fel: sid: extend assembly to dump arbitrary range

To workaround a hardware erratum on the H3 SoC, we use an MMIO register
based assembly routine to dump the SID registers, if needed. This is
hard-coded to read the first four 32-bit words of the SID fuses.

For the sid-dump command we need to access any arbitrary regions of the
fuses, so extend the routine to take a start and an end address to dump.

This changes the assembly source in the thunks/ directory:
- We load the start address into r1, instead of zeroing it. The start
  address is put right after the SIO MMIO base address, at the end of
  the code.
- When storing the read value into the result buffer, we automatically
  increase the pointer register (r3), instead of adding the offset
  address, since this is now no longer zero based.
- To check for the end, we read the end pointer (stored at the end of
  the code, right after the offset), and compare against that instead of
  the hardcoded value of 16.
This assembly file was put through the thunks Makefile, and the resulting
content was copied from thunks/sid_read_root.h into fel_lib.c.

For now we are still putting the constant values of 0 and 16 in, but
this time from the C code.

Signed-off-by: Andre Przywara <osp@andrep.de>

3 files changed, 38 insertions, 27 deletions

diff --git a/fel_lib.c b/fel_lib.c
index 310e836..c79eebb 100644
--- a/fel_lib.c
+++ b/fel_lib.c
@@ -551,9 +551,10 @@ void fel_clrsetbits_le32(feldev_handle *dev,
 static void fel_get_sid_registers(feldev_handle *dev, uint32_t *result)
 {
 	uint32_t arm_code[] = {
-		htole32(0xe59f0040), /*    0:  ldr   r0, [pc, #64]           */
-		htole32(0xe3a01000), /*    4:  mov   r1, #0                  */
-		htole32(0xe28f303c), /*    8:  add   r3, pc, #60             */
+		/* <sid_read_root_key>: */
+		htole32(0xe59f0044), /*    0:  ldr   r0, [pc, #68]           */
+		htole32(0xe59f1044), /*    4:  ldr   r1, [pc, #68]           */
+		htole32(0xe28f3048), /*    8:  add   r3, pc, #72             */
 		/* <sid_read_loop>: */
 		htole32(0xe1a02801), /*    c:  lsl   r2, r1, #16             */
 		htole32(0xe3822b2b), /*   10:  orr   r2, r2, #44032          */
@@ -564,14 +565,20 @@ static void fel_get_sid_registers(feldev_handle *dev, uint32_t *result)
 		htole32(0xe3120002), /*   20:  tst   r2, #2                  */
 		htole32(0x1afffffc), /*   24:  bne   1c <sid_read_wait>      */
 		htole32(0xe5902060), /*   28:  ldr   r2, [r0, #96]           */
-		htole32(0xe7832001), /*   2c:  str   r2, [r3, r1]            */
+		htole32(0xe4832004), /*   2c:  str   r2, [r3], #4            */
 		htole32(0xe2811004), /*   30:  add   r1, r1, #4              */
-		htole32(0xe3510010), /*   34:  cmp   r1, #16                 */
-		htole32(0x3afffff3), /*   38:  bcc   c <sid_read_loop>       */
-		htole32(0xe3a02000), /*   3c:  mov   r2, #0                  */
-		htole32(0xe5802040), /*   40:  str   r2, [r0, #64]           */
-		htole32(0xe12fff1e), /*   44:  bx    lr                      */
+		htole32(0xe59f2018), /*   34:  ldr   r2, [pc, #24]           */
+		htole32(0xe1510002), /*   38:  cmp   r1, r2                  */
+		htole32(0x3afffff2), /*   3c:  bcc   c <sid_read_loop>       */
+		htole32(0xe3a02000), /*   40:  mov   r2, #0                  */
+		htole32(0xe5802040), /*   44:  str   r2, [r0, #64]           */
+		htole32(0xe12fff1e), /*   48:  bx    lr                      */
+		/* <sid_base>: */
 		htole32(dev->soc_info->sid_base), /* SID base addr */
+		/* <offset>: */
+		htole32(0),			/* first word to read */
+		/* <end>: */
+		htole32(16),			/* where to stop to read */
 		/* retrieved SID values go here */
 	};
 	/* write and execute code */
diff --git a/thunks/sid_read_root.S b/thunks/sid_read_root.S
index 9fd04b1..3d8d719 100644
--- a/thunks/sid_read_root.S
+++ b/thunks/sid_read_root.S
@@ -42,7 +42,7 @@ sid_key_index	.req	r1
 
