drivers/memory/tegra/tegra186-emc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2019 NVIDIA CORPORATION.  All rights reserved.
   4  */
   5
   6 #include <linux/clk.h>
   7 #include <linux/debugfs.h>
   8 #include <linux/module.h>
   9 #include <linux/mod_devicetable.h>
  10 #include <linux/platform_device.h>
  11
  12 #include <soc/tegra/bpmp.h>
  13
  14 struct tegra186_emc_dvfs {
  15         unsigned long latency;
  16         unsigned long rate;
  17 };
  18
  19 struct tegra186_emc {
  20         struct tegra_bpmp *bpmp;
  21         struct device *dev;
  22         struct clk *clk;
  23
  24         struct tegra186_emc_dvfs *dvfs;
  25         unsigned int num_dvfs;
  26
  27         struct {
  28                 struct dentry *root;
  29                 unsigned long min_rate;
  30                 unsigned long max_rate;
  31         } debugfs;
  32 };
  33
  34 /*
  35  * debugfs interface
  36  *
  37  * The memory controller driver exposes some files in debugfs that can be used
  38  * to control the EMC frequency. The top-level directory can be found here:
  39  *
  40  *   /sys/kernel/debug/emc
  41  *
  42  * It contains the following files:
  43  *
  44  *   - available_rates: This file contains a list of valid, space-separated
  45  *     EMC frequencies.
  46  *
  47  *   - min_rate: Writing a value to this file sets the given frequency as the
  48  *       floor of the permitted range. If this is higher than the currently
  49  *       configured EMC frequency, this will cause the frequency to be
  50  *       increased so that it stays within the valid range.
  51  *
  52  *   - max_rate: Similarily to the min_rate file, writing a value to this file
  53  *       sets the given frequency as the ceiling of the permitted range. If
  54  *       the value is lower than the currently configured EMC frequency, this
  55  *       will cause the frequency to be decreased so that it stays within the
  56  *       valid range.
  57  */
  58
  59 static bool tegra186_emc_validate_rate(struct tegra186_emc *emc,
  60                                        unsigned long rate)
  61 {
  62         unsigned int i;
  63
  64         for (i = 0; i < emc->num_dvfs; i++)
  65                 if (rate == emc->dvfs[i].rate)
  66                         return true;
  67
  68         return false;
  69 }
  70
  71 static int tegra186_emc_debug_available_rates_show(struct seq_file *s,
  72                                                    void *data)
  73 {
  74         struct tegra186_emc *emc = s->private;
  75         const char *prefix = "";
  76         unsigned int i;
  77
  78         for (i = 0; i < emc->num_dvfs; i++) {
  79                 seq_printf(s, "%s%lu", prefix, emc->dvfs[i].rate);
  80                 prefix = " ";
  81         }
  82
  83         seq_puts(s, "\n");
  84
  85         return 0;
  86 }
  87
  88 static int tegra186_emc_debug_available_rates_open(struct inode *inode,
  89                                                    struct file *file)
  90 {
  91         return single_open(file, tegra186_emc_debug_available_rates_show,
  92                            inode->i_private);
  93 }
  94
  95 static const struct file_operations tegra186_emc_debug_available_rates_fops = {
  96         .open = tegra186_emc_debug_available_rates_open,
  97         .read = seq_read,
  98         .llseek = seq_lseek,
  99         .release = single_release,
 100 };
 101
 102 static int tegra186_emc_debug_min_rate_get(void *data, u64 *rate)
 103 {
 104         struct tegra186_emc *emc = data;
 105
 106         *rate = emc->debugfs.min_rate;
 107
 108         return 0;
 109 }
 110
 111 static int tegra186_emc_debug_min_rate_set(void *data, u64 rate)
 112 {
 113         struct tegra186_emc *emc = data;
 114         int err;
 115
 116         if (!tegra186_emc_validate_rate(emc, rate))
 117                 return -EINVAL;
 118
 119         err = clk_set_min_rate(emc->clk, rate);
 120         if (err < 0)
 121                 return err;
 122
 123         emc->debugfs.min_rate = rate;
 124
 125         return 0;
 126 }
 127
 128 DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_min_rate_fops,
 129                         tegra186_emc_debug_min_rate_get,
 130                         tegra186_emc_debug_min_rate_set, "%llu\n");
 131
 132 static int tegra186_emc_debug_max_rate_get(void *data, u64 *rate)
 133 {
 134         struct tegra186_emc *emc = data;
 135
 136         *rate = emc->debugfs.max_rate;
 137
 138         return 0;
 139 }
 140
 141 static int tegra186_emc_debug_max_rate_set(void *data, u64 rate)
 142 {
 143         struct tegra186_emc *emc = data;
 144         int err;
 145
 146         if (!tegra186_emc_validate_rate(emc, rate))
 147                 return -EINVAL;
 148
 149         err = clk_set_max_rate(emc->clk, rate);
 150         if (err < 0)
 151                 return err;
 152
 153         emc->debugfs.max_rate = rate;
 154
 155         return 0;
 156 }
 157
 158 DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_max_rate_fops,
 159                         tegra186_emc_debug_max_rate_get,
