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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
parent
97f265f14f
commit
f790ef6ff1
@ -20,7 +20,7 @@
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#include "serial.h"
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__attribute__((always_inline))
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static inline uint32_t serial_init(void)
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static inline void serial_init(void)
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{
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#ifdef __ADSPBF54x__
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# ifdef BFIN_BOOT_UART_USE_RTS
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@ -61,25 +61,16 @@ static inline uint32_t serial_init(void)
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}
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#endif
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uint32_t old_baud;
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if (BFIN_DEBUG_EARLY_SERIAL || CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART)
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old_baud = serial_early_get_baud();
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else
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old_baud = CONFIG_BAUDRATE;
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if (BFIN_DEBUG_EARLY_SERIAL) {
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int ucen = *pUART_GCTL & UCEN;
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serial_early_init();
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/* If the UART is off, that means we need to program
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* the baud rate ourselves initially.
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*/
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if (!old_baud) {
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old_baud = CONFIG_BAUDRATE;
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if (ucen != UCEN)
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serial_early_set_baud(CONFIG_BAUDRATE);
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}
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}
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return old_baud;
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}
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__attribute__((always_inline))
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@ -93,30 +84,6 @@ static inline void serial_deinit(void)
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#endif
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}
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/* We need to reset the baud rate when we have early debug turned on
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* or when we are booting over the UART.
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* XXX: we should fix this to calc the old baud and restore it rather
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* than hardcoding it via CONFIG_LDR_LOAD_BAUD ... but we have
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* to figure out how to avoid the division in the baud calc ...
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*/
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__attribute__((always_inline))
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static inline void serial_reset_baud(uint32_t baud)
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{
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if (!BFIN_DEBUG_EARLY_SERIAL && CONFIG_BFIN_BOOT_MODE != BFIN_BOOT_UART)
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return;
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#ifndef CONFIG_LDR_LOAD_BAUD
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# define CONFIG_LDR_LOAD_BAUD 115200
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#endif
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if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_BYPASS)
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serial_early_set_baud(baud);
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else if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART)
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serial_early_set_baud(CONFIG_LDR_LOAD_BAUD);
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else
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serial_early_set_baud(CONFIG_BAUDRATE);
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}
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__attribute__((always_inline))
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static inline void serial_putc(char c)
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{
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@ -239,7 +206,14 @@ static inline void serial_putc(char c)
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BOOTROM_CALLED_FUNC_ATTR
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void initcode(ADI_BOOT_DATA *bootstruct)
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{
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uint32_t old_baud = serial_init();
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/* Save the clock pieces that are used in baud rate calculation */
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unsigned int sdivB, divB, vcoB;
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serial_init();
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if (BFIN_DEBUG_EARLY_SERIAL || CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART) {
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sdivB = bfin_read_PLL_DIV() & 0xf;
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vcoB = (bfin_read_PLL_CTL() >> 9) & 0x3f;
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divB = serial_early_get_div();
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}
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#ifdef CONFIG_HW_WATCHDOG
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# ifndef CONFIG_HW_WATCHDOG_TIMEOUT_INITCODE
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@ -334,8 +308,20 @@ void initcode(ADI_BOOT_DATA *bootstruct)
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/* Since we've changed the SCLK above, we may need to update
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* the UART divisors (UART baud rates are based on SCLK).
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* Do the division by hand as there are no native instructions
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* for dividing which means we'd generate a libgcc reference.
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*/
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serial_reset_baud(old_baud);
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if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_UART) {
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unsigned int sdivR, vcoR;
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sdivR = bfin_read_PLL_DIV() & 0xf;
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vcoR = (bfin_read_PLL_CTL() >> 9) & 0x3f;
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int dividend = sdivB * divB * vcoR;
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int divisor = vcoB * sdivR;
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unsigned int quotient;
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for (quotient = 0; dividend > 0; ++quotient)
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dividend -= divisor;
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serial_early_put_div(quotient - ANOMALY_05000230);
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}
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serial_putc('F');
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@ -156,44 +156,8 @@ static inline void serial_early_init(void)
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}
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__attribute__((always_inline))
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static inline uint32_t serial_early_get_baud(void)
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static inline void serial_early_put_div(uint16_t divisor)
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{
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/* If the UART isnt enabled, then we are booting an LDR
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* from a non-UART source (so like flash) which means
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* the baud rate here is meaningless.
