linux/drivers/clk/tegra/clk-device.c

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/pm_domain.h>
#include <linux/pm_opp.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>

#include <soc/tegra/common.h>

#include "clk.h"

/*
 * This driver manages performance state of the core power domain for the
 * independent PLLs and system clocks.  We created a virtual clock device
 * for such clocks, see tegra_clk_dev_register().
 */

struct tegra_clk_device {
	struct notifier_block clk_nb;
	struct device *dev;
	struct clk_hw *hw;
	struct mutex lock;
};

static int tegra_clock_set_pd_state(struct tegra_clk_device *clk_dev,
				    unsigned long rate)
{
	struct device *dev = clk_dev->dev;
	struct dev_pm_opp *opp;
	unsigned int pstate;

	opp = dev_pm_opp_find_freq_ceil(dev, &rate);
	if (opp == ERR_PTR(-ERANGE)) {
		/*
		 * Some clocks may be unused by a particular board and they
		 * may have uninitiated clock rate that is overly high.  In
		 * this case clock is expected to be disabled, but still we
		 * need to set up performance state of the power domain and
		 * not error out clk initialization.  A typical example is
		 * a PCIe clock on Android tablets.
		 */
		dev_dbg(dev, "failed to find ceil OPP for %luHz\n", rate);
		opp = dev_pm_opp_find_freq_floor(dev, &rate);
	}

	if (IS_ERR(opp)) {
		dev_err(dev, "failed to find OPP for %luHz: %pe\n", rate, opp);
		return PTR_ERR(opp);
	}

	pstate = dev_pm_opp_get_required_pstate(opp, 0);
	dev_pm_opp_put(opp);

	return dev_pm_genpd_set_performance_state(dev, pstate);
}

static int tegra_clock_change_notify(struct notifier_block *nb,
				     unsigned long msg, void *data)
{
	struct clk_notifier_data *cnd = data;
	struct tegra_clk_device *clk_dev;
	int err = 0;

	clk_dev = container_of(nb, struct tegra_clk_device, clk_nb);

	mutex_lock(&clk_dev->lock);
	switch (msg) {
	case PRE_RATE_CHANGE:
		if (cnd->new_rate > cnd->old_rate)
			err = tegra_clock_set_pd_state(clk_dev, cnd->new_rate);
		break;

	case ABORT_RATE_CHANGE:
		err = tegra_clock_set_pd_state(clk_dev, cnd->old_rate);
		break;

	case POST_RATE_CHANGE:
		if (cnd->new_rate < cnd->old_rate)
			err = tegra_clock_set_pd_state(clk_dev, cnd->new_rate);
		break;

	default:
		break;
	}
	mutex_unlock(&clk_dev->lock);

	return notifier_from_errno(err);
}

static int tegra_clock_sync_pd_state(struct tegra_clk_device *clk_dev)
{
	unsigned long rate;
	int ret;

	mutex_lock(&clk_dev->lock);

	rate = clk_hw_get_rate(clk_dev->hw);
	ret = tegra_clock_set_pd_state(clk_dev, rate);

	mutex_unlock(&clk_dev->lock);

	return ret;
}

static int tegra_clock_probe(struct platform_device *pdev)
{
	struct tegra_core_opp_params opp_params = {};
	struct tegra_clk_device *clk_dev;
	struct device *dev = &pdev->dev;
	struct clk *clk;
	int err;

	if (!dev->pm_domain)
		return -EINVAL;

	clk_dev = devm_kzalloc(dev, sizeof(*clk_dev), GFP_KERNEL);
	if (!clk_dev)
		return -ENOMEM;

	clk = devm_clk_get(dev, NULL);
	if (IS_ERR(clk))
		return PTR_ERR(clk);

	clk_dev->dev = dev;
	clk_dev->hw = __clk_get_hw(clk);
	clk_dev->clk_nb.notifier_call = tegra_clock_change_notify;
	mutex_init(&clk_dev->lock);

	platform_set_drvdata(pdev, clk_dev);

	/*
	 * Runtime PM was already enabled for this device by the parent clk
	 * driver and power domain state should be synced under clk_dev lock,
	 * hence we don't use the common OPP helper that initializes OPP
	 * state. For some clocks common OPP helper may fail to find ceil
	 * rate, it's handled by this driver.
	 */
	err = devm_tegra_core_dev_init_opp_table(dev, &opp_params);
	if (err)
		return err;

	err = clk_notifier_register(clk, &clk_dev->clk_nb);
	if (err) {
		dev_err(dev, "failed to register clk notifier: %d\n", err);
		return err;
	}

	/*
	 * The driver is attaching to a potentially active/resumed clock, hence
	 * we need to sync the power domain performance state in a accordance to
	 * the clock rate if clock is resumed.
	 */
	err = tegra_clock_sync_pd_state(clk_dev);
	if (err)
		goto unreg_clk;

	return 0;

unreg_clk:
	clk_notifier_unregister(clk, &clk_dev->clk_nb);

	return err;
}

/*
 * Tegra GENPD driver enables clocks during NOIRQ phase. It can't be done
 * for clocks served by this driver because runtime PM is unavailable in
 * NOIRQ phase. We will keep clocks resumed during suspend to mitigate this
 * problem. In practice this makes no difference from a power management
 * perspective since voltage is kept at a nominal level during suspend anyways.
 */
static const struct dev_pm_ops tegra_clock_pm = {
	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_resume_and_get, pm_runtime_put)
};

static const struct of_device_id tegra_clock_match[] = {
	{ .compatible = "nvidia,tegra20-sclk" },
	{ .compatible = "nvidia,tegra30-sclk" },
	{ .compatible = "nvidia,tegra30-pllc" },
	{ .compatible = "nvidia,tegra30-plle" },
	{ .compatible = "nvidia,tegra30-pllm" },
	{ }
};

static struct platform_driver tegra_clock_driver = {
	.driver = {
		.name = "tegra-clock",
		.of_match_table = tegra_clock_match,
		.pm = &tegra_clock_pm,
		.suppress_bind_attrs = true,
	},
	.probe = tegra_clock_probe,
};
builtin_platform_driver(tegra_clock_driver);