[U-Boot] [patch] i.MX use u-boot baud rate and don't assume UART master clock
Andrew Dyer
adyer at righthandtech.com
Tue Aug 26 23:43:06 CEST 2008
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 at righthandtech.com>
---
cpu/arm920t/imx/serial.c | 34 ++++++++++++++++++++++++++++++----
1 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/cpu/arm920t/imx/serial.c b/cpu/arm920t/imx/serial.c
index 6c56acb..ea5f42c 100644
--- a/cpu/arm920t/imx/serial.c
+++ b/cpu/arm920t/imx/serial.c
@@ -52,6 +52,8 @@ struct imx_serial {
volatile uint32_t uts;
};
+DECLARE_GLOBAL_DATA_PTR;
+
void serial_setbrg (void)
{
serial_init();
@@ -67,6 +69,9 @@ extern void imx_gpio_mode(int gpio_mode);
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 @@ int serial_init (void)
/* 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;
@@ -123,8 +150,7 @@ int serial_init (void)
USR2_WAKE |
USR2_RTSF |
USR2_BRCD |
- USR2_ORE |
- USR2_RDR;
+ USR2_ORE;
/* Clear status flags */
base->usr1 |= USR1_PARITYERR |
--
1.5.4.3
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