[RFC PATCH v4 2/4] lib: sbi: Implement SBI CPPC extension
Sunil V L
sunilvl at ventanamicro.com
Mon Mar 27 21:29:07 PDT 2023
Implement SBI CPPC extension. This extension is only available when
OpenSBI platform provides a CPPC device to generic library.
Signed-off-by: Sunil V L <sunilvl at ventanamicro.com>
Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
---
include/sbi/sbi_cppc.h | 35 +++++++++
lib/sbi/Kconfig | 4 +
lib/sbi/objects.mk | 4 +
lib/sbi/sbi_cppc.c | 156 +++++++++++++++++++++++++++++++++++++++
lib/sbi/sbi_ecall_cppc.c | 63 ++++++++++++++++
5 files changed, 262 insertions(+)
create mode 100644 include/sbi/sbi_cppc.h
create mode 100644 lib/sbi/sbi_cppc.c
create mode 100644 lib/sbi/sbi_ecall_cppc.c
diff --git a/include/sbi/sbi_cppc.h b/include/sbi/sbi_cppc.h
new file mode 100644
index 0000000..edf73f5
--- /dev/null
+++ b/include/sbi/sbi_cppc.h
@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ *
+ */
+
+#ifndef __SBI_CPPC_H__
+#define __SBI_CPPC_H__
+
+#include <sbi/sbi_types.h>
+
+/** CPPC device */
+struct sbi_cppc_device {
+ /** Name of the CPPC device */
+ char name[32];
+
+ /** probe - returns register width if implemented, 0 otherwise */
+ int (*cppc_probe)(unsigned long reg);
+
+ /** read the cppc register*/
+ int (*cppc_read)(unsigned long reg, uint64_t *val);
+
+ /** write to the cppc register*/
+ int (*cppc_write)(unsigned long reg, uint64_t val);
+};
+
+int sbi_cppc_probe(unsigned long reg);
+int sbi_cppc_read(unsigned long reg, uint64_t *val);
+int sbi_cppc_write(unsigned long reg, uint64_t val);
+
+const struct sbi_cppc_device *sbi_cppc_get_device(void);
+void sbi_cppc_set_device(const struct sbi_cppc_device *dev);
+
+#endif
diff --git a/lib/sbi/Kconfig b/lib/sbi/Kconfig
index 7eb3273..477775e 100644
--- a/lib/sbi/Kconfig
+++ b/lib/sbi/Kconfig
@@ -34,6 +34,10 @@ config SBI_ECALL_DBCN
bool "Debug Console extension"
default y
+config SBI_ECALL_CPPC
+ bool "CPPC extension"
+ default y
+
config SBI_ECALL_LEGACY
bool "SBI v0.1 legacy extensions"
default y
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 770238b..7d691c6 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -43,6 +43,9 @@ libsbi-objs-$(CONFIG_SBI_ECALL_PMU) += sbi_ecall_pmu.o
carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_DBCN) += ecall_dbcn
libsbi-objs-$(CONFIG_SBI_ECALL_DBCN) += sbi_ecall_dbcn.o
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_CPPC) += ecall_cppc
+libsbi-objs-$(CONFIG_SBI_ECALL_CPPC) += sbi_ecall_cppc.o
+
carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_LEGACY) += ecall_legacy
libsbi-objs-$(CONFIG_SBI_ECALL_LEGACY) += sbi_ecall_legacy.o
@@ -74,3 +77,4 @@ libsbi-objs-y += sbi_tlb.o
libsbi-objs-y += sbi_trap.o
libsbi-objs-y += sbi_unpriv.o
libsbi-objs-y += sbi_expected_trap.o
+libsbi-objs-y += sbi_cppc.o
diff --git a/lib/sbi/sbi_cppc.c b/lib/sbi/sbi_cppc.c
new file mode 100644
index 0000000..dddc539
--- /dev/null
+++ b/lib/sbi/sbi_cppc.c
@@ -0,0 +1,156 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ *
+ */
+
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_cppc.h>
+
+static const struct sbi_cppc_device *cppc_dev = NULL;
+
+const struct sbi_cppc_device *sbi_cppc_get_device(void)
+{
+ return cppc_dev;
+}
+
+void sbi_cppc_set_device(const struct sbi_cppc_device *dev)
+{
+ if (!dev || cppc_dev)
+ return;
+
+ cppc_dev = dev;
+}
+
+static int sbi_cppc_probe_mandatory(unsigned long reg)
+{
+ switch (reg) {
+ case SBI_CPPC_HIGHEST_PERF:
+ case SBI_CPPC_NOMINAL_PERF:
+ case SBI_CPPC_LOW_NON_LINEAR_PERF:
+ case SBI_CPPC_LOWEST_PERF:
+ case SBI_CPPC_PERF_LIMITED:
+ return 32;
+ }
+
+ return 0;
+}
+
+static bool sbi_cppc_is_reserved(unsigned long reg)
+{
+ if ((reg > SBI_CPPC_ACPI_LAST && reg < SBI_CPPC_TRANSITION_LATENCY) ||
+ reg > SBI_CPPC_NON_ACPI_LAST)
+ return true;
+
+ return false;
+}
+
+static bool sbi_cppc_readable(unsigned long reg)
