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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>
This commit is contained in:
Mike Frysinger 2008-12-10 12:33:54 -05:00
parent 97f265f14f
commit f790ef6ff1
2 changed files with 53 additions and 101 deletions
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62
cpu/blackfin/initcode.c
View File

@ -20,7 +20,7 @@
#include "serial.h" #include "serial.h"
__attribute__((always_inline)) __attribute__((always_inline))
static inline uint32_t serial_init(void) static inline void serial_init(void)
{ {
#ifdef __ADSPBF54x__ #ifdef __ADSPBF54x__
# ifdef BFIN_BOOT_UART_USE_RTS # ifdef BFIN_BOOT_UART_USE_RTS
@ -61,25 +61,16 @@ static inline uint32_t serial_init(void)
} }
#endif #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) { if (BFIN_DEBUG_EARLY_SERIAL) {
int ucen = *pUART_GCTL & UCEN;
serial_early_init(); serial_early_init();
/* If the UART is off, that means we need to program /* If the UART is off, that means we need to program
* the baud rate ourselves initially. * the baud rate ourselves initially.
*/ */
if (!old_baud) { if (ucen != UCEN)
old_baud = CONFIG_BAUDRATE;
serial_early_set_baud(CONFIG_BAUDRATE); serial_early_set_baud(CONFIG_BAUDRATE);
}
} }
return old_baud;
} }
__attribute__((always_inline)) __attribute__((always_inline))
@ -93,30 +84,6 @@ static inline void serial_deinit(void)
#endif #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)) __attribute__((always_inline))
static inline void serial_putc(char c) static inline void serial_putc(char c)
{ {
@ -239,7 +206,14 @@ static inline void serial_putc(char c)
BOOTROM_CALLED_FUNC_ATTR BOOTROM_CALLED_FUNC_ATTR
void initcode(ADI_BOOT_DATA *bootstruct) 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 #ifdef CONFIG_HW_WATCHDOG
# ifndef CONFIG_HW_WATCHDOG_TIMEOUT_INITCODE # ifndef CONFIG_HW_WATCHDOG_TIMEOUT_INITCODE
@ -334,8 +308,20 @@ void initcode(ADI_BOOT_DATA *bootstruct)
/* Since we've changed the SCLK above, we may need to update /* Since we've changed the SCLK above, we may need to update
* the UART divisors (UART baud rates are based on SCLK). * 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'); serial_putc('F');

92
cpu/blackfin/serial.h
View File

@ -156,44 +156,8 @@ static inline void serial_early_init(void)
} }
__attribute__((always_inline)) __attribute__((always_inline))
static inline uint32_t serial_early_get_baud(void) static inline void serial_early_put_div(uint16_t divisor)
{ {
/* If the UART isnt enabled, then we are booting an LDR
* from a non-UART source (so like flash) which means
* the baud rate here is meaningless.
*/
if ((*pUART_GCTL & UCEN) != UCEN)
return 0;
#if (0) /* See comment for serial_reset_baud() in initcode.c */
/* Set DLAB in LCR to Access DLL and DLH */
ACCESS_LATCH();
SSYNC();
uint8_t dll = *pUART_DLL;
uint8_t dlh = *pUART_DLH;
uint16_t divisor = (dlh << 8) | dll;
uint32_t baud = get_sclk() / (divisor * 16);
/* Clear DLAB in LCR to Access THR RBR IER */
ACCESS_PORT_IER();
SSYNC();
return baud;
#else
return CONFIG_BAUDRATE;
#endif
}
__attribute__((always_inline))
static inline void serial_early_set_baud(uint32_t baud)
{
/* Translate from baud into divisor in terms of SCLK. The
* weird multiplication is to make sure we over sample just
* a little rather than under sample the incoming signals.
*/
uint16_t divisor = (get_sclk() + (baud * 8)) / (baud * 16) - ANOMALY_05000230;
/* Set DLAB in LCR to Access DLL and DLH */ /* Set DLAB in LCR to Access DLL and DLH */
ACCESS_LATCH(); ACCESS_LATCH();
SSYNC(); SSYNC();
@ -208,6 +172,34 @@ static inline void serial_early_set_baud(uint32_t baud)
SSYNC(); SSYNC();
} }
__attribute__((always_inline))
static inline uint16_t serial_early_get_div(void)
{
/* Set DLAB in LCR to Access DLL and DLH */
ACCESS_LATCH();
SSYNC();
uint8_t dll = *pUART_DLL;
uint8_t dlh = *pUART_DLH;
uint16_t divisor = (dlh << 8) | dll;
/* Clear DLAB in LCR to Access THR RBR IER */
ACCESS_PORT_IER();
SSYNC();
return divisor;
}
__attribute__((always_inline))
static inline void serial_early_set_baud(uint32_t baud)
{
/* Translate from baud into divisor in terms of SCLK. The
* weird multiplication is to make sure we over sample just
* a little rather than under sample the incoming signals.
*/
serial_early_put_div((get_sclk() + (baud * 8)) / (baud * 16) - ANOMALY_05000230);
}
#ifndef BFIN_IN_INITCODE #ifndef BFIN_IN_INITCODE
__attribute__((always_inline)) __attribute__((always_inline))
static inline void serial_early_puts(const char *s) static inline void serial_early_puts(const char *s)
@ -235,32 +227,6 @@ static inline void serial_early_puts(const char *s)
#endif #endif
.endm .endm
/* Recursively expand calls to _serial_putc for every byte
* passed to us. Append a newline when we're all done.
*/
.macro _serial_early_putc byte:req morebytes:vararg
#ifdef CONFIG_DEBUG_EARLY_SERIAL
R0 = \byte;
call _serial_putc;
.ifnb \morebytes
_serial_early_putc \morebytes
.else
.if (\byte != '\n')
_serial_early_putc '\n'
.endif
.endif
#endif
.endm
/* Wrapper around recurisve _serial_early_putc macro which
* simply prepends the string "Early: "
*/
.macro serial_early_putc byte:req morebytes:vararg
#ifdef CONFIG_DEBUG_EARLY_SERIAL
_serial_early_putc 'E', 'a', 'r', 'l', 'y', ':', ' ', \byte, \morebytes
#endif
.endm
/* Since we embed the string right into our .text section, we need /* Since we embed the string right into our .text section, we need
* to find its address. We do this by getting our PC and adding 2 * to find its address. We do this by getting our PC and adding 2
* bytes (which is the length of the jump instruction). Then we * bytes (which is the length of the jump instruction). Then we