Hi,
my points to this discussion:
On 13/03/12 16:54, Stefan Roese wrote:
The STM SPEAr platform can only access the i2c controller register
via 16bit read/write functions. This patch adds support to
automatically detect this 16bit access mode.
Signed-off-by: Stefan Roese<sr@xxxxxxx>
---
drivers/i2c/busses/i2c-designware-core.c | 22 ++++++++++++++++++++--
drivers/i2c/busses/i2c-designware-core.h | 1 +
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index df87992..d1facbc 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -164,7 +164,14 @@ static char *abort_sources[] = {
u32 dw_readl(struct dw_i2c_dev *dev, int offset)
{
- u32 value = readl(dev->base + offset);
+ u32 value;
+
+ if (dev->access_16bit) {
+ value = readw(dev->base + offset) |
+ (readw(dev->base + offset + 2)<< 16);
+ } else {
+ value = readl(dev->base + offset);
+ }
Since both blocks just have one statement, please remove the braces.
if (dev->swab)
return swab32(value);
@@ -177,7 +184,12 @@ void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
if (dev->swab)
b = swab32(b);
- writel(b, dev->base + offset);
+ if (dev->access_16bit) {
+ writew((u16)b, dev->base + offset);
+ writew((u16)(b>> 16), dev->base + offset + 2);
+ } else {
+ writel(b, dev->base + offset);
+ }
}
static u32
@@ -258,6 +270,12 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
reg = DW_IC_COMP_TYPE_VALUE;
}
+ /* Configure register access mode 16bit */
+ if (reg == (DW_IC_COMP_TYPE_VALUE& 0x0000ffff)) {
No need for a macro IMO. You are missing a space before &, though.
+ dev->access_16bit = 1;
+ reg = DW_IC_COMP_TYPE_VALUE;
+ }
+
if (reg != DW_IC_COMP_TYPE_VALUE) {
dev_err(dev->dev, "Unknown Synopsys component type: "
"0x%08x\n", reg);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 02d1a2d..f5af101 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -83,6 +83,7 @@ struct dw_i2c_dev {
u32 abort_source;
int irq;
int swab;
+ int access_16bit;
This struct is already quite large. My favourite would be convert swab
and access_16bit to 'unsigend accessor_flags' and proper flags. A
bitfield at the end of the struct should also do.
struct i2c_adapter adapter;
u32 functionality;
u32 master_cfg;
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