drivers/cpufreq/loongson1-cpufreq.c

0001 /*
0002  * CPU Frequency Scaling for Loongson 1 SoC
0003  *
0004  * Copyright (C) 2014-2016 Zhang, Keguang <keguang.zhang@gmail.com>
0005  *
0006  * This file is licensed under the terms of the GNU General Public
0007  * License version 2. This program is licensed "as is" without any
0008  * warranty of any kind, whether express or implied.
0009  */
0010
0011 #include <linux/clk.h>
0012 #include <linux/clk-provider.h>
0013 #include <linux/cpu.h>
0014 #include <linux/cpufreq.h>
0015 #include <linux/delay.h>
0016 #include <linux/io.h>
0017 #include <linux/module.h>
0018 #include <linux/platform_device.h>
0019 #include <linux/slab.h>
0020
0021 #include <cpufreq.h>
0022 #include <loongson1.h>
0023
0024 struct ls1x_cpufreq {
0025     struct device *dev;
0026     struct clk *clk;    /* CPU clk */
0027     struct clk *mux_clk;    /* MUX of CPU clk */
0028     struct clk *pll_clk;    /* PLL clk */
0029     struct clk *osc_clk;    /* OSC clk */
0030     unsigned int max_freq;
0031     unsigned int min_freq;
0032 };
0033
0034 static struct ls1x_cpufreq *cpufreq;
0035
0036 static int ls1x_cpufreq_notifier(struct notifier_block *nb,
0037                  unsigned long val, void *data)
0038 {
0039     if (val == CPUFREQ_POSTCHANGE)
0040         current_cpu_data.udelay_val = loops_per_jiffy;
0041
0042     return NOTIFY_OK;
0043 }
0044
0045 static struct notifier_block ls1x_cpufreq_notifier_block = {
0046     .notifier_call = ls1x_cpufreq_notifier
0047 };
0048
0049 static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
0050                    unsigned int index)
0051 {
0052     struct device *cpu_dev = get_cpu_device(policy->cpu);
0053     unsigned int old_freq, new_freq;
0054
0055     old_freq = policy->cur;
0056     new_freq = policy->freq_table[index].frequency;
0057
0058     /*
0059      * The procedure of reconfiguring CPU clk is as below.
0060      *
0061      *  - Reparent CPU clk to OSC clk
0062      *  - Reset CPU clock (very important)
0063      *  - Reconfigure CPU DIV
0064      *  - Reparent CPU clk back to CPU DIV clk
0065      */
0066
0067     clk_set_parent(policy->clk, cpufreq->osc_clk);
0068     __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
0069              LS1X_CLK_PLL_DIV);
0070     __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
0071              LS1X_CLK_PLL_DIV);
0072     clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
0073     clk_set_parent(policy->clk, cpufreq->mux_clk);
0074     dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
0075
0076     return 0;
0077 }
0078
0079 static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
0080 {
0081     struct device *cpu_dev = get_cpu_device(policy->cpu);
0082     struct cpufreq_frequency_table *freq_tbl;
0083     unsigned int pll_freq, freq;
0084     int steps, i;
0085
0086     pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
0087
0088     steps = 1 << DIV_CPU_WIDTH;
0089     freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
0090     if (!freq_tbl)
0091         return -ENOMEM;
0092
0093     for (i = 0; i < (steps - 1); i++) {
0094         freq = pll_freq / (i + 1);
0095         if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
0096             freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
0097         else
0098             freq_tbl[i].frequency = freq;
0099         dev_dbg(cpu_dev,
0100             "cpufreq table: index %d: frequency %d\n", i,
0101             freq_tbl[i].frequency);
0102     }
0103     freq_tbl[i].frequency = CPUFREQ_TABLE_END;
0104
0105     policy->clk = cpufreq->clk;
0106     cpufreq_generic_init(policy, freq_tbl, 0);
0107
0108     return 0;
