@ -45,46 +45,54 @@ 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 .
*
* When target - freq is equal to intermediate freq we don ' t need to
* switch to an intermediate freq and so this routine isn ' t called .
* Also , we wouldn ' t be using pll_x anymore and must not take extra
* reference to it , as it can be disabled now to save some power .
*/
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 ( 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 ;
}
if ( ret )
clk_disable_unprepare ( pll_x_clk ) ;
else
pll_x_prepared = true ;
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 +106,30 @@ 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 +165,18 @@ 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
} ;
Rafael J. Wysocki
11 years ago