Cleanup earth

earth/bus_gpio.c

@@ -10,13 +10,12 @@
  * The commented functions can control the LED lights on the Arty board.
  */
 
-#include "egos.h"
-
 #define GPIO0_BASE 0x10012000UL
 #define GPIO0_IOF_ENABLE 56UL
 #define GPIO0_IOF_SELECT 60UL
 
 /*
+#include "egos.h"
 #define LED0_RED 1
 #define LED0_GREEN 2
 #define LED0_BLUE 3

earth/cpu_intr.c

@@ -12,6 +12,9 @@
 static void (*intr_handler)(int);
 static void (*excp_handler)(int);
 
+int intr_register(void (*_handler)(int)) { intr_handler = _handler; }
+int excp_register(void (*_handler)(int)) { excp_handler = _handler; }
+
 void trap_entry() __attribute__((interrupt ("machine"), aligned(128)));
 void trap_entry() {
  int mcause;
@@ -36,9 +39,6 @@ int intr_enable() {
  asm("csrw mie, %0" ::"r"(mie | 0x88));
 }
 
-int intr_register(void (*_handler)(int)) { intr_handler = _handler; }
-int excp_register(void (*_handler)(int)) { excp_handler = _handler; }
-
 void intr_init() {
  INFO("Use direct mode and put the address of trap_entry() to mtvec");
  asm("csrw mtvec, %0" ::"r"(trap_entry));

earth/cpu_mmu.c

@@ -14,9 +14,9 @@
 #include <string.h>
 
 /* Interface of the paging device, see earth/dev_page.c */
-void paging_init();
-int paging_invalidate_cache(int frame_id);
-int paging_write(int frame_id, int page_no);
+void  paging_init();
+int  paging_invalidate_cache(int frame_id);
+int  paging_write(int frame_id, int page_no);
 char* paging_read(int frame_id, int alloc_only);
 
 /* Allocation and free of physical frames */
@@ -71,7 +71,8 @@ int soft_tlb_switch(int pid) {
 
 /* Page Table Translation
  *
- * The code below creates an identity mapping using RISC-V Sv32.
+ * The code below creates an identity mapping using RISC-V Sv32;
+ * Read section4.3 of RISC-V manual (references/riscv-privileged-v1.10.pdf)
  *
  * mmu_map() and mmu_switch() using page tables is given to students
  * as a course project. After this project, every process should have
@@ -117,7 +118,7 @@ void pagetable_identity_mapping(int pid) {
 }
 
 int page_table_map(int pid, int page_no, int frame_id) {
- if (pid >= MAX_NPROCESS) FATAL("pagetable_mmu_map: too many processes");
+ if (pid >= MAX_NPROCESS) FATAL("page_table_map: too many processes");
 
  /* Student's code goes here (page table translation). */
 
@@ -137,52 +138,41 @@ int page_table_switch(int pid) {
  /* Student's code goes here (page table translation). */
 
  /* Remove the following line of code and, instead,
- * switch the page table base register (satp) similar to mmu_init();
- * Remember to use the argument pid
+ * modify the page table base register (satp) similar to
+ * the code in mmu_init(); Remember to use the pid argument
  */
  soft_tlb_switch(pid);
 
  /* Student's code ends here. */
 }
 
 /* MMU Initialization */
-void platform_detect(int id) {
- earth->platform = ARTY;
- /* Skip the illegal store instruction */
- int mepc;
- asm("csrr %0, mepc" : "=r"(mepc));
- asm("csrw mepc, %0" ::"r"(mepc + 4));
-}
-
 void mmu_init() {
  /* Initialize the paging device */
  paging_init();
 
- /* Choose memory translation mechanism */
+ /* Initialize MMU interface functions */
+ earth->mmu_free = mmu_free;
+ earth->mmu_alloc = mmu_alloc;
+ earth->mmu_map = soft_tlb_map;
+ earth->mmu_switch = soft_tlb_switch;
+
+ if (earth->platform == ARTY) {
+ /* Arty board does not support supervisor mode or page tables */
+ earth->translation = SOFT_TLB;
+ INFO("ARTY is detected and therefore use softTLB translation");
+ return;
+ }
+
+ /* Choose memory translation mechanism in QEMU */
  CRITICAL("Choose a memory translation mechanism:");
- printf(" Enter 0: page tables (QEMU)\r\n");
- printf(" Enter 1: software TLB (QEMU or Arty board)\r\n");
+ printf("Enter 0: page tables\r\nEnter 1: software TLB\r\n");
 
  char buf[2];
  for (buf[0] = 0; buf[0] != '0' && buf[0] != '1'; earth->tty_read(buf, 2));
  earth->translation = (buf[0] == '0') ? PAGE_TABLE : SOFT_TLB;
  INFO("%s translation is chosen", earth->translation == PAGE_TABLE ? "Page table" : "Software");
 
