BH: Add 2M TLB window support for driver use

- Add 2M PCIe TLB window register layout.
- Claim topmost 2M window as the driver's.
- Map topmost 2M window and window config registers.
- Add program_tlb() and noc_read32() functions.

blackhole.c

@@ -10,7 +10,90 @@
 
 #define MAX_MRRS 4096
 
+#define TLB_2M_WINDOW_COUNT 202
+#define TLB_2M_SHIFT 21
+#define TLB_2M_REG_SIZE 12
+#define TLB_2M_WINDOW_SIZE (1 << TLB_2M_SHIFT)
+#define TLB_2M_WINDOW_MASK (TLB_2M_WINDOW_SIZE - 1)
+
+#define TLB_REGS_START 0x1FC00000   // BAR0
+#define TLB_REGS_LEN 0x00001000     // Covers all TLB registers
+
+#define KERNEL_TLB_INDEX (TLB_2M_WINDOW_COUNT - 1)	// Last 2M window is ours
+#define KERNEL_TLB_START (KERNEL_TLB_INDEX * TLB_2M_WINDOW_SIZE)
+#define KERNEL_TLB_LEN TLB_2M_WINDOW_SIZE
+
+struct TLB_2M_REG {
+	union {
+		struct {
+			u32 low32;
+			u32 mid32;
+			u32 high32;
+		};
+		struct {
+			u64 address : 43;
+			u64 x_end : 6;
+			u64 y_end : 6;
+			u64 x_start : 6;
+			u64 y_start : 6;
+			u64 noc : 2;
+			u64 multicast : 1;
+			u64 ordering : 2;
+			u64 linked : 1;
+			u64 use_static_vc : 1;
+			u64 stream_header : 1;
+			u64 static_vc : 3;
+			u64 reserved : 18;
+		};
+	};
+};
+
+static u64 program_tlb(struct blackhole_device *bh, u32 x, u32 y, u64 addr) {
+	struct TLB_2M_REG conf = {0};
+	u8 __iomem *regs = bh->tlb_regs + (KERNEL_TLB_INDEX * TLB_2M_REG_SIZE);
+
+	conf.address = addr >> TLB_2M_SHIFT;
+	conf.x_end = x;
+	conf.y_end = y;
+
+	mb();
+	iowrite32(conf.low32, regs + 0);
+	iowrite32(conf.mid32, regs + 4);
+	iowrite32(conf.high32, regs + 8);
+	mb();
+
+	return addr & TLB_2M_WINDOW_MASK;
+}
+
+static u32 noc_read32(struct blackhole_device *bh, u32 x, u32 y, u64 addr) {
+	u64 offset;
+	u32 val;
+
+	mutex_lock(&bh->mutex);
+
+	offset = program_tlb(bh, x, y, addr);
+	val = ioread32(bh->kernel_tlb + offset);
+
+	mutex_unlock(&bh->mutex);
+
+	return val;
+}
+
 static bool blackhole_init(struct tenstorrent_device *tt_dev) {
+	struct blackhole_device *bh = tt_dev_to_bh_dev(tt_dev);
+
+	bh->tlb_regs = pci_iomap_range(bh->tt.pdev, 0, TLB_REGS_START, TLB_REGS_LEN);
+	bh->kernel_tlb = pci_iomap_range(bh->tt.pdev, 0, KERNEL_TLB_START, KERNEL_TLB_LEN);
+
+	if (!bh->tlb_regs || !bh->kernel_tlb) {
+		if (bh->tlb_regs)
+			pci_iounmap(bh->tt.pdev, bh->tlb_regs);
+
+		if (bh->kernel_tlb)
+			pci_iounmap(bh->tt.pdev, bh->kernel_tlb);
+		return false;
+	}
+
 	return true;
 }
 

blackhole.h

@@ -9,6 +9,10 @@
 
 struct blackhole_device {
 	struct tenstorrent_device tt;
+
+	struct mutex mutex;     // Guards access to kernel_tlb
+	u8 __iomem *tlb_regs;   // All TLB registers
+	u8 __iomem *kernel_tlb; // Topmost 2M window, reserved for kernel
 };
 
 #define tt_dev_to_bh_dev(ttdev) \