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cpufreq: Tegra: implement intermediate frequency callbacks 

Tegra has been switching to intermediate frequency (pll_p_clk) forever.
CPUFreq core has better support for handling notifications for these
frequencies and so we can adapt Tegra's driver to it.

Also do a WARN() if clk_set_parent() fails while moving back to pll_x
as we should have atleast restored to earlier frequency on error.

Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hifive-unleashed-5.1
Viresh Kumar 2014-06-02 22:49:29 +05:30 committed by Rafael J. Wysocki
parent 1c03a2d04d
commit 00917ddc7c
1 changed files with 62 additions and 35 deletions
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97
drivers/cpufreq/tegra-cpufreq.c
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@ -45,46 +45,51 @@ static struct clk *cpu_clk;
static struct clk *pll_x_clk;
static struct clk *pll_p_clk;
static struct clk *emc_clk;
static bool pll_x_prepared;
static int tegra_cpu_clk_set_rate(unsigned long rate)
static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
unsigned int index)
{
unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
/*
* Don't switch to intermediate freq if:
* - we are already at it, i.e. policy->cur == ifreq
* - index corresponds to ifreq
*/
if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
return 0;
return ifreq;
}
static int tegra_target_intermediate(struct cpufreq_policy *policy,
unsigned int index)
{
int ret;
/*
* Take an extra reference to the main pll so it doesn't turn
* off when we move the cpu off of it
* off when we move the cpu off of it as enabling it again while we
* switch to it from tegra_target() would take additional time. Though
* when target-freq is intermediate freq, we don't need to take this
* reference.
*/
clk_prepare_enable(pll_x_clk);
ret = clk_set_parent(cpu_clk, pll_p_clk);
if (ret) {
pr_err("Failed to switch cpu to clock pll_p\n");
goto out;
}
if (ret)
clk_disable_unprepare(pll_x_clk);
else
pll_x_prepared = true;
if (rate == clk_get_rate(pll_p_clk))
goto out;
ret = clk_set_rate(pll_x_clk, rate);
if (ret) {
pr_err("Failed to change pll_x to %lu\n", rate);
goto out;
}
ret = clk_set_parent(cpu_clk, pll_x_clk);
if (ret) {
pr_err("Failed to switch cpu to clock pll_x\n");
goto out;
}
out:
clk_disable_unprepare(pll_x_clk);
return ret;
}
static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
{
unsigned long rate = freq_table[index].frequency;
unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
int ret = 0;
/*
@ -98,10 +103,30 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
else
clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */
ret = tegra_cpu_clk_set_rate(rate * 1000);
/*
* target freq == pll_p, don't need to take extra reference to pll_x_clk
* as it isn't used anymore.
*/
if (rate == ifreq)
return clk_set_parent(cpu_clk, pll_p_clk);
ret = clk_set_rate(pll_x_clk, rate * 1000);
/* Restore to earlier frequency on error, i.e. pll_x */
if (ret)
pr_err("cpu-tegra: Failed to set cpu frequency to %lu kHz\n",
rate);
pr_err("Failed to change pll_x to %lu\n", rate);
ret = clk_set_parent(cpu_clk, pll_x_clk);
/* This shouldn't fail while changing or restoring */
WARN_ON(ret);
/*
* Drop count to pll_x clock only if we switched to intermediate freq
* earlier while transitioning to a target frequency.
*/
if (pll_x_prepared) {
clk_disable_unprepare(pll_x_clk);
pll_x_prepared = false;
}
return ret;
}
@ -137,16 +162,18 @@ static int tegra_cpu_exit(struct cpufreq_policy *policy)
}
static struct cpufreq_driver tegra_cpufreq_driver = {
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = tegra_target,
.get = cpufreq_generic_get,
.init = tegra_cpu_init,
.exit = tegra_cpu_exit,
.name = "tegra",
.attr = cpufreq_generic_attr,
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.get_intermediate = tegra_get_intermediate,
.target_intermediate = tegra_target_intermediate,
.target_index = tegra_target,
.get = cpufreq_generic_get,
.init = tegra_cpu_init,
.exit = tegra_cpu_exit,
.name = "tegra",
.attr = cpufreq_generic_attr,
#ifdef CONFIG_PM
.suspend = cpufreq_generic_suspend,
.suspend = cpufreq_generic_suspend,
#endif
};