drm/nouveau/secboot/gm20b,gp10b: Read WPR configuration from GPU registers

The GPUs found on Tegra SoCs have registers that can be used to read the
WPR configuration. Use these registers instead of reaching into the
memory controller's register space to read the same information.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/secboot/gm200.h

@@ -41,6 +41,6 @@ int gm200_secboot_run_blob(struct nvkm_secboot *, struct nvkm_gpuobj *,
 			   struct nvkm_falcon *);
 
 /* Tegra-only */
-int gm20b_secboot_tegra_read_wpr(struct gm200_secboot *, u32);
+int gm20b_secboot_tegra_read_wpr(struct gm200_secboot *);
 
 #endif

drivers/gpu/drm/nouveau/nvkm/subdev/secboot/gm20b.c

@@ -23,39 +23,65 @@
 #include "acr.h"
 #include "gm200.h"
 
-#define TEGRA210_MC_BASE			0x70019000
-
 #ifdef CONFIG_ARCH_TEGRA
-#define MC_SECURITY_CARVEOUT2_CFG0		0xc58
-#define MC_SECURITY_CARVEOUT2_BOM_0		0xc5c
-#define MC_SECURITY_CARVEOUT2_BOM_HI_0		0xc60
-#define MC_SECURITY_CARVEOUT2_SIZE_128K		0xc64
-#define TEGRA_MC_SECURITY_CARVEOUT_CFG_LOCKED	(1 << 1)
 /**
  * gm20b_secboot_tegra_read_wpr() - read the WPR registers on Tegra
  *
- * On dGPU, we can manage the WPR region ourselves, but on Tegra the WPR region
- * is reserved from system memory by the bootloader and irreversibly locked.
- * This function reads the address and size of the pre-configured WPR region.
+ * On dGPU, we can manage the WPR region ourselves, but on Tegra this region
+ * is allocated from system memory by the secure firmware. The region is then
+ * marked as a "secure carveout" and irreversibly locked. Furthermore, the WPR
+ * secure carveout is also configured to be sent to the GPU via a dedicated
+ * serial bus between the memory controller and the GPU. The GPU requests this
+ * information upon leaving reset and exposes it through a FIFO register at
+ * offset 0x100cd4.
+ *
+ * The FIFO register's lower 4 bits can be used to set the read index into the
+ * FIFO. After each read of the FIFO register, the read index is incremented.
+ *
+ * Indices 2 and 3 contain the lower and upper addresses of the WPR. These are
+ * stored in units of 256 B. The WPR is inclusive of both addresses.
+ *
+ * Unfortunately, for some reason the WPR info register doesn't contain the
+ * correct values for the secure carveout. It seems like the upper address is
+ * always too small by 128 KiB - 1. Given that the secure carvout size in the
+ * memory controller configuration is specified in units of 128 KiB, it's
+ * possible that the computation of the upper address of the WPR is wrong and
+ * causes this difference.
  */
 int
-gm20b_secboot_tegra_read_wpr(struct gm200_secboot *gsb, u32 mc_base)
+gm20b_secboot_tegra_read_wpr(struct gm200_secboot *gsb)
 {
+	struct nvkm_device *device = gsb->base.subdev.device;
 	struct nvkm_secboot *sb = &gsb->base;
-	void __iomem *mc;
-	u32 cfg;
+	u64 base, limit;
+	u32 value;
+
+	/* set WPR info register to point at WPR base address register */
+	value = nvkm_rd32(device, 0x100cd4);
+	value &= ~0xf;
+	value |= 0x2;
+	nvkm_wr32(device, 0x100cd4, value);
+
+	/* read base address */
+	value = nvkm_rd32(device, 0x100cd4);
+	base = (u64)(value >> 4) << 12;
+
+	/* read limit */
+	value = nvkm_rd32(device, 0x100cd4);
+	limit = (u64)(value >> 4) << 12;
+
+	/*
+	 * The upper address of the WPR seems to be computed wrongly and is
+	 * actually SZ_128K - 1 bytes lower than it should be. Adjust the
+	 * value accordingly.
+	 */
+	limit += SZ_128K - 1;
 
-	mc = ioremap(mc_base, 0xd00);
-	if (!mc) {
-		nvkm_error(&sb->subdev, "Cannot map Tegra MC registers\n");
-		return -ENOMEM;
-	}
-	sb->wpr_addr = ioread32_native(mc + MC_SECURITY_CARVEOUT2_BOM_0) |
-	      ((u64)ioread32_native(mc + MC_SECURITY_CARVEOUT2_BOM_HI_0) << 32);
-	sb->wpr_size = ioread32_native(mc + MC_SECURITY_CARVEOUT2_SIZE_128K)
-		<< 17;
-	cfg = ioread32_native(mc + MC_SECURITY_CARVEOUT2_CFG0);
-	iounmap(mc);
+	sb->wpr_size = limit - base + 1;
+	sb->wpr_addr = base;
+
+	nvkm_info(&sb->subdev, "WPR: %016llx-%016llx\n", sb->wpr_addr,
+		  sb->wpr_addr + sb->wpr_size - 1);
 
 	/* Check that WPR settings are valid */
 	if (sb->wpr_size == 0) {
@@ -63,16 +89,11 @@ gm20b_secboot_tegra_read_wpr(struct gm200_secboot *gsb, u32 mc_base)
 		return -EINVAL;
 	}
 
-	if (!(cfg & TEGRA_MC_SECURITY_CARVEOUT_CFG_LOCKED)) {
-		nvkm_error(&sb->subdev, "WPR region not locked\n");
-		return -EINVAL;
-	}
-
 	return 0;
 }
 #else
 int
-gm20b_secboot_tegra_read_wpr(struct gm200_secboot *gsb, u32 mc_base)
+gm20b_secboot_tegra_read_wpr(struct gm200_secboot *gsb)
 {
 	nvkm_error(&gsb->base.subdev, "Tegra support not compiled in\n");
 	return -EINVAL;
@@ -85,7 +106,7 @@ gm20b_secboot_oneinit(struct nvkm_secboot *sb)
 	struct gm200_secboot *gsb = gm200_secboot(sb);
 	int ret;
 
-	ret = gm20b_secboot_tegra_read_wpr(gsb, TEGRA210_MC_BASE);
+	ret = gm20b_secboot_tegra_read_wpr(gsb);
 	if (ret)
 		return ret;
 

drivers/gpu/drm/nouveau/nvkm/subdev/secboot/gp10b.c

@@ -23,15 +23,13 @@
 #include "acr.h"
 #include "gm200.h"
 
-#define TEGRA186_MC_BASE			0x02c10000
-
 static int
 gp10b_secboot_oneinit(struct nvkm_secboot *sb)
 {
 	struct gm200_secboot *gsb = gm200_secboot(sb);
 	int ret;
 
-	ret = gm20b_secboot_tegra_read_wpr(gsb, TEGRA186_MC_BASE);
+	ret = gm20b_secboot_tegra_read_wpr(gsb);
 	if (ret)
 		return ret;