[PATCH] arm: mvebu: Add support for reading LD0 and LD1 eFuse

[Pali Rohár]

Armada 385 contains 64 lines of HD eFuse and 2 lines of LD eFuse. HD eFuse
is used for secure boot and each line is 64 bits long + 1 lock bit. LD
eFuse lines are 256 bits long + 1 lock bit. LD 0 line is reserved for
Marvell Internal Use and LD 1 line is for General Purpose Data. U-Boot
already contains HD eFuse reading and programming support.

This patch implements LD eFuse reading support. LD 0 line is mapped to
U-Boot fuse bank 64 and LD 1 line to fuse bank 65.

LD 0 Marvell Internal Use line seems that was burned in factory with some
data and can be read by U-Boot fuse command:

  => fuse read 64 0 9

LD 1 General Purpose Data line is by default empty and can be read by
U-Boot fuse command:

  => fuse read 65 0 9

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 arch/arm/mach-mvebu/efuse.c              | 28 ++++++++++++++++++++++++
 arch/arm/mach-mvebu/include/mach/efuse.h |  5 +++++
 2 files changed, 33 insertions(+)

diff --git a/arch/arm/mach-mvebu/efuse.c b/arch/arm/mach-mvebu/efuse.c
index c79eee98fe98..80318c339eb7 100644
--- a/arch/arm/mach-mvebu/efuse.c
+++ b/arch/arm/mach-mvebu/efuse.c
@@ -27,6 +27,7 @@
 
 enum {
 	MVEBU_EFUSE_CTRL_PROGRAM_ENABLE = (1 << 31),
+	MVEBU_EFUSE_LD1_SELECT          = (1 <<  6),
 };
 
 struct mvebu_hd_efuse {
@@ -39,8 +40,10 @@ struct mvebu_hd_efuse {
 #ifndef DRY_RUN
 static struct mvebu_hd_efuse *efuses =
 	(struct mvebu_hd_efuse *)(MBUS_EFUSE_BASE + 0xF9000);
+static u32 *ld_efuses = (void *)MBUS_EFUSE_BASE + 0xF8F00;
 #else
 static struct mvebu_hd_efuse efuses[EFUSE_LINE_MAX + 1];
+static u32 ld_efuses[EFUSE_LD_WORDS];
 #endif
 
 static int efuse_initialised;
@@ -169,6 +172,21 @@ int mvebu_read_efuse(int nr, struct efuse_val *val)
 	return 0;
 }
 
+void mvebu_read_ld_efuse(int ld1, u32 *line)
+{
+	int i;
+
+#ifndef DRY_RUN
+	if (ld1)
+		setbits_le32(MVEBU_EFUSE_CONTROL, MVEBU_EFUSE_LD1_SELECT);
+	else
+		clrbits_le32(MVEBU_EFUSE_CONTROL, MVEBU_EFUSE_LD1_SELECT);
+#endif
+
+	for (i = 0; i < EFUSE_LD_WORDS; i++)
+		line[i] = readl(ld_efuses + i);
+}
+
 int mvebu_write_efuse(int nr, struct efuse_val *val)
 {
 	return prog_efuse(nr, val, ~0, ~0);
@@ -199,8 +217,18 @@ static int valid_prog_words;
 int fuse_read(u32 bank, u32 word, u32 *val)
 {
 	struct efuse_val fuse_line;
+	u32 ld_line[EFUSE_LD_WORDS];
 	int res;
 
+	if ((bank == EFUSE_LD0_LINE || bank == EFUSE_LD1_LINE) && word < EFUSE_LD_WORDS) {
+		res = mvebu_efuse_init_hw();
+		if (res)
+			return res;
+		mvebu_read_ld_efuse(bank == EFUSE_LD1_LINE, ld_line);
+		*val = ld_line[word];
+		return 0;
+	}
+
 	if (bank < EFUSE_LINE_MIN || bank > EFUSE_LINE_MAX || word > 2)
 		return -EINVAL;
 
diff --git a/arch/arm/mach-mvebu/include/mach/efuse.h b/arch/arm/mach-mvebu/include/mach/efuse.h
index bbc5844d849c..122e735f2fc7 100644
--- a/arch/arm/mach-mvebu/include/mach/efuse.h
+++ b/arch/arm/mach-mvebu/include/mach/efuse.h
@@ -53,8 +53,13 @@ enum efuse_line {
 
 	EFUSE_LINE_MIN = 0,
 	EFUSE_LINE_MAX = 63,
+
+	EFUSE_LD0_LINE = 64,
+	EFUSE_LD1_LINE = 65,
 };
 
+#define EFUSE_LD_WORDS 9
+
 #endif
 
 int mvebu_efuse_init_hw(void);
-- 
2.20.1