Kelvin Cheung | a0a22cf | 2014-10-17 18:23:31 +0800 | [diff] [blame] | 1 | /* |
| 2 | * CPU Frequency Scaling for Loongson 1 SoC |
| 3 | * |
| 4 | * Copyright (C) 2014 Zhang, Keguang <keguang.zhang@gmail.com> |
| 5 | * |
| 6 | * This file is licensed under the terms of the GNU General Public |
| 7 | * License version 2. This program is licensed "as is" without any |
| 8 | * warranty of any kind, whether express or implied. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/clk.h> |
| 12 | #include <linux/clk-provider.h> |
| 13 | #include <linux/cpu.h> |
| 14 | #include <linux/cpufreq.h> |
| 15 | #include <linux/delay.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/platform_device.h> |
| 18 | #include <linux/slab.h> |
| 19 | |
Huacai Chen | 30ad29b | 2015-04-21 10:00:35 +0800 | [diff] [blame^] | 20 | #include <cpufreq.h> |
| 21 | #include <loongson1.h> |
Kelvin Cheung | a0a22cf | 2014-10-17 18:23:31 +0800 | [diff] [blame] | 22 | |
| 23 | static struct { |
| 24 | struct device *dev; |
| 25 | struct clk *clk; /* CPU clk */ |
| 26 | struct clk *mux_clk; /* MUX of CPU clk */ |
| 27 | struct clk *pll_clk; /* PLL clk */ |
| 28 | struct clk *osc_clk; /* OSC clk */ |
| 29 | unsigned int max_freq; |
| 30 | unsigned int min_freq; |
| 31 | } ls1x_cpufreq; |
| 32 | |
| 33 | static int ls1x_cpufreq_notifier(struct notifier_block *nb, |
| 34 | unsigned long val, void *data) |
| 35 | { |
| 36 | if (val == CPUFREQ_POSTCHANGE) |
| 37 | current_cpu_data.udelay_val = loops_per_jiffy; |
| 38 | |
| 39 | return NOTIFY_OK; |
| 40 | } |
| 41 | |
| 42 | static struct notifier_block ls1x_cpufreq_notifier_block = { |
| 43 | .notifier_call = ls1x_cpufreq_notifier |
| 44 | }; |
| 45 | |
| 46 | static int ls1x_cpufreq_target(struct cpufreq_policy *policy, |
| 47 | unsigned int index) |
| 48 | { |
| 49 | unsigned int old_freq, new_freq; |
| 50 | |
| 51 | old_freq = policy->cur; |
| 52 | new_freq = policy->freq_table[index].frequency; |
| 53 | |
| 54 | /* |
| 55 | * The procedure of reconfiguring CPU clk is as below. |
| 56 | * |
| 57 | * - Reparent CPU clk to OSC clk |
| 58 | * - Reset CPU clock (very important) |
| 59 | * - Reconfigure CPU DIV |
| 60 | * - Reparent CPU clk back to CPU DIV clk |
| 61 | */ |
| 62 | |
| 63 | dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq); |
| 64 | clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk); |
| 65 | __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU, |
| 66 | LS1X_CLK_PLL_DIV); |
| 67 | __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU), |
| 68 | LS1X_CLK_PLL_DIV); |
| 69 | clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000); |
| 70 | clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk); |
| 71 | |
| 72 | return 0; |
| 73 | } |
| 74 | |
| 75 | static int ls1x_cpufreq_init(struct cpufreq_policy *policy) |
| 76 | { |
| 77 | struct cpufreq_frequency_table *freq_tbl; |
| 78 | unsigned int pll_freq, freq; |
| 79 | int steps, i, ret; |
| 80 | |
| 81 | pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000; |
| 82 | |
| 83 | steps = 1 << DIV_CPU_WIDTH; |
| 84 | freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL); |
| 85 | if (!freq_tbl) { |
| 86 | dev_err(ls1x_cpufreq.dev, |
| 87 | "failed to alloc cpufreq_frequency_table\n"); |
| 88 | ret = -ENOMEM; |
| 89 | goto out; |
| 90 | } |
| 91 | |
| 92 | for (i = 0; i < (steps - 1); i++) { |
| 93 | freq = pll_freq / (i + 1); |
| 94 | if ((freq < ls1x_cpufreq.min_freq) || |
| 95 | (freq > ls1x_cpufreq.max_freq)) |
| 96 | freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID; |
| 97 | else |
| 98 | freq_tbl[i].frequency = freq; |
| 99 | dev_dbg(ls1x_cpufreq.dev, |
| 100 | "cpufreq table: index %d: frequency %d\n", i, |
| 101 | freq_tbl[i].frequency); |
| 102 | } |
| 103 | freq_tbl[i].frequency = CPUFREQ_TABLE_END; |
| 104 | |
| 105 | policy->clk = ls1x_cpufreq.clk; |