 160                         tegra186_emc_debug_max_rate_set, "%llu\n");
 161
 162 static int tegra186_emc_probe(struct platform_device *pdev)
 163 {
 164         struct mrq_emc_dvfs_latency_response response;
 165         struct tegra_bpmp_message msg;
 166         struct tegra186_emc *emc;
 167         unsigned int i;
 168         int err;
 169
 170         emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
 171         if (!emc)
 172                 return -ENOMEM;
 173
 174         emc->bpmp = tegra_bpmp_get(&pdev->dev);
 175         if (IS_ERR(emc->bpmp)) {
 176                 err = PTR_ERR(emc->bpmp);
 177
 178                 if (err != -EPROBE_DEFER)
 179                         dev_err(&pdev->dev, "failed to get BPMP: %d\n", err);
 180
 181                 return err;
 182         }
 183
 184         emc->clk = devm_clk_get(&pdev->dev, "emc");
 185         if (IS_ERR(emc->clk)) {
 186                 err = PTR_ERR(emc->clk);
 187                 dev_err(&pdev->dev, "failed to get EMC clock: %d\n", err);
 188                 return err;
 189         }
 190
 191         platform_set_drvdata(pdev, emc);
 192         emc->dev = &pdev->dev;
 193
 194         memset(&msg, 0, sizeof(msg));
 195         msg.mrq = MRQ_EMC_DVFS_LATENCY;
 196         msg.tx.data = NULL;
 197         msg.tx.size = 0;
 198         msg.rx.data = &response;
 199         msg.rx.size = sizeof(response);
 200
 201         err = tegra_bpmp_transfer(emc->bpmp, &msg);
 202         if (err < 0) {
 203                 dev_err(&pdev->dev, "failed to EMC DVFS pairs: %d\n", err);
 204                 return err;
 205         }
 206
 207         emc->debugfs.min_rate = ULONG_MAX;
 208         emc->debugfs.max_rate = 0;
 209
 210         emc->num_dvfs = response.num_pairs;
 211
 212         emc->dvfs = devm_kmalloc_array(&pdev->dev, emc->num_dvfs,
 213                                        sizeof(*emc->dvfs), GFP_KERNEL);
 214         if (!emc->dvfs)
 215                 return -ENOMEM;
 216
 217         dev_dbg(&pdev->dev, "%u DVFS pairs:\n", emc->num_dvfs);
 218
 219         for (i = 0; i < emc->num_dvfs; i++) {
 220                 emc->dvfs[i].rate = response.pairs[i].freq * 1000;
 221                 emc->dvfs[i].latency = response.pairs[i].latency;
 222
 223                 if (emc->dvfs[i].rate < emc->debugfs.min_rate)
 224                         emc->debugfs.min_rate = emc->dvfs[i].rate;
 225
 226                 if (emc->dvfs[i].rate > emc->debugfs.max_rate)
 227                         emc->debugfs.max_rate = emc->dvfs[i].rate;
 228
 229                 dev_dbg(&pdev->dev, "  %2u: %lu Hz -> %lu us\n", i,
 230                         emc->dvfs[i].rate, emc->dvfs[i].latency);
 231         }
 232
 233         err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
 234                                  emc->debugfs.max_rate);
 235         if (err < 0) {
 236                 dev_err(&pdev->dev,
 237                         "failed to set rate range [%lu-%lu] for %pC\n",
 238                         emc->debugfs.min_rate, emc->debugfs.max_rate,
 239                         emc->clk);
 240                 return err;
 241         }
 242
 243         emc->debugfs.root = debugfs_create_dir("emc", NULL);
 244         if (!emc->debugfs.root) {
 245                 dev_err(&pdev->dev, "failed to create debugfs directory\n");
 246                 return 0;
 247         }
 248
 249         debugfs_create_file("available_rates", S_IRUGO, emc->debugfs.root,
 250                             emc, &tegra186_emc_debug_available_rates_fops);
 251         debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
 252                             emc, &tegra186_emc_debug_min_rate_fops);
 253         debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
 254                             emc, &tegra186_emc_debug_max_rate_fops);
 255
 256         return 0;
 257 }
 258
 259 static int tegra186_emc_remove(struct platform_device *pdev)
 260 {
 261         struct tegra186_emc *emc = platform_get_drvdata(pdev);
 262
 263         debugfs_remove_recursive(emc->debugfs.root);
 264         tegra_bpmp_put(emc->bpmp);
 265
 266         return 0;
 267 }
 268
 269 static const struct of_device_id tegra186_emc_of_match[] = {
 270 #if defined(CONFIG_ARCH_TEGRA186_SOC)
 271         { .compatible = "nvidia,tegra186-emc" },
 272 #endif
 273 #if defined(CONFIG_ARCH_TEGRA194_SOC)
 274         { .compatible = "nvidia,tegra194-emc" },
 275 #endif
 276         { /* sentinel */ }
 277 };
 278 MODULE_DEVICE_TABLE(of, tegra186_emc_of_match);
 279
 280 static struct platform_driver tegra186_emc_driver = {
 281         .driver = {
 282                 .name = "tegra186-emc",
 283                 .of_match_table = tegra186_emc_of_match,
 284                 .suppress_bind_attrs = true,
 285         },
 286         .probe = tegra186_emc_probe,
 287         .remove = tegra186_emc_remove,
 288 };
 289 module_platform_driver(tegra186_emc_driver);
 290
 291 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
 292 MODULE_DESCRIPTION("NVIDIA Tegra186 External Memory Controller driver");
 293 MODULE_LICENSE("GPL v2");