Blackfin: dynamically update UART speed when initializing
Previously, booting over the UART required the baud rate to be known ahead
of time. Using a bit of tricky simple math, we can calculate the new board
rate based on the old divisors.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
diff --git a/cpu/blackfin/initcode.c b/cpu/blackfin/initcode.c
index 704b791..ae0016d 100644
--- a/cpu/blackfin/initcode.c
+++ b/cpu/blackfin/initcode.c
@@ -20,7 +20,7 @@
#include "serial.h"
__attribute__((always_inline))
-static inline uint32_t serial_init(void)
+static inline void serial_init(void)
{
#ifdef __ADSPBF54x__
# ifdef BFIN_BOOT_UART_USE_RTS
@@ -61,25 +61,16 @@
}
#endif
- uint32_t old_baud;
- if (BFIN_DEBUG_EARLY_SERIAL || CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART)
- old_baud = serial_early_get_baud();
- else
- old_baud = CONFIG_BAUDRATE;
-
if (BFIN_DEBUG_EARLY_SERIAL) {
+ int ucen = *pUART_GCTL & UCEN;
serial_early_init();
/* If the UART is off, that means we need to program
* the baud rate ourselves initially.
*/
- if (!old_baud) {
- old_baud = CONFIG_BAUDRATE;
+ if (ucen != UCEN)
serial_early_set_baud(CONFIG_BAUDRATE);
- }
}
-
- return old_baud;
}
__attribute__((always_inline))
@@ -93,30 +84,6 @@
#endif
}
-/* We need to reset the baud rate when we have early debug turned on
- * or when we are booting over the UART.
- * XXX: we should fix this to calc the old baud and restore it rather
- * than hardcoding it via CONFIG_LDR_LOAD_BAUD ... but we have
- * to figure out how to avoid the division in the baud calc ...
- */
-__attribute__((always_inline))
-static inline void serial_reset_baud(uint32_t baud)
-{
- if (!BFIN_DEBUG_EARLY_SERIAL && CONFIG_BFIN_BOOT_MODE != BFIN_BOOT_UART)
- return;
-
-#ifndef CONFIG_LDR_LOAD_BAUD
-# define CONFIG_LDR_LOAD_BAUD 115200
-#endif
-
- if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_BYPASS)
- serial_early_set_baud(baud);
- else if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART)
- serial_early_set_baud(CONFIG_LDR_LOAD_BAUD);
- else
- serial_early_set_baud(CONFIG_BAUDRATE);
-}
-
__attribute__((always_inline))
static inline void serial_putc(char c)
{
@@ -239,7 +206,14 @@
BOOTROM_CALLED_FUNC_ATTR
void initcode(ADI_BOOT_DATA *bootstruct)
{
- uint32_t old_baud = serial_init();
+ /* Save the clock pieces that are used in baud rate calculation */
+ unsigned int sdivB, divB, vcoB;
+ serial_init();
+ if (BFIN_DEBUG_EARLY_SERIAL || CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART) {
+ sdivB = bfin_read_PLL_DIV() & 0xf;
+ vcoB = (bfin_read_PLL_CTL() >> 9) & 0x3f;
+ divB = serial_early_get_div();
+ }
#ifdef CONFIG_HW_WATCHDOG
# ifndef CONFIG_HW_WATCHDOG_TIMEOUT_INITCODE
@@ -334,8 +308,20 @@
/* Since we've changed the SCLK above, we may need to update
* the UART divisors (UART baud rates are based on SCLK).
+ * Do the division by hand as there are no native instructions
+ * for dividing which means we'd generate a libgcc reference.
*/
- serial_reset_baud(old_baud);
+ if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART) {
+ unsigned int sdivR, vcoR;
+ sdivR = bfin_read_PLL_DIV() & 0xf;
+ vcoR = (bfin_read_PLL_CTL() >> 9) & 0x3f;
+ int dividend = sdivB * divB * vcoR;
+ int divisor = vcoB * sdivR;
+ unsigned int quotient;
+ for (quotient = 0; dividend > 0; ++quotient)
+ dividend -= divisor;
+ serial_early_put_div(quotient - ANOMALY_05000230);
+ }
serial_putc('F');