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Commit 00917ddc authored by Viresh Kumar's avatar Viresh Kumar Committed by Rafael J. Wysocki
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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: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: default avatarDoug Anderson <dianders@chromium.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 1c03a2d0

drivers/cpufreq/tegra-cpufreq.c

+62 −35
Original line number Diff line number Diff line
@@ -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)

{

	int ret;

	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;



	/*

	 * Take an extra reference to the main pll so it doesn't turn

	 * off when we move the cpu off of it

	 * Don't switch to intermediate freq if:

	 * - we are already at it, i.e. policy->cur == ifreq

	 * - index corresponds to ifreq

	 */

	clk_prepare_enable(pll_x_clk);

	if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))

		return 0;



	ret = clk_set_parent(cpu_clk, pll_p_clk);

	if (ret) {

		pr_err("Failed to switch cpu to clock pll_p\n");

		goto out;

	return ifreq;

}



	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;

	}

static int tegra_target_intermediate(struct cpufreq_policy *policy,

				     unsigned int index)

{

	int ret;



	ret = clk_set_parent(cpu_clk, pll_x_clk);

	if (ret) {

		pr_err("Failed to switch cpu to clock pll_x\n");

		goto out;

	}

	/*

	 * Take an extra reference to the main pll so it doesn't turn

	 * 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);



out:

	ret = clk_set_parent(cpu_clk, pll_p_clk);

	if (ret)

		clk_disable_unprepare(pll_x_clk);

	else

		pll_x_prepared = true;



	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;

}
@@ -139,6 +164,8 @@ 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,

	.get_intermediate	= tegra_get_intermediate,

	.target_intermediate	= tegra_target_intermediate,

	.target_index		= tegra_target,

	.get			= cpufreq_generic_get,

	.init			= tegra_cpu_init,