:52 PM, Simon Horman wrote:
> On Thu, Jan 09, 2025 at 09:11:05PM +0800, Lei Wei wrote:
>>
>>
>> On 1/8/2025 6:03 PM, Simon Horman wrote:
>>> On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
>>>> This patch adds the following PCS functionality for the PCS driver
>>>> for IPQ9574 SoC:
>>>>
>>>> a.) Parses PCS MII DT nodes and instantiate each MII PCS instance.
>>>> b.) Exports PCS instance get and put APIs. The network driver calls
>>>> the PCS get API to get and associate the PCS instance with the port
>>>> MAC.
>>>> c.) PCS phylink operations for SGMII/QSGMII interface modes.
>>>>
>>>> Signed-off-by: Lei Wei <quic_leiwei@quicinc.com>
>>>
>>> ...
>>>
>>>> +static int ipq_pcs_enable(struct phylink_pcs *pcs)
>>>> +{
>>>> +	struct ipq_pcs_mii *qpcs_mii = phylink_pcs_to_qpcs_mii(pcs);
>>>> +	struct ipq_pcs *qpcs = qpcs_mii->qpcs;
>>>> +	int index = qpcs_mii->index;
>>>> +	int ret;
>>>> +
>>>> +	ret = clk_prepare_enable(qpcs_mii->rx_clk);
>>>> +	if (ret) {
>>>> +		dev_err(qpcs->dev, "Failed to enable MII %d RX clock\n", index);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	ret = clk_prepare_enable(qpcs_mii->tx_clk);
>>>> +	if (ret) {
>>>> +		dev_err(qpcs->dev, "Failed to enable MII %d TX clock\n", index);
>>>> +		return ret;
>>>
>>> Hi Lei Wei,
>>>
>>> I think you need something like the following to avoid leaking qpcs_mii->rx_clk.
>>>
>>> 		goto err_disable_unprepare_rx_clk;
>>> 	}
>>>
>>> 	return 0;
>>>
>>> err_disable_unprepare_rx_clk:
>>> 	clk_disable_unprepare(qpcs_mii->rx_clk);
>>> 	return ret;
>>> }
>>>
>>> Flagged by Smatch.
>>>
>>
>> We had a conversation with Russell King in v2 that even if the phylink pcs
>> enable sequence encounters an error, it does not unwind the steps it has
>> already done. So we removed the call to unprepare in case of error here,
>> since an error here is essentially fatal in this path with no unwind
>> possibility.
>>
>> https://lore.kernel.org/all/38d7191f-e4bf-4457-9898-bb2b186ec3c7@quicinc.com/
>>
>> However to satisfy this smatch warning/error, we may need to revert back to
>> the adding the unprepare call in case of error. Request Russel to comment as
>> well if this is fine.
> 
> Thanks, I had missed that.
> 
> I don't think there is a need to update the code just to make Smatch happy.
> Only if there is a real problem. Which, with the discussion at the link
> above in mind, does not seem to be the case here.
> 

OK.

>> Is it possible to share the log/command-options of the smatch failure so
>> that we can reproduce this? Thanks.
> 
> Sure, I hope this answers your question.
> 
> Smatch can be found here https://github.com/error27/smatch/
> 
> And I invoked it like this:
> $ PATH=".../smatch/bin:$PATH" .../smatch/smatch_scripts/kchecker drivers/net/pcs/pcs-qcom-ipq9574.o
> 
> Which yields the following warning:
> drivers/net/pcs/pcs-qcom-ipq9574.c:283 ipq_pcs_enable() warn: 'qpcs_mii->rx_clk' from clk_prepare_enable() not released on lines: 280.
>

Thanks for sharing this information.

> 
> 

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Lei Wei]

On 1/11/2025 8:32 AM, Jakub Kicinski wrote:
> On Fri, 10 Jan 2025 10:52:52 +0000 Simon Horman wrote:
>> I don't think there is a need to update the code just to make Smatch happy.
>> Only if there is a real problem. Which, with the discussion at the link
>> above in mind, does not seem to be the case here.
> 
> Maybe be good to add a one line comment in the code to make it clear
> this is intentional. Chances are we'll get a semi-automated "fixes"
> for this before long.

Sure, I will add the comment to make it clear.

