[RESEND PATCH v16 mfd 0/8] add support for VSC7512 control over SPI

@@ -14741,6 +14741,11 @@ F:	net/dsa/tag_ocelot.c
 F:	net/dsa/tag_ocelot_8021q.c
 F:	tools/testing/selftests/drivers/net/ocelot/*
 
+OCELOT EXTERNAL SWITCH CONTROL
+M:	Colin Foster <colin.foster@in-advantage.com>
+S:	Supported
+F:	include/linux/mfd/ocelot.h
+
 OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER
 M:	Frederic Barrat <fbarrat@linux.ibm.com>
 M:	Andrew Donnellan <ajd@linux.ibm.com>

@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/* Copyright 2022 Innovative Advantage Inc. */
+
+#ifndef _LINUX_MFD_OCELOT_H
+#define _LINUX_MFD_OCELOT_H
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+struct resource;
+
+static inline struct regmap *
+ocelot_regmap_from_resource_optional(struct platform_device *pdev,
+				     unsigned int index,
+				     const struct regmap_config *config)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	void __iomem *regs;
+
+	/*
+	 * Don't use _get_and_ioremap_resource() here, since that will invoke
+	 * prints of "invalid resource" which will simply add confusion.
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
+	if (res) {
+		regs = devm_ioremap_resource(dev, res);
+		if (IS_ERR(regs))
+			return ERR_CAST(regs);
+		return devm_regmap_init_mmio(dev, regs, config);
+	}
+
+	/*
+	 * Fall back to using REG and getting the resource from the parent
+	 * device, which is possible in an MFD configuration
+	 */
+	if (dev->parent) {
+		res = platform_get_resource(pdev, IORESOURCE_REG, index);
+		if (!res)
+			return NULL;
+
+		return dev_get_regmap(dev->parent, res->name);
+	}
+
+	return NULL;
+}
+
+static inline struct regmap *
+ocelot_regmap_from_resource(struct platform_device *pdev, unsigned int index,
+			    const struct regmap_config *config)
+{
+	struct regmap *map;
+
+	map = ocelot_regmap_from_resource_optional(pdev, index, config);
+	return map ?: ERR_PTR(-ENOENT);
+}
+
+#endif

@@ -10,6 +10,7 @@
 #include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/mfd/ocelot.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>

@@ -1975,7 +1976,6 @@ static int ocelot_pinctrl_probe(struct platform_device *pdev)
 	struct ocelot_pinctrl *info;
 	struct reset_control *reset;
 	struct regmap *pincfg;
-	void __iomem *base;
 	int ret;
 	struct regmap_config regmap_config = {
 		.reg_bits = 32,

@@ -2004,20 +2004,14 @@ static int ocelot_pinctrl_probe(struct platform_device *pdev)
 				     "Failed to get reset\n");
 	reset_control_reset(reset);
 
-	base = devm_ioremap_resource(dev,
-			platform_get_resource(pdev, IORESOURCE_MEM, 0));
-	if (IS_ERR(base))
-		return PTR_ERR(base);
-
 	info->stride = 1 + (info->desc->npins - 1) / 32;
 
 	regmap_config.max_register = OCELOT_GPIO_SD_MAP * info->stride + 15 * 4;
 
-	info->map = devm_regmap_init_mmio(dev, base, &regmap_config);
-	if (IS_ERR(info->map)) {
-		dev_err(dev, "Failed to create regmap\n");
-		return PTR_ERR(info->map);
-	}
+	info->map = ocelot_regmap_from_resource(pdev, 0, &regmap_config);
+	if (IS_ERR(info->map))
+		return dev_err_probe(dev, PTR_ERR(info->map),
+				     "Failed to create regmap\n");
 	dev_set_drvdata(dev, info->map);
 	info->dev = dev;
 

@@ -12,6 +12,7 @@
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/mdio/mdio-mscc-miim.h>
+#include <linux/mfd/ocelot.h>
 #include <linux/module.h>
 #include <linux/of_mdio.h>
 #include <linux/phy.h>

@@ -270,44 +271,25 @@ static int mscc_miim_clk_set(struct mii_bus *bus)
 
 static int mscc_miim_probe(struct platform_device *pdev)
 {
-	struct regmap *mii_regmap, *phy_regmap = NULL;
 	struct device_node *np = pdev->dev.of_node;
+	struct regmap *mii_regmap, *phy_regmap;
 	struct device *dev = &pdev->dev;
-	void __iomem *regs, *phy_regs;
 	struct mscc_miim_dev *miim;
-	struct resource *res;
 	struct mii_bus *bus;
 	int ret;
 