- /* Check whether the hardware platform supports supervisor mode */
- earth->platform = QEMU;
- earth->excp_register(platform_detect);
- /* This memory access triggers an exception on Arty, but not QEMU */
- *(int*)(0x1000) = 1;
- earth->excp_register(NULL);
- if (earth->platform == ARTY && earth->translation == PAGE_TABLE)
- FATAL("Arty board doesn't support page tables (supervisor mode).");
-
- /* Initialize MMU interface functions */
- earth->mmu_free = mmu_free;
- earth->mmu_alloc = mmu_alloc;
- earth->mmu_map = soft_tlb_map;
- earth->mmu_switch = soft_tlb_switch;
-
  if (earth->translation == PAGE_TABLE) {
  /* Setup an identity mapping using page tables */
  pagetable_identity_mapping(0);

earth/dev_disk.c

@@ -36,17 +36,22 @@ int disk_write(int block_no, int nblocks, char* src) {
 }
 
 void disk_init() {
+ earth->disk_read = disk_read;
+ earth->disk_write = disk_write;
+
+ if (earth->platform == QEMU) {
+ type = FLASH_ROM;
+ INFO("QEMU is detected and therefore use on-board ROM as disk");
+ return;
+ }
+
  CRITICAL("Choose a disk:");
- printf(" Enter 0: microSD card (Arty board)\r\n");
- printf(" Enter 1: on-board ROM (Arty board or QEMU)\r\n");
+ printf("Enter 0: microSD card\r\nEnter 1: on-board ROM\r\n");
 
  char buf[2];
  for (buf[0] = 0; buf[0] != '0' && buf[0] != '1'; earth->tty_read(buf, 2));
-
  type = (buf[0] == '0')? SD_CARD : FLASH_ROM;
- if (type == SD_CARD) sdinit();
  INFO("%s is chosen", type == SD_CARD? "microSD" : "on-board ROM");
 
- earth->disk_read = disk_read;
- earth->disk_write = disk_write;
+ if (type == SD_CARD) sdinit();
 }

earth/dev_page.c

@@ -71,4 +71,3 @@ char* paging_read(int frame_id, int alloc_only) {
 
  return pages_start + PAGE_SIZE * free_idx;
 }
-

earth/earth.c

@@ -12,6 +12,7 @@
 #include "elf.h"
 #include "disk.h"
 #include "egos.h"
+#include <string.h>
 
 void tty_init();
 void disk_init();
@@ -22,18 +23,31 @@ struct grass *grass = (void*)APPS_STACK_TOP;
 struct earth *earth = (void*)GRASS_STACK_TOP;
 extern char bss_start, bss_end, data_rom, data_start, data_end;
 
+static void platform_detect(int id) {
+ earth->platform = ARTY;
+ /* Skip the illegal store instruction */
+ int mepc;
+ asm("csrr %0, mepc" : "=r"(mepc));
+ asm("csrw mepc, %0" ::"r"(mepc + 4));
+}
+
 static void earth_init() {
  tty_init();
- CRITICAL("-----------------------------------");
- CRITICAL("Start to initialize the earth layer");
+ CRITICAL("------------- Booting -------------");
  SUCCESS("Finished initializing the tty device");
 
- disk_init();
- SUCCESS("Finished initializing the disk device");
-
  intr_init();
  SUCCESS("Finished initializing the CPU interrupts");
 
+ /* Detect the hardware platform */
+ earth->platform = QEMU;
+ earth->excp_register(platform_detect);
+ /* This memory access triggers an exception on Arty, but not QEMU */
+ *(int*)(0x1000) = 1;
+
+ disk_init();
+ SUCCESS("Finished initializing the disk device");
+
  mmu_init();
  SUCCESS("Finished initializing the CPU memory management unit");
 }
@@ -43,21 +57,20 @@ static int grass_read(int block_no, char* dst) {
 }
 
 int main() {
- for (int i = 0; i < (&bss_end - &bss_start); i++)
- ((char*)&bss_start)[i] = 0;
- for (int i = 0; i < (&data_end - &data_start); i++)
- ((char*)&data_start)[i] = ((char*)&data_rom)[i];
+ /* Prepare the bss and data memory regions */
+ memset(&bss_start, 0, (&bss_end - &bss_start));
+ memcpy(&data_start, &data_rom, (&data_end - &data_start));
 
+ /* Initialize the earth layer */
  earth_init();
- elf_load(0, grass_read, 0, 0);
 
+ /* Load and enter the grass layer */
+ elf_load(0, grass_read, 0, 0);
  if (earth->translation == SOFT_TLB){
- /* Arty board does not support supervisor mode */
+ /* No need to enter supervisor mode if using softTLB translation */
  void (*grass_entry)() = (void*)GRASS_ENTRY;
  grass_entry();
  } else {
- /* QEMU supports supervisor mode */
-
  /* Enable machine-mode interrupt before entering supervisor mode */
  earth->intr_enable();
 

earth/sd/sd_init.c

@@ -5,7 +5,7 @@
 
 /* Author: Yunhao Zhang
  * Description: initialize the SD card
- * Only SDHC and SDXC cards are supported.
+ * Only SDHC and SDXC cards are supported
  */
 
