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