-	regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
-	if (IS_ERR(regs)) {
-		dev_err(dev, "Unable to map MIIM registers\n");
-		return PTR_ERR(regs);
-	}
-
-	mii_regmap = devm_regmap_init_mmio(dev, regs, &mscc_miim_regmap_config);
-
-	if (IS_ERR(mii_regmap)) {
-		dev_err(dev, "Unable to create MIIM regmap\n");
-		return PTR_ERR(mii_regmap);
-	}
+	mii_regmap = ocelot_regmap_from_resource(pdev, 0,
+						 &mscc_miim_regmap_config);
+	if (IS_ERR(mii_regmap))
+		return dev_err_probe(dev, PTR_ERR(mii_regmap),
+				     "Unable to create MIIM regmap\n");
 
 	/* This resource is optional */
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-	if (res) {
-		phy_regs = devm_ioremap_resource(dev, res);
-		if (IS_ERR(phy_regs)) {
-			dev_err(dev, "Unable to map internal phy registers\n");
-			return PTR_ERR(phy_regs);
-		}
-
-		phy_regmap = devm_regmap_init_mmio(dev, phy_regs,
-						   &mscc_miim_phy_regmap_config);
-		if (IS_ERR(phy_regmap)) {
-			dev_err(dev, "Unable to create phy register regmap\n");
-			return PTR_ERR(phy_regmap);
-		}
-	}
+	phy_regmap = ocelot_regmap_from_resource_optional(pdev, 1,
+						 &mscc_miim_phy_regmap_config);
+	if (IS_ERR(phy_regmap))
+		return dev_err_probe(dev, PTR_ERR(phy_regmap),
+				     "Unable to create phy register regmap\n");
 
 	ret = mscc_miim_setup(dev, &bus, "mscc_miim", mii_regmap, 0);
 	if (ret < 0) {

@@ -0,0 +1,160 @@
+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mfd/mscc,ocelot.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Ocelot Externally-Controlled Ethernet Switch
+
+maintainers:
+  - Colin Foster <colin.foster@in-advantage.com>
+
+description: |
+  The Ocelot ethernet switch family contains chips that have an internal CPU
+  (VSC7513, VSC7514) and chips that don't (VSC7511, VSC7512). All switches have
+  the option to be controlled externally, which is the purpose of this driver.
+
+  The switch family is a multi-port networking switch that supports many
+  interfaces. Additionally, the device can perform pin control, MDIO buses, and
+  external GPIO expanders.
+
+properties:
+  compatible:
+    enum:
+      - mscc,vsc7512
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+  spi-max-frequency:
+    maxItems: 1
+
+patternProperties:
+  "^pinctrl@[0-9a-f]+$":
+    type: object
+    $ref: /schemas/pinctrl/mscc,ocelot-pinctrl.yaml
+
+  "^gpio@[0-9a-f]+$":
+    type: object
+    $ref: /schemas/pinctrl/microchip,sparx5-sgpio.yaml
+    properties:
+      compatible:
+        enum:
+          - mscc,ocelot-sgpio
+
+  "^mdio@[0-9a-f]+$":
+    type: object
+    $ref: /schemas/net/mscc,miim.yaml
+    properties:
+      compatible:
+        enum:
+          - mscc,ocelot-miim
+
+required:
+  - compatible
+  - reg
+  - '#address-cells'
+  - '#size-cells'
+  - spi-max-frequency
+
+additionalProperties: false
+
+examples:
+  - |
+    ocelot_clock: ocelot-clock {
+          compatible = "fixed-clock";
+          #clock-cells = <0>;
+          clock-frequency = <125000000>;
+      };
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        soc@0 {
+            compatible = "mscc,vsc7512";
+            spi-max-frequency = <2500000>;
+            reg = <0>;
+            #address-cells = <1>;
+            #size-cells = <1>;
+
+            mdio@7107009c {
+                compatible = "mscc,ocelot-miim";
+                #address-cells = <1>;
+                #size-cells = <0>;
+                reg = <0x7107009c 0x24>;
+
+                sw_phy0: ethernet-phy@0 {
+                    reg = <0x0>;
+                };
+            };
+
+            mdio@710700c0 {
+                compatible = "mscc,ocelot-miim";
+                pinctrl-names = "default";
+                pinctrl-0 = <&miim1_pins>;
+                #address-cells = <1>;
+                #size-cells = <0>;
+                reg = <0x710700c0 0x24>;
+
+                sw_phy4: ethernet-phy@4 {
+                    reg = <0x4>;
+                };
+            };
+
+            gpio: pinctrl@71070034 {
+                compatible = "mscc,ocelot-pinctrl";
+                gpio-controller;
+                #gpio-cells = <2>;
+                gpio-ranges = <&gpio 0 0 22>;
+                reg = <0x71070034 0x6c>;
+
+                sgpio_pins: sgpio-pins {
+                    pins = "GPIO_0", "GPIO_1", "GPIO_2", "GPIO_3";
+                    function = "sg0";
+                };
+
+                miim1_pins: miim1-pins {
+                    pins = "GPIO_14", "GPIO_15";
+                    function = "miim";
+                };
+            };
+
+            gpio@710700f8 {
+                compatible = "mscc,ocelot-sgpio";
+                #address-cells = <1>;
+                #size-cells = <0>;
+                bus-frequency = <12500000>;
+                clocks = <&ocelot_clock>;
+                microchip,sgpio-port-ranges = <0 15>;
+                pinctrl-names = "default";
+                pinctrl-0 = <&sgpio_pins>;
+                reg = <0x710700f8 0x100>;
+
+                sgpio_in0: gpio@0 {
+                    compatible = "microchip,sparx5-sgpio-bank";
+                    reg = <0>;
+                    gpio-controller;
+                    #gpio-cells = <3>;
+                    ngpios = <64>;
+                };
+
+                sgpio_out1: gpio@1 {
+                    compatible = "microchip,sparx5-sgpio-bank";
+                    reg = <1>;
+                    gpio-controller;
+                    #gpio-cells = <3>;
+                    ngpios = <64>;
+                };
+            };
+        };
+    };
+
+...
+

