cpufreq: arm_big_little: add SCPI interface driver

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.holla@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org

diff --git a/MAINTAINERS b/MAINTAINERS
index 613a116..e39ae88 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9155,6 +9155,7 @@ L:        linux-arm-kernel@lists.infradead.org
 S:     Maintained
 F:     Documentation/devicetree/bindings/arm/arm,scpi.txt
 F:     drivers/clk/clk-scpi.c
+F:     drivers/cpufreq/scpi-cpufreq.c
 F:     drivers/firmware/arm_scpi.c
 F:     include/linux/scpi_protocol.h
 

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index cd0391e..c737f73 100644 (file)
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -199,6 +199,16 @@ config ARM_SA1100_CPUFREQ
 config ARM_SA1110_CPUFREQ
        bool
 
+config ARM_SCPI_CPUFREQ
+        tristate "SCPI based CPUfreq driver"
+       depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL
+        help
+         This adds the CPUfreq driver support for ARM big.LITTLE platforms
+         using SCPI protocol for CPU power management.
+
+         This driver uses SCPI Message Protocol driver to interact with the
+         firmware providing the CPU DVFS functionality.
+
 config ARM_SPEAR_CPUFREQ
        bool "SPEAr CPUFreq support"
        depends on PLAT_SPEAR

diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 4134038..ccfaa4c 100644 (file)
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -72,6 +72,7 @@ obj-$(CONFIG_ARM_S3C64XX_CPUFREQ)     += s3c64xx-cpufreq.o
 obj-$(CONFIG_ARM_S5PV210_CPUFREQ)      += s5pv210-cpufreq.o
 obj-$(CONFIG_ARM_SA1100_CPUFREQ)       += sa1100-cpufreq.o
 obj-$(CONFIG_ARM_SA1110_CPUFREQ)       += sa1110-cpufreq.o
+obj-$(CONFIG_ARM_SCPI_CPUFREQ)         += scpi-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)                += spear-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)      += tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)     += tegra124-cpufreq.o

diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
new file mode 100644 (file)
index 0000000..2c3b16f
--- /dev/null
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -0,0 +1,124 @@
+/*
+ * System Control and Power Interface (SCPI) based CPUFreq Interface driver
+ *
+ * It provides necessary ops to arm_big_little cpufreq driver.
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@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 struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
+{
+       u8 domain = topology_physical_package_id(cpu_dev->id);
+
+       if (domain < 0)
+               return ERR_PTR(-EINVAL);
+       return scpi_ops->dvfs_get_info(domain);
+}
+
+static int scpi_opp_table_ops(struct device *cpu_dev, bool remove)
+{
+       int idx, ret = 0;
+       struct scpi_opp *opp;
+       struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
+
+       if (IS_ERR(info))
+               return PTR_ERR(info);
+
+       if (!info->opps)
+               return -EIO;
+
+       for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
+               if (remove)
+                       dev_pm_opp_remove(cpu_dev, opp->freq);
+               else
+                       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);
+                       while (idx-- > 0)
+                               dev_pm_opp_remove(cpu_dev, (--opp)->freq);
+                       return ret;
+               }
+       }
+       return ret;
+}
+
+static int scpi_get_transition_latency(struct device *cpu_dev)
+{
+       struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
+
+       if (IS_ERR(info))
+               return PTR_ERR(info);
+       return info->latency;
+}
+
+static int scpi_init_opp_table(struct device *cpu_dev)
+{
+       return scpi_opp_table_ops(cpu_dev, false);
+}
+
+static void scpi_free_opp_table(struct device *cpu_dev)
+{
+       scpi_opp_table_ops(cpu_dev, true);
+}
+
+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,
+       .free_opp_table = scpi_free_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);
+       scpi_ops = NULL;
+       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_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
+MODULE_LICENSE("GPL v2");