[PATCH 6/6 v9] cpufreq, highbank: add support for highbank cpufreq

Mark Langsdorf
2012-12-06T22:43:25Z

Highbank processors depend on the external ECME to perform voltage
management based on a requested frequency. Communication between the
A9 cores and the ECME happens over the pl320 IPC channel.

Signed-off-by: Mark Langsdorf <mark.langsdorf@calxeda.com>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Cc: mturquette@linaro.org
---
Changes from v8
Added Shawn Guo's reviewed by.
Removed some magic numbers.
Changed failure returns in clk_notify from NOTIFY_STOP to NOTIFY_BAD.
Changes from v7
Removed old attribution to cpufreq-cpu0.
Added some description in the documentation.
Made cpu_dev, cpu_clk into local variables.
Removed __devinit.
Removed some unneeded includes.
Added a brace to clarify some nested if logic.
Changes from v6
Removed devicetree bindings documentation.
Restructured driver to use clk notifications.
Core driver logic is now cpufreq-clk0.
Changes from v5
Changed ipc_transmit() to pl320_ipc_transmit().
Changes from v4
Removed erroneous changes to arch/arm/Kconfig.
Removed unnecessary changes to drivers/cpufreq/Kconfig.arm
Alphabetized additions to arch/arm/mach-highbank/Kconfig
Changed ipc call and header to match new ipc location in
drivers/mailbox.
Changes from v3
None.
Changes from v2
Changed transition latency binding in code to match documentation.
Changes from v1
Added highbank specific Kconfig changes.

arch/arm/boot/dts/highbank.dts | 10 ++++
arch/arm/mach-highbank/Kconfig | 2 +
drivers/cpufreq/Kconfig.arm | 16 ++++++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/highbank-cpufreq.c | 109 +++++++++++++++++++++++++++++++++++++
5 files changed, 138 insertions(+)
create mode 100644 drivers/cpufreq/highbank-cpufreq.c

diff --git a/arch/arm/boot/dts/highbank.dts b/arch/arm/boot/dts/highbank.dts
index 0c6fc34..7c4c27d 100644
--- a/arch/arm/boot/dts/highbank.dts
+++ b/arch/arm/boot/dts/highbank.dts
@@ -36,6 +36,16 @@
next-level-cache = <&L2>;
clocks = <&a9pll>;
clock-names = "cpu";
+ operating-points = <
+ /* kHz ignored */
+ 1300000 1000000
+ 1200000 1000000
+ 1100000 1000000
+ 800000 1000000
+ 400000 1000000
+ 200000 1000000
+ >;
+ clock-latency = <100000>;
};

cpu@1 {
diff --git a/arch/arm/mach-highbank/Kconfig b/arch/arm/mach-highbank/Kconfig
index 2896881..b7862da 100644
--- a/arch/arm/mach-highbank/Kconfig
+++ b/arch/arm/mach-highbank/Kconfig
@@ -1,5 +1,7 @@
config ARCH_HIGHBANK
bool "Calxeda ECX-1000 (Highbank)" if ARCH_MULTI_V7
+ select ARCH_HAS_CPUFREQ
+ select ARCH_HAS_OPP
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARM_AMBA
select ARM_GIC
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 5961e64..7aaac9f 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -76,3 +76,19 @@ config ARM_EXYNOS5250_CPUFREQ
help
This adds the CPUFreq driver for Samsung EXYNOS5250
SoC.
+
+config ARM_HIGHBANK_CPUFREQ
+ tristate "Calxeda Highbank-based"
+ depends on ARCH_HIGHBANK
+ select CPU_FREQ_TABLE
+ select GENERIC_CPUFREQ_CPU0
+ select PM_OPP
+ select REGULATOR
+
+ default m
+ help
+ This adds the CPUFreq driver for Calxeda Highbank SoC
+ based boards.
+
+ If in doubt, say N.
+
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 1bc90e1..9e8f12a 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_ARM_EXYNOS4210_CPUFREQ) += exynos4210-cpufreq.o
obj-$(CONFIG_ARM_EXYNOS4X12_CPUFREQ) += exynos4x12-cpufreq.o
obj-$(CONFIG_ARM_EXYNOS5250_CPUFREQ) += exynos5250-cpufreq.o
obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += omap-cpufreq.o
+obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ) += highbank-cpufreq.o

##################################################################################
# PowerPC platform drivers
diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c
new file mode 100644
index 0000000..863bb39
--- /dev/null
+++ b/drivers/cpufreq/highbank-cpufreq.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2012 Calxeda, Inc.
+ *
+ * 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 driver provides the clk notifier callbacks that are used when
+ * the cpufreq-cpu0 driver changes to frequency to alert the highbank
+ * EnergyCore Management Engine (ECME) about the need to change
+ * voltage. The ECME interfaces with the actual voltage regulators.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/mailbox.h>
+
+#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
+#define HB_CPUFREQ_IPC_LEN 7
+#define HB_CPUFREQ_VOLT_RETRIES 15
+
+static int hb_voltage_change(unsigned int freq)
+{
+ int i;
+ u32 msg[HB_CPUFREQ_IPC_LEN];
+
+ msg[0] = HB_CPUFREQ_CHANGE_NOTE;
+ msg[1] = freq / 1000000;
+ for (i = 2; i < HB_CPUFREQ_IPC_LEN; i++)
+ msg[i] = 0;
+
+ return pl320_ipc_transmit(msg);
+}
+
+static int hb_cpufreq_clk_notify(struct notifier_block *nb,
+ unsigned long action, void *hclk)
+{
+ struct clk_notifier_data *clk_data = hclk;
+ int i = 0;
+
+ if (action == PRE_RATE_CHANGE) {
+ if (clk_data->new_rate > clk_data->old_rate)
+ while (hb_voltage_change(clk_data->new_rate))
+ if (i++ > HB_CPUFREQ_VOLT_RETRIES)
+ return NOTIFY_BAD;
+ } else if (action == POST_RATE_CHANGE) {
+ if (clk_data->new_rate < clk_data->old_rate)
+ while (hb_voltage_change(clk_data->new_rate))
+ if (i++ > HB_CPUFREQ_VOLT_RETRIES)
+ return NOTIFY_BAD;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block hb_cpufreq_clk_nb = {
+ .notifier_call = hb_cpufreq_clk_notify,
+};
+
+static int hb_cpufreq_driver_init(void)
+{
+ struct device *cpu_dev;
+ struct clk *cpu_clk;
+ struct device_node *np;
+ int ret;
+
+ np = of_find_node_by_path("/cpus/cpu@0");
+ if (!np) {
+ pr_err("failed to find highbank cpufreq node\n");
+ return -ENOENT;
+ }
+
+ cpu_dev = get_cpu_device(0);
+ if (!cpu_dev) {
+ pr_err("failed to get highbank cpufreq device\n");
+ ret = -ENODEV;
+ goto out_put_node;
+ }
+
+ cpu_dev->of_node = np;
+
+ cpu_clk = clk_get(cpu_dev, NULL);
+ if (IS_ERR(cpu_clk)) {
+ ret = PTR_ERR(cpu_clk);
+ pr_err("failed to get cpu0 clock: %d\n", ret);
+ goto out_put_node;
+ }
+
+ ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
+ if (ret) {
+ pr_err("failed to register clk notifier: %d\n", ret);
+ goto out_put_node;
+ }
+
+out_put_node:
+ of_node_put(np);
+ return ret;
+}
+late_initcall(hb_cpufreq_driver_init);
+
+MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
+MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
+MODULE_LICENSE("GPL");
--
1.7.11.7