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i.MX use u-boot baud rate and don't assume UART master clock

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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>
This commit is contained in:
Andrew Dyer 2008-09-12 02:20:46 +02:00 committed by Jean-Christophe PLAGNIOL-VILLARD
parent 6e1551a870
commit 48fed40575
1 changed files with 41 additions and 15 deletions
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56
cpu/arm920t/imx/serial.c
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@ -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;
@ -117,22 +144,21 @@ int serial_init (void)
/* 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);
}