arm: mvebu: Add support for programming LD0 and LD1 eFuse

This patch implements LD eFuse programming support. Armada 385 contains two
LD eFuse lines, each is 256 bit long with one additional lock bit. LD 0
line is mapped to U-Boot fuse bank 64 and LD 1 line to fuse bank 65. U-Boot
32-bit fuse words 0-8 are mapped to LD eFuse line bits 0-255. U-Boot fuse
word 9 is mapped to LD eFuse line lock bit.

So to program LD 1 General Purpose Data line, use U-Boot fuse command:

    => fuse prog -y 65 0 0x76543210
    => fuse prog -y 65 1 0xfedcba98
    => fuse prog -y 65 2 0x76543210
    => fuse prog -y 65 3 0xfedcba98
    => fuse prog -y 65 4 0x76543210
    => fuse prog -y 65 5 0xfedcba98
    => fuse prog -y 65 6 0x76543210
    => fuse prog -y 65 7 0xfedcba98
    => fuse prog -y 65 8 0x1

Signed-off-by: Pali Rohár <pali@kernel.org>

arch/arm/mach-mvebu/efuse.c

@@ -132,6 +132,46 @@ static int prog_efuse(int nr, struct efuse_val *new_val, u32 mask0, u32 mask1)
 	return res;
 }
 
+int mvebu_prog_ld_efuse(int ld1, u32 word, u32 val)
+{
+	int i, res;
+	u32 line[EFUSE_LD_WORDS];
+
+	res = mvebu_efuse_init_hw();
+	if (res)
+		return res;
+
+	mvebu_read_ld_efuse(ld1, line);
+
+	/* check if lock bit is already programmed */
+	if (line[EFUSE_LD_WORDS - 1])
+		return -EPERM;
+
+	/* check if word is valid */
+	if (word >= EFUSE_LD_WORDS)
+		return -EINVAL;
+
+	/* check if there is some bit for programming */
+	if (val == (line[word] & val))
+		return 0;
+
+	enable_efuse_program();
+
+	mvebu_read_ld_efuse(ld1, line);
+	line[word] |= val;
+
+	for (i = 0; i < EFUSE_LD_WORDS; i++) {
+		writel(line[i], ld_efuses + i);
+		mdelay(1);
+	}
+
+	mdelay(5);
+
+	disable_efuse_program();
+
+	return 0;
+}
+
 int mvebu_efuse_init_hw(void)
 {
 	int ret;
@@ -254,6 +294,9 @@ int fuse_prog(u32 bank, u32 word, u32 val)
 {
 	int res = 0;
 
+	if (bank == EFUSE_LD0_LINE || bank == EFUSE_LD1_LINE)
+		return mvebu_prog_ld_efuse(bank == EFUSE_LD1_LINE, word, val);
+
 	/*
 	 * NOTE: Fuse line should be written as whole.
 	 * So how can we do that with this API?

arch/arm/mach-mvebu/include/mach/efuse.h

@@ -70,4 +70,8 @@ int mvebu_write_efuse(int nr, struct efuse_val *val);
 
 int mvebu_lock_efuse(int nr);
 
+void mvebu_read_ld_efuse(int ld1, u32 *line);
+
+int mvebu_prog_ld_efuse(int ld1, u32 word, u32 val);
+
 #endif