diff options
author | Mark Langsdorf <mark.langsdorf@calxeda.com> | 2013-01-28 16:13:15 (GMT) |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-02-01 23:01:15 (GMT) |
commit | 6754f556103be5bd172263b1075ddbb7157afbad (patch) | |
tree | cd913973afd0247175e3adeecaf19d484753580a /drivers/cpufreq/highbank-cpufreq.c | |
parent | 300586778d405f0a4d1f6dc51fcfb4fed567d020 (diff) | |
download | linux-fsl-qoriq-6754f556103be5bd172263b1075ddbb7157afbad.tar.xz |
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.c | 115 |
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 0000000..53f25e5 --- /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"); |