bootstd: Provide a bootmeth method to obtain state info

Some bootmeths can provide information about what is available to boot.
For example, VBE simple provides access to the firmware state.

Add a new method for this, along with a sandbox test.

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

boot/bootmeth-uclass.c

@@ -20,6 +20,16 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+int bootmeth_get_state_desc(struct udevice *dev, char *buf, int maxsize)
+{
+	const struct bootmeth_ops *ops = bootmeth_get_ops(dev);
+
+	if (!ops->get_state_desc)
+		return -ENOSYS;
+
+	return ops->get_state_desc(dev, buf, maxsize);
+}
+
 int bootmeth_check(struct udevice *dev, struct bootflow_iter *iter)
 {
 	const struct bootmeth_ops *ops = bootmeth_get_ops(dev);

boot/bootmeth_distro.c

@@ -22,6 +22,19 @@
 #include <mmc.h>
 #include <pxe_utils.h>
 
+static int distro_get_state_desc(struct udevice *dev, char *buf, int maxsize)
+{
+	if (IS_ENABLED(CONFIG_SANDBOX)) {
+		int len;
+
+		len = snprintf(buf, maxsize, "OK");
+
+		return len + 1 < maxsize ? 0 : -ENOSPC;
+	}
+
+	return 0;
+}
+
 static int disto_getfile(struct pxe_context *ctx, const char *file_path,
 			 char *file_addr, ulong *sizep)
 {
@@ -123,6 +136,7 @@ static int distro_bootmeth_bind(struct udevice *dev)
 }
 
 static struct bootmeth_ops distro_bootmeth_ops = {
+	.get_state_desc	= distro_get_state_desc,
 	.check		= distro_check,
 	.read_bootflow	= distro_read_bootflow,
 	.read_file	= bootmeth_common_read_file,

include/bootmeth.h

@@ -24,7 +24,25 @@ struct bootmeth_uc_plat {
 /** struct bootmeth_ops - Operations for boot methods */
 struct bootmeth_ops {
 	/**
-	 * check_supported() - check if a bootmeth supports this bootflow
+	 * get_state_desc() - get detailed state information
+	 *
+	 * Prodecues a textual description of the state of the bootmeth. This
+	 * can include newline characters if it extends to multiple lines. It
+	 * must be a nul-terminated string.
+	 *
+	 * This may involve reading state from the system, e.g. some data in
+	 * the firmware area.
+	 *
+	 * @dev:	Bootmethod device to check
+	 * @buf:	Buffer to place the info in (terminator must fit)
+	 * @maxsize:	Size of buffer
+	 * Returns: 0 if OK, -ENOSPC is buffer is too small, other -ve error if
+	 * something else went wrong
+	 */
+	int (*get_state_desc)(struct udevice *dev, char *buf, int maxsize);
+
+	/**
+	 * check_supported() - check if a bootmeth supports this bootdev
 	 *
 	 * This is optional. If not provided, the bootdev is assumed to be
 	 * supported
@@ -91,6 +109,24 @@ struct bootmeth_ops {
 
 #define bootmeth_get_ops(dev)  ((struct bootmeth_ops *)(dev)->driver->ops)
 
+/**
+ * bootmeth_get_state_desc() - get detailed state information
+ *
+ * Prodecues a textual description of the state of the bootmeth. This
+ * can include newline characters if it extends to multiple lines. It
+ * must be a nul-terminated string.
+ *
+ * This may involve reading state from the system, e.g. some data in
+ * the firmware area.
+ *
+ * @dev:	Bootmethod device to check
+ * @buf:	Buffer to place the info in (terminator must fit)
+ * @maxsize:	Size of buffer
+ * Returns: 0 if OK, -ENOSPC is buffer is too small, other -ve error if
+ * something else went wrong
+ */
+int bootmeth_get_state_desc(struct udevice *dev, char *buf, int maxsize);
+
 /**
  * bootmeth_check() - check if a bootmeth supports this bootflow
  *

test/boot/bootmeth.c

@@ -7,7 +7,9 @@
  */
 
 #include <common.h>
+#include <bootmeth.h>
 #include <bootstd.h>
+#include <dm.h>
 #include <test/suites.h>
 #include <test/ut.h>
 #include "bootstd_common.h"
@@ -120,3 +122,19 @@ static int bootmeth_env(struct unit_test_state *uts)
 	return 0;
 }
 BOOTSTD_TEST(bootmeth_env, UT_TESTF_DM | UT_TESTF_SCAN_FDT);
+
+/* Check the get_state_desc() method */
+static int bootmeth_state(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	char buf[50];
+
+	ut_assertok(uclass_first_device(UCLASS_BOOTMETH, &dev));
+	ut_assertnonnull(dev);
+
+	ut_assertok(bootmeth_get_state_desc(dev, buf, sizeof(buf)));
+	ut_asserteq_str("OK", buf);
+
+	return 0;
+}
+BOOTSTD_TEST(bootmeth_state, UT_TESTF_DM | UT_TESTF_SCAN_FDT);