misc: Add gdsys_soc driver

This patch adds a driver for the bus associated with a IHS FPGA.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

Documentation/devicetree/bindings/misc/gdsys,soc.txt

@@ -0,0 +1,16 @@
+gdsys soc bus driver
+
+This driver provides a simple interface for the busses associated with gdsys
+IHS FPGAs. The bus itself contains devices whose register maps are contained
+within the FPGA's register space.
+
+Required properties:
+- fpga: A phandle to the controlling IHS FPGA
+
+Example:
+
+FPGA0BUS: fpga0bus {
+	compatible = "gdsys,soc";
+	ranges = <0x0 0xe0600000 0x00004000>;
+	fpga = <&FPGA0>;
+};

drivers/misc/Kconfig

@@ -312,4 +312,12 @@ config FS_LOADER
 	  The consumer driver would then use this loader to program whatever,
 	  ie. the FPGA device.
 
+config GDSYS_SOC
+	bool "Enable gdsys SOC driver"
+	depends on MISC
+	help
+	  Support for gdsys IHS SOC, a simple bus associated with each gdsys
+	  IHS (Integrated Hardware Systems) FPGA, which holds all devices whose
+	  register maps are contained within the FPGA's register map.
+
 endmenu

drivers/misc/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_FSL_SEC_MON) += fsl_sec_mon.o
 obj-$(CONFIG_FS_LOADER) += fs_loader.o
 obj-$(CONFIG_GDSYS_IOEP) += gdsys_ioep.o
 obj-$(CONFIG_GDSYS_RXAUI_CTRL) += gdsys_rxaui_ctrl.o
+obj-$(CONFIG_GDSYS_SOC) += gdsys_soc.o
 obj-$(CONFIG_$(SPL_)I2C_EEPROM) += i2c_eeprom.o
 obj-$(CONFIG_IMX8) += imx8/
 obj-$(CONFIG_LED_STATUS) += status_led.o

drivers/misc/gdsys_soc.c

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/lists.h>
+
+#include "gdsys_soc.h"
+
+/**
+ * struct gdsys_soc_priv - Private data for gdsys soc bus
+ * @fpga: The gdsys IHS FPGA this bus is associated with
+ */
+struct gdsys_soc_priv {
+	struct udevice *fpga;
+};
+
+static const struct udevice_id gdsys_soc_ids[] = {
+	{ .compatible = "gdsys,soc" },
+	{ /* sentinel */ }
+};
+
+int gdsys_soc_get_fpga(struct udevice *child, struct udevice **fpga)
+{
+	struct gdsys_soc_priv *bus_priv;
+
+	if (!child->parent) {
+		debug("%s: Invalid parent\n", child->name);
+		return -EINVAL;
+	}
+
+	if (!device_is_compatible(child->parent, "gdsys,soc")) {
+		debug("%s: Not child of a gdsys soc\n", child->name);
+		return -EINVAL;
+	}
+
+	bus_priv = dev_get_priv(child->parent);
+
+	*fpga = bus_priv->fpga;
+
+	return 0;
+}
+
+static int gdsys_soc_probe(struct udevice *dev)
+{
+	struct gdsys_soc_priv *priv = dev_get_priv(dev);
+	struct udevice *fpga;
+	int res = uclass_get_device_by_phandle(UCLASS_MISC, dev, "fpga",
+					       &fpga);
+	if (res == -ENOENT) {
+		debug("%s: Could not find 'fpga' phandle\n", dev->name);
+		return -EINVAL;
+	}
+
+	if (res == -ENODEV) {
+		debug("%s: Could not get FPGA device\n", dev->name);
+		return -EINVAL;
+	}
+
+	priv->fpga = fpga;
+
+	return 0;
+}
+
+U_BOOT_DRIVER(gdsys_soc_bus) = {
+	.name           = "gdsys_soc_bus",
+	.id             = UCLASS_SIMPLE_BUS,
+	.of_match       = gdsys_soc_ids,
+	.probe          = gdsys_soc_probe,
+	.priv_auto_alloc_size = sizeof(struct gdsys_soc_priv),
+};

drivers/misc/gdsys_soc.h

@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#ifndef _GDSYS_SOC_H_
+#define _GDSYS_SOC_H_
+
+/**
+ * gdsys_soc_get_fpga() - Retrieve pointer to parent bus' FPGA device
+ * @child:	The child device on the FPGA bus needing access to the FPGA.
+ * @fpga:	Pointer to the retrieved FPGA device.
+ *
+ * To access their register maps, devices on gdsys soc buses usually have
+ * facilitate the accessor function of the IHS FPGA their parent bus is
+ * attached to. To access the FPGA device from within the bus' children, this
+ * function returns a pointer to it.
+ *
+ * Return: 0 on success, -ve on failure
+ */
+int gdsys_soc_get_fpga(struct udevice *child, struct udevice **fpga);
+#endif /* _GDSYS_SOC_H_ */