blob: 794123fcf3e3ebce87cdbcbf0a66b60f4b70db2c [file] [log] [blame]
Mark Langsdorf6754f552013-01-28 16:13:15 +00001/*
2 * Copyright (C) 2012 Calxeda, Inc.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This driver provides the clk notifier callbacks that are used when
9 * the cpufreq-cpu0 driver changes to frequency to alert the highbank
10 * EnergyCore Management Engine (ECME) about the need to change
11 * voltage. The ECME interfaces with the actual voltage regulators.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/clk.h>
19#include <linux/cpu.h>
20#include <linux/err.h>
21#include <linux/of.h>
22#include <linux/mailbox.h>
Shawn Guo5553f9e2013-01-30 14:27:49 +000023#include <linux/platform_device.h>
Mark Langsdorf6754f552013-01-28 16:13:15 +000024
25#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
26#define HB_CPUFREQ_IPC_LEN 7
27#define HB_CPUFREQ_VOLT_RETRIES 15
28
29static int hb_voltage_change(unsigned int freq)
30{
Emilio Lópezf5f43dc2013-02-25 11:07:45 +000031 u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
Mark Langsdorf6754f552013-01-28 16:13:15 +000032
33 return pl320_ipc_transmit(msg);
34}
35
36static int hb_cpufreq_clk_notify(struct notifier_block *nb,
37 unsigned long action, void *hclk)
38{
39 struct clk_notifier_data *clk_data = hclk;
40 int i = 0;
41
42 if (action == PRE_RATE_CHANGE) {
43 if (clk_data->new_rate > clk_data->old_rate)
44 while (hb_voltage_change(clk_data->new_rate))
45 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
46 return NOTIFY_BAD;
47 } else if (action == POST_RATE_CHANGE) {
48 if (clk_data->new_rate < clk_data->old_rate)
49 while (hb_voltage_change(clk_data->new_rate))
50 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
51 return NOTIFY_BAD;
52 }
53
54 return NOTIFY_DONE;
55}
56
57static struct notifier_block hb_cpufreq_clk_nb = {
58 .notifier_call = hb_cpufreq_clk_notify,
59};
60
61static int hb_cpufreq_driver_init(void)
62{
Shawn Guo5553f9e2013-01-30 14:27:49 +000063 struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
Mark Langsdorf6754f552013-01-28 16:13:15 +000064 struct device *cpu_dev;
65 struct clk *cpu_clk;
66 struct device_node *np;
67 int ret;
68
69 if (!of_machine_is_compatible("calxeda,highbank"))
70 return -ENODEV;
71
Sudeep KarkadaNagesha5de6e942013-06-17 15:07:28 +010072 cpu_dev = get_cpu_device(0);
73 if (!cpu_dev) {
74 pr_err("failed to get highbank cpufreq device\n");
75 return -ENODEV;
76 }
Mark Langsdorf6754f552013-01-28 16:13:15 +000077
Sudeep KarkadaNagesha5de6e942013-06-17 15:07:28 +010078 np = of_node_get(cpu_dev->of_node);
Mark Langsdorf6754f552013-01-28 16:13:15 +000079 if (!np) {
80 pr_err("failed to find highbank cpufreq node\n");
81 return -ENOENT;
82 }
83
Mark Langsdorf6754f552013-01-28 16:13:15 +000084 cpu_clk = clk_get(cpu_dev, NULL);
85 if (IS_ERR(cpu_clk)) {
86 ret = PTR_ERR(cpu_clk);
87 pr_err("failed to get cpu0 clock: %d\n", ret);
88 goto out_put_node;
89 }
90
91 ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
92 if (ret) {
93 pr_err("failed to register clk notifier: %d\n", ret);
94 goto out_put_node;
95 }
96
Shawn Guo5553f9e2013-01-30 14:27:49 +000097 /* Instantiate cpufreq-cpu0 */
98 platform_device_register_full(&devinfo);
99
Mark Langsdorf6754f552013-01-28 16:13:15 +0000100out_put_node:
101 of_node_put(np);
102 return ret;
103}
104module_init(hb_cpufreq_driver_init);
105
106MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
107MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
108MODULE_LICENSE("GPL");