platform/mellanox: Add bootctl driver for Mellanox BlueField Soc

This commit adds the bootctl platform driver for Mellanox BlueField
Soc, which queries secure state and controls the eMMC boot partition
swapping by sending SMC calls to ATF running at EL3.

Below are the sequences of typical use case.

  1. User requests boot partition swapping, which could be on-demand or
     during boot-image upgrade via UEFI capsule;

  2. This bootctl driver handles the request and sends SMC call
     to ATF. ATF programs register BREADCRUMB0 which has value
     preserved during warm reset. It also programs eMMC to swap
     the boot partition;

  3. After software reset (rebooting), ATF BL1 (BootRom) checks
     register BREADCRUMB0 and enable watchdog if configured;

  4. If booting fails, the watchdog timer will trigger rebooting.
     In such case, ATF Boot ROM will switch the boot partition
     back to the previous one. This is a robust feature and used
     to prevent failure during boot partition upgrade.

Reviewed-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Liming Sun <lsun@mellanox.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

1 files changed, 321 insertions, 0 deletions

diff --git a/drivers/platform/mellanox/mlxbf-bootctl.c b/drivers/platform/mellanox/mlxbf-bootctl.c
new file mode 100644
index 000000000000..61753b648506
--- /dev/null
+++ b/drivers/platform/mellanox/mlxbf-bootctl.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Mellanox boot control driver
+ *
+ * This driver provides a sysfs interface for systems management
+ * software to manage reset-time actions.
+ *
+ * Copyright (C) 2019 Mellanox Technologies
+ */
+
+#include <linux/acpi.h>
+#include <linux/arm-smccc.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include "mlxbf-bootctl.h"
+
+#define MLXBF_BOOTCTL_SB_SECURE_MASK		0x03
+#define MLXBF_BOOTCTL_SB_TEST_MASK		0x0c
+
+#define MLXBF_SB_KEY_NUM			4
+
+/* UUID used to probe ATF service. */
+static const char *mlxbf_bootctl_svc_uuid_str =
+	"89c036b4-e7d7-11e6-8797-001aca00bfc4";
+
+struct mlxbf_bootctl_name {
+	u32 value;
+	const char *name;
+};
+
+static struct mlxbf_bootctl_name boot_names[] = {
+	{ MLXBF_BOOTCTL_EXTERNAL, "external" },
+	{ MLXBF_BOOTCTL_EMMC, "emmc" },
+	{ MLNX_BOOTCTL_SWAP_EMMC, "swap_emmc" },
+	{ MLXBF_BOOTCTL_EMMC_LEGACY, "emmc_legacy" },
+	{ MLXBF_BOOTCTL_NONE, "none" },
+};
+
+static const char * const mlxbf_bootctl_lifecycle_states[] = {
+	[0] = "Production",
+	[1] = "GA Secured",
+	[2] = "GA Non-Secured",
+	[3] = "RMA",
+};
+
+/* ARM SMC call which is atomic and no need for lock. */
+static int mlxbf_bootctl_smc(unsigned int smc_op, int smc_arg)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(smc_op, smc_arg, 0, 0, 0, 0, 0, 0, &res);
+
+	return res.a0;
+}
+
+/* Return the action in integer or an error code. */
+static int mlxbf_bootctl_reset_action_to_val(const char *action)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(boot_names); i++)
+		if (sysfs_streq(boot_names[i].name, action))
+			return boot_names[i].value;
+
+	return -EINVAL;
+}
+
+/* Return the action in string. */
+static const char *mlxbf_bootctl_action_to_string(int action)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(boot_names); i++)
+		if (boot_names[i].value == action)