Re: [PATCH net-next v4 3/5] net: pcs: qcom-ipq9574: Add PCS instantiation and phylink operations

[Lei Wei]

On 1/10/2025 9:38 AM, Daniel Golle wrote:
> Hi Lei,
> 
> On Wed, Jan 08, 2025 at 10:50:26AM +0800, Lei Wei wrote:
>> ...
>> +/**
>> + * ipq_pcs_get() - Get the IPQ PCS MII instance
>> + * @np: Device tree node to the PCS MII
>> + *
>> + * Description: Get the phylink PCS instance for the given PCS MII node @np.
>> + * This instance is associated with the specific MII of the PCS and the
>> + * corresponding Ethernet netdevice.
>> + *
>> + * Return: A pointer to the phylink PCS instance or an error-pointer value.
>> + */
>> +struct phylink_pcs *ipq_pcs_get(struct device_node *np)
>> +{
>> +	struct platform_device *pdev;
>> +	struct ipq_pcs_mii *qpcs_mii;
>> +	struct ipq_pcs *qpcs;
>> +	u32 index;
>> +
>> +	if (of_property_read_u32(np, "reg", &index))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (index >= PCS_MAX_MII_NRS)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	/* Get the parent device */
>> +	pdev = of_find_device_by_node(np->parent);
>> +	if (!pdev)
>> +		return ERR_PTR(-ENODEV);
>> +
>> +	qpcs = platform_get_drvdata(pdev);
> 
> What if the node referenced belongs to another driver?
> 

Usually this case would not happen, unless the DTS for the ethernet 
ports are incorrectly configured. However I can add the 'compatible 
string' check to catch such cases.

>> +	if (!qpcs) {
>> +		put_device(&pdev->dev);
>> +
>> +		/* If probe is not yet completed, return DEFER to
>> +		 * the dependent driver.
>> +		 */
>> +		return ERR_PTR(-EPROBE_DEFER);
>> +	}
>> +
>> +	qpcs_mii = qpcs->qpcs_mii[index];
>> +	if (!qpcs_mii) {
>> +		put_device(&pdev->dev);
>> +		return ERR_PTR(-ENOENT);
>> +	}
>> +
>> +	return &qpcs_mii->pcs;
>> +}
>> +EXPORT_SYMBOL(ipq_pcs_get);
> 
> All the above seems a bit fragile to me, and most of the comments
> Russell King has made on my series implementing a PCS driver for the
> MediaTek SoCs apply here as well, esp.:
> 
> "If we are going to have device drivers for PCS, then we need to
> seriously think about how we look up PCS and return the phylink_pcs
> pointer - and also how we handle the PCS device going away. None of that
> should be coded into _any_ PCS driver."
> 
> It would hence be better to implement a generic way to get/put
> phylink_pcs instances from a DT node, and take care of what happens
> if the PCS device goes away.
> 
> See also
> https://patchwork.kernel.org/comment/25625601/
> 
> I've since (unsucessfully) started to work on such infrastructure.
> In order to avoid repeating the same debate and mistakes, you may want
> to take a look at at:
> 
> https://patchwork.kernel.org/project/netdevbpf/patch/ba4e359584a6b3bc4b3470822c42186d5b0856f9.1721910728.git.daniel@makrotopia.org/
> 
> 
> Cheers
> 
> 
> Daniel

I reviewed the discussion shared above. As I understand, there were two 
concerns from Russel, that can be potentially resolved using a common 
framework for all PCS drivers:

a.) Safe handling of PCS device removals
b.) Consistency in the PCS instance lookup API

For a), please note that the PCS device in IPQ chipsets such as IPQ9574 
is built into the SoC chip and is not pluggable. Also, the PCS driver 
module is not unloadable until the GMAC driver that depends on it is 
unloaded. Therefore, marking the driver '.suppress_bind_attrs = true' to 
disable user unbind action may be good enough to cover all possible 
scenarios of device going away for IPQ9574 PCS driver.

In relation to b), while a common infrastructure is certainly preferable
for the longer term to have a consistent lookup, the urgency is perhaps
more to resolve the issue of hot-pluggable devices going away, and less
for devices that do not support it.

One another issue we can notice currently is the lack of consistency in
the PCS lookup API signatures across drivers (For ex: xxx_get() vs
xxx_create() vs xxx_select_pcs() etc). A common 
naming-convention/signature can be enforced for the lookup API across 
the newer PCS drivers like these, to bring in some consistency in lookup.

Perhaps Russel could provide his comments as well. Thanks.