1 files changed, 109 insertions, 0 deletions
diff --git a/lib/extensions/sme/sme.c b/lib/extensions/sme/sme.c
new file mode 100644
index 0000000..ec8cca8
--- /dev/null
+++ b/lib/extensions/sme/sme.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2021-2022, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <lib/el3_runtime/context_mgmt.h>
+#include <lib/extensions/sme.h>
+#include <lib/extensions/sve.h>
+
+static bool feat_sme_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64pfr1_el1() >> ID_AA64PFR1_EL1_SME_SHIFT;
+	return (features & ID_AA64PFR1_EL1_SME_MASK) != 0U;
+}
+
+static bool feat_sme_fa64_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64smfr0_el1();
+	return (features & ID_AA64SMFR0_EL1_FA64_BIT) != 0U;
+}
+
+void sme_enable(cpu_context_t *context)
+{
+	u_register_t reg;
+	u_register_t cptr_el3;
+	el3_state_t *state;
+
+	/* Make sure SME is implemented in hardware before continuing. */
+	if (!feat_sme_supported()) {
+		/* Perhaps the hardware supports SVE only */
+		sve_enable(context);
+		return;
+	}
+
+	/* Get the context state. */
+	state = get_el3state_ctx(context);
+
+	/* Enable SME in CPTR_EL3. */
+	reg = read_ctx_reg(state, CTX_CPTR_EL3);
+	reg |= ESM_BIT;
+	write_ctx_reg(state, CTX_CPTR_EL3, reg);
+
+	/* Set the ENTP2 bit in SCR_EL3 to enable access to TPIDR2_EL0. */
+	reg = read_ctx_reg(state, CTX_SCR_EL3);
+	reg |= SCR_ENTP2_BIT;
+	write_ctx_reg(state, CTX_SCR_EL3, reg);
+
+	/* Set CPTR_EL3.ESM bit so we can write SMCR_EL3 without trapping. */
+	cptr_el3 = read_cptr_el3();
+	write_cptr_el3(cptr_el3 | ESM_BIT);
+	isb();
+
+	/*
+	 * Set the max LEN value and FA64 bit. This register is set up globally
+	 * to be the least restrictive, then lower ELs can restrict as needed
+	 * using SMCR_EL2 and SMCR_EL1.
+	 */
+	reg = SMCR_ELX_LEN_MASK;
+	if (feat_sme_fa64_supported()) {
+		VERBOSE("[SME] FA64 enabled\n");
+		reg |= SMCR_ELX_FA64_BIT;
+	}
+	write_smcr_el3(reg);
+
+	/* Reset CPTR_EL3 value. */
+	write_cptr_el3(cptr_el3);
+	isb();
+
+	/* Enable SVE/FPU in addition to SME. */
+	sve_enable(context);
+}
+
+void sme_disable(cpu_context_t *context)
+{
+	u_register_t reg;
+	el3_state_t *state;
+
+	/* Make sure SME is implemented in hardware before continuing. */
+	if (!feat_sme_supported()) {
+		/* Perhaps the hardware supports SVE only */
+		sve_disable(context);
+		return;
+	}
+
+	/* Get the context state. */
+	state = get_el3state_ctx(context);
+
+	/* Disable SME, SVE, and FPU since they all share registers. */
+	reg = read_ctx_reg(state, CTX_CPTR_EL3);
+	reg &= ~ESM_BIT;	/* Trap SME */
+	reg &= ~CPTR_EZ_BIT;	/* Trap SVE */
+	reg |= TFP_BIT;		/* Trap FPU/SIMD */
+	write_ctx_reg(state, CTX_CPTR_EL3, reg);
+
+	/* Disable access to TPIDR2_EL0. */
+	reg = read_ctx_reg(state, CTX_SCR_EL3);
+	reg &= ~SCR_ENTP2_BIT;
+	write_ctx_reg(state, CTX_SCR_EL3, reg);
+}