[PATCH 3/4 v5a] OMAP: McBSP: Introduce caching in register write operations

Janusz Krzysztofik
2009-12-05T13:46:53Z

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>

---

Tony,

Since I was not sure what your primary concern was, I've prepared two
alternative versions of patch 3/4.
Please take this one as a base for further discussion if your primary concern
was potentially dangerous #else clause. I've replaced it with #elif, that
should be more future proof.
Otherwise, have a look the other one (v5b).

Thanks,
Janusz

--- 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 2009-12-05 03:37:21.000000000 +0100
@@ -415,6 +415,13 @@ struct omap_mcbsp {
u16 max_tx_thres;
u16 max_rx_thres;
#endif
+#if defined(CONFIG_ARCH_OMAP15XX) || defined(CONFIG_ARCH_OMAP16XX) || \
+ defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP850)
+ u16 reg_cache[OMAP_MCBSP_REG_XCERH / sizeof(u16) + 1];
+#elif defined(CONFIG_ARCH_OMAP24XX) || defined(CONFIG_ARCH_OMAP34XX) || \
+ defined(CONFIG_ARCH_OMAP4)
+ 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 2009-12-01 03:37:21.000000000 +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];