diff options
Diffstat (limited to 'drivers/cpufreq/highbank-cpufreq.c')
-rw-r--r-- | drivers/cpufreq/highbank-cpufreq.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c new file mode 100644 index 000000000000..66e3a71b81a3 --- /dev/null +++ b/drivers/cpufreq/highbank-cpufreq.c | |||
@@ -0,0 +1,120 @@ | |||
1 | /* | ||
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> | ||
23 | #include <linux/platform_device.h> | ||
24 | |||
25 | #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 | ||
26 | #define HB_CPUFREQ_IPC_LEN 7 | ||
27 | #define HB_CPUFREQ_VOLT_RETRIES 15 | ||
28 | |||
29 | static int hb_voltage_change(unsigned int freq) | ||
30 | { | ||
31 | int i; | ||
32 | u32 msg[HB_CPUFREQ_IPC_LEN]; | ||
33 | |||
34 | msg[0] = HB_CPUFREQ_CHANGE_NOTE; | ||
35 | msg[1] = freq / 1000000; | ||
36 | for (i = 2; i < HB_CPUFREQ_IPC_LEN; i++) | ||
37 | msg[i] = 0; | ||
38 | |||
39 | return pl320_ipc_transmit(msg); | ||
40 | } | ||
41 | |||
42 | static int hb_cpufreq_clk_notify(struct notifier_block *nb, | ||
43 | unsigned long action, void *hclk) | ||
44 | { | ||
45 | struct clk_notifier_data *clk_data = hclk; | ||
46 | int i = 0; | ||
47 | |||
48 | if (action == PRE_RATE_CHANGE) { | ||
49 | if (clk_data->new_rate > clk_data->old_rate) | ||
50 | while (hb_voltage_change(clk_data->new_rate)) | ||
51 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) | ||
52 | return NOTIFY_BAD; | ||
53 | } else if (action == POST_RATE_CHANGE) { | ||
54 | if (clk_data->new_rate < clk_data->old_rate) | ||
55 | while (hb_voltage_change(clk_data->new_rate)) | ||
56 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) | ||
57 | return NOTIFY_BAD; | ||
58 | } | ||
59 | |||
60 | return NOTIFY_DONE; | ||
61 | } | ||
62 | |||
63 | static struct notifier_block hb_cpufreq_clk_nb = { | ||
64 | .notifier_call = hb_cpufreq_clk_notify, | ||
65 | }; | ||
66 | |||
67 | static int hb_cpufreq_driver_init(void) | ||
68 | { | ||
69 | struct platform_device_info devinfo = { .name = "cpufreq-cpu0", }; | ||
70 | struct device *cpu_dev; | ||
71 | struct clk *cpu_clk; | ||
72 | struct device_node *np; | ||
73 | int ret; | ||
74 | |||
75 | if (!of_machine_is_compatible("calxeda,highbank")) | ||
76 | return -ENODEV; | ||
77 | |||
78 | for_each_child_of_node(of_find_node_by_path("/cpus"), np) | ||
79 | if (of_get_property(np, "operating-points", NULL)) | ||
80 | break; | ||
81 | |||
82 | if (!np) { | ||
83 | pr_err("failed to find highbank cpufreq node\n"); | ||
84 | return -ENOENT; | ||
85 | } | ||
86 | |||
87 | cpu_dev = get_cpu_device(0); | ||
88 | if (!cpu_dev) { | ||
89 | pr_err("failed to get highbank cpufreq device\n"); | ||
90 | ret = -ENODEV; | ||
91 | goto out_put_node; | ||
92 | } | ||
93 | |||
94 | cpu_dev->of_node = np; | ||
95 | |||
96 | cpu_clk = clk_get(cpu_dev, NULL); | ||
97 | if (IS_ERR(cpu_clk)) { | ||
98 | ret = PTR_ERR(cpu_clk); | ||
99 | pr_err("failed to get cpu0 clock: %d\n", ret); | ||
100 | goto out_put_node; | ||
101 | } | ||
102 | |||
103 | ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); | ||
104 | if (ret) { | ||
105 | pr_err("failed to register clk notifier: %d\n", ret); | ||
106 | goto out_put_node; | ||
107 | } | ||
108 | |||
109 | /* Instantiate cpufreq-cpu0 */ | ||
110 | platform_device_register_full(&devinfo); | ||
111 | |||
112 | out_put_node: | ||
113 | of_node_put(np); | ||
114 | return ret; | ||
115 | } | ||
116 | module_init(hb_cpufreq_driver_init); | ||
117 | |||
118 | MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); | ||
119 | MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); | ||
120 | MODULE_LICENSE("GPL"); | ||