@@ -14744,6 +14744,7 @@ F:	tools/testing/selftests/drivers/net/ocelot/*
 OCELOT EXTERNAL SWITCH CONTROL
 M:	Colin Foster <colin.foster@in-advantage.com>
 S:	Supported
+F:	Documentation/devicetree/bindings/mfd/mscc,ocelot.yaml
 F:	include/linux/mfd/ocelot.h
 
 OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER

@@ -172,6 +172,11 @@ enum {
 #define DEFINE_RES_MEM(_start, _size)					\
 	DEFINE_RES_MEM_NAMED((_start), (_size), NULL)
 
+#define DEFINE_RES_REG_NAMED(_start, _size, _name)			\
+	DEFINE_RES_NAMED((_start), (_size), (_name), IORESOURCE_REG)
+#define DEFINE_RES_REG(_start, _size)					\
+	DEFINE_RES_REG_NAMED((_start), (_size), NULL)
+
 #define DEFINE_RES_IRQ_NAMED(_irq, _name)				\
 	DEFINE_RES_NAMED((_irq), 1, (_name), IORESOURCE_IRQ)
 #define DEFINE_RES_IRQ(_irq)						\

@@ -292,7 +292,7 @@ config PINCTRL_MCP23S08
 	  corresponding interrupt-controller.
 
 config PINCTRL_MICROCHIP_SGPIO
-	bool "Pinctrl driver for Microsemi/Microchip Serial GPIO"
+	tristate "Pinctrl driver for Microsemi/Microchip Serial GPIO"
 	depends on OF
 	depends on HAS_IOMEM
 	select GPIOLIB

@@ -310,6 +310,9 @@ config PINCTRL_MICROCHIP_SGPIO
 	  connect control signals from SFP modules and to act as an
 	  LED controller.
 