+{
+ /* there are no write-only cppc registers currently */
+ return true;
+}
+
+static bool sbi_cppc_writable(unsigned long reg)
+{
+ switch (reg) {
+ case SBI_CPPC_HIGHEST_PERF:
+ case SBI_CPPC_NOMINAL_PERF:
+ case SBI_CPPC_LOW_NON_LINEAR_PERF:
+ case SBI_CPPC_LOWEST_PERF:
+ case SBI_CPPC_GUARANTEED_PERF:
+ case SBI_CPPC_CTR_WRAP_TIME:
+ case SBI_CPPC_REFERENCE_CTR:
+ case SBI_CPPC_DELIVERED_CTR:
+ case SBI_CPPC_REFERENCE_PERF:
+ case SBI_CPPC_LOWEST_FREQ:
+ case SBI_CPPC_NOMINAL_FREQ:
+ case SBI_CPPC_TRANSITION_LATENCY:
+ return false;
+ }
+
+ return true;
+}
+
+int sbi_cppc_probe(unsigned long reg)
+{
+ int ret;
+
+ if (!cppc_dev || !cppc_dev->cppc_probe)
+ return SBI_EFAIL;
+
+ /* Check whether register is reserved */
+ if (sbi_cppc_is_reserved(reg))
+ return SBI_ERR_INVALID_PARAM;
+
+ /* Return width for mandatory registers */
+ ret = sbi_cppc_probe_mandatory(reg);
+ if (ret)
+ return ret;
+
+ ret = cppc_dev->cppc_probe(reg);
+ if (ret >= 0)
+ return ret;
+
+ switch (reg) {
+ case SBI_CPPC_GUARANTEED_PERF:
+ case SBI_CPPC_MIN_PERF:
+ case SBI_CPPC_MAX_PERF:
+ case SBI_CPPC_PERF_REDUC_TOLERANCE:
+ case SBI_CPPC_TIME_WINDOW:
+ case SBI_CPPC_ENABLE:
+ case SBI_CPPC_AUTO_SEL_ENABLE:
+ case SBI_CPPC_AUTO_ACT_WINDOW:
+ case SBI_CPPC_ENERGY_PERF_PREFERENCE:
+ case SBI_CPPC_REFERENCE_PERF:
+ case SBI_CPPC_LOWEST_FREQ:
+ case SBI_CPPC_NOMINAL_FREQ:
+ case SBI_CPPC_TRANSITION_LATENCY:
+ return 32;
+ }
+
+ return SBI_ERR_FAILED;
+}
+
+int sbi_cppc_read(unsigned long reg, uint64_t *val)
+{
+ int ret;
+
+ if (!cppc_dev || !cppc_dev->cppc_read)
+ return SBI_EFAIL;
+
+ /* Check whether register is implemented */
+ ret = sbi_cppc_probe(reg);
+ if (ret < 0)
+ return ret;
+ else if (!ret)
+ return SBI_ERR_NOT_SUPPORTED;
+
+ /* Check whether the register is write-only */
+ if (!sbi_cppc_readable(reg))
+ return SBI_ERR_DENIED;
+
+ return cppc_dev->cppc_read(reg, val);
+}
+
+int sbi_cppc_write(unsigned long reg, uint64_t val)
+{
+ int ret;
+
+ if (!cppc_dev || !cppc_dev->cppc_write)
+ return SBI_EFAIL;
+
+ /* Check whether register is implemented */
+ ret = sbi_cppc_probe(reg);
+ if (ret < 0)
+ return ret;
+ else if (!ret)
+ return SBI_ERR_NOT_SUPPORTED;
+
+ /* Check whether the register is read-only */
+ if (!sbi_cppc_writable(reg))
+ return SBI_ERR_DENIED;
+
+ return cppc_dev->cppc_write(reg, val);
+}
diff --git a/lib/sbi/sbi_ecall_cppc.c b/lib/sbi/sbi_ecall_cppc.c
new file mode 100644
index 0000000..91585f3
--- /dev/null
+++ b/lib/sbi/sbi_ecall_cppc.c
@@ -0,0 +1,63 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ *
+ */
+
+#include <sbi/sbi_ecall.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_trap.h>
+#include <sbi/sbi_cppc.h>
+
+static int sbi_ecall_cppc_handler(unsigned long extid, unsigned long funcid,
+ const struct sbi_trap_regs *regs,
+ unsigned long *out_val,
+ struct sbi_trap_info *out_trap)
+{
+ int ret = 0;
+ uint64_t temp;
+
+ switch (funcid) {
+ case SBI_EXT_CPPC_READ:
+ ret = sbi_cppc_read(regs->a0, &temp);
+ *out_val = temp;
+ break;
+ case SBI_EXT_CPPC_READ_HI:
+#if __riscv_xlen == 32
+ ret = sbi_cppc_read(regs->a0, &temp);
+ *out_val = temp >> 32;
+#else
+ *out_val = 0;
+#endif
+ break;
+ case SBI_EXT_CPPC_WRITE:
+ ret = sbi_cppc_write(regs->a0, regs->a1);
+ break;
+ case SBI_EXT_CPPC_PROBE:
+ ret = sbi_cppc_probe(regs->a0);
+ if (ret >= 0) {
+ *out_val = ret;
+ ret = 0;
+ }
+ break;
+ default:
+ ret = SBI_ENOTSUPP;
+ }
+
+ return ret;
+}
+
+static int sbi_ecall_cppc_probe(unsigned long extid, unsigned long *out_val)
+{
+ *out_val = sbi_cppc_get_device() ? 1 : 0;
+ return 0;
+}
+
+struct sbi_ecall_extension ecall_cppc = {
+ .extid_start = SBI_EXT_CPPC,
+ .extid_end = SBI_EXT_CPPC,
+ .handle = sbi_ecall_cppc_handler,
+ .probe = sbi_ecall_cppc_probe,
+};
--
2.34.1
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