[PATCH v1 6/8] bootcount: gpt: introduce GPT-backed bootcount device

[dmukhin at ford.com]

From: Denis Mukhin <dmukhin at ford.com> 

Introduce bootcount device backed by GPT PTE attributes (bits 48:63).

Signed-off-by: Denis Mukhin <dmukhin at ford.com>
---
 drivers/bootcount/Kconfig         |   7 ++
 drivers/bootcount/Makefile        |   1 +
 drivers/bootcount/bootcount-gpt.c | 140 ++++++++++++++++++++++++++++++
 3 files changed, 148 insertions(+)
 create mode 100644 drivers/bootcount/bootcount-gpt.c

diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
index 4c0c8d89bb40..eccd610e3390 100644
--- a/drivers/bootcount/Kconfig
+++ b/drivers/bootcount/Kconfig
@@ -171,6 +171,13 @@ config DM_BOOTCOUNT_ZYNQMP
 	  Enable support for the bootcount API by utilising the Persistent
 	  Global General Storage Register 2 of the PMU.
 
+config DM_BOOTCOUNT_GPT
+	bool "Support GPT PTE-backed boot counter"
+	depends on EFI_PARTITION
+	help
+	  Add support for maintaining boot count within bits 48:63 of GUID
+	  partition table entry attributes (similarly to ChromiumOS).
+
 endmenu
 
 endif
diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
index 0cf79e428d68..927694979801 100644
--- a/drivers/bootcount/Makefile
+++ b/drivers/bootcount/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_DM_BOOTCOUNT_I2C)	+= bootcount_dm_i2c.o
 obj-$(CONFIG_DM_BOOTCOUNT_SPI_FLASH)	+= spi-flash.o
 obj-$(CONFIG_DM_BOOTCOUNT_SYSCON) += bootcount_syscon.o
 obj-$(CONFIG_DM_BOOTCOUNT_ZYNQMP)	+= bootcount_zynqmp.o
+obj-$(CONFIG_DM_BOOTCOUNT_GPT)	+= bootcount-gpt.o
diff --git a/drivers/bootcount/bootcount-gpt.c b/drivers/bootcount/bootcount-gpt.c
new file mode 100644
index 000000000000..d2bbff2ba120
--- /dev/null
+++ b/drivers/bootcount/bootcount-gpt.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#define pr_fmt(fmt)		"bootcount-gpt: " fmt
+#define LOG_CATEGORY	UCLASS_BOOTCOUNT
+
+#include <blk.h>
+#include <bootcount.h>
+#include <dm.h>
+#include <linux/printk.h>
+#include <part.h>
+
+struct bootcount_gpt_priv {
+	struct blk_desc *blk_desc;
+	const char *partition_name;
+	int uclass_id;
+	int devnum;
+	int partnum;
+};
+
+static int bootcount_gpt_find(struct udevice *dev)
+{
+	struct bootcount_gpt_priv *priv = dev_get_priv(dev);
+	struct udevice *bdev;
+	struct disk_partition info;
+	int partnum, rc;
+
+	rc = blk_get_device(priv->uclass_id, priv->devnum, &bdev);
+	if (rc < 0)
+		return -ENODEV;
+
+	partnum = part_get_info_by_name(dev_get_uclass_plat(bdev),
+	                                priv->partition_name, &info);
+	if (partnum < 0)
+		return -ENODEV;
+
+	if (info.bootable & PART_BOOTABLE) {
+		pr_warn("partition %s: legacy boot flag enabled, no GPT accounting\n",
+		        priv->partition_name);
+		return -EPERM;
+	}
+
+	priv->blk_desc = dev_get_uclass_plat(bdev);
+	priv->partnum = partnum;
+
+	return 0;
+}
+
+static int bootcount_gpt_get(struct udevice *dev, u32 *val)
+{
+	struct bootcount_gpt_priv *priv = dev_get_priv(dev);
+	int rc;
+
+	if (!priv->blk_desc) {
+		rc = bootcount_gpt_find(dev);
+		if (rc < 0)
+			return rc;
+	}
+
+	rc = read_disk_flags(priv->blk_desc, priv->partnum, (u16 *)val);
+	if (rc < 0) {
+		pr_err("partnum %d: failed to read GPT flags: %d\n",
+		       priv->partnum, rc);
+		return rc;
+	}
+
+	pr_debug("partnum %d: read  GPT flags 0x%04x\n", priv->partnum, *val);
+
+	return 0;
+}
+
+static int bootcount_gpt_set(struct udevice *dev, const u32 val)
+{
+	struct bootcount_gpt_priv *priv = dev_get_priv(dev);
+	int rc;
+
+	if (!priv->blk_desc) {
+		rc = bootcount_gpt_find(dev);
+		if (rc < 0)
+			return rc;
+	}
+
+	pr_debug("partnum %d: write GPT flags 0x%04x\n", priv->partnum, val);
+
+	rc = write_disk_flags(priv->blk_desc, priv->partnum, (u16)val);
+	if (rc < 0) {
+		pr_err("partnum %d: failed to write GPT flags: %d\n",
+		       priv->partnum, rc);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int bootcount_gpt_probe(struct udevice *dev)
+{
+	struct bootcount_gpt_priv *priv = dev_get_priv(dev);
+	const char *str;
+	int uclass_id, devnum;
+
+	str = dev_read_string(dev, "device-type");
+	if (!str)
+		return -ENOSYS;
+
+	uclass_id = uclass_get_by_name(str);
+	if (uclass_id == UCLASS_INVALID)
+		return -ENOSYS;
+
+	devnum = dev_read_s32_default(dev, "devnum", 0);
+	if (devnum < 0)
+		return -ENOSYS;
+
+	str = dev_read_string(dev, "partition-name");
+	if (!str)
+		return -ENOSYS;
+
+	priv->uclass_id = uclass_id;
+	priv->devnum = devnum;
+	priv->partition_name = str;
+
+	return 0;
+}
+
+static const struct bootcount_ops bootcount_gpt_ops = {
+	.get = bootcount_gpt_get,
+	.set = bootcount_gpt_set,
+};
+
+static const struct udevice_id bootcount_gpt_ids[] = {
+	{ .compatible = "u-boot,bootcount-gpt" },
+	{ }
+};
+
+U_BOOT_DRIVER(bootcount_gpt) = {
+	.name		= "bootcount-gpt",
+	.id		= UCLASS_BOOTCOUNT,
+	.priv_auto	= sizeof(struct bootcount_gpt_priv),
+	.probe		= bootcount_gpt_probe,
+	.of_match	= bootcount_gpt_ids,
+	.ops		= &bootcount_gpt_ops,
+};
-- 
2.54.0