+			return boot_names[i].name;
+
+	return "invalid action";
+}
+
+static ssize_t post_reset_wdog_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	int ret;
+
+	ret = mlxbf_bootctl_smc(MLXBF_BOOTCTL_GET_POST_RESET_WDOG, 0);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t post_reset_wdog_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &value);
+	if (ret)
+		return ret;
+
+	ret = mlxbf_bootctl_smc(MLXBF_BOOTCTL_SET_POST_RESET_WDOG, value);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t mlxbf_bootctl_show(int smc_op, char *buf)
+{
+	int action;
+
+	action = mlxbf_bootctl_smc(smc_op, 0);
+	if (action < 0)
+		return action;
+
+	return sprintf(buf, "%s\n", mlxbf_bootctl_action_to_string(action));
+}
+
+static int mlxbf_bootctl_store(int smc_op, const char *buf, size_t count)
+{
+	int ret, action;
+
+	action = mlxbf_bootctl_reset_action_to_val(buf);
+	if (action < 0)
+		return action;
+
+	ret = mlxbf_bootctl_smc(smc_op, action);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t reset_action_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	return mlxbf_bootctl_show(MLXBF_BOOTCTL_GET_RESET_ACTION, buf);
+}
+
+static ssize_t reset_action_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	return mlxbf_bootctl_store(MLXBF_BOOTCTL_SET_RESET_ACTION, buf, count);
+}
+
+static ssize_t second_reset_action_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	return mlxbf_bootctl_show(MLXBF_BOOTCTL_GET_SECOND_RESET_ACTION, buf);
+}
+
+static ssize_t second_reset_action_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	return mlxbf_bootctl_store(MLXBF_BOOTCTL_SET_SECOND_RESET_ACTION, buf,
+				   count);
+}
+
+static ssize_t lifecycle_state_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	int lc_state;
+
+	lc_state = mlxbf_bootctl_smc(MLXBF_BOOTCTL_GET_TBB_FUSE_STATUS,
+				     MLXBF_BOOTCTL_FUSE_STATUS_LIFECYCLE);
+	if (lc_state < 0)
+		return lc_state;
+
+	lc_state &=
+		MLXBF_BOOTCTL_SB_TEST_MASK | MLXBF_BOOTCTL_SB_SECURE_MASK;
+
+	/*
+	 * If the test bits are set, we specify that the current state may be
+	 * due to using the test bits.
+	 */
+	if (lc_state & MLXBF_BOOTCTL_SB_TEST_MASK) {
+		lc_state &= MLXBF_BOOTCTL_SB_SECURE_MASK;
+
+		return sprintf(buf, "%s(test)\n",
+			       mlxbf_bootctl_lifecycle_states[lc_state]);
+	}
+
+	return sprintf(buf, "%s\n", mlxbf_bootctl_lifecycle_states[lc_state]);
+}
+
+static ssize_t secure_boot_fuse_state_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	int burnt, valid, key, key_state, buf_len = 0, upper_key_used = 0;
+	const char *status;
+
+	key_state = mlxbf_bootctl_smc(MLXBF_BOOTCTL_GET_TBB_FUSE_STATUS,
+				      MLXBF_BOOTCTL_FUSE_STATUS_KEYS);
+	if (key_state < 0)
+		return key_state;
+
+	/*
+	 * key_state contains the bits for 4 Key versions, loaded from eFuses
+	 * after a hard reset. Lower 4 bits are a thermometer code indicating
+	 * key programming has started for key n (0000 = none, 0001 = version 0,
+	 * 0011 = version 1, 0111 = version 2, 1111 = version 3). Upper 4 bits
+	 * are a thermometer code indicating key programming has completed for
+	 * key n (same encodings as the start bits). This allows for detection
+	 * of an interruption in the progamming process which has left the key
+	 * partially programmed (and thus invalid). The process is to burn the
