powerpc/mpc85xx: Set SYSCLK to the required frequency

For ICS307-02, there is one general expression to generate SYSCLK:
CLK1Frequency = InputFrequency * 2 * (VDW + 8) / ((RDW + 2) * OD)

If we want the required frequency for SYSCLK, we must find one solution
to generate this frequency, this solution includes VDW, RDW and OD.
For OD, there are only eight option value: 10, 2, 8, 4, 5, 7, 3, 6.
For RDW, the range is 1 to 127.
For VDW, the range is 4 to 511.

First, we use one OD, RDW and required SYSCLK to calculate the VDW,
if VDW is in it's range, we will calculate the CLK1Frequency with
the OD, RDW and VDW calculated, and we will check this percent
(CLK1Frequency / required SYSCLK), and the precision is 1/1000.
if the percent is less than 1/1000, we think the CLK1Frequency is we want.
Otherwise, We will continue to calculate it with the next OD and RDW.

Signed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/board/freescale/common/ngpixis.c b/board/freescale/common/ngpixis.c
index 765f0359bf..276ae3c5cf 100644
--- a/board/freescale/common/ngpixis.c
+++ b/board/freescale/common/ngpixis.c
@@ -156,9 +156,29 @@ static void pixis_dump_regs(void)
 }
 #endif
 
+void pixis_sysclk_set(unsigned long sysclk)
+{
+	unsigned long freq_word;
+	u8 sclk0, sclk1, sclk2;
+
+	freq_word = ics307_sysclk_calculator(sysclk);
+	sclk2 = freq_word & 0xff;
+	sclk1 = (freq_word >> 8) & 0xff;
+	sclk0 = (freq_word >> 16) & 0xff;
+
+	/* set SYSCLK enable bit */
+	PIXIS_WRITE(vcfgen0, 0x01);
+
+	/* SYSCLK to required frequency */
+	PIXIS_WRITE(sclk[0], sclk0);
+	PIXIS_WRITE(sclk[1], sclk1);
+	PIXIS_WRITE(sclk[2], sclk2);
+}
+
 int pixis_reset_cmd(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned int i;
+	unsigned long sysclk;
 	char *p_altbank = NULL;
 #ifdef DEBUG
 	char *p_dump = NULL;
@@ -182,6 +202,12 @@ int pixis_reset_cmd(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 			continue;
 		}
 #endif
+		if (strcmp(argv[i], "sysclk") == 0) {
+			sysclk = simple_strtoul(argv[i + 1], NULL, 0);
+			i += 1;
+			pixis_sysclk_set(sysclk);
+			continue;
+		}
 
 		unknown_param = argv[i];
 	}
@@ -219,4 +245,5 @@ U_BOOT_CMD(
 #ifdef DEBUG
 	"pixis_reset dump - display the PIXIS registers\n"
 #endif
+	"pixis_reset sysclk <SYSCLK_freq> - reset with SYSCLK frequency(KHz)\n"
 	);