+	  If compiled as a module, the module name will be
+	  pinctrl-microchip-sgpio.
+
 config PINCTRL_OCELOT
 	tristate "Pinctrl driver for the Microsemi Ocelot and Jaguar2 SoCs"
 	depends on OF

@@ -999,6 +999,7 @@ static const struct of_device_id microchip_sgpio_gpio_of_match[] = {
 		/* sentinel */
 	}
 };
+MODULE_DEVICE_TABLE(of, microchip_sgpio_gpio_of_match);
 
 static struct platform_driver microchip_sgpio_pinctrl_driver = {
 	.driver = {

@@ -1008,4 +1009,7 @@ static struct platform_driver microchip_sgpio_pinctrl_driver = {
 	},
 	.probe = microchip_sgpio_probe,
 };
-builtin_platform_driver(microchip_sgpio_pinctrl_driver);
+module_platform_driver(microchip_sgpio_pinctrl_driver);
+
+MODULE_DESCRIPTION("Microchip SGPIO Pinctrl Driver");
+MODULE_LICENSE("GPL");

@@ -12,6 +12,7 @@
 #include <linux/clk.h>
 #include <linux/gpio/driver.h>
 #include <linux/io.h>
+#include <linux/mfd/ocelot.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/pinctrl/pinmux.h>

@@ -904,7 +905,6 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
 	struct reset_control *reset;
 	struct sgpio_priv *priv;
 	struct clk *clk;
-	u32 __iomem *regs;
 	u32 val;
 	struct regmap_config regmap_config = {
 		.reg_bits = 32,

@@ -937,11 +937,7 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	regs = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(regs))
-		return PTR_ERR(regs);
-
-	priv->regs = devm_regmap_init_mmio(dev, regs, &regmap_config);
+	priv->regs = ocelot_regmap_from_resource(pdev, 0, &regmap_config);
 	if (IS_ERR(priv->regs))
 		return PTR_ERR(priv->regs);
 

@@ -14745,6 +14745,7 @@ OCELOT EXTERNAL SWITCH CONTROL
 M:	Colin Foster <colin.foster@in-advantage.com>
 S:	Supported
 F:	Documentation/devicetree/bindings/mfd/mscc,ocelot.yaml
+F:	drivers/mfd/ocelot*
 F:	include/linux/mfd/ocelot.h
 
 OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER

@@ -963,6 +963,27 @@ config MFD_MENF21BMC
 	  This driver can also be built as a module. If so the module
 	  will be called menf21bmc.
 
+config MFD_OCELOT
+	tristate "Microsemi Ocelot External Control Support"
+	depends on SPI_MASTER
+	select MFD_CORE
+	select REGMAP_SPI
+	help
+	  Ocelot is a family of networking chips that support multiple ethernet
+	  and fibre interfaces. In addition to networking, they contain several
+	  other functions, including pinctrl, MDIO, and communication with
+	  external chips. While some chips have an internal processor capable of
+	  running an OS, others don't. All chips can be controlled externally
+	  through different interfaces, including SPI, I2C, and PCIe.
+
+	  Say yes here to add support for Ocelot chips (VSC7511, VSC7512,
+	  VSC7513, VSC7514) controlled externally.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ocelot-soc.
+
+	  If unsure, say N.
+
 config EZX_PCAP
 	bool "Motorola EZXPCAP Support"
 	depends on SPI_MASTER

@@ -120,6 +120,9 @@ obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
+ocelot-soc-objs			:= ocelot-core.o ocelot-spi.o
+obj-$(CONFIG_MFD_OCELOT)	+= ocelot-soc.o
+
 obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
 obj-$(CONFIG_MFD_CPCAP)		+= motorola-cpcap.o
 

