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/serial.h b/cpu/blackfin/serial.h
index f671096..ce39148 100644
--- a/cpu/blackfin/serial.h
+++ b/cpu/blackfin/serial.h
@@ -156,44 +156,8 @@
}
__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 */
ACCESS_LATCH();
SSYNC();
@@ -208,6 +172,34 @@
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
__attribute__((always_inline))
static inline void serial_early_puts(const char *s)
@@ -235,32 +227,6 @@
#endif
.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
* 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