Hi Stefan,
> -----Original Message-----
> From: Stefan Roese [mailto:s...@denx.de]
> Sent: Tuesday, March 13, 2012 9:24 PM
> To: linux-i2c@vger.kernel.org
> Cc: spear-devel; ben-li...@fluff.org
> Subject: [PATCH] i2c: designware: Add support for 16bit register access
>
> 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 <s...@denx.de>
> ---
> 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);
> + }
We can do away with '{' parenthesis as these are single line
of code inside both the 'if-else' blocks.
> 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)) {
> + dev->access_16bit = 1;
Can we use a suitable macro for 0x0000ffff?
Also, if dev->access_16bit is bool we can simply set:
dev->access_16bit = true;
more on that below...
> + 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;
...
int?? Probably we are better off with making this as bool.
> struct i2c_adapter adapter;
> u32 functionality;
> u32 master_cfg;
> --
Regards,
Bhupesh
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