| 106 | ret = cpufreq_generic_init(policy, freq_tbl, 0); |
| 107 | if (ret) |
| 108 | kfree(freq_tbl); |
| 109 | out: |
| 110 | return ret; |
| 111 | } |
| 112 | |
| 113 | static int ls1x_cpufreq_exit(struct cpufreq_policy *policy) |
| 114 | { |
| 115 | kfree(policy->freq_table); |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | static struct cpufreq_driver ls1x_cpufreq_driver = { |
| 120 | .name = "cpufreq-ls1x", |
| 121 | .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, |
| 122 | .verify = cpufreq_generic_frequency_table_verify, |
| 123 | .target_index = ls1x_cpufreq_target, |
| 124 | .get = cpufreq_generic_get, |
| 125 | .init = ls1x_cpufreq_init, |
| 126 | .exit = ls1x_cpufreq_exit, |
| 127 | .attr = cpufreq_generic_attr, |
| 128 | }; |
| 129 | |
| 130 | static int ls1x_cpufreq_remove(struct platform_device *pdev) |
| 131 | { |
| 132 | cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block, |
| 133 | CPUFREQ_TRANSITION_NOTIFIER); |
| 134 | cpufreq_unregister_driver(&ls1x_cpufreq_driver); |
| 135 | |
| 136 | return 0; |
| 137 | } |
| 138 | |
| 139 | static int ls1x_cpufreq_probe(struct platform_device *pdev) |
| 140 | { |
| 141 | struct plat_ls1x_cpufreq *pdata = pdev->dev.platform_data; |
| 142 | struct clk *clk; |
| 143 | int ret; |
| 144 | |
| 145 | if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) |
| 146 | return -EINVAL; |
| 147 | |
| 148 | ls1x_cpufreq.dev = &pdev->dev; |
| 149 | |
| 150 | clk = devm_clk_get(&pdev->dev, pdata->clk_name); |
| 151 | if (IS_ERR(clk)) { |
| 152 | dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n", |
| 153 | pdata->clk_name); |
| 154 | ret = PTR_ERR(clk); |
| 155 | goto out; |
| 156 | } |
| 157 | ls1x_cpufreq.clk = clk; |
| 158 | |
| 159 | clk = clk_get_parent(clk); |
| 160 | if (IS_ERR(clk)) { |
| 161 | dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n", |
| 162 | __clk_get_name(ls1x_cpufreq.clk)); |
| 163 | ret = PTR_ERR(clk); |
| 164 | goto out; |
| 165 | } |
| 166 | ls1x_cpufreq.mux_clk = clk; |
| 167 | |
| 168 | clk = clk_get_parent(clk); |
| 169 | if (IS_ERR(clk)) { |
| 170 | dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n", |
| 171 | __clk_get_name(ls1x_cpufreq.mux_clk)); |
| 172 | ret = PTR_ERR(clk); |
| 173 | goto out; |
| 174 | } |
| 175 | ls1x_cpufreq.pll_clk = clk; |
| 176 | |
| 177 | clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name); |
| 178 | if (IS_ERR(clk)) { |
| 179 | dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n", |
| 180 | pdata->osc_clk_name); |
| 181 | ret = PTR_ERR(clk); |
| 182 | goto out; |
| 183 | } |
| 184 | ls1x_cpufreq.osc_clk = clk; |
| 185 | |
| 186 | ls1x_cpufreq.max_freq = pdata->max_freq; |
| 187 | ls1x_cpufreq.min_freq = pdata->min_freq; |
| 188 | |
| 189 | ret = cpufreq_register_driver(&ls1x_cpufreq_driver); |
| 190 | if (ret) { |
| 191 | dev_err(ls1x_cpufreq.dev, |
| 192 | "failed to register cpufreq driver: %d\n", ret); |
| 193 | goto out; |
| 194 | } |
| 195 | |
| 196 | ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block, |
| 197 | CPUFREQ_TRANSITION_NOTIFIER); |
| 198 | |
| 199 | if (!ret) |
| 200 | goto out; |
| 201 | |
| 202 | dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n", |
| 203 | ret); |
| 204 | |
| 205 | cpufreq_unregister_driver(&ls1x_cpufreq_driver); |
| 206 | out: |
| 207 | return ret; |
| 208 | } |
| 209 | |
| 210 | static struct platform_driver ls1x_cpufreq_platdrv = { |
| 211 | .driver = { |
| 212 | .name = "ls1x-cpufreq", |
Kelvin Cheung | a0a22cf | 2014-10-17 18:23:31 +0800 | [diff] [blame] | 213 | }, |
| 214 | .probe = ls1x_cpufreq_probe, |
| 215 | .remove = ls1x_cpufreq_remove, |
| 216 | }; |
| 217 | |
| 218 | module_platform_driver(ls1x_cpufreq_platdrv); |
| 219 | |
| 220 | MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>"); |
| 221 | MODULE_DESCRIPTION("Loongson 1 CPUFreq driver"); |
| 222 | MODULE_LICENSE("GPL"); |