diff options
Diffstat (limited to 'drivers/devfreq/tegra20-devfreq.c')
| -rw-r--r-- | drivers/devfreq/tegra20-devfreq.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/drivers/devfreq/tegra20-devfreq.c b/drivers/devfreq/tegra20-devfreq.c new file mode 100644 index 000000000000..ff82bac9ee4e --- /dev/null +++ b/drivers/devfreq/tegra20-devfreq.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * NVIDIA Tegra20 devfreq driver + * + * Copyright (C) 2019 GRATE-DRIVER project + */ + +#include <linux/clk.h> +#include <linux/devfreq.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/pm_opp.h> +#include <linux/slab.h> + +#include <soc/tegra/mc.h> + +#include "governor.h" + +#define MC_STAT_CONTROL 0x90 +#define MC_STAT_EMC_CLOCK_LIMIT 0xa0 +#define MC_STAT_EMC_CLOCKS 0xa4 +#define MC_STAT_EMC_CONTROL 0xa8 +#define MC_STAT_EMC_COUNT 0xb8 + +#define EMC_GATHER_CLEAR (1 << 8) +#define EMC_GATHER_ENABLE (3 << 8) + +struct tegra_devfreq { + struct devfreq *devfreq; + struct clk *emc_clock; + void __iomem *regs; +}; + +static int tegra_devfreq_target(struct device *dev, unsigned long *freq, + u32 flags) +{ + struct tegra_devfreq *tegra = dev_get_drvdata(dev); + struct devfreq *devfreq = tegra->devfreq; + struct dev_pm_opp *opp; + unsigned long rate; + int err; + + opp = devfreq_recommended_opp(dev, freq, flags); + if (IS_ERR(opp)) + return PTR_ERR(opp); + + rate = dev_pm_opp_get_freq(opp); + dev_pm_opp_put(opp); + + err = clk_set_min_rate(tegra->emc_clock, rate); + if (err) + return err; + + err = clk_set_rate(tegra->emc_clock, 0); + if (err) + goto restore_min_rate; + + return 0; + +restore_min_rate: + clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq); + + return err; +} + +static int tegra_devfreq_get_dev_status(struct device *dev, + struct devfreq_dev_status *stat) +{ + struct tegra_devfreq *tegra = dev_get_drvdata(dev); + + /* + * EMC_COUNT returns number of memory events, that number is lower + * than the number of clocks. Conversion ratio of 1/8 results in a + * bit higher bandwidth than actually needed, it is good enough for + * the time being because drivers don't support requesting minimum + * needed memory bandwidth yet. + * + * TODO: adjust the ratio value once relevant drivers will support + * memory bandwidth management. + */ + stat->busy_time = readl_relaxed(tegra->regs + MC_STAT_EMC_COUNT); + stat->total_time = readl_relaxed(tegra->regs + MC_STAT_EMC_CLOCKS) / 8; + stat->current_frequency = clk_get_rate(tegra->emc_clock); + + writel_relaxed(EMC_GATHER_CLEAR, tegra->regs + MC_STAT_CONTROL); + writel_relaxed(EMC_GATHER_ENABLE, tegra->regs + MC_STAT_CONTROL); + + return 0; +} + +static struct devfreq_dev_profile tegra_devfreq_profile = { + .polling_ms = 500, + .target = tegra_devfreq_target, + .get_dev_status = tegra_devfreq_get_dev_status, +}; + +static struct tegra_mc *tegra_get_memory_controller(void) +{ + struct platform_device *pdev; + struct device_node *np; + struct tegra_mc *mc; + + np = of_find_compatible_node(NULL, NULL, "nvidia,tegra20-mc-gart"); + if (!np) + return ERR_PTR(-ENOENT); + + pdev = of_find_device_by_node(np); + of_node_put(np); + if (!pdev) + return ERR_PTR(-ENODEV); + + mc = platform_get_drvdata(pdev); + if (!mc) + return ERR_PTR(-EPROBE_DEFER); + + return mc; +} + +static int tegra_devfreq_probe(struct platform_device *pdev) +{ + struct tegra_devfreq *tegra; + struct tegra_mc *mc; + unsigned long max_rate; + unsigned long rate; + int err; + + mc = tegra_get_memory_controller(); + if (IS_ERR(mc)) { + err = PTR_ERR(mc); + dev_err(&pdev->dev, "failed to get memory controller: %d\n", + err); + return err; + } + + tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL); + if (!tegra) + return -ENOMEM; + + /* EMC is a system-critical clock that is always enabled */ + tegra->emc_clock = devm_clk_get(&pdev->dev, "emc"); + if (IS_ERR(tegra->emc_clock)) { + err = PTR_ERR(tegra->emc_clock); + dev_err(&pdev->dev, "failed to get emc clock: %d\n", err); + return err; + } + + tegra->regs = mc->regs; + + max_rate = clk_round_rate(tegra->emc_clock, ULONG_MAX); + + for (rate = 0; rate <= max_rate; rate++) { + rate = clk_round_rate(tegra->emc_clock, rate); + + err = dev_pm_opp_add(&pdev->dev, rate, 0); + if (err) { + dev_err(&pdev->dev, "failed to add opp: %d\n", err); + goto remove_opps; + } + } + + /* + * Reset statistic gathers state, select global bandwidth for the + * statistics collection mode and set clocks counter saturation + * limit to maximum. + */ + writel_relaxed(0x00000000, tegra->regs + MC_STAT_CONTROL); + writel_relaxed(0x00000000, tegra->regs + MC_STAT_EMC_CONTROL); + writel_relaxed(0xffffffff, tegra->regs + MC_STAT_EMC_CLOCK_LIMIT); + + platform_set_drvdata(pdev, tegra); + + tegra->devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile, + DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL); + if (IS_ERR(tegra->devfreq)) { + err = PTR_ERR(tegra->devfreq); + goto remove_opps; + } + + return 0; + +remove_opps: + dev_pm_opp_remove_all_dynamic(&pdev->dev); + + return err; +} + +static int tegra_devfreq_remove(struct platform_device *pdev) +{ + struct tegra_devfreq *tegra = platform_get_drvdata(pdev); + + devfreq_remove_device(tegra->devfreq); + dev_pm_opp_remove_all_dynamic(&pdev->dev); + + return 0; +} + +static struct platform_driver tegra_devfreq_driver = { + .probe = tegra_devfreq_probe, + .remove = tegra_devfreq_remove, + .driver = { + .name = "tegra20-devfreq", + }, +}; +module_platform_driver(tegra_devfreq_driver); + +MODULE_ALIAS("platform:tegra20-devfreq"); +MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>"); +MODULE_DESCRIPTION("NVIDIA Tegra20 devfreq driver"); +MODULE_LICENSE("GPL v2"); |