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authorMark Langsdorf <mark.langsdorf@calxeda.com>2013-01-28 16:13:15 +0000
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-02-02 00:01:15 +0100
commit6754f556103be5bd172263b1075ddbb7157afbad (patch)
treecd913973afd0247175e3adeecaf19d484753580a /drivers/cpufreq/highbank-cpufreq.c
parent300586778d405f0a4d1f6dc51fcfb4fed567d020 (diff)
downloadleg-kernel-6754f556103be5bd172263b1075ddbb7157afbad.tar.gz
cpufreq / highbank: add support for highbank cpufreq
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> Reviewed-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/highbank-cpufreq.c')
-rw-r--r--drivers/cpufreq/highbank-cpufreq.c115
1 files changed, 115 insertions, 0 deletions
diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c
new file mode 100644
index 000000000000..53f25e5aa6b7
--- /dev/null
+++ b/drivers/cpufreq/highbank-cpufreq.c
@@ -0,0 +1,115 @@
+/*
+ * 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;
+
+ if (!of_machine_is_compatible("calxeda,highbank"))
+ return -ENODEV;
+
+ for_each_child_of_node(of_find_node_by_path("/cpus"), np)
+ if (of_get_property(np, "operating-points", NULL))
+ break;
+
+ 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;
+}
+module_init(hb_cpufreq_driver_init);
+
+MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
+MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
+MODULE_LICENSE("GPL");