projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 6754f556 ML |
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 | ||
| 24 | #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 | |
| 25 | #define HB_CPUFREQ_IPC_LEN 7 | |
| 26 | #define HB_CPUFREQ_VOLT_RETRIES 15 | |
| 27 | ||
| 28 | static int hb_voltage_change(unsigned int freq) | |
| 29 | { | |
| 30 | int i; | |
| 31 | u32 msg[HB_CPUFREQ_IPC_LEN]; | |
| 32 | ||
| 33 | msg[0] = HB_CPUFREQ_CHANGE_NOTE; | |
| 34 | msg[1] = freq / 1000000; | |
| 35 | for (i = 2; i < HB_CPUFREQ_IPC_LEN; i++) | |
| 36 | msg[i] = 0; | |
| 37 | ||
| 38 | return pl320_ipc_transmit(msg); | |
| 39 | } | |
| 40 | ||
| 41 | static int hb_cpufreq_clk_notify(struct notifier_block *nb, | |
| 42 | unsigned long action, void *hclk) | |
| 43 | { | |
| 44 | struct clk_notifier_data *clk_data = hclk; | |
| 45 | int i = 0; | |
| 46 | ||
| 47 | if (action == PRE_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 | } else if (action == POST_RATE_CHANGE) { | |
| 53 | if (clk_data->new_rate < clk_data->old_rate) | |
| 54 | while (hb_voltage_change(clk_data->new_rate)) | |
| 55 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) | |
| 56 | return NOTIFY_BAD; | |
| 57 | } | |
| 58 | ||
| 59 | return NOTIFY_DONE; | |
| 60 | } | |
| 61 | ||
| 62 | static struct notifier_block hb_cpufreq_clk_nb = { | |
| 63 | .notifier_call = hb_cpufreq_clk_notify, | |
| 64 | }; | |
| 65 | ||
| 66 | static int hb_cpufreq_driver_init(void) | |
| 67 | { | |
| 68 | struct device *cpu_dev; | |
| 69 | struct clk *cpu_clk; | |
| 70 | struct device_node *np; | |
| 71 | int ret; | |
| 72 | ||
| 73 | if (!of_machine_is_compatible("calxeda,highbank")) | |
| 74 | return -ENODEV; | |
| 75 | ||
| 76 | for_each_child_of_node(of_find_node_by_path("/cpus"), np) | |
| 77 | if (of_get_property(np, "operating-points", NULL)) | |
| 78 | break; | |
| 79 | ||
| 80 | if (!np) { | |
| 81 | pr_err("failed to find highbank cpufreq node\n"); | |
| 82 | return -ENOENT; | |
| 83 | } | |
| 84 | ||
| 85 | cpu_dev = get_cpu_device(0); | |
| 86 | if (!cpu_dev) { | |
| 87 | pr_err("failed to get highbank cpufreq device\n"); | |
| 88 | ret = -ENODEV; | |
| 89 | goto out_put_node; | |
| 90 | } | |
| 91 | ||
| 92 | cpu_dev->of_node = np; | |
| 93 | ||
| 94 | cpu_clk = clk_get(cpu_dev, NULL); | |
| 95 | if (IS_ERR(cpu_clk)) { | |
| 96 | ret = PTR_ERR(cpu_clk); | |
| 97 | pr_err("failed to get cpu0 clock: %d\n", ret); | |
| 98 | goto out_put_node; | |
| 99 | } | |
| 100 | ||
| 101 | ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); | |
| 102 | if (ret) { | |
| 103 | pr_err("failed to register clk notifier: %d\n", ret); | |
| 104 | goto out_put_node; | |
| 105 | } | |
| 106 | ||
| 107 | out_put_node: | |
| 108 | of_node_put(np); | |
| 109 | return ret; | |
| 110 | } | |
| 111 | module_init(hb_cpufreq_driver_init); | |
| 112 | ||
| 113 | MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); | |
| 114 | MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); | |
| 115 | MODULE_LICENSE("GPL"); |