[U-Boot] [PATCH 6/6] i2c: designware_i2c: Add support for PCI(e) based I2C cores (x86)

[Bin Meng]

Hi Stefan,

On Mon, Mar 21, 2016 at 8:04 PM, Stefan Roese <sr at denx.de> wrote:
> Hi Bin,
>
> On 21.03.2016 10:03, Stefan Roese wrote:
>
> <snip>
>
>>>>    static int designware_i2c_probe_chip(struct udevice *bus, uint chip_addr,
>>>> @@ -476,14 +519,45 @@ static int designware_i2c_probe(struct udevice *bus)
>>>>    {
>>>>           struct dw_i2c *priv = dev_get_priv(bus);
>>>>
>>>> +#ifdef CONFIG_X86
>>>> +       /* Save base address from PCI BAR */
>>>> +       priv->regs = (struct i2c_regs *)
>>>> +               dm_pci_map_bar(bus, PCI_BASE_ADDRESS_0, PCI_REGION_MEM);
>>>> +       /* Use BayTrail specific timing values */
>>>> +       priv->scl_sda_cfg = &byt_config;
>>>> +#else
>>>
>>> How about:
>>>
>>>       if (device_is_on_pci_bus(dev)) {
>>>       do the PCI I2C stuff here;
>>>       }
>>
>> I've tried this but it generated compilation errors on socfpga, as the
>> dm_pci_xxx functions are not available there. So it definitely needs
>> some #ifdef here. I could go with your suggestion and use
>> #if CONFIG_DM_PCI as well.
>>
>>> See driver/net/designware.c for example.
>>>
>>>>           /* Save base address from device-tree */
>>>>           priv->regs = (struct i2c_regs *)dev_get_addr(bus);
>>>> +#endif
>
> Enabling this code for x86 via if (device_is_on_pci_bus(dev)) results
> in this ugly compilation warning:
>
> drivers/i2c/designware_i2c.c: In function ‘designware_i2c_probe’:
> drivers/i2c/designware_i2c.c:530:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
>    priv->regs = (struct i2c_regs *)dev_get_addr(bus);
>                 ^
>
> This is because x86 defines fdt_addr_t / phys_addr_t as 64bit. So
> I'm wondering, how dev_get_addr() should get used on x86. Has it
> been used anywhere here at all? Should we perhaps go back to
> a 32bit phy_addr representation again? So that dev_get_addr()
> matches the (void *) size again?
>

dev_get_addr() is being used on x86 drivers. See
ns16550_serial_ofdata_to_platdata() for example. There is no build
warning for the ns16550 driver.

> The other option would to just leave the code as in v1 so that
> dev_get_addr() is not referenced on x86 here.
>

Regards,
Bin