dm: Add support for generic system controllers (syscon)

Many SoCs have a number of system controllers which are dealt with as a
group by a single driver. It is a pain to have to add lots of compatible
strings and/or separate drivers for each. Instead we can identify the
controllers by a number and request the address of the one we want.

Add a simple implementation of this which can be used by SoC driver code.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/Makefile

@@ -11,3 +11,4 @@ endif
 obj-$(CONFIG_DM_DEVICE_REMOVE)	+= device-remove.o
 obj-$(CONFIG_DM)	+= dump.o
 obj-$(CONFIG_OF_CONTROL)	+= regmap.o
+obj-$(CONFIG_OF_CONTROL)	+= syscon-uclass.o

drivers/core/syscon-uclass.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <syscon.h>
+#include <dm.h>
+#include <errno.h>
+#include <regmap.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
+#include <linux/err.h>
+
+struct regmap *syscon_get_regmap(struct udevice *dev)
+{
+	struct syscon_uc_info *priv = dev_get_uclass_priv(dev);
+
+	return priv->regmap;
+}
+
+static int syscon_pre_probe(struct udevice *dev)
+{
+	struct syscon_uc_info *priv = dev_get_uclass_priv(dev);
+
+	return regmap_init_mem(dev, &priv->regmap);
+}
+
+struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data)
+{
+	struct udevice *dev;
+	struct uclass *uc;
+	int ret;
+
+	ret = uclass_get(UCLASS_SYSCON, &uc);
+	if (ret)
+		return ERR_PTR(ret);
+	uclass_foreach_dev(dev, uc) {
+		if (dev->driver_data == driver_data) {
+			struct syscon_uc_info *priv;
+			int ret;
+
+			ret = device_probe(dev);
+			if (ret)
+				return ERR_PTR(ret);
+			priv = dev_get_uclass_priv(dev);
+
+			return priv->regmap;
+		}
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+void *syscon_get_first_range(ulong driver_data)
+{
+	struct regmap *map;
+
+	map = syscon_get_regmap_by_driver_data(driver_data);
+	if (IS_ERR(map))
+		return map;
+	return regmap_get_range(map, 0);
+}
+
+UCLASS_DRIVER(syscon) = {
+	.id		= UCLASS_SYSCON,
+	.name		= "syscon",
+	.per_device_auto_alloc_size = sizeof(struct syscon_uc_info),
+	.pre_probe = syscon_pre_probe,
+};

include/dm/uclass-id.h

@@ -46,6 +46,7 @@ enum uclass_id {
 	UCLASS_SPI,		/* SPI bus */
 	UCLASS_SPI_FLASH,	/* SPI flash */
 	UCLASS_SPI_GENERIC,	/* Generic SPI flash target */
+	UCLASS_SYSCON,		/* System configuration device */
 	UCLASS_THERMAL,		/* Thermal sensor */
 	UCLASS_USB,		/* USB bus */
 	UCLASS_USB_DEV_GENERIC,	/* USB generic device */

include/syscon.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __SYSCON_H
+#define __SYSCON_H
+
+/**
+ * struct syscon_uc_info - Information stored by the syscon UCLASS_UCLASS
+ *
+ * @regmap:	Register map for this controller
+ */
+struct syscon_uc_info {
+	struct regmap *regmap;
+};
+
+/* So far there are no ops so this is a placeholder */
+struct syscon_ops {
+};
+
+#define syscon_get_ops(dev)        ((struct syscon_ops *)(dev)->driver->ops)
+
+/**
+ * syscon_get_regmap() - Get access to a register map
+ *
+ * @dev:	Device to check (UCLASS_SCON)
+ * @info:	Returns regmap for the device
+ * @return 0 if OK, -ve on error
+ */
+struct regmap *syscon_get_regmap(struct udevice *dev);
+
+/**
+ * syscon_get_regmap_by_driver_data() - Look up a controller by its ID
+ *
+ * Each system controller can be accessed by its driver data, which is
+ * assumed to be unique through the scope of all system controllers that
+ * are in use. This function looks up the regmap given this driver data.
+ *
+ * @driver_data:	Driver data value to look up
+ * @return register map correponding to @driver_data, or -ve error code
+ */
+struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data);
+
+/**
+ * syscon_get_first_range() - get the first memory range from a syscon regmap
+ *
+ * @driver_data:	Driver data value to look up
+ * @return first region of register map correponding to @driver_data, or
+ *			-ve error code
+ */
+void *syscon_get_first_range(ulong driver_data);
+
+#endif