+	 * eFuse for the new key start bit, burn the key eFuses, then burn the
+	 * eFuse for the new key complete bit.
+	 *
+	 * For example 0000_0000: no key valid, 0001_0001: key version 0 valid,
+	 * 0011_0011: key 1 version valid, 0011_0111: key version 2 started
+	 * programming but did not complete, etc. The most recent key for which
+	 * both start and complete bit is set is loaded. On soft reset, this
+	 * register is not modified.
+	 */
+	for (key = MLXBF_SB_KEY_NUM - 1; key >= 0; key--) {
+		burnt = key_state & BIT(key);
+		valid = key_state & BIT(key + MLXBF_SB_KEY_NUM);
+
+		if (burnt && valid)
+			upper_key_used = 1;
+
+		if (upper_key_used) {
+			if (burnt)
+				status = valid ? "Used" : "Wasted";
+			else
+				status = valid ? "Invalid" : "Skipped";
+		} else {
+			if (burnt)
+				status = valid ? "InUse" : "Incomplete";
+			else
+				status = valid ? "Invalid" : "Free";
+		}
+		buf_len += sprintf(buf + buf_len, "%d:%s ", key, status);
+	}
+	buf_len += sprintf(buf + buf_len, "\n");
+
+	return buf_len;
+}
+
+static DEVICE_ATTR_RW(post_reset_wdog);
+static DEVICE_ATTR_RW(reset_action);
+static DEVICE_ATTR_RW(second_reset_action);
+static DEVICE_ATTR_RO(lifecycle_state);
+static DEVICE_ATTR_RO(secure_boot_fuse_state);
+
+static struct attribute *mlxbf_bootctl_attrs[] = {
+	&dev_attr_post_reset_wdog.attr,
+	&dev_attr_reset_action.attr,
+	&dev_attr_second_reset_action.attr,
+	&dev_attr_lifecycle_state.attr,
+	&dev_attr_secure_boot_fuse_state.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(mlxbf_bootctl);
+
+static const struct acpi_device_id mlxbf_bootctl_acpi_ids[] = {
+	{"MLNXBF04", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, mlxbf_bootctl_acpi_ids);
+
+static bool mlxbf_bootctl_guid_match(const guid_t *guid,
+				     const struct arm_smccc_res *res)
+{
+	guid_t id = GUID_INIT(res->a0, res->a1, res->a1 >> 16,
+			      res->a2, res->a2 >> 8, res->a2 >> 16,
+			      res->a2 >> 24, res->a3, res->a3 >> 8,
+			      res->a3 >> 16, res->a3 >> 24);
+
+	return guid_equal(guid, &id);
+}
+
+static int mlxbf_bootctl_probe(struct platform_device *pdev)
+{
+	struct arm_smccc_res res = { 0 };
+	guid_t guid;
+	int ret;
+
+	/* Ensure we have the UUID we expect for this service. */
+	arm_smccc_smc(MLXBF_BOOTCTL_SIP_SVC_UID, 0, 0, 0, 0, 0, 0, 0, &res);
+	guid_parse(mlxbf_bootctl_svc_uuid_str, &guid);
+	if (!mlxbf_bootctl_guid_match(&guid, &res))
+		return -ENODEV;
+
+	/*
+	 * When watchdog is used, it sets boot mode to MLXBF_BOOTCTL_SWAP_EMMC
+	 * in case of boot failures. However it doesn't clear the state if there
+	 * is no failure. Restore the default boot mode here to avoid any
+	 * unnecessary boot partition swapping.
+	 */
+	ret = mlxbf_bootctl_smc(MLXBF_BOOTCTL_SET_RESET_ACTION,
+				MLXBF_BOOTCTL_EMMC);
+	if (ret < 0)
+		dev_warn(&pdev->dev, "Unable to reset the EMMC boot mode\n");
+
+	return 0;
+}
+
+static struct platform_driver mlxbf_bootctl_driver = {
+	.probe = mlxbf_bootctl_probe,
+	.driver = {
+		.name = "mlxbf-bootctl",
+		.groups = mlxbf_bootctl_groups,
+		.acpi_match_table = mlxbf_bootctl_acpi_ids,
+	}
+};
+
+module_platform_driver(mlxbf_bootctl_driver);
+
+MODULE_DESCRIPTION("Mellanox boot control driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Mellanox Technologies");