@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Core driver for the Ocelot chip family.
+ *
+ * The VSC7511, 7512, 7513, and 7514 can be controlled internally via an
+ * on-chip MIPS processor, or externally via SPI, I2C, PCIe. This core driver is
+ * intended to be the bus-agnostic glue between, for example, the SPI bus and
+ * the child devices.
+ *
+ * Copyright 2021-2022 Innovative Advantage Inc.
+ *
+ * Author: Colin Foster <colin.foster@in-advantage.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/iopoll.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/ocelot.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <soc/mscc/ocelot.h>
+
+#include "ocelot.h"
+
+#define REG_GCB_SOFT_RST		0x0008
+
+#define BIT_SOFT_CHIP_RST		BIT(0)
+
+#define VSC7512_MIIM0_RES_START		0x7107009c
+#define VSC7512_MIIM1_RES_START		0x710700c0
+#define VSC7512_MIIM_RES_SIZE		0x024
+
+#define VSC7512_PHY_RES_START		0x710700f0
+#define VSC7512_PHY_RES_SIZE		0x004
+
+#define VSC7512_GPIO_RES_START		0x71070034
+#define VSC7512_GPIO_RES_SIZE		0x06c
+
+#define VSC7512_SIO_CTRL_RES_START	0x710700f8
+#define VSC7512_SIO_CTRL_RES_SIZE	0x100
+
+#define VSC7512_GCB_RST_SLEEP_US	100
+#define VSC7512_GCB_RST_TIMEOUT_US	100000
+
+static int ocelot_gcb_chip_rst_status(struct ocelot_ddata *ddata)
+{
+	int val, err;
+
+	err = regmap_read(ddata->gcb_regmap, REG_GCB_SOFT_RST, &val);
+	if (err)
+		return err;
+
+	return val;
+}
+
+int ocelot_chip_reset(struct device *dev)
+{
+	struct ocelot_ddata *ddata = dev_get_drvdata(dev);
+	int ret, val;
+
+	/*
+	 * Reset the entire chip here to put it into a completely known state.
+	 * Other drivers may want to reset their own subsystems. The register
+	 * self-clears, so one write is all that is needed and wait for it to
+	 * clear.
+	 */
+	ret = regmap_write(ddata->gcb_regmap, REG_GCB_SOFT_RST, BIT_SOFT_CHIP_RST);
+	if (ret)
+		return ret;
+
+	return readx_poll_timeout(ocelot_gcb_chip_rst_status, ddata, val, !val,
+				  VSC7512_GCB_RST_SLEEP_US, VSC7512_GCB_RST_TIMEOUT_US);
+}
+EXPORT_SYMBOL_NS(ocelot_chip_reset, MFD_OCELOT);
+
+static const struct resource vsc7512_miim0_resources[] = {
+	DEFINE_RES_REG_NAMED(VSC7512_MIIM0_RES_START, VSC7512_MIIM_RES_SIZE, "gcb_miim0"),
+	DEFINE_RES_REG_NAMED(VSC7512_PHY_RES_START, VSC7512_PHY_RES_SIZE, "gcb_phy"),
+};
+
+static const struct resource vsc7512_miim1_resources[] = {
+	DEFINE_RES_REG_NAMED(VSC7512_MIIM1_RES_START, VSC7512_MIIM_RES_SIZE, "gcb_miim1"),
+};
+
+static const struct resource vsc7512_pinctrl_resources[] = {
+	DEFINE_RES_REG_NAMED(VSC7512_GPIO_RES_START, VSC7512_GPIO_RES_SIZE, "gcb_gpio"),
+};
+
+static const struct resource vsc7512_sgpio_resources[] = {
+	DEFINE_RES_REG_NAMED(VSC7512_SIO_CTRL_RES_START, VSC7512_SIO_CTRL_RES_SIZE, "gcb_sio"),
+};
+
+static const struct mfd_cell vsc7512_devs[] = {
+	{
+		.name = "ocelot-pinctrl",
+		.of_compatible = "mscc,ocelot-pinctrl",
+		.num_resources = ARRAY_SIZE(vsc7512_pinctrl_resources),
+		.resources = vsc7512_pinctrl_resources,
+	}, {
+		.name = "ocelot-sgpio",
+		.of_compatible = "mscc,ocelot-sgpio",
+		.num_resources = ARRAY_SIZE(vsc7512_sgpio_resources),
+		.resources = vsc7512_sgpio_resources,
+	}, {
+		.name = "ocelot-miim0",
+		.of_compatible = "mscc,ocelot-miim",
+		.of_reg = VSC7512_MIIM0_RES_START,
+		.use_of_reg = true,
+		.num_resources = ARRAY_SIZE(vsc7512_miim0_resources),
+		.resources = vsc7512_miim0_resources,
+	}, {
+		.name = "ocelot-miim1",
+		.of_compatible = "mscc,ocelot-miim",
+		.of_reg = VSC7512_MIIM1_RES_START,
+		.use_of_reg = true,
+		.num_resources = ARRAY_SIZE(vsc7512_miim1_resources),
+		.resources = vsc7512_miim1_resources,
+	},
+};
+
+static void ocelot_core_try_add_regmap(struct device *dev,
+				       const struct resource *res)
+{
+	if (dev_get_regmap(dev, res->name))
+		return;
+
+	ocelot_spi_init_regmap(dev, res);
+}
+
+static void ocelot_core_try_add_regmaps(struct device *dev,
+					const struct mfd_cell *cell)
+{
+	int i;
+
+	for (i = 0; i < cell->num_resources; i++)
+		ocelot_core_try_add_regmap(dev, &cell->resources[i]);
+}
+
+int ocelot_core_init(struct device *dev)
+{
+	int i, ndevs;
+
+	ndevs = ARRAY_SIZE(vsc7512_devs);
+
+	for (i = 0; i < ndevs; i++)
+		ocelot_core_try_add_regmaps(dev, &vsc7512_devs[i]);
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, vsc7512_devs, ndevs, NULL, 0, NULL);
+}
+EXPORT_SYMBOL_NS(ocelot_core_init, MFD_OCELOT);
+
+MODULE_DESCRIPTION("Externally Controlled Ocelot Chip Driver");
+MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(MFD_OCELOT_SPI);

