mpc83xx: Replace CONFIG_83XX_CLKIN in calculations

CONFIG_SYS_CLK_FREQ is the standard way to set the system clock
frequency. On MPC83xx, CONFIG_83XX_CLKIN is used for this purpose.
Hence, the obvious way is to replace CONFIG_83XX_CLKIN with
CONFIG_SYS_CLK_FREQ.

A few MPC83xx boards use the CONFIG_83XX_CLKIN variable for computing
CONFIG_SYS_NS16550_CLK. This makes it harder to replace
CONFIG_83XX_CLKIN.

But the value of the multiplicator can be read from the SPMR register.

Hence, replace the static calculations with a call to a new get_bus_freq
function, as other architectures do.
Signed-off-by: NMario Six <mario.six@gdsys.cc>

arch/powerpc/cpu/mpc83xx/spl_minimal.c

@@ -89,3 +89,11 @@ void puts(const char *str)
 	while (*str)
 		putc(*str++);
 }
+
+ulong get_bus_freq(ulong dummy)
+{
+	volatile immap_t *im = (immap_t *) CONFIG_SYS_IMMR;
+	u8 spmf = (im->clk.spmr & SPMR_SPMF) >> SPMR_SPMF_SHIFT;
+
+	return CONFIG_83XX_CLKIN * spmf;
+}

include/configs/MPC8315ERDB.h

@@ -271,7 +271,7 @@
  */
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	1
-#define CONFIG_SYS_NS16550_CLK		(CONFIG_83XX_CLKIN * 2)
+#define CONFIG_SYS_NS16550_CLK		(get_bus_freq(0))
 
 #define CONFIG_SYS_BAUDRATE_TABLE  \
 		{300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200}

include/configs/ids8313.h

@@ -301,7 +301,7 @@
 	{300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 115200}
 #define CONFIG_SYS_NS16550_COM1	(CONFIG_SYS_IMMR + 0x4500)
 #define CONFIG_SYS_NS16550_COM2	(CONFIG_SYS_IMMR + 0x4600)
-#define CONFIG_SYS_NS16550_CLK		(CONFIG_83XX_CLKIN * 2)
+#define CONFIG_SYS_NS16550_CLK		(get_bus_freq(0))
 
 #define CONFIG_HAS_FSL_DR_USB
 #define CONFIG_SYS_SCCR_USBDRCM	3