efi/earlycon: Fix early printk for wider fonts

[ Upstream commit 8f592ada59b321d248391bae175cd78a12972223 ]

When I play with terminus fonts I noticed the efi early printk does
not work because the earlycon code assumes font width is 8.

Here add the code to adapt with larger fonts.  Tested with all kinds
of kernel built-in fonts on my laptop. Also tested with a local draft
patch for 14x28 !bold terminus font.

Signed-off-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/r/20200412024927.GA6884@dhcp-128-65.nay.redhat.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
index 5d4f84781aa036bf83d7b842442d24e438111649..a52236e11e5f73ddea5bb1f42ca2ca7c42425dab 100644 (file)
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -114,14 +114,16 @@ static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
        const u32 color_black = 0x00000000;
        const u32 color_white = 0x00ffffff;
        const u8 *src;
-       u8 s8;
-       int m;
+       int m, n, bytes;
+       u8 x;
 
-       src = font->data + c * font->height;
-       s8 = *(src + h);
+       bytes = BITS_TO_BYTES(font->width);
+       src = font->data + c * font->height * bytes + h * bytes;
 
-       for (m = 0; m < 8; m++) {
-               if ((s8 >> (7 - m)) & 1)
+       for (m = 0; m < font->width; m++) {
+               n = m % 8;
+               x = *(src + m / 8);
+               if ((x >> (7 - n)) & 1)
                        *dst = color_white;
                else
                        *dst = color_black;