Wolfgang Grandegger wrote:
> On 09/01/2010 02:37 PM, Marc Kleine-Budde wrote:
>> Wolfgang Grandegger wrote:
>>> On 09/01/2010 02:10 PM, Marc Kleine-Budde wrote:
>>>> Wolfgang Grandegger wrote:
>>>>>> static u16 spear1310_can_read_reg(const struct bosch_ccan_priv *priv,
>>>>>> enum ccan_regs reg)
>>>>>> {
>>>>>> u16 val;
>>>>>>
>>>>>> /* 16 bit registers are aligned at 16-bit boundary */
>>>>>> val = readw(priv->reg_base + reg);
>>>>>> return val;
>>>>>> }
>>>>>>
>>>>>> static void spear1310_can_write_reg(const struct bosch_ccan_priv *priv,
>>>>>> enum ccan_regs reg, u16 val)
>>>>>> {
>>>>>> /* 16 bit registers are aligned at 16-bit boundary */
>>>>>> writew(val, priv->reg_base + reg);
>>>>>> }
>>>>>>
>>>>>> The one for SPEAr320 will look like:
>>>>>> static u16 spear320_can_read_reg(const struct bosch_ccan_priv *priv,
>>>>>> enum ccan_regs reg)
>>>>>> {
>>>>>> u16 val;
>>>>>>
>>>>>> /* shifting 1 place because 16 bit registers are word aligned */
>>>>>> val = readw(priv->reg_base + (reg << 1));
>>>>>> return val;
>>>>>> }
>>>>>>
>>>>>> static void spear320_can_write_reg(const struct bosch_ccan_priv *priv,
>>>>>> enum ccan_regs reg, u16 val)
>>>>>> {
>>>>>> /* shifting 1 place because 16 bit registers are word aligned */
>>>>>> writew(val, priv->reg_base + (reg << 1));
>>>>>> }
>>>>> These functions are still pretty generic and could be handled by a
>>>>> generic platform C_CAN driver via platform data field "reg_shift".
>>>> the sja1000 uses IORESOURCE_MEM_xxBIT for this. See [1].
>>>>
>>>> cheers, Marc
>>>>
>>>> [1]
>>>> http://lxr.linux.no/linux+v2.6.35/drivers/net/can/sja1000/sja1000_platform.c#L119
>>> Well, yes and no. I think for the SPEAr *word* accesses are required on
>>> a 2 and 4 byte boundary? Bhupesh? We could use IORESOURCE_MEM_16BIT and
>>> IORESOURCE_MEM_32BIT for these access types. But that might need to be
>>> extended. In the C_CAN manual there is written:
>>>
>>> "Up to now the C_CAN module is delivered with three different
>>> interfaces. An 8-bit interface for the Motorola HC08 controller and
>>> two 16-bit interfaces to the AMBA APB bus from ARM. They can easily
>>> be replaced by a user-defined module interface."
>> We can do a regshift of 1 and a full 32 bit access even with
>> IORESOURCE_MEM_16BIT, at least for now. Does 16 bit access work, too?
>
> I don't understand!? So far I have only seen 16 bit accesses
> (readw/writew) in Bhupesh's driver.
Doh....I, never having programmed under Windows or DOS, always mixes up
the width of these read{b,w,l}.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
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