Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / cpufreq / highbank-cpufreq.c

diff --git a/kernel/drivers/cpufreq/highbank-cpufreq.c b/kernel/drivers/cpufreq/highbank-cpufreq.c
new file mode 100644 (file)
index 0000000..1608f71
--- /dev/null
+++ b/kernel/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-dt 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/pl320-ipc.h>
+#include <linux/platform_device.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)
+{
+       u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
+
+       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 platform_device_info devinfo = { .name = "cpufreq-dt", };
+       struct device *cpu_dev;
+       struct clk *cpu_clk;
+       struct device_node *np;
+       int ret;
+
+       if ((!of_machine_is_compatible("calxeda,highbank")) &&
+               (!of_machine_is_compatible("calxeda,ecx-2000")))
+               return -ENODEV;
+
+       cpu_dev = get_cpu_device(0);
+       if (!cpu_dev) {
+               pr_err("failed to get highbank cpufreq device\n");
+               return -ENODEV;
+       }
+
+       np = of_node_get(cpu_dev->of_node);
+       if (!np) {
+               pr_err("failed to find highbank cpufreq node\n");
+               return -ENOENT;
+       }
+
+       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;
+       }
+
+       /* Instantiate cpufreq-dt */
+       platform_device_register_full(&devinfo);
+
+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");