@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * SPI core driver for the Ocelot chip family.
+ *
+ * This driver will handle everything necessary to allow for communication over
+ * SPI to the VSC7511, VSC7512, VSC7513 and VSC7514 chips. The main functions
+ * are to prepare the chip's SPI interface for a specific bus speed, and a host
+ * processor's endianness. This will create and distribute regmaps for any
+ * children.
+ *
+ * Copyright 2021-2022 Innovative Advantage Inc.
+ *
+ * Author: Colin Foster <colin.foster@in-advantage.com>
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/ioport.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include "ocelot.h"
+
+#define REG_DEV_CPUORG_IF_CTRL		0x0000
+#define REG_DEV_CPUORG_IF_CFGSTAT	0x0004
+
+#define CFGSTAT_IF_NUM_VCORE		(0 << 24)
+#define CFGSTAT_IF_NUM_VRAP		(1 << 24)
+#define CFGSTAT_IF_NUM_SI		(2 << 24)
+#define CFGSTAT_IF_NUM_MIIM		(3 << 24)
+
+#define VSC7512_DEVCPU_ORG_RES_START	0x71000000
+#define VSC7512_DEVCPU_ORG_RES_SIZE	0x38
+
+#define VSC7512_CHIP_REGS_RES_START	0x71070000
+#define VSC7512_CHIP_REGS_RES_SIZE	0x14
+
+static const struct resource vsc7512_dev_cpuorg_resource =
+	DEFINE_RES_REG_NAMED(VSC7512_DEVCPU_ORG_RES_START,
+			     VSC7512_DEVCPU_ORG_RES_SIZE,
+			     "devcpu_org");
+
+static const struct resource vsc7512_gcb_resource =
+	DEFINE_RES_REG_NAMED(VSC7512_CHIP_REGS_RES_START,
+			     VSC7512_CHIP_REGS_RES_SIZE,
+			     "devcpu_gcb_chip_regs");
+
+static int ocelot_spi_initialize(struct device *dev)
+{
+	struct ocelot_ddata *ddata = dev_get_drvdata(dev);
+	u32 val, check;
+	int err;
+
+	val = OCELOT_SPI_BYTE_ORDER;
+
+	/*
+	 * The SPI address must be big-endian, but we want the payload to match
+	 * our CPU. These are two bits (0 and 1) but they're repeated such that
+	 * the write from any configuration will be valid. The four
+	 * configurations are:
+	 *
+	 * 0b00: little-endian, MSB first
+	 * |            111111   | 22221111 | 33222222 |
+	 * | 76543210 | 54321098 | 32109876 | 10987654 |
+	 *
+	 * 0b01: big-endian, MSB first
+	 * | 33222222 | 22221111 | 111111   |          |
+	 * | 10987654 | 32109876 | 54321098 | 76543210 |
+	 *
+	 * 0b10: little-endian, LSB first
+	 * |              111111 | 11112222 | 22222233 |
+	 * | 01234567 | 89012345 | 67890123 | 45678901 |
+	 *
+	 * 0b11: big-endian, LSB first
+	 * | 22222233 | 11112222 |   111111 |          |
+	 * | 45678901 | 67890123 | 89012345 | 01234567 |
+	 */
+	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CTRL, val);
+	if (err)
+		return err;
+
+	/*
+	 * Apply the number of padding bytes between a read request and the data
+	 * payload. Some registers have access times of up to 1us, so if the
+	 * first payload bit is shifted out too quickly, the read will fail.
+	 */
+	val = ddata->spi_padding_bytes;
+	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, val);
+	if (err)
+		return err;
+
+	/*
+	 * After we write the interface configuration, read it back here. This
+	 * will verify several different things. The first is that the number of
+	 * padding bytes actually got written correctly. These are found in bits
+	 * 0:3.
+	 *
+	 * The second is that bit 16 is cleared. Bit 16 is IF_CFGSTAT:IF_STAT,
+	 * and will be set if the register access is too fast. This would be in
+	 * the condition that the number of padding bytes is insufficient for
+	 * the SPI bus frequency.
+	 *
+	 * The last check is for bits 31:24, which define the interface by which
+	 * the registers are being accessed. Since we're accessing them via the
+	 * serial interface, it must return IF_NUM_SI.
+	 */
+	check = val | CFGSTAT_IF_NUM_SI;
+
+	err = regmap_read(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, &val);
+	if (err)
+		return err;
+
+	if (check != val)
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct regmap_config ocelot_spi_regmap_config = {
+	.reg_bits = 24,
+	.reg_stride = 4,
+	.reg_downshift = 2,
+	.val_bits = 32,
+
+	.write_flag_mask = 0x80,
+
+	.use_single_write = true,
+	.can_multi_write = false,
+
+	.reg_format_endian = REGMAP_ENDIAN_BIG,
+	.val_format_endian = REGMAP_ENDIAN_NATIVE,
+};
+