 sid_read_root_key:
 	ldr	SID_BASE, sid_base
-	mov	sid_key_index, #0
+	ldr	sid_key_index, offset
 	adr	r3, sid_result			/* result pointer */
 sid_read_loop:
 	mov	r2, sid_key_index, lsl #16	/* PG_INDEX value */
@@ -55,10 +55,11 @@ sid_read_wait:
 	bne	sid_read_wait		/* loop while bit 1 still set */
 
 	ldr	r2, [SID_BASE, #SID_RDKEY]	/* read SID key value */
-	str	r2, [r3, sid_key_index]		/* store SID value */
+	str	r2, [r3], #4			/* store SID value */
 
 	add	sid_key_index, #4
-	cmp	sid_key_index, #16
+	ldr	r2, end
+	cmp	sid_key_index, r2
 	blo	sid_read_loop		/* loop while (sid_key_index < 0x10) */
 
 	mov	r2, #0
@@ -66,7 +67,6 @@ sid_read_wait:
 	bx	lr
 
 sid_base:	.word 0
-sid_result:	.word 0 /* receives the four "root key" 32-bit words */
-		.word 0
-		.word 0
-		.word 0
+offset:		.word 0
+end:		.word 0
+sid_result:	/* receives the values read from the SID registers */
diff --git a/thunks/sid_read_root.h b/thunks/sid_read_root.h
index 48596bb..fc11e14 100644
--- a/thunks/sid_read_root.h
+++ b/thunks/sid_read_root.h
@@ -1,7 +1,7 @@
 		/* <sid_read_root_key>: */
-		htole32(0xe59f0040), /*    0:  ldr   r0, [pc, #64]           */
-		htole32(0xe3a01000), /*    4:  mov   r1, #0                  */
-		htole32(0xe28f303c), /*    8:  add   r3, pc, #60             */
+		htole32(0xe59f0044), /*    0:  ldr   r0, [pc, #68]           */
+		htole32(0xe59f1044), /*    4:  ldr   r1, [pc, #68]           */
+		htole32(0xe28f3048), /*    8:  add   r3, pc, #72             */
 		/* <sid_read_loop>: */
 		htole32(0xe1a02801), /*    c:  lsl   r2, r1, #16             */
 		htole32(0xe3822b2b), /*   10:  orr   r2, r2, #44032          */
@@ -12,13 +12,17 @@
 		htole32(0xe3120002), /*   20:  tst   r2, #2                  */
 		htole32(0x1afffffc), /*   24:  bne   1c <sid_read_wait>      */
 		htole32(0xe5902060), /*   28:  ldr   r2, [r0, #96]           */
-		htole32(0xe7832001), /*   2c:  str   r2, [r3, r1]            */
+		htole32(0xe4832004), /*   2c:  str   r2, [r3], #4            */
 		htole32(0xe2811004), /*   30:  add   r1, r1, #4              */
-		htole32(0xe3510010), /*   34:  cmp   r1, #16                 */
-		htole32(0x3afffff3), /*   38:  bcc   c <sid_read_loop>       */
-		htole32(0xe3a02000), /*   3c:  mov   r2, #0                  */
-		htole32(0xe5802040), /*   40:  str   r2, [r0, #64]           */
-		htole32(0xe12fff1e), /*   44:  bx    lr                      */
+		htole32(0xe59f2018), /*   34:  ldr   r2, [pc, #24]           */
+		htole32(0xe1510002), /*   38:  cmp   r1, r2                  */
+		htole32(0x3afffff2), /*   3c:  bcc   c <sid_read_loop>       */
+		htole32(0xe3a02000), /*   40:  mov   r2, #0                  */
+		htole32(0xe5802040), /*   44:  str   r2, [r0, #64]           */
+		htole32(0xe12fff1e), /*   48:  bx    lr                      */
 		/* <sid_base>: */
-		htole32(0x00000000), /*   48:  .word 0x00000000              */
-		/* <sid_result>: */
+		htole32(0x00000000), /*   4c:  .word 0x00000000              */
+		/* <offset>: */
+		htole32(0x00000000), /*   50:  .word 0x00000000              */
+		/* <end>: */
+		htole32(0x00000000), /*   54:  .word 0x00000000              */