On Mon, Oct 22, 2012 at 10:24:32AM -0600, Stephen Warren wrote:

On 10/22/2012 02:18 AM, Peter De Schrijver wrote:

quoted

quoted

+
+#define checkuart(rp, rv, lhu, bit, uart) \
+               /* Load address of CLK_RST register */ \
+               movw    rp, #TEGRA_CLK_RST_DEVICES_##lhu & 0xffff ; \
+               movt    rp, #TEGRA_CLK_RST_DEVICES_##lhu >> 16 ; \
+               /* Load value from CLK_RST register */ \
+               ldr     rp, [rp, #0] ; \
+               /* Test UART's reset bit */ \
+               tst     rp, #(1 << bit) ; \
+               /* If set, can't use UART; jump to save no UART */ \
+               bne     90f ; \
+               /* Load address of CLK_OUT_ENB register */ \
+               movw    rp, #TEGRA_CLK_OUT_ENB_##lhu & 0xffff ; \
+               movt    rp, #TEGRA_CLK_OUT_ENB_##lhu >> 16 ; \
+               /* Load value from CLK_OUT_ENB register */ \
+               ldr     rp, [rp, #0] ; \
+               /* Test UART's clock enable bit */ \
+               tst     rp, #(1 << bit) ; \
+               /* If clear, can't use UART; jump to save no UART */ \
+               beq     90f ; \
+               /* Passed all tests, load address of UART registers */ \
+               movw    rp, #TEGRA_UART##uart##_BASE & 0xffff ; \
+               movt    rp, #TEGRA_UART##uart##_BASE >> 16 ; \
+               /* Jump to save UART address */ \
+               b 91f

Maybe make this a subroutine?

The addruart macro (which in turn uses the checkuart macro) is only
allowed to use 3 registers; rp, rv, rtmp. I'm also not 100% sure if the
stack is guaranteed to be set up when addruart is called either. So, I
don't think making this a function is possible.

There's no stack.  Remember, this stuff can be inserted as early as the
front of the kernel assembly code, where there is _nothing_ - the MMU
is off so virtual addresses are meaningless.  etc.