1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2012 Calxeda, Inc.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * This driver provides the clk notifier callbacks that are used when
6*4882a593Smuzhiyun * the cpufreq-dt driver changes to frequency to alert the highbank
7*4882a593Smuzhiyun * EnergyCore Management Engine (ECME) about the need to change
8*4882a593Smuzhiyun * voltage. The ECME interfaces with the actual voltage regulators.
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #include <linux/kernel.h>
14*4882a593Smuzhiyun #include <linux/module.h>
15*4882a593Smuzhiyun #include <linux/clk.h>
16*4882a593Smuzhiyun #include <linux/cpu.h>
17*4882a593Smuzhiyun #include <linux/err.h>
18*4882a593Smuzhiyun #include <linux/of.h>
19*4882a593Smuzhiyun #include <linux/pl320-ipc.h>
20*4882a593Smuzhiyun #include <linux/platform_device.h>
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define HB_CPUFREQ_CHANGE_NOTE 0x80000001
23*4882a593Smuzhiyun #define HB_CPUFREQ_IPC_LEN 7
24*4882a593Smuzhiyun #define HB_CPUFREQ_VOLT_RETRIES 15
25*4882a593Smuzhiyun
hb_voltage_change(unsigned int freq)26*4882a593Smuzhiyun static int hb_voltage_change(unsigned int freq)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun return pl320_ipc_transmit(msg);
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun
hb_cpufreq_clk_notify(struct notifier_block * nb,unsigned long action,void * hclk)33*4882a593Smuzhiyun static int hb_cpufreq_clk_notify(struct notifier_block *nb,
34*4882a593Smuzhiyun unsigned long action, void *hclk)
35*4882a593Smuzhiyun {
36*4882a593Smuzhiyun struct clk_notifier_data *clk_data = hclk;
37*4882a593Smuzhiyun int i = 0;
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun if (action == PRE_RATE_CHANGE) {
40*4882a593Smuzhiyun if (clk_data->new_rate > clk_data->old_rate)
41*4882a593Smuzhiyun while (hb_voltage_change(clk_data->new_rate))
42*4882a593Smuzhiyun if (i++ > HB_CPUFREQ_VOLT_RETRIES)
43*4882a593Smuzhiyun return NOTIFY_BAD;
44*4882a593Smuzhiyun } else if (action == POST_RATE_CHANGE) {
45*4882a593Smuzhiyun if (clk_data->new_rate < clk_data->old_rate)
46*4882a593Smuzhiyun while (hb_voltage_change(clk_data->new_rate))
47*4882a593Smuzhiyun if (i++ > HB_CPUFREQ_VOLT_RETRIES)
48*4882a593Smuzhiyun return NOTIFY_BAD;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun return NOTIFY_DONE;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun static struct notifier_block hb_cpufreq_clk_nb = {
55*4882a593Smuzhiyun .notifier_call = hb_cpufreq_clk_notify,
56*4882a593Smuzhiyun };
57*4882a593Smuzhiyun
hb_cpufreq_driver_init(void)58*4882a593Smuzhiyun static int hb_cpufreq_driver_init(void)
59*4882a593Smuzhiyun {
60*4882a593Smuzhiyun struct platform_device_info devinfo = { .name = "cpufreq-dt", };
61*4882a593Smuzhiyun struct device *cpu_dev;
62*4882a593Smuzhiyun struct clk *cpu_clk;
63*4882a593Smuzhiyun struct device_node *np;
64*4882a593Smuzhiyun int ret;
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun if ((!of_machine_is_compatible("calxeda,highbank")) &&
67*4882a593Smuzhiyun (!of_machine_is_compatible("calxeda,ecx-2000")))
68*4882a593Smuzhiyun return -ENODEV;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun cpu_dev = get_cpu_device(0);
71*4882a593Smuzhiyun if (!cpu_dev) {
72*4882a593Smuzhiyun pr_err("failed to get highbank cpufreq device\n");
73*4882a593Smuzhiyun return -ENODEV;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun np = of_node_get(cpu_dev->of_node);
77*4882a593Smuzhiyun if (!np) {
78*4882a593Smuzhiyun pr_err("failed to find highbank cpufreq node\n");
79*4882a593Smuzhiyun return -ENOENT;
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun cpu_clk = clk_get(cpu_dev, NULL);
83*4882a593Smuzhiyun if (IS_ERR(cpu_clk)) {
84*4882a593Smuzhiyun ret = PTR_ERR(cpu_clk);
85*4882a593Smuzhiyun pr_err("failed to get cpu0 clock: %d\n", ret);
86*4882a593Smuzhiyun goto out_put_node;
87*4882a593Smuzhiyun }
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
90*4882a593Smuzhiyun if (ret) {
91*4882a593Smuzhiyun pr_err("failed to register clk notifier: %d\n", ret);
92*4882a593Smuzhiyun goto out_put_node;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun /* Instantiate cpufreq-dt */
96*4882a593Smuzhiyun platform_device_register_full(&devinfo);
97*4882a593Smuzhiyun
98*4882a593Smuzhiyun out_put_node:
99*4882a593Smuzhiyun of_node_put(np);
100*4882a593Smuzhiyun return ret;
101*4882a593Smuzhiyun }
102*4882a593Smuzhiyun module_init(hb_cpufreq_driver_init);
103*4882a593Smuzhiyun
104*4882a593Smuzhiyun static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = {
105*4882a593Smuzhiyun { .compatible = "calxeda,highbank" },
106*4882a593Smuzhiyun { .compatible = "calxeda,ecx-2000" },
107*4882a593Smuzhiyun { },
108*4882a593Smuzhiyun };
109*4882a593Smuzhiyun MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match);
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
112*4882a593Smuzhiyun MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
113*4882a593Smuzhiyun MODULE_LICENSE("GPL");
114