 #include "sd.h"
@@ -18,12 +18,12 @@ static int sd_check_type();
 static void sd_check_capacity();
 
 enum {
- SD_CARD_TYPE_SD1,
- SD_CARD_TYPE_SD2,
- SD_CARD_TYPE_SDHC,
- SD_CARD_TYPE_UNKNOWN
+ SD_TYPE_SD1,
+ SD_TYPE_SD2,
+ SD_TYPE_SDHC,
+ SD_TYPE_UNKNOWN
 };
-static int SD_CARD_TYPE = SD_CARD_TYPE_UNKNOWN;
+static int SD_CARD_TYPE = SD_TYPE_UNKNOWN;
 
 void sdinit() {
  spi_set_clock(100000);
@@ -36,7 +36,7 @@ void sdinit() {
  INFO("Check SD card type and voltage with cmd8");
  if (0 != sd_check_type()) FATAL("Fail to check SD card type");
 
- char acmd41[] = {0x69, (SD_CARD_TYPE == SD_CARD_TYPE_SD2)? 0x40 : 0x00, 0x00, 0x00, 0x00, 0xFF};
+ char acmd41[] = {0x69, (SD_CARD_TYPE == SD_TYPE_SD2)? 0x40 : 0x00, 0x00, 0x00, 0x00, 0xFF};
  while (sd_exec_acmd(acmd41));
  while (recv_data_byte() != 0xFF);
 
@@ -45,8 +45,8 @@ void sdinit() {
  char reply = sd_exec_cmd(cmd16);
  while (recv_data_byte() != 0xFF);
 
- if (SD_CARD_TYPE == SD_CARD_TYPE_SD2) sd_check_capacity();
- if (SD_CARD_TYPE != SD_CARD_TYPE_SDHC) FATAL("Only SDHC/SDXC cards are supported");
+ if (SD_CARD_TYPE == SD_TYPE_SD2) sd_check_capacity();
+ if (SD_CARD_TYPE != SD_TYPE_SDHC) FATAL("Only SDHC/SDXC supported");
 }
 
 static int sd_check_type() {
@@ -56,7 +56,7 @@ static int sd_check_type() {
  INFO("SD card replies cmd8 with status 0x%.2x", reply);
  if (reply & 0x04) {
  /* Illegal command */
- SD_CARD_TYPE = SD_CARD_TYPE_SD1;
+ SD_CARD_TYPE = SD_TYPE_SD1;
  } else {
  /* Only need last byte of r7 response */
  unsigned long payload;
@@ -65,7 +65,7 @@ static int sd_check_type() {
  INFO("SD card replies cmd8 with payload 0x%.8x", payload);
 
  if ((payload & 0xFFF) != 0x1AA) return -1;
- SD_CARD_TYPE = SD_CARD_TYPE_SD2;
+ SD_CARD_TYPE = SD_TYPE_SD2;
  }
 
  while (recv_data_byte() != 0xFF);
@@ -76,22 +76,19 @@ static void sd_check_capacity() {
  INFO("Check SD card capacity with cmd58");
  while (recv_data_byte() != 0xFF);
 
- char reply, cmd58[] = {0x7A, 0x00, 0x00, 0x00, 0x00, 0xFF};
+ char reply, payload[4], cmd58[] = {0x7A, 0x00, 0x00, 0x00, 0x00, 0xFF};
  if (sd_exec_cmd(cmd58)) FATAL("SD card cmd58 fails");
-
- char payload[4];
  for (int i = 0; i < 4; i++) payload[3 - i] = recv_data_byte();
 
- if ((payload[3] & 0xC0) == 0xC0) SD_CARD_TYPE = SD_CARD_TYPE_SDHC;
+ if ((payload[3] & 0xC0) == 0xC0) SD_CARD_TYPE = SD_TYPE_SDHC;
  INFO("SD card replies cmd58 with payload 0x%.8x", *(int*)payload);
 
  while (recv_data_byte() != 0xFF);
 }
 
 static void sd_reset() {
- INFO("Set CS and MOSI to 1 and toggle clock.");
-
  /* Keep chip select line high */
+ INFO("Set CS and MOSI to 1 and toggle clock.");
  REGW(SPI1_BASE, SPI1_CSMODE) = 2;
 
  unsigned long i, rxdata;

earth/sd/sd_utils.c

@@ -18,9 +18,7 @@ char send_data_byte(char byte) {
  return (char)(rxdata & 0xFF);
 }
 
-inline char recv_data_byte() {
- return send_data_byte(0xFF);
-}
+char recv_data_byte() { return send_data_byte(0xFF); }
 
 char sd_exec_cmd(char* cmd) {
  for (int i = 0; i < 6; i++) send_data_byte(cmd[i]);

library/egos.h

@@ -25,7 +25,7 @@ struct earth {
  int (*tty_success)(const char *format, ...);
  int (*tty_critical)(const char *format, ...);
 
- /* QEMU or Arty, detected in mmu_init() */
+ /* Some information about earth layer configuration */
  enum { QEMU, ARTY } platform;
  enum { PAGE_TABLE, SOFT_TLB } translation;
 };