RISC-V: Add kernel device functionalty

- Create device untypeds for platform devices that can be passed to user
space.
- Create kernel device mapping for devices required by the kernel.
Note that the current kernel device mapping is simply a 1GiB of page
physical memory as that contains all devices for all RISC-V platforms
that are currently supported.

include/plat/spike/plat/instance/hifive/hardware.h

@@ -24,4 +24,19 @@ static p_region_t BOOT_DATA avail_p_regs[] = {
 #endif
 };
 
+static const paddr_t BOOT_RODATA kernel_devices[] = {
+    /* Plic0 */
+    0x00000000,
+};
+
+static const p_region_t BOOT_RODATA dev_p_regs[] = {
+    { 0x10010000, 0x10011000 }, /* UART0 */
+    { 0x10011000, 0x10012000 }, /* UART1 */
+    { 0x10020000, 0x10021000 }, /* PWM0 */
+    { 0x10021000, 0x10022000 }, /* PWM1 */
+    { 0x10060000, 0x10061000 }, /* GPIO */
+    { 0x10090000, 0x10091000 }, /* ETH */
+};
+
+
 #endif

include/plat/spike/plat/instance/qemu/hardware.h

@@ -24,4 +24,8 @@ static p_region_t BOOT_DATA avail_p_regs[] = {
 #endif
 };
 
+static const paddr_t BOOT_RODATA *kernel_devices = NULL;
+
+static const p_region_t BOOT_RODATA *dev_p_regs = NULL;
+
 #endif

include/plat/spike/plat/instance/rocket-chip/hardware.h

@@ -20,4 +20,7 @@ static p_region_t BOOT_DATA avail_p_regs[] = {
     { /*.start = */ 0x0, /* .end = */ 0x10000000}
 };
 
+static const paddr_t BOOT_RODATA *kernel_devices = NULL;
+
+static const p_region_t BOOT_RODATA *dev_p_regs = NULL;
 #endif

include/plat/spike/plat/machine/hardware.h

@@ -62,6 +62,8 @@
 
 int get_num_avail_p_regs(void);
 p_region_t *get_avail_p_regs(void);
+int get_num_dev_p_regs(void);
+p_region_t get_dev_p_reg(word_t i);
 void map_kernel_devices(void);
 
 bool_t CONST isReservedIRQ(irq_t irq);

src/arch/riscv/kernel/boot.c

@@ -42,10 +42,22 @@ BOOT_CODE static bool_t create_untypeds(cap_t root_cnode_cap, region_t boot_mem_
 {
     seL4_SlotPos   slot_pos_before;
     seL4_SlotPos   slot_pos_after;
+    region_t       dev_reg;
 
     slot_pos_before = ndks_boot.slot_pos_cur;
     bool_t res = create_kernel_untypeds(root_cnode_cap, boot_mem_reuse_reg, slot_pos_before);
 
+    UNUSED paddr_t current_region_pos = 0;
+    for (int i = 0; i < get_num_dev_p_regs(); i++) {
+        assert(get_dev_p_reg(i).start >= current_region_pos);
+        current_region_pos = get_dev_p_reg(i).end;
+        dev_reg = paddr_to_pptr_reg(get_dev_p_reg(i));
+        if (!create_untypeds_for_region(root_cnode_cap, true,
+                                        dev_reg, slot_pos_before)) {
+            return false;
+        }
+    }
+
     slot_pos_after = ndks_boot.slot_pos_cur;
     ndks_boot.bi_frame->untyped = (seL4_SlotRegion) {
         slot_pos_before, slot_pos_after

src/arch/riscv/kernel/vspace.c

@@ -98,6 +98,12 @@ static pte_t pte_next(word_t phys_addr, bool_t is_leaf)
 
 /* ==================== BOOT CODE STARTS HERE ==================== */
 
+BOOT_CODE void map_kernel_frame(paddr_t paddr, pptr_t vaddr, vm_rights_t vm_rights)
+{
+    assert((paddr % RISCV_GET_LVL_PGSIZE(1)) == 0);
+    kernel_root_pageTable[RISCV_GET_PT_INDEX(vaddr, 1)] = pte_next(paddr, true);
+}
+
 BOOT_CODE VISIBLE void map_kernel_window(void)
 {
     /* mapping of kernelBase (virtual address) to kernel's physBase  */
@@ -142,8 +148,9 @@ BOOT_CODE VISIBLE void map_kernel_window(void)
     }
 #endif
 
-    /* There should be 1GiB free where we will put device mapping some day */
+    /* There should be 1GiB free where we put device mapping */
     assert(pptr == UINTPTR_MAX - RISCV_GET_LVL_PGSIZE(1) + 1);
+    map_kernel_devices();
 }
 
 BOOT_CODE void map_it_pt_cap(cap_t vspace_cap, cap_t pt_cap)

src/plat/spike/machine/hardware.c

@@ -50,6 +50,41 @@ BOOT_CODE p_region_t *get_avail_p_regs(void)
     return (p_region_t *) avail_p_regs;
 }
 
+BOOT_CODE int get_num_dev_p_regs(void)
+{
+    if (dev_p_regs != NULL) {
+        return (sizeof(dev_p_regs) / sizeof(p_region_t));
+    } else {
+        return 0;
+    }
+}
+
+BOOT_CODE p_region_t get_dev_p_reg(word_t i)
+{
+    /* We need this if guard as some RISC-V configurations don't declare any
+     * device regions and some compilers complain about indexing an empty array
+     * due to not being able to infer that get_dev_p_reg is only called if
+     * dev_p_regs contains entries.
+     */
+    if (get_num_dev_p_regs() == 0) {
+        printf("%s: No devices present.\n", __func__);
+        halt();
+    }
+    return dev_p_regs[i];
+}
+
+BOOT_CODE void map_kernel_devices(void)
+{
+    if (kernel_devices == NULL) {
+        return;
+    }
+
+    for (int i = 0; i < (sizeof(kernel_devices) / sizeof(paddr_t)); i++) {
+        map_kernel_frame(kernel_devices[i], PPTR_KDEV,
+                         VMKernelOnly);
+    }
+}
+
 /**
    DONT_TRANSLATE
  */