diff options
Diffstat (limited to 'drivers/cpufreq/loongson1-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/loongson1-cpufreq.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/cpufreq/loongson1-cpufreq.c b/drivers/cpufreq/loongson1-cpufreq.c new file mode 100644 index 000000000..fb72d709d --- /dev/null +++ b/drivers/cpufreq/loongson1-cpufreq.c @@ -0,0 +1,222 @@ +/* + * CPU Frequency Scaling for Loongson 1 SoC + * + * Copyright (C) 2014-2016 Zhang, Keguang <keguang.zhang@gmail.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/cpu.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +#include <cpufreq.h> +#include <loongson1.h> + +struct ls1x_cpufreq { + struct device *dev; + struct clk *clk; /* CPU clk */ + struct clk *mux_clk; /* MUX of CPU clk */ + struct clk *pll_clk; /* PLL clk */ + struct clk *osc_clk; /* OSC clk */ + unsigned int max_freq; + unsigned int min_freq; +}; + +static struct ls1x_cpufreq *cpufreq; + +static int ls1x_cpufreq_notifier(struct notifier_block *nb, + unsigned long val, void *data) +{ + if (val == CPUFREQ_POSTCHANGE) + current_cpu_data.udelay_val = loops_per_jiffy; + + return NOTIFY_OK; +} + +static struct notifier_block ls1x_cpufreq_notifier_block = { + .notifier_call = ls1x_cpufreq_notifier +}; + +static int ls1x_cpufreq_target(struct cpufreq_policy *policy, + unsigned int index) +{ + struct device *cpu_dev = get_cpu_device(policy->cpu); + unsigned int old_freq, new_freq; + + old_freq = policy->cur; + new_freq = policy->freq_table[index].frequency; + + /* + * The procedure of reconfiguring CPU clk is as below. + * + * - Reparent CPU clk to OSC clk + * - Reset CPU clock (very important) + * - Reconfigure CPU DIV + * - Reparent CPU clk back to CPU DIV clk + */ + + clk_set_parent(policy->clk, cpufreq->osc_clk); + __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU, + LS1X_CLK_PLL_DIV); + __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU), + LS1X_CLK_PLL_DIV); + clk_set_rate(cpufreq->mux_clk, new_freq * 1000); + clk_set_parent(policy->clk, cpufreq->mux_clk); + dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq); + + return 0; +} + +static int ls1x_cpufreq_init(struct cpufreq_policy *policy) +{ + struct device *cpu_dev = get_cpu_device(policy->cpu); + struct cpufreq_frequency_table *freq_tbl; + unsigned int pll_freq, freq; + int steps, i; + + pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000; + + steps = 1 << DIV_CPU_WIDTH; + freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL); + if (!freq_tbl) + return -ENOMEM; + + for (i = 0; i < (steps - 1); i++) { + freq = pll_freq / (i + 1); + if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq)) + freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID; + else + freq_tbl[i].frequency = freq; + dev_dbg(cpu_dev, + "cpufreq table: index %d: frequency %d\n", i, + freq_tbl[i].frequency); + } + freq_tbl[i].frequency = CPUFREQ_TABLE_END; + + policy->clk = cpufreq->clk; + cpufreq_generic_init(policy, freq_tbl, 0); + + return 0; +} + +static int ls1x_cpufreq_exit(struct cpufreq_policy *policy) +{ + kfree(policy->freq_table); + return 0; +} + +static struct cpufreq_driver ls1x_cpufreq_driver = { + .name = "cpufreq-ls1x", + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = ls1x_cpufreq_target, + .get = cpufreq_generic_get, + .init = ls1x_cpufreq_init, + .exit = ls1x_cpufreq_exit, + .attr = cpufreq_generic_attr, +}; + +static int ls1x_cpufreq_remove(struct platform_device *pdev) +{ + cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block, + CPUFREQ_TRANSITION_NOTIFIER); + cpufreq_unregister_driver(&ls1x_cpufreq_driver); + + return 0; +} + +static int ls1x_cpufreq_probe(struct platform_device *pdev) +{ + struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev); + struct clk *clk; + int ret; + + if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) { + dev_err(&pdev->dev, "platform data missing\n"); + return -EINVAL; + } + + cpufreq = + devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL); + if (!cpufreq) + return -ENOMEM; + + cpufreq->dev = &pdev->dev; + + clk = devm_clk_get(&pdev->dev, pdata->clk_name); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "unable to get %s clock\n", + pdata->clk_name); + return PTR_ERR(clk); + } + cpufreq->clk = clk; + + clk = clk_get_parent(clk); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "unable to get parent of %s clock\n", + __clk_get_name(cpufreq->clk)); + return PTR_ERR(clk); + } + cpufreq->mux_clk = clk; + + clk = clk_get_parent(clk); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "unable to get parent of %s clock\n", + __clk_get_name(cpufreq->mux_clk)); + return PTR_ERR(clk); + } + cpufreq->pll_clk = clk; + + clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "unable to get %s clock\n", + pdata->osc_clk_name); + return PTR_ERR(clk); + } + cpufreq->osc_clk = clk; + + cpufreq->max_freq = pdata->max_freq; + cpufreq->min_freq = pdata->min_freq; + + ret = cpufreq_register_driver(&ls1x_cpufreq_driver); + if (ret) { + dev_err(&pdev->dev, + "failed to register CPUFreq driver: %d\n", ret); + return ret; + } + + ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block, + CPUFREQ_TRANSITION_NOTIFIER); + + if (ret) { + dev_err(&pdev->dev, + "failed to register CPUFreq notifier: %d\n",ret); + cpufreq_unregister_driver(&ls1x_cpufreq_driver); + } + + return ret; +} + +static struct platform_driver ls1x_cpufreq_platdrv = { + .probe = ls1x_cpufreq_probe, + .remove = ls1x_cpufreq_remove, + .driver = { + .name = "ls1x-cpufreq", + }, +}; + +module_platform_driver(ls1x_cpufreq_platdrv); + +MODULE_ALIAS("platform:ls1x-cpufreq"); +MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>"); +MODULE_DESCRIPTION("Loongson1 CPUFreq driver"); +MODULE_LICENSE("GPL"); |