diff options
Diffstat (limited to 'drivers/cpufreq/davinci-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/davinci-cpufreq.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/drivers/cpufreq/davinci-cpufreq.c b/drivers/cpufreq/davinci-cpufreq.c new file mode 100644 index 000000000..7e336d20c --- /dev/null +++ b/drivers/cpufreq/davinci-cpufreq.c @@ -0,0 +1,181 @@ +/* + * CPU frequency scaling for DaVinci + * + * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/ + * + * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows: + * + * Copyright (C) 2005 Nokia Corporation + * Written by Tony Lindgren <tony@atomide.com> + * + * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King + * + * Copyright (C) 2007-2008 Texas Instruments, Inc. + * Updated to support OMAP3 + * Rajendra Nayak <rnayak@ti.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/types.h> +#include <linux/cpufreq.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/platform_device.h> +#include <linux/export.h> + +#include <mach/hardware.h> +#include <mach/cpufreq.h> +#include <mach/common.h> + +struct davinci_cpufreq { + struct device *dev; + struct clk *armclk; + struct clk *asyncclk; + unsigned long asyncrate; +}; +static struct davinci_cpufreq cpufreq; + +static int davinci_verify_speed(struct cpufreq_policy *policy) +{ + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct cpufreq_frequency_table *freq_table = pdata->freq_table; + struct clk *armclk = cpufreq.armclk; + + if (freq_table) + return cpufreq_frequency_table_verify(policy, freq_table); + + if (policy->cpu) + return -EINVAL; + + cpufreq_verify_within_cpu_limits(policy); + policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; + policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; + cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, + policy->cpuinfo.max_freq); + return 0; +} + +static int davinci_target(struct cpufreq_policy *policy, unsigned int idx) +{ + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct clk *armclk = cpufreq.armclk; + unsigned int old_freq, new_freq; + int ret = 0; + + old_freq = policy->cur; + new_freq = pdata->freq_table[idx].frequency; + + /* if moving to higher frequency, up the voltage beforehand */ + if (pdata->set_voltage && new_freq > old_freq) { + ret = pdata->set_voltage(idx); + if (ret) + return ret; + } + + ret = clk_set_rate(armclk, idx); + if (ret) + return ret; + + if (cpufreq.asyncclk) { + ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); + if (ret) + return ret; + } + + /* if moving to lower freq, lower the voltage after lowering freq */ + if (pdata->set_voltage && new_freq < old_freq) + pdata->set_voltage(idx); + + return 0; +} + +static int davinci_cpu_init(struct cpufreq_policy *policy) +{ + int result = 0; + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct cpufreq_frequency_table *freq_table = pdata->freq_table; + + if (policy->cpu != 0) + return -EINVAL; + + /* Finish platform specific initialization */ + if (pdata->init) { + result = pdata->init(); + if (result) + return result; + } + + policy->clk = cpufreq.armclk; + + /* + * Time measurement across the target() function yields ~1500-1800us + * time taken with no drivers on notification list. + * Setting the latency to 2000 us to accommodate addition of drivers + * to pre/post change notification list. + */ + return cpufreq_generic_init(policy, freq_table, 2000 * 1000); +} + +static struct cpufreq_driver davinci_driver = { + .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = davinci_verify_speed, + .target_index = davinci_target, + .get = cpufreq_generic_get, + .init = davinci_cpu_init, + .name = "davinci", + .attr = cpufreq_generic_attr, +}; + +static int __init davinci_cpufreq_probe(struct platform_device *pdev) +{ + struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; + struct clk *asyncclk; + + if (!pdata) + return -EINVAL; + if (!pdata->freq_table) + return -EINVAL; + + cpufreq.dev = &pdev->dev; + + cpufreq.armclk = clk_get(NULL, "arm"); + if (IS_ERR(cpufreq.armclk)) { + dev_err(cpufreq.dev, "Unable to get ARM clock\n"); + return PTR_ERR(cpufreq.armclk); + } + + asyncclk = clk_get(cpufreq.dev, "async"); + if (!IS_ERR(asyncclk)) { + cpufreq.asyncclk = asyncclk; + cpufreq.asyncrate = clk_get_rate(asyncclk); + } + + return cpufreq_register_driver(&davinci_driver); +} + +static int __exit davinci_cpufreq_remove(struct platform_device *pdev) +{ + clk_put(cpufreq.armclk); + + if (cpufreq.asyncclk) + clk_put(cpufreq.asyncclk); + + return cpufreq_unregister_driver(&davinci_driver); +} + +static struct platform_driver davinci_cpufreq_driver = { + .driver = { + .name = "cpufreq-davinci", + }, + .remove = __exit_p(davinci_cpufreq_remove), +}; + +int __init davinci_cpufreq_init(void) +{ + return platform_driver_probe(&davinci_cpufreq_driver, + davinci_cpufreq_probe); +} + |