On some ARM based systems, a separate Cortex-M based System Control
Processor(SCP) provides the overall power, clock, reset and system
control including CPU DVFS. SCPI Message Protocol is used to
communicate with the SCPI.
This patch adds a interface driver for adding OPPs and registering
the arm_big_little cpufreq driver for such systems.
Signed-off-by: Sudeep Holla <sudeep.ho...@arm.com>
Cc: Viresh Kumar <viresh.ku...@linaro.org>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
Cc: linux...@vger.kernel.org
---
drivers/cpufreq/Kconfig.arm | 9 ++++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/scpi-cpufreq.c | 103 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 113 insertions(+)
create mode 100644 drivers/cpufreq/scpi-cpufreq.c
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 4f3dbc8cf729..9e678bf1687c 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -24,6 +24,15 @@ config ARM_VEXPRESS_SPC_CPUFREQ
This add the CPUfreq driver support for Versatile Express
big.LITTLE platforms using SPC for power management.
+config ARM_SCPI_CPUFREQ
+ tristate "SCPI based CPUfreq driver"
+ depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL
+ help
+ This add the CPUfreq driver support for ARM big.LITTLE platforms
+ using SCPI interface for CPU power management.
+
+ This driver works only if firmware the supporting CPU DVFS adhere
+ to SCPI protocol.
config ARM_EXYNOS_CPUFREQ
tristate "SAMSUNG EXYNOS CPUfreq Driver"
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index cdce92ae2e8b..02fc9f849d4b 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ) += sa1110-cpufreq.o
obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o
obj-$(CONFIG_ARM_TEGRA_CPUFREQ) += tegra-cpufreq.o
obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
+obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi-cpufreq.o
##################################################################################
# PowerPC platform drivers
diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
new file mode 100644
index 000000000000..4c2c11a9dfc6
--- /dev/null
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -0,0 +1,103 @@
+/*
+ * SCPI CPUFreq Interface driver
+ *
+ * It provides necessary ops to arm_big_little cpufreq driver.
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Sudeep Holla <sudeep.ho...@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/scpi_protocol.h>
+#include <linux/types.h>
+
+#include "arm_big_little.h"
+
+static struct scpi_ops *scpi_ops;
+
+static int scpi_init_opp_table(struct device *cpu_dev)
+{
+ u8 domain = topology_physical_package_id(cpu_dev->id);
+ struct scpi_dvfs_info *info;
+ struct scpi_opp *opp;
+ int idx, ret = 0;
+
+ if ((dev_pm_opp_get_opp_count(cpu_dev)) > 0)
+ return 0;
+ info = scpi_ops->dvfs_get_info(domain);
+ if (IS_ERR(info))
+ return PTR_ERR(info);
+
+ opp = info->opps;
+ if (!opp)
+ return -EIO;
+
+ for (idx = 0; idx < info->count; idx++, opp++) {
+ ret = dev_pm_opp_add(cpu_dev, opp->freq, opp->m_volt * 1000);
+ if (ret) {
+ dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
+ opp->freq, opp->m_volt);
+ return ret;
+ }
+ }
+ return ret;
+}
+
+static int scpi_get_transition_latency(struct device *cpu_dev)
+{
+ u8 domain = topology_physical_package_id(cpu_dev->id);
+ struct scpi_dvfs_info *info;
+
+ info = scpi_ops->dvfs_get_info(domain);
+ if (IS_ERR(info))
+ return PTR_ERR(info);
+
+ return info->latency;
+}
+
+static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
+ .name = "scpi",
+ .get_transition_latency = scpi_get_transition_latency,
+ .init_opp_table = scpi_init_opp_table,
+};
+
+static int scpi_cpufreq_probe(struct platform_device *pdev)
+{
+ scpi_ops = get_scpi_ops();
+ if (!scpi_ops)
+ return -EIO;
+
+ return bL_cpufreq_register(&scpi_cpufreq_ops);
+}
+
+static int scpi_cpufreq_remove(struct platform_device *pdev)
+{
+ bL_cpufreq_unregister(&scpi_cpufreq_ops);
+ return 0;
+}
+
+static struct platform_driver scpi_cpufreq_platdrv = {
+ .driver = {
+ .name = "scpi-cpufreq",
+ .owner = THIS_MODULE,
+ },
+ .probe = scpi_cpufreq_probe,
+ .remove = scpi_cpufreq_remove,
+};
+module_platform_driver(scpi_cpufreq_platdrv);
+
+MODULE_LICENSE("GPL");
--
1.9.1
--
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