@@ -245,6 +245,16 @@ config PARTIAL_EMULATION
not been emulated to their complete functionality. Enabling this might
result in unwanted/non-spec compliant behavior.
+config SCMI_SMC
+ bool "Enable forwarding SCMI over SMC calls from Dom0 to EL3 firmware"
+ default y
+ help
+ This option enables basic awareness for SCMI calls using SMC as
+ doorbell mechanism and Shared Memory for transport ("arm,scmi-smc"
+ compatible only). The value of "arm,smc-id" DT property from SCMI
+ firmware node is used to trap and forward corresponding SCMI SMCs
+ to firmware running at EL3, if the call comes from Dom0.
+
endmenu
menu "ARM errata workaround via the alternative framework"
@@ -45,6 +45,7 @@ obj-y += platform_hypercall.o
obj-y += physdev.o
obj-y += processor.o
obj-y += psci.o
+obj-$(CONFIG_SCMI_SMC) += scmi-smc.o
obj-y += setup.o
obj-y += shutdown.o
obj-y += smp.o
new file mode 100644
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * xen/arch/arm/include/asm/scmi-smc.h
+ *
+ * ARM System Control and Management Interface (SCMI) over SMC
+ * Generic handling layer
+ *
+ * Andrei Cherechesu <andrei.cherechesu@nxp.com>
+ * Copyright 2024 NXP
+ */
+
+#ifndef __ASM_SCMI_SMC_H__
+#define __ASM_SCMI_SMC_H__
+
+#include <xen/types.h>
+#include <asm/regs.h>
+
+#ifdef CONFIG_SCMI_SMC
+
+bool scmi_is_enabled(void);
+bool scmi_is_valid_smc_id(uint32_t fid);
+bool scmi_handle_smc(struct cpu_user_regs *regs);
+
+#else
+
+static inline bool scmi_is_enabled(void)
+{
+ return false;
+}
+
+static inline bool scmi_is_valid_smc_id(uint32_t fid)
+{
+ return false;
+}
+
+static inline bool scmi_handle_smc(struct cpu_user_regs *regs)
+{
+ return false;
+}
+
+#endif /* CONFIG_SCMI_SMC */
+
+#endif /* __ASM_SCMI_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
new file mode 100644
@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * xen/arch/arm/scmi-smc.c
+ *
+ * ARM System Control and Management Interface (SCMI) over SMC
+ * Generic handling layer
+ *
+ * Andrei Cherechesu <andrei.cherechesu@nxp.com>
+ * Copyright 2024 NXP
+ */
+
+#include <xen/acpi.h>
+#include <xen/device_tree.h>
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/sched.h>
+#include <xen/types.h>
+
+#include <asm/scmi-smc.h>
+#include <asm/smccc.h>
+
+#define SCMI_SMC_ID_PROP "arm,smc-id"
+
+static bool scmi_support;
+static uint32_t scmi_smc_id;
+
+/* Check if SCMI layer correctly initialized and can be used. */
+bool scmi_is_enabled(void)
+{
+ return scmi_support;
+}
+
+/*
+ * Check if provided SMC Function Identifier matches the one known by the SCMI
+ * layer, as read from DT prop 'arm,smc-id' during initialiation.
+ */
+bool scmi_is_valid_smc_id(uint32_t fid)
+{
+ return (fid == scmi_smc_id);
+}
+
+/*
+ * Generic handler for SCMI-SMC requests, currently only forwarding the
+ * request to FW running at EL3 if it came from Dom0. Is called from the vSMC
+ * layer for SiP SMCs, since SCMI calls are usually provided this way.
+ * Can also be called from `platform_smc()` plat-specific callback.
+ *
+ * Returns true if SMC was handled (regardless of response), false otherwise.
+ */
+bool scmi_handle_smc(struct cpu_user_regs *regs)
+{
+ struct arm_smccc_res res;
+
+ /* Only the hardware domain should use SCMI calls */
+ if ( !is_hardware_domain(current->domain) )
+ {
+ gprintk(XENLOG_ERR, "SCMI: Unprivileged d%d cannot use SCMI.\n",
+ current->domain->domain_id);
+ return false;
+ }
+
+ /* For the moment, forward the SCMI Request to FW running at EL3 */
+ arm_smccc_1_1_smc(scmi_smc_id,
+ get_user_reg(regs, 1),
+ get_user_reg(regs, 2),
+ get_user_reg(regs, 3),
+ get_user_reg(regs, 4),
+ get_user_reg(regs, 5),
+ get_user_reg(regs, 6),
+ get_user_reg(regs, 7),
+ &res);
+
+ set_user_reg(regs, 0, res.a0);
+ set_user_reg(regs, 1, res.a1);
+ set_user_reg(regs, 2, res.a2);
+ set_user_reg(regs, 3, res.a3);
+
+ return true;
+}
+
+static int __init scmi_check_smccc_ver(void)
+{
+ if ( smccc_ver < ARM_SMCCC_VERSION_1_1 )
+ {
+ printk(XENLOG_ERR
+ "SCMI: No SMCCC 1.1 support, SCMI calls forwarding disabled\n");
+ return -ENOSYS;
+ }
+
+ return 0;
+}
+
+static int __init scmi_dt_init_smccc(void)
+{
+ static const struct dt_device_match scmi_ids[] __initconst =
+ {
+ /* We only support "arm,scmi-smc" binding for now */
+ DT_MATCH_COMPATIBLE("arm,scmi-smc"),
+ { /* sentinel */ },
+ };
+ const struct dt_device_node *scmi_node;
+ const char *smc_id_prop = SCMI_SMC_ID_PROP;
+ int ret;
+
+ /* If no SCMI firmware node found, fail silently as it's not mandatory */
+ scmi_node = dt_find_matching_node(NULL, scmi_ids);
+ if ( !scmi_node )
+ return -EOPNOTSUPP;
+
+ ret = dt_property_read_u32(scmi_node, smc_id_prop, &scmi_smc_id);
+ if ( !ret )
+ {
+ printk(XENLOG_ERR "SCMI: No valid \"%s\" property in \"%s\" DT node\n",
+ smc_id_prop, scmi_node->full_name);
+ return -ENOENT;
+ }
+
+ scmi_support = true;
+
+ return 0;
+}
+
+/* Initialize the SCMI layer based on SMCs and Device-tree */
+static int __init scmi_init(void)
+{
+ int ret;
+
+ if ( !acpi_disabled )
+ {
+ printk("SCMI is not supported when using ACPI\n");
+ return -EINVAL;
+ }
+
+ ret = scmi_check_smccc_ver();
+ if ( ret )
+ goto err;
+
+ ret = scmi_dt_init_smccc();
+ if ( ret == -EOPNOTSUPP )
+ return ret;
+ if ( ret )
+ goto err;
+
+ printk(XENLOG_INFO "Using SCMI with SMC ID: 0x%x\n", scmi_smc_id);
+
+ return 0;
+
+err:
+ printk(XENLOG_ERR "SCMI: Initialization failed (ret = %d)\n", ret);
+ return ret;
+}
+
+presmp_initcall(scmi_init);
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */