boot: Move PIC challenge to 1BL low ROM, before 2BL RAM copy

Author: haxar

boot_rom/2bBootStartBios.c

@@ -261,12 +261,9 @@ void BootStartBiosLoader(void)
 	SHA1Input(&context,(void*)(PROGRAMM_Memory_2bl+20),bootloadersize-20);
 	SHA1Result(&context,SHA1_result);
 
-        if (memcmp(&bootloaderChecksum[0],&SHA1_result[0],20)==0) {
-		// HEHE, the Image we copy'd into ram is SHA-1 hash identical, this is Optimum
-		BootPerformPicChallengeResponseAction();
-
-	} else {
-		// Bad, the checksum does not match, but we can nothing do now, we wait until PIC kills us
+	if (memcmp(&bootloaderChecksum[0],&SHA1_result[0],20)) {
+		// Bad, the checksum does not match, we did not get a valid image copied to RAM, so we stop and display an error.
+		setLED("rrrr");
 		while(1);
 	}
 
@@ -358,9 +355,6 @@ void BootStartBiosLoader(void)
 		// We are not Longer here
 	}
 
-	// Bad, we did not get a valid im age to RAM, we stop and display a error
-	//setLED("rrrr");
-
 	setLED("oooo");
 
 //	I2CTransmitWord(0x10, 0x1901); // no reset on eject

boot_rom/2bBootStartup.S

@@ -211,8 +211,12 @@
 
         cld
 
-	// copy everything into RAM
+	// Set the stack pointer to give us a valid stack
+	movl $0x1ffff0, %esp
+
+	call pic_challenge_response
 
+	// Copy 2BL into RAM
 	mov 	$_ram_location, %edi
 	mov 	$_start_ramcopy, %esi
 	mov 	$(_size_ramcopy + 100), %ecx
@@ -309,9 +313,6 @@ reload_cs:
 	mov %eax, %fs
 	mov %eax, %gs
 
-	// Set the stack pointer to give us a valid stack
-	movl $0x1ffff0, %esp
-
 	// Clear out .bss
 	xor %eax, %eax
 	mov $BSS_SIZE_L, %ecx

boot_rom/2bPicResponseAction.c

@@ -14,6 +14,36 @@
 
 #include "2bload.h"
 
+void pic_challenge_response(void)
+{
+    register u8 x1c, x1d, x1e, x1f;
+    register u8 b1, b2, b3, b4;
+    register int i;
+
+    smbus_set_addr(0x21); /* set PIC address; read command */
+    smbus_read_start(0x1c);
+    if (!smbus_cycle_completed()) return;
+    x1c = smbus_read_data();
+    x1d = smbus_read(0x1d);
+    x1e = smbus_read(0x1e);
+    x1f = smbus_read(0x1f);
+
+    b1  = 0x33;
+    b2  = 0xed;
+    b3  = x1c << 2;
+    b3 ^= x1d + 0x39;
+    b3 ^= x1e >> 2;
+    b3 ^= x1f + 0x63;
+    b4  = x1c + 0x0b;
+    b4 ^= x1d >> 2;
+    b4 ^= x1e + 0x1b;
+
+    for (i = 0; i < 4; b1 += b2 ^ b3, b2 += b1 ^ b4, ++i);
+
+    smbus_set_addr(0x20); /* set PIC address; write command */
+    smbus_write(0x20, b1);
+    smbus_write(0x21, b2);
+}
 
 // ----------------------------  I2C -----------------------------------------------------------
 //
@@ -85,65 +115,6 @@ int I2CTransmitWord(u8 bPicAddressI2cFormat, u16 wDataToWrite)
 	return ERR_I2C_ERROR_BUS;
 }
 
-// ----------------------------  PIC challenge/response -----------------------------------------------------------
-//
-// given four bytes, returns a u16
-// LSB of return is the 'first' byte, MSB is the 'second' response byte
-
-u16 BootPicManipulation(
-	u8 bC,
-	u8  bD,
-	u8  bE,
-	u8  bF
-) {
-	int n=4;
-	u8
-		b1 = 0x33,
-		b2 = 0xed,
-		b3 = ((bC<<2) ^ (bD +0x39) ^ (bE >>2) ^ (bF +0x63)),
-		b4 = ((bC+0x0b) ^ (bD>>2) ^ (bE +0x1b))
-	;
-
-	while(n--) {
-		b1 += b2 ^ b3;
-		b2 += b1 ^ b4;
-	}
-
-	return (u16) ((((u16)b2)<<8) | b1);
-}
-
-// actual business of getting I2C data from PIC and reissuing munged version
-// returns zero if all okay, else error code
-
-int BootPerformPicChallengeResponseAction()
-{
-	u8 bC, bD, bE, bF;
-	int n;
-
-	n=I2CTransmitByteGetReturn( 0x10, 0x1c );
-	if(n<0) return n;
-	bC=n;
-	n=I2CTransmitByteGetReturn( 0x10, 0x1d );
-	if(n<0) return n;
-	bD=n;
-	n=I2CTransmitByteGetReturn( 0x10, 0x1e );
-	if(n<0) return n;
-	bE=n;
-	n=I2CTransmitByteGetReturn( 0x10, 0x1f );
-	if(n<0) return n;
-	bF=n;
-
-	{
-		u16 w=BootPicManipulation(bC, bD, bE, bF);
-
-		I2CTransmitWord( 0x10, 0x2000 | (w&0xff));
-		I2CTransmitWord( 0x10, 0x2100 | (w>>8) );
-	}
-
-	// continues as part of video setup....
-	return ERR_SUCCESS;
-}
-
 extern int I2cSetFrontpanelLed(u8 b)
 {
 	I2CTransmitWord( 0x10, 0x800 | b);  // sequencing thanks to Jarin the Penguin!

boot_rom/2bload.h

@@ -14,23 +14,6 @@
 #include "stdint.h"
 #include "cromwell_types.h"
 
-
-/////////////////////////////////
-// LED-flashing codes
-// or these together as argument to I2cSetFrontpanelLed
-
-enum {
-	I2C_LED_RED0 = 0x80,
-	I2C_LED_RED1 = 0x40,
-	I2C_LED_RED2 = 0x20,
-	I2C_LED_RED3 = 0x10,
-	I2C_LED_GREEN0 = 0x08,
-	I2C_LED_GREEN1 = 0x04,
-	I2C_LED_GREEN2 = 0x02,
-	I2C_LED_GREEN3 = 0x01
-};
-
-///////////////////////////////
 /* BIOS-wide error codes		all have b31 set  */
 
 enum {
@@ -42,10 +25,7 @@ enum {
 	ERR_BOOT_PIC_ALG_BROKEN = 0x80000101 // PIC algorithm did not pass its self-test
 };
 
-//////// BootPerformPicChallengeResponseAction.c
-
-/* ----------------------------  IO primitives -----------------------------------------------------------
-*/
+// ----------------------------  IO primitives -----------------------------------------------------------
 
 static INLINE void IoOutputByte(u16 wAds, u8 bValue)
 {
@@ -167,21 +147,27 @@ static INLINE u8 smbus_read(u8 cmd)
     return smbus_read_data();
 }
 
-// boot process
-int BootPerformPicChallengeResponseAction(void);
-// LED control (see associated enum above)
-int I2cSetFrontpanelLed(u8 b);
-int I2cResetFrontpanelLed(void);
-
-////////// 2bBootStartBios.c
-
+/* 2bBootStartBios.c */
 void BootSystemInitialization(void) __attribute__((section(".reset_vector.1bl"),aligned(16),naked));
 void BootStartBiosLoader(void);
 
-///////// BootPerformPicChallengeResponseAction.c
-
+/* 2bPicResponseAction.c */
+void pic_challenge_response(void) __attribute__((section(".low_rom"),aligned(16)));
 int I2CTransmitWord(u8 bPicAddressI2cFormat, u16 wDataToWrite);
 int I2CTransmitByteGetReturn(u8 bPicAddressI2cFormat, u8 bDataToWrite);
+/* LED control; see associated enum as argument to I2cSetFrontpanelLed */
+enum {
+	I2C_LED_RED0 = 0x80,
+	I2C_LED_RED1 = 0x40,
+	I2C_LED_RED2 = 0x20,
+	I2C_LED_RED3 = 0x10,
+	I2C_LED_GREEN0 = 0x08,
+	I2C_LED_GREEN1 = 0x04,
+	I2C_LED_GREEN2 = 0x02,
+	I2C_LED_GREEN3 = 0x01
+};
+int I2cSetFrontpanelLed(u8 b);
+int I2cResetFrontpanelLed(void);
 
 void *memcpy(void *dest, const void *src,  size_t size);
 void *memset(void *dest, int data,  size_t size);
@@ -191,3 +177,4 @@ extern unsigned char *BufferIN;
 extern int BufferINlen;
 extern unsigned char *BufferOUT;
 extern int BufferOUTPos;
+