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linux
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>
authored by
Viresh Kumar
and committed by
Rafael J. Wysocki
00917ddc
1c03a2d0
+62
-35
+62
-35
drivers/cpufreq/tegra-cpufreq.c
+62
-35
drivers/cpufreq/tegra-cpufreq.c
···
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static struct clk *pll_x_clk;
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static struct clk *pll_p_clk;
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static struct clk *emc_clk;
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+
static bool pll_x_prepared;
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-
static int tegra_cpu_clk_set_rate(unsigned long rate)
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static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
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unsigned int index)
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{
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unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
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+
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/*
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* Don't switch to intermediate freq if:
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* - we are already at it, i.e. policy->cur == ifreq
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* - index corresponds to ifreq
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*/
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if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
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return 0;
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return ifreq;
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}
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static int tegra_target_intermediate(struct cpufreq_policy *policy,
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unsigned int index)
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{
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int ret;
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/*
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* Take an extra reference to the main pll so it doesn't turn
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* off when we move the cpu off of it
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* off when we move the cpu off of it as enabling it again while we
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* switch to it from tegra_target() would take additional time. Though
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* when target-freq is intermediate freq, we don't need to take this
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* reference.
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*/
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clk_prepare_enable(pll_x_clk);
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ret = clk_set_parent(cpu_clk, pll_p_clk);
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-
if (ret) {
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pr_err("Failed to switch cpu to clock pll_p\n");
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goto out;
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}
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if (ret)
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clk_disable_unprepare(pll_x_clk);
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else
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pll_x_prepared = true;
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if (rate == clk_get_rate(pll_p_clk))
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goto out;
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-
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ret = clk_set_rate(pll_x_clk, rate);
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if (ret) {
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pr_err("Failed to change pll_x to %lu\n", rate);
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goto out;
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}
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-
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ret = clk_set_parent(cpu_clk, pll_x_clk);
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if (ret) {
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pr_err("Failed to switch cpu to clock pll_x\n");
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goto out;
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}
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out:
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clk_disable_unprepare(pll_x_clk);
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return ret;
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}
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static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
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{
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unsigned long rate = freq_table[index].frequency;
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unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
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int ret = 0;
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/*
···
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else
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clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */
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-
ret = tegra_cpu_clk_set_rate(rate * 1000);
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/*
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* target freq == pll_p, don't need to take extra reference to pll_x_clk
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* as it isn't used anymore.
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*/
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if (rate == ifreq)
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return clk_set_parent(cpu_clk, pll_p_clk);
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ret = clk_set_rate(pll_x_clk, rate * 1000);
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/* Restore to earlier frequency on error, i.e. pll_x */
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if (ret)
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-
pr_err("cpu-tegra: Failed to set cpu frequency to %lu kHz\n",
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rate);
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pr_err("Failed to change pll_x to %lu\n", rate);
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ret = clk_set_parent(cpu_clk, pll_x_clk);
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/* This shouldn't fail while changing or restoring */
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WARN_ON(ret);
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/*
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* Drop count to pll_x clock only if we switched to intermediate freq
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* earlier while transitioning to a target frequency.
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*/
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if (pll_x_prepared) {
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clk_disable_unprepare(pll_x_clk);
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pll_x_prepared = false;
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}
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return ret;
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}
···
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}
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static struct cpufreq_driver tegra_cpufreq_driver = {
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-
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
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-
.verify = cpufreq_generic_frequency_table_verify,
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.target_index = tegra_target,
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.get = cpufreq_generic_get,
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.init = tegra_cpu_init,
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.exit = tegra_cpu_exit,
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.name = "tegra",
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.attr = cpufreq_generic_attr,
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.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
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.verify = cpufreq_generic_frequency_table_verify,
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.get_intermediate = tegra_get_intermediate,
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+
.target_intermediate = tegra_target_intermediate,
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.target_index = tegra_target,
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.get = cpufreq_generic_get,
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.init = tegra_cpu_init,
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.exit = tegra_cpu_exit,
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.name = "tegra",
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.attr = cpufreq_generic_attr,
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#ifdef CONFIG_PM
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-
.suspend = cpufreq_generic_suspend,
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.suspend = cpufreq_generic_suspend,
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#endif
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};
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