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0553d7b204
Derated timings are used to ensure that the memory chips keep operating correctly at high temperatures. This adds code to support polling of the chip operating state when high temperatures are measured on the chip and change the refresh mode accordingly. Under very high temperatures, the driver will switch to the derated tables to ensure proper operation of the memory chips. Signed-off-by: Thierry Reding <treding@nvidia.com>
90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
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*/
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#include <linux/of_reserved_mem.h>
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#include "tegra210-emc.h"
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#define TEGRA_EMC_MAX_FREQS 16
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static int tegra210_emc_table_device_init(struct reserved_mem *rmem,
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struct device *dev)
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{
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struct tegra210_emc *emc = dev_get_drvdata(dev);
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struct tegra210_emc_timing *timings;
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unsigned int i, count = 0;
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timings = memremap(rmem->base, rmem->size, MEMREMAP_WB);
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if (!timings) {
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dev_err(dev, "failed to map EMC table\n");
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return -ENOMEM;
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}
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count = 0;
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for (i = 0; i < TEGRA_EMC_MAX_FREQS; i++) {
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if (timings[i].revision == 0)
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break;
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count++;
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}
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/* only the nominal and derated tables are expected */
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if (emc->derated) {
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dev_warn(dev, "excess EMC table '%s'\n", rmem->name);
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goto out;
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}
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if (emc->nominal) {
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if (count != emc->num_timings) {
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dev_warn(dev, "%u derated vs. %u nominal entries\n",
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count, emc->num_timings);
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memunmap(timings);
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return -EINVAL;
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}
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emc->derated = timings;
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} else {
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emc->num_timings = count;
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emc->nominal = timings;
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}
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out:
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/* keep track of which table this is */
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rmem->priv = timings;
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return 0;
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}
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static void tegra210_emc_table_device_release(struct reserved_mem *rmem,
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struct device *dev)
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{
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struct tegra210_emc_timing *timings = rmem->priv;
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struct tegra210_emc *emc = dev_get_drvdata(dev);
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if ((emc->nominal && timings != emc->nominal) &&
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(emc->derated && timings != emc->derated))
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dev_warn(dev, "trying to release unassigned EMC table '%s'\n",
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rmem->name);
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memunmap(timings);
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}
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static const struct reserved_mem_ops tegra210_emc_table_ops = {
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.device_init = tegra210_emc_table_device_init,
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.device_release = tegra210_emc_table_device_release,
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};
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static int tegra210_emc_table_init(struct reserved_mem *rmem)
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{
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pr_debug("Tegra210 EMC table at %pa, size %lu bytes\n", &rmem->base,
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(unsigned long)rmem->size);
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rmem->ops = &tegra210_emc_table_ops;
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return 0;
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}
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RESERVEDMEM_OF_DECLARE(tegra210_emc_table, "nvidia,tegra210-emc-table",
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tegra210_emc_table_init);
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