Because FIQ handlers get copied straight into the vectors page to
the FIQ vector entry point, FIQ handlers in a Thumb-2 kernel must
start in Thumb-2. A Thumb-2 kernel enters all exception vectors in
Thumb-2.
This patch adapts the mxc SSI FIQ code suitable for a Thumb-2
kernel.
The code contained use of r13 (sp) which isn't allowed in Thumb-2.
r11 and r13 have been swapped throughout the file to work around
this.
Currently, the way that the function to be copied is located using
labels is a bit ugly: we cannot annotate the FIQ handler properly
as a Thumb-2 function, because this would set bit 0 of the label
address seen by the linker, causing off-by-one errors when copying
the function. Ideally, the copy would be done with fncpy(), but
this would require changes to the common set_fiq_handler()
function. For now, we don't touch this.
References to locally-defined global symbols with adr and ldr may
not be accepted by the assembler in Thumb-2. Local shadow symbols
are added to work around this.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Directives such as .long and .word do not magically cause the
assembler location counter to become aligned in gas. As a
result, using these directives in code sections can result in
misaligned data words when building a Thumb-2 kernel
(CONFIG_THUMB2_KERNEL).
This is a Bad Thing, since the ABI permits the compiler to
assume that fundamental types of word size or above are word-
aligned when accessing them from C. If the data is not really
word-aligned, this can cause impaired performance and stray
alignment faults in some circumstances.
In general, the following rules should be applied when using
data word declaration directives inside code sections:
* .quad and .double:
.align 3
* .long, .word, .single, .float:
.align (or .align 2)
* .short:
No explicit alignment required, since Thumb-2
instructions are always 2 or 4 bytes in size.
immediately after an instruction.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
LAKML-Reference: 1289913217-8672-1-git-send-email-dave.martin@linaro.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
The old driver has the number of SSI units in the system hardcoded,
does not make use of the device model and works only on i.MX21/27.
This driver replaces it. It works in DMA mode on i.MX21/27 and using
an FIQ handler on other systems. It also supports AC97 mode of
the SSI units.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Javier Martin <javier.martin@vista-silicon.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
