It took me a while to find this model datasheet, since it is
an OCR scan. Add a reference to save other developers time.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/i2c/ppc4xx_i2c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/i2c/ppc4xx_i2c.c b/hw/i2c/ppc4xx_i2c.c
index c0a8e045670..f4c5bc12d36 100644
--- a/hw/i2c/ppc4xx_i2c.c
+++ b/hw/i2c/ppc4xx_i2c.c
@@ -1,6 +1,8 @@
 /*
  * PPC4xx I2C controller emulation
  *
+ * Documentation: PPC405GP User's Manual, Chapter 22. IIC Bus Interface
+ *
  * Copyright (c) 2007 Jocelyn Mayer
  * Copyright (c) 2012 François Revol
  * Copyright (c) 2016-2018 BALATON Zoltan
-- 
2.31.1