[PATCH 3/4 v4] OMAP: McBSP: Introduce caching in register write operations

Janusz Krzysztofik
2009-12-03T12:30:43Z

Reserve space inside omap_mcbsp structure for storing cached copies of McBSP
register values.
Modify the MCBSP_WRITE() macro to update the cache with every register write
operation.
Introduce a new macro that reads from the cache instead of hardware.

Applies on top of patch 2 from this series:
[PATCH v3 2/4] OMAP: McBSP: Prepare register read/write macros API for caching

Tested on OMAP1510 based Amstrad Delta using linux-omap for-next,
commit 4421752e331cfb1d942b47ffdb26e451a8da58a0.
Compile-tested with omap_3430sdp_defconfig.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>

---
Thursday 03 December 2009 08:49:21 Jarkko Nikula wrote:
> On Tue, 1 Dec 2009 04:15:50 +0100
> Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> wrote:
> > #define MCBSP_WRITE(mcbsp, reg, val) \
> > - omap_mcbsp_write(mcbsp->io_base, OMAP_MCBSP_REG_##reg, val)
> > + omap_mcbsp_write(mcbsp->io_base, OMAP_MCBSP_REG_##reg, \
> > + mcbsp->reg_cache[OMAP_MCBSP_REG_##reg / OMAP_MCBSP_REG_DRR1] \
> > + = val)
> > +#define MCBSP_READ_CACHE(mcbsp, reg) \
> > + (mcbsp->reg_cache[OMAP_MCBSP_REG_##reg / OMAP_MCBSP_REG_DRR1])
>
> These divisions by DDR1 are confusing. Use rather sizeof:
>
> reg_cache[OMAP_MCBSP_REG_##reg / sizeof(*mcbsp->reg_cache)]

Done.

Jarkko, many thanks for your cooperation :).

Janusz

arch/arm/plat-omap/include/plat/mcbsp.h | 5 +++++
arch/arm/plat-omap/mcbsp.c | 7 ++++++-
2 files changed, 11 insertions(+), 1 deletion(-)

--- git/arch/arm/plat-omap/include/plat/mcbsp.h.orig 2009-11-27 11:53:45.000000000 +0100
+++ git/arch/arm/plat-omap/include/plat/mcbsp.h 2009-12-01 03:37:21.000000000 +0100
@@ -415,6 +415,11 @@ struct omap_mcbsp {
u16 max_tx_thres;
u16 max_rx_thres;
#endif
+#ifdef CONFIG_ARCH_OMAP1
+ u16 reg_cache[OMAP_MCBSP_REG_XCERH / sizeof(u16) + 1];
+#else
+ u32 reg_cache[OMAP_MCBSP_REG_RCCR / sizeof(u32) + 1];
+#endif
};
extern struct omap_mcbsp **mcbsp_ptr;
extern int omap_mcbsp_count;
--- git/arch/arm/plat-omap/mcbsp.c.orig 2009-12-01 03:19:56.000000000 +0100
+++ git/arch/arm/plat-omap/mcbsp.c 2009-12-03 11:37:21.000000000 +0100
@@ -49,7 +49,12 @@ int omap_mcbsp_read(void __iomem *io_bas
#define MCBSP_READ(mcbsp, reg) \
omap_mcbsp_read(mcbsp->io_base, OMAP_MCBSP_REG_##reg)
#define MCBSP_WRITE(mcbsp, reg, val) \
- omap_mcbsp_write(mcbsp->io_base, OMAP_MCBSP_REG_##reg, val)
+ omap_mcbsp_write(mcbsp->io_base, OMAP_MCBSP_REG_##reg, \
+ mcbsp->reg_cache[OMAP_MCBSP_REG_##reg / \
+ sizeof(*mcbsp->reg_cache)] = val)
+#define MCBSP_READ_CACHE(mcbsp, reg) \
+ (mcbsp->reg_cache[OMAP_MCBSP_REG_##reg / \
+ sizeof(*mcbsp->reg_cache)])

#define omap_mcbsp_check_valid_id(id) (id < omap_mcbsp_count)
#define id_to_mcbsp_ptr(id) mcbsp_ptr[id];