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*/
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if ((*pUART_GCTL & UCEN) != UCEN)
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return 0;
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#if (0) /* See comment for serial_reset_baud() in initcode.c */
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/* Set DLAB in LCR to Access DLL and DLH */
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ACCESS_LATCH();
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SSYNC();
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uint8_t dll = *pUART_DLL;
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uint8_t dlh = *pUART_DLH;
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uint16_t divisor = (dlh << 8) | dll;
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uint32_t baud = get_sclk() / (divisor * 16);
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/* Clear DLAB in LCR to Access THR RBR IER */
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ACCESS_PORT_IER();
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SSYNC();
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return baud;
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#else
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return CONFIG_BAUDRATE;
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#endif
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}
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__attribute__((always_inline))
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static inline void serial_early_set_baud(uint32_t baud)
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{
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/* Translate from baud into divisor in terms of SCLK. The
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* weird multiplication is to make sure we over sample just
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* a little rather than under sample the incoming signals.
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*/
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uint16_t divisor = (get_sclk() + (baud * 8)) / (baud * 16) - ANOMALY_05000230;
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/* Set DLAB in LCR to Access DLL and DLH */
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ACCESS_LATCH();
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SSYNC();
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@ -208,6 +172,34 @@ static inline void serial_early_set_baud(uint32_t baud)
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SSYNC();
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}
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__attribute__((always_inline))
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static inline uint16_t serial_early_get_div(void)
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{
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/* Set DLAB in LCR to Access DLL and DLH */
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ACCESS_LATCH();
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SSYNC();
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uint8_t dll = *pUART_DLL;
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uint8_t dlh = *pUART_DLH;
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uint16_t divisor = (dlh << 8) | dll;
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/* Clear DLAB in LCR to Access THR RBR IER */
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ACCESS_PORT_IER();
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SSYNC();
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return divisor;
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}
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__attribute__((always_inline))
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static inline void serial_early_set_baud(uint32_t baud)
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{
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/* Translate from baud into divisor in terms of SCLK. The
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* weird multiplication is to make sure we over sample just
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* a little rather than under sample the incoming signals.
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*/
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serial_early_put_div((get_sclk() + (baud * 8)) / (baud * 16) - ANOMALY_05000230);
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}
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#ifndef BFIN_IN_INITCODE
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__attribute__((always_inline))
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static inline void serial_early_puts(const char *s)
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@ -235,32 +227,6 @@ static inline void serial_early_puts(const char *s)
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#endif
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.endm
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/* Recursively expand calls to _serial_putc for every byte
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* passed to us. Append a newline when we're all done.
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*/
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.macro _serial_early_putc byte:req morebytes:vararg
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#ifdef CONFIG_DEBUG_EARLY_SERIAL
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R0 = \byte;
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call _serial_putc;
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.ifnb \morebytes
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_serial_early_putc \morebytes
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.else
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.if (\byte != '\n')
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_serial_early_putc '\n'
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.endif
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.endif
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#endif
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.endm
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/* Wrapper around recurisve _serial_early_putc macro which
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* simply prepends the string "Early: "
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*/
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.macro serial_early_putc byte:req morebytes:vararg
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#ifdef CONFIG_DEBUG_EARLY_SERIAL
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_serial_early_putc 'E', 'a', 'r', 'l', 'y', ':', ' ', \byte, \morebytes
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#endif
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.endm
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/* Since we embed the string right into our .text section, we need
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* to find its address. We do this by getting our PC and adding 2
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* bytes (which is the length of the jump instruction). Then we
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