drivers/iommu/bcm2712-iommu-cache.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IOMMU driver for BCM2712
   4  *
   5  * Copyright (c) 2023 Raspberry Pi Ltd.
   6  */
   7
   8 #include "bcm2712-iommu.h"
   9
  10 #include <linux/err.h>
  11 #include <linux/of_platform.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/spinlock.h>
  14
  15 #define MMUC_CONTROL_ENABLE   1
  16 #define MMUC_CONTROL_FLUSH    2
  17 #define MMUC_CONTROL_FLUSHING 4
  18
  19 void bcm2712_iommu_cache_flush(struct bcm2712_iommu_cache *cache)
  20 {
  21         unsigned long flags;
  22         int i;
  23
  24         spin_lock_irqsave(&cache->hw_lock, flags);
  25         if (cache->reg_base) {
  26                 /* Enable and flush the TLB cache */
  27                 writel(MMUC_CONTROL_ENABLE | MMUC_CONTROL_FLUSH,
  28                        cache->reg_base);
  29
  30                 /* Wait for flush to complete: it should be very quick */
  31                 for (i = 0; i < 1024; i++) {
  32                         if (!(MMUC_CONTROL_FLUSHING & readl(cache->reg_base)))
  33                                 break;
  34                         cpu_relax();
  35                 }
  36         }
  37         spin_unlock_irqrestore(&cache->hw_lock, flags);
  38 }
  39
  40 static int bcm2712_iommu_cache_probe(struct platform_device *pdev)
  41 {
  42         struct bcm2712_iommu_cache *cache;
  43
  44         dev_info(&pdev->dev, __func__);
  45         cache = devm_kzalloc(&pdev->dev, sizeof(*cache), GFP_KERNEL);
  46         if (!cache)
  47                 return -ENOMEM;
  48
  49         cache->dev = &pdev->dev;
  50         platform_set_drvdata(pdev, cache);
  51         spin_lock_init(&cache->hw_lock);
  52
  53         /* Get IOMMUC registers; we only use the first register (IOMMUC_CTRL) */
  54         cache->reg_base = devm_platform_ioremap_resource(pdev, 0);
  55         if (IS_ERR(cache->reg_base)) {
  56                 dev_err(&pdev->dev, "Failed to get IOMMU Cache registers address\n");
  57                 cache->reg_base = NULL;
  58         }
  59         return 0;
  60 }
  61
  62 static const struct of_device_id bcm2712_iommu_cache_of_match[] = {
  63         {
  64                 . compatible = "brcm,bcm2712-iommuc"
  65         },
  66         { /* sentinel */ },
  67 };
  68
  69 static struct platform_driver bcm2712_iommu_cache_driver = {
  70         .probe = bcm2712_iommu_cache_probe,
  71         .driver = {
  72                 .name = "bcm2712-iommu-cache",
  73                 .of_match_table = bcm2712_iommu_cache_of_match
  74         },
  75 };
  76
  77 builtin_platform_driver(bcm2712_iommu_cache_driver);