+static int ocelot_spi_regmap_bus_read(void *context, const void *reg, size_t reg_size,
+				      void *val, size_t val_size)
+{
+	struct spi_transfer xfers[3] = {0};
+	struct device *dev = context;
+	struct ocelot_ddata *ddata;
+	struct spi_device *spi;
+	struct spi_message msg;
+	unsigned int index = 0;
+
+	ddata = dev_get_drvdata(dev);
+	spi = to_spi_device(dev);
+
+	xfers[index].tx_buf = reg;
+	xfers[index].len = reg_size;
+	index++;
+
+	if (ddata->spi_padding_bytes) {
+		xfers[index].len = ddata->spi_padding_bytes;
+		xfers[index].tx_buf = ddata->dummy_buf;
+		xfers[index].dummy_data = 1;
+		index++;
+	}
+
+	xfers[index].rx_buf = val;
+	xfers[index].len = val_size;
+	index++;
+
+	spi_message_init_with_transfers(&msg, xfers, index);
+
+	return spi_sync(spi, &msg);
+}
+
+static int ocelot_spi_regmap_bus_write(void *context, const void *data, size_t count)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+
+	return spi_write(spi, data, count);
+}
+
+static const struct regmap_bus ocelot_spi_regmap_bus = {
+	.write = ocelot_spi_regmap_bus_write,
+	.read = ocelot_spi_regmap_bus_read,
+};
+
+struct regmap *ocelot_spi_init_regmap(struct device *dev, const struct resource *res)
+{
+	struct regmap_config regmap_config;
+
+	memcpy(&regmap_config, &ocelot_spi_regmap_config, sizeof(regmap_config));
+
+	regmap_config.name = res->name;
+	regmap_config.max_register = resource_size(res) - 1;
+	regmap_config.reg_base = res->start;
+
+	return devm_regmap_init(dev, &ocelot_spi_regmap_bus, dev, &regmap_config);
+}
+EXPORT_SYMBOL_NS(ocelot_spi_init_regmap, MFD_OCELOT_SPI);
+
+static int ocelot_spi_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct ocelot_ddata *ddata;
+	struct regmap *r;
+	int err;
+
+	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, ddata);
+
+	if (spi->max_speed_hz <= 500000) {
+		ddata->spi_padding_bytes = 0;
+	} else {
+		/*
+		 * Calculation taken from the manual for IF_CFGSTAT:IF_CFG.
+		 * Register access time is 1us, so we need to configure and send
+		 * out enough padding bytes between the read request and data
+		 * transmission that lasts at least 1 microsecond.
+		 */
+		ddata->spi_padding_bytes = 1 + (spi->max_speed_hz / HZ_PER_MHZ + 2) / 8;
+
+		ddata->dummy_buf = devm_kzalloc(dev, ddata->spi_padding_bytes, GFP_KERNEL);
+		if (!ddata->dummy_buf)
+			return -ENOMEM;
+	}
+
+	spi->bits_per_word = 8;
+
+	err = spi_setup(spi);
+	if (err)
+		return dev_err_probe(&spi->dev, err, "Error performing SPI setup\n");
+
+	r = ocelot_spi_init_regmap(dev, &vsc7512_dev_cpuorg_resource);
+	if (IS_ERR(r))
+		return PTR_ERR(r);
+
+	ddata->cpuorg_regmap = r;
+
+	r = ocelot_spi_init_regmap(dev, &vsc7512_gcb_resource);
+	if (IS_ERR(r))
+		return PTR_ERR(r);
+
+	ddata->gcb_regmap = r;
+
+	/*
+	 * The chip must be set up for SPI before it gets initialized and reset.
+	 * This must be done before calling init, and after a chip reset is
+	 * performed.
+	 */
+	err = ocelot_spi_initialize(dev);
+	if (err)
+		return dev_err_probe(dev, err, "Error initializing SPI bus\n");
+
+	err = ocelot_chip_reset(dev);
+	if (err)
+		return dev_err_probe(dev, err, "Error resetting device\n");
+
+	/*
+	 * A chip reset will clear the SPI configuration, so it needs to be done
+	 * again before we can access any registers.
+	 */
+	err = ocelot_spi_initialize(dev);
+	if (err)
+		return dev_err_probe(dev, err, "Error initializing SPI bus after reset\n");
+
+	err = ocelot_core_init(dev);
+	if (err)
+		return dev_err_probe(dev, err, "Error initializing Ocelot core\n");
+
+	return 0;
+}
+
+static const struct spi_device_id ocelot_spi_ids[] = {
+	{ "vsc7512", 0 },
+	{ }
+};
+
+static const struct of_device_id ocelot_spi_of_match[] = {
+	{ .compatible = "mscc,vsc7512" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ocelot_spi_of_match);
+
+static struct spi_driver ocelot_spi_driver = {
+	.driver = {
+		.name = "ocelot-soc",
+		.of_match_table = ocelot_spi_of_match,
+	},
+	.id_table = ocelot_spi_ids,
+	.probe = ocelot_spi_probe,
+};
+module_spi_driver(ocelot_spi_driver);
+
+MODULE_DESCRIPTION("SPI Controlled Ocelot Chip Driver");
+MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_IMPORT_NS(MFD_OCELOT);

