hi Shubhrajyoti,

2012/2/17 Shubhrajyoti Datta [off-list ref]:

Hello,

On Wed, Feb 8, 2012 at 8:58 PM, Barry Song [off-list ref] wrote:

quoted

From: Zhiwu Song <redacted>

SiRFprimaII is the latest generation application processor from CSR?s
multi-function SoC product family.
The SoC support codes are in arch/arm/mach-prima2 from Linux mainline
3.0.
There are two I2C controllers on primaII, features include:
* Two I2C controller modules are on chip
* RISC I/O bus read write register
* Up to 16 bytes data buffer for issuing commands and writing data
?at the same time
* Up to 16 commands, and receiving read data 16 bytes at a time
* Error INT report (ACK check)
* No-ACK bus protocols (SCCB bus protocols)

Signed-off-by: Zhiwu Song <redacted>
Signed-off-by: Xiangzhen Ye <redacted>
Signed-off-by: Yuping Luo <redacted>
Signed-off-by: Barry Song <redacted>
---
?-v6:
?fix/cleanup lots of minor issues pointed out by wolfram;
?add OF property clock-frequency to support freq setting by DT;
?add lost devicetree binding document;

?Documentation/devicetree/bindings/i2c/sirf-i2c.txt | ? 19 +
?drivers/i2c/busses/Kconfig ? ? ? ? ? ? ? ? ? ? ? ? | ? 10 +
?drivers/i2c/busses/Makefile ? ? ? ? ? ? ? ? ? ? ? ?| ? ?1 +
?drivers/i2c/busses/i2c-sirf.c ? ? ? ? ? ? ? ? ? ? ?| ?459 ++++++++++++++++++++
?4 files changed, 489 insertions(+), 0 deletions(-)
?create mode 100644 Documentation/devicetree/bindings/i2c/sirf-i2c.txt
?create mode 100644 drivers/i2c/busses/i2c-sirf.c

diff --git a/Documentation/devicetree/bindings/i2c/sirf-i2c.txt b/Documentation/devicetree/bindings/i2c/sirf-i2c.txt
new file mode 100644
index 0000000..7baf9e1
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/sirf-i2c.txt

<snip>

quoted

+
+ ? ? ? ? ? ? ? if (i2c_stat & SIRFSOC_I2C_STAT_NACK)
+ ? ? ? ? ? ? ? ? ? ? ? dev_err(&siic->adapter.dev, "ACK not received\n");

Could we send stop here?

no. when the interrupt happens and goes into the irq, the whole i2c hw
sequence has finished.

quoted

+ ? ? ? ? ? ? ? else
+ ? ? ? ? ? ? ? ? ? ? ? dev_err(&siic->adapter.dev, "I2C error\n");
+
+ ? ? ? ? ? ? ? complete(&siic->done);

<Snip>

quoted

+static int i2c_sirfsoc_resume(struct device *dev)
+{
+ ? ? ? struct platform_device *pdev = to_platform_device(dev);
+ ? ? ? struct i2c_adapter *adapter = platform_get_drvdata(pdev);
+ ? ? ? struct sirfsoc_i2c *siic = adapter->algo_data;
+
+ ? ? ? clk_enable(siic->clk);
+ ? ? ? writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);

Could you explain why is a reset needed.
Or am I missing something.

this is helping the i2c controller restore to a stable status. this
reset is not always needed, but it is sure that it can help to fix
some unstable issues of hardware if they do exist.

quoted

+ ? ? ? writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
+ ? ? ? ? ? ? ? siic->base + SIRFSOC_I2C_CTRL);
+ ? ? ? writel(siic->clk_div, siic->base + SIRFSOC_I2C_CLK_CTRL);
+ ? ? ? writel(siic->sda_delay, siic->base + SIRFSOC_I2C_SDA_DELAY);
+ ? ? ? clk_disable(siic->clk);
+ ? ? ? return 0;
+}
+
+static const struct dev_pm_ops i2c_sirfsoc_pm_ops = {
+ ? ? ? .suspend = i2c_sirfsoc_suspend,
+ ? ? ? .resume = i2c_sirfsoc_resume,

Could we use simple dev_pm ops here?

i guess you mean SIMPLE_DEV_PM_OPS. the only problem is i2c bus driver
doesn't need entries like:
 .freeze = suspend_fn, \
 .thaw = resume_fn, \
 .poweroff = suspend_fn, \
 .restore = resume_fn,

at least in our test, without these entries,  suspend to ram, suspend
to disk(hibernation) and poweroff have always worked well.

quoted

+};
+#endif
+
+static const struct of_device_id sirfsoc_i2c_of_match[] __devinitconst = {
+ ? ? ? { .compatible = "sirf,prima2-i2c", },

-barry