0109 }
0110
0111 static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
0112 {
0113     kfree(policy->freq_table);
0114     return 0;
0115 }
0116
0117 static struct cpufreq_driver ls1x_cpufreq_driver = {
0118     .name       = "cpufreq-ls1x",
0119     .flags      = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
0120     .verify     = cpufreq_generic_frequency_table_verify,
0121     .target_index   = ls1x_cpufreq_target,
0122     .get        = cpufreq_generic_get,
0123     .init       = ls1x_cpufreq_init,
0124     .exit       = ls1x_cpufreq_exit,
0125     .attr       = cpufreq_generic_attr,
0126 };
0127
0128 static int ls1x_cpufreq_remove(struct platform_device *pdev)
0129 {
0130     cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
0131                     CPUFREQ_TRANSITION_NOTIFIER);
0132     cpufreq_unregister_driver(&ls1x_cpufreq_driver);
0133
0134     return 0;
0135 }
0136
0137 static int ls1x_cpufreq_probe(struct platform_device *pdev)
0138 {
0139     struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
0140     struct clk *clk;
0141     int ret;
0142
0143     if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
0144         dev_err(&pdev->dev, "platform data missing\n");
0145         return -EINVAL;
0146     }
0147
0148     cpufreq =
0149         devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
0150     if (!cpufreq)
0151         return -ENOMEM;
0152
0153     cpufreq->dev = &pdev->dev;
0154
0155     clk = devm_clk_get(&pdev->dev, pdata->clk_name);
0156     if (IS_ERR(clk)) {
0157         dev_err(&pdev->dev, "unable to get %s clock\n",
0158             pdata->clk_name);
0159         return PTR_ERR(clk);
0160     }
0161     cpufreq->clk = clk;
0162
0163     clk = clk_get_parent(clk);
0164     if (IS_ERR(clk)) {
0165         dev_err(&pdev->dev, "unable to get parent of %s clock\n",
0166             __clk_get_name(cpufreq->clk));
0167         return PTR_ERR(clk);
0168     }
0169     cpufreq->mux_clk = clk;
0170
0171     clk = clk_get_parent(clk);
0172     if (IS_ERR(clk)) {
0173         dev_err(&pdev->dev, "unable to get parent of %s clock\n",
0174             __clk_get_name(cpufreq->mux_clk));
0175         return PTR_ERR(clk);
0176     }
0177     cpufreq->pll_clk = clk;
0178
0179     clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
0180     if (IS_ERR(clk)) {
0181         dev_err(&pdev->dev, "unable to get %s clock\n",
0182             pdata->osc_clk_name);
0183         return PTR_ERR(clk);
0184     }
0185     cpufreq->osc_clk = clk;
0186
0187     cpufreq->max_freq = pdata->max_freq;
0188     cpufreq->min_freq = pdata->min_freq;
0189
0190     ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
0191     if (ret) {
0192         dev_err(&pdev->dev,
0193             "failed to register CPUFreq driver: %d\n", ret);
0194         return ret;
0195     }
0196
0197     ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
0198                     CPUFREQ_TRANSITION_NOTIFIER);
0199
0200     if (ret) {
0201         dev_err(&pdev->dev,
0202             "failed to register CPUFreq notifier: %d\n",ret);
0203         cpufreq_unregister_driver(&ls1x_cpufreq_driver);
0204     }
0205
0206     return ret;
0207 }
0208
0209 static struct platform_driver ls1x_cpufreq_platdrv = {
0210     .probe  = ls1x_cpufreq_probe,
0211     .remove = ls1x_cpufreq_remove,
0212     .driver = {
0213         .name   = "ls1x-cpufreq",
0214     },
0215 };
0216
0217 module_platform_driver(ls1x_cpufreq_platdrv);
0218
0219 MODULE_ALIAS("platform:ls1x-cpufreq");
0220 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
0221 MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
0222 MODULE_LICENSE("GPL");