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/* Copyright 2021, 2022 Innovative Advantage Inc. */
+
+#ifndef _MFD_OCELOT_H
+#define _MFD_OCELOT_H
+
+#include <linux/kconfig.h>
+
+struct device;
+struct regmap;
+struct resource;
+
+/**
+ * struct ocelot_ddata - Private data for an external Ocelot chip
+ * @gcb_regmap:		General Configuration Block regmap. Used for
+ *			operations like chip reset.
+ * @cpuorg_regmap:	CPU Device Origin Block regmap. Used for operations
+ *			like SPI bus configuration.
+ * @spi_padding_bytes:	Number of padding bytes that must be thrown out before
+ *			read data gets returned. This is calculated during
+ *			initialization based on bus speed.
+ * @dummy_buf:		Zero-filled buffer of spi_padding_bytes size. The dummy
+ *			bytes that will be sent out between the address and
+ *			data of a SPI read operation.
+ */
+struct ocelot_ddata {
+	struct regmap *gcb_regmap;
+	struct regmap *cpuorg_regmap;
+	int spi_padding_bytes;
+	void *dummy_buf;
+};
+
+int ocelot_chip_reset(struct device *dev);
+int ocelot_core_init(struct device *dev);
+
+/* SPI-specific routines that won't be necessary for other interfaces */
+struct regmap *ocelot_spi_init_regmap(struct device *dev,
+				      const struct resource *res);
+
+#define OCELOT_SPI_BYTE_ORDER_LE 0x00000000
+#define OCELOT_SPI_BYTE_ORDER_BE 0x81818181
+
+#ifdef __LITTLE_ENDIAN
+#define OCELOT_SPI_BYTE_ORDER OCELOT_SPI_BYTE_ORDER_LE
+#else
+#define OCELOT_SPI_BYTE_ORDER OCELOT_SPI_BYTE_ORDER_BE
+#endif
+
+#endif