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authorYuri Tikhonov <yur@emcraft.com>2007-08-10 08:25:22 +0200
committerStefan Roese <sr@denx.de>2007-08-10 08:25:22 +0200
commit29cb25da56afe18cf5e7072a92a9d98ea8af1fd4 (patch)
tree2d7027e23b03068f08e7aaf6b965d3aa111bb619 /post/cpu/ppc4xx
parent537223afa61f64480df31ce440a9cb386df4a814 (diff)
downloadtalos-obmc-uboot-29cb25da56afe18cf5e7072a92a9d98ea8af1fd4.tar.gz
talos-obmc-uboot-29cb25da56afe18cf5e7072a92a9d98ea8af1fd4.zip
POST: Add ppc4xx UART POST support without external uart clock (lwmon5)
The patch adds support for UART POST on ppc44x-based boards with no external serial clocks installed. Signed-off-by: Yuri Tikhonov <yur@emcraft.com> Acked-by: Stefan Roese <sr@denx.de>
Diffstat (limited to 'post/cpu/ppc4xx')
-rw-r--r--post/cpu/ppc4xx/uart.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/post/cpu/ppc4xx/uart.c b/post/cpu/ppc4xx/uart.c
index b047d42dfd..0aeed75ae6 100644
--- a/post/cpu/ppc4xx/uart.c
+++ b/post/cpu/ppc4xx/uart.c
@@ -84,6 +84,49 @@
DECLARE_GLOBAL_DATA_PTR;
+#if !defined(CFG_EXT_SERIAL_CLOCK)
+static void serial_divs (int baudrate, unsigned long *pudiv,
+ unsigned short *pbdiv)
+{
+ sys_info_t sysinfo;
+ unsigned long div; /* total divisor udiv * bdiv */
+ unsigned long umin; /* minimum udiv */
+ unsigned short diff; /* smallest diff */
+ unsigned long udiv; /* best udiv */
+ unsigned short idiff; /* current diff */
+ unsigned short ibdiv; /* current bdiv */
+ unsigned long i;
+ unsigned long est; /* current estimate */
+
+ get_sys_info(&sysinfo);
+
+ udiv = 32; /* Assume lowest possible serial clk */
+ div = sysinfo.freqPLB / (16 * baudrate); /* total divisor */
+ umin = sysinfo.pllOpbDiv << 1; /* 2 x OPB divisor */
+ diff = 32; /* highest possible */
+
+ /* i is the test udiv value -- start with the largest
+ * possible (32) to minimize serial clock and constrain
+ * search to umin.
+ */
+ for (i = 32; i > umin; i--) {
+ ibdiv = div / i;
+ est = i * ibdiv;
+ idiff = (est > div) ? (est-div) : (div-est);
+ if (idiff == 0) {
+ udiv = i;
+ break; /* can't do better */
+ } else if (idiff < diff) {
+ udiv = i; /* best so far */
+ diff = idiff; /* update lowest diff*/
+ }
+ }
+
+ *pudiv = udiv;
+ *pbdiv = div / udiv;
+}
+#endif
+
static int uart_post_init (unsigned long dev_base)
{
unsigned long reg;
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