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Force UARTBAUD on before uncompressing.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Index: linux-2.6.22/include/asm-arm/arch-ep93xx/uncompress.h
===================================================================
--- linux-2.6.22.orig/include/asm-arm/arch-ep93xx/uncompress.h
+++ linux-2.6.22/include/asm-arm/arch-ep93xx/uncompress.h
@@ -77,9 +77,56 @@ static void ethernet_reset(void)
}
+/*
+ * Some bootloaders don't turn on the UARTBAUD bit, which means that
+ * the UARTs will be running off a divided 7.3728 MHz clock instead of
+ * the 14.7456 MHz peripheral clock when linux boots.
+ *
+ * We detect that condition here and fix it by turning on UARTBAUD, and
+ * then reprogramming the divisors on all enabled UARTs to twice what
+ * they were before we turned UARTBAUD on, to preserve the programmed
+ * baud rate.
+ */
+#define PHYS_SYSCON_CLOCK_CONTROL 0x80930004
+#define SYSCON_CLOCK_UARTBAUD 0x20000000
+#define PHYS_UART1_BASE 0x808c0000
+#define PHYS_UART2_BASE 0x808d0000
+#define PHYS_UART3_BASE 0x808e0000
+
+static void uart_divisor_times_two(unsigned int base)
+{
+ u16 divisor;
+
+ divisor = __raw_readb(base + 0x0c) << 8;
+ divisor |= __raw_readb(base + 0x10);
+ if (divisor) {
+ divisor = (2 * (divisor + 1)) - 1;
+ __raw_writeb(divisor >> 8, base + 0x0c);
+ __raw_writeb(divisor & 0xff, base + 0x10);
+ __raw_writeb(__raw_readb(base + 0x08), base + 0x08);
+ }
+}
+
+static void fix_uart_base(void)
+{
+ unsigned int v;
+
+ v = __raw_readl(PHYS_SYSCON_CLOCK_CONTROL);
+ if ((v & SYSCON_CLOCK_UARTBAUD) == 0) {
+ v |= SYSCON_CLOCK_UARTBAUD;
+ __raw_writel(v, PHYS_SYSCON_CLOCK_CONTROL);
+
+ uart_divisor_times_two(PHYS_UART1_BASE);
+ uart_divisor_times_two(PHYS_UART2_BASE);
+ uart_divisor_times_two(PHYS_UART3_BASE);
+ }
+}
+
+
static void arch_decomp_setup(void)
{
ethernet_reset();
+ fix_uart_base();
}
#define arch_decomp_wdog()
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