env: Add a new implementation of environment access

We plan to move to a environment access via drivers for each location
where the environment can be stored. Add an implementation for this. So
far it is not used, but will be pressed into service in a future patch.

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

env/Makefile

@@ -5,7 +5,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y += common.o
+obj-y += common.o env.o
 
 ifndef CONFIG_SPL_BUILD
 obj-y += attr.o

env/env.c

@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <environment.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static struct env_driver *env_driver_lookup(enum env_location loc)
+{
+	struct env_driver *drv;
+	const int n_ents = ll_entry_count(struct env_driver, env_driver);
+	struct env_driver *entry;
+
+	drv = ll_entry_start(struct env_driver, env_driver);
+	for (entry = drv; entry != drv + n_ents; entry++) {
+		if (loc == entry->location)
+			return entry;
+	}
+
+	/* Not found */
+	return NULL;
+}
+
+static enum env_location env_get_default_location(void)
+{
+	if IS_ENABLED(CONFIG_ENV_IS_IN_DATAFLASH)
+		return ENVL_DATAFLASH;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_EEPROM)
+		return ENVL_EEPROM;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_FAT)
+		return ENVL_FAT;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_FLASH)
+		return ENVL_FLASH;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_MMC)
+		return ENVL_MMC;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_NAND)
+		return ENVL_NAND;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_NVRAM)
+		return ENVL_NVRAM;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_REMOTE)
+		return ENVL_REMOTE;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_SPI_FLASH)
+		return ENVL_SPI_FLASH;
+	else if IS_ENABLED(CONFIG_ENV_IS_IN_UBI)
+		return ENVL_UBI;
+	else if IS_ENABLED(CONFIG_ENV_IS_NOWHERE)
+		return ENVL_NOWHERE;
+	else
+		return ENVL_UNKNOWN;
+}
+
+static struct env_driver *env_driver_lookup_default(void)
+{
+	enum env_location loc = env_get_default_location();
+	struct env_driver *drv;
+
+	drv = env_driver_lookup(loc);
+	if (!drv) {
+		debug("%s: No environment driver for location %d\n", __func__,
+		      loc);
+		return NULL;
+	}
+
+	return drv;
+}
+
+int env_get_char_new(int index)
+{
+	struct env_driver *drv = env_driver_lookup_default();
+	int ret;
+
+	if (!drv)
+		return -ENODEV;
+	if (!drv->get_char)
+		return *(uchar *)(gd->env_addr + index);
+	ret = drv->get_char(index);
+	if (ret < 0) {
+		debug("%s: Environment failed to load (err=%d)\n",
+		      __func__, ret);
+	}
+
+	return ret;
+}
+
+int env_load(void)
+{
+	struct env_driver *drv = env_driver_lookup_default();
+	int ret = 0;
+
+	if (!drv)
+		return -ENODEV;
+	if (!drv->load)
+		return 0;
+	drv->load();  /* TODO(sjg@chromium.org): Make this return an error */
+	if (ret) {
+		debug("%s: Environment failed to load (err=%d)\n", __func__,
+		      ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int env_save(void)
+{
+	struct env_driver *drv = env_driver_lookup_default();
+	int ret;
+
+	if (!drv)
+		return -ENODEV;
+	if (!drv->save)
+		return -ENOSYS;
+	ret = drv->save();
+	if (ret) {
+		debug("%s: Environment failed to save (err=%d)\n", __func__,
+		      ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int env_init_new(void)
+{
+	struct env_driver *drv = env_driver_lookup_default();
+	int ret;
+
+	if (!drv)
+		return -ENODEV;
+	if (!drv->init)
+		return -ENOSYS;
+	ret = drv->init();
+	if (ret) {
+		debug("%s: Environment failed to init (err=%d)\n", __func__,
+		      ret);
+		return ret;
+	}
+
+	return 0;
+}