i.MX use u-boot baud rate and don't assume UART master clock
1) Change the i.MX serial driver to use the baud rate set in the
u-boot environment
2) don't assume a 16MHz value for PERCLK1 in baud rate calculations
3) don't write a 1 to the RDR bit in the USR2 reg. (bit is not "write
one to clear" like other status bits in the reg.)
Signed-off-by: Andrew Dyer <adyer@righthandtech.com>
diff --git a/cpu/arm920t/imx/serial.c b/cpu/arm920t/imx/serial.c
index 6c56acb..85f1167 100644
--- a/cpu/arm920t/imx/serial.c
+++ b/cpu/arm920t/imx/serial.c
@@ -52,6 +52,8 @@
volatile uint32_t uts;
};
+DECLARE_GLOBAL_DATA_PTR;
+
void serial_setbrg (void)
{
serial_init();
@@ -67,6 +69,9 @@
int serial_init (void)
{
volatile struct imx_serial* base = (struct imx_serial *)UART_BASE;
+ unsigned int ufcr_rfdiv;
+ unsigned int refclk;
+
#ifdef CONFIG_IMX_SERIAL1
imx_gpio_mode(PC11_PF_UART1_TXD);
imx_gpio_mode(PC12_PF_UART1_RXD);
@@ -95,11 +100,33 @@
/* Configure FIFOs */
base->ufcr = 0xa81;
+ /* set the baud rate.
+ *
+ * baud * 16 x
+ * --------- = -
+ * refclk y
+ *
+ * x - 1 = UBIR
+ * y - 1 = UBMR
+ *
+ * each register is 16 bits wide. refclk max is 96 MHz
+ *
+ */
+
+ ufcr_rfdiv = ((base->ufcr) & UFCR_RFDIV) >> 7;
+ if (ufcr_rfdiv == 6)
+ ufcr_rfdiv = 7;
+ else
+ ufcr_rfdiv = 6 - ufcr_rfdiv;
+
+ refclk = get_PERCLK1();
+ refclk /= ufcr_rfdiv;
+
/* Set the numerator value minus one of the BRM ratio */
- base->ubir = (CONFIG_BAUDRATE / 100) - 1;
+ base->ubir = (gd->baudrate / 100) - 1;
/* Set the denominator value minus one of the BRM ratio */
- base->ubmr = 10000 - 1;
+ base->ubmr = (refclk/(16 * 100)) - 1;
/* Set to 8N1 */
base->ucr2 &= ~UCR2_PREN;
@@ -117,22 +144,21 @@
/* Clear status flags */
base->usr2 |= USR2_ADET |
- USR2_DTRF |
- USR2_IDLE |
- USR2_IRINT |
- USR2_WAKE |
- USR2_RTSF |
- USR2_BRCD |
- USR2_ORE |
- USR2_RDR;
+ USR2_DTRF |
+ USR2_IDLE |
+ USR2_IRINT |
+ USR2_WAKE |
+ USR2_RTSF |
+ USR2_BRCD |
+ USR2_ORE;
/* Clear status flags */
base->usr1 |= USR1_PARITYERR |
- USR1_RTSD |
- USR1_ESCF |
- USR1_FRAMERR |
- USR1_AIRINT |
- USR1_AWAKE;
+ USR1_RTSD |
+ USR1_ESCF |
+ USR1_FRAMERR |
+ USR1_AIRINT |
+ USR1_AWAKE;
return (0);
}