[U-Boot] [PATCH] spi: kirkwood_spi: Add support for multiple chip-selects on MVEBU

[Stefan Roese]

Hi Jagan,

please excuse the long delay here. Some comments below.

On 12.02.2016 21:27, Jagan Teki wrote:
> On 12 February 2016 at 18:15, Stefan Roese <sr at denx.de> wrote:
>> Currently only chip-select 0 is supported by the kirkwood SPI driver.
>> The Armada XP / 38x SoCs also use this driver and support multiple chip
>> selects. This patch adds support for multiple CS on MVEBU.
>>
>> The register definitions are restructured a bit with this patch. Grouping
>> them to the corresponding registers.
>>
>> Signed-off-by: Stefan Roese <sr at denx.de>
>> Cc: Luka Perkov <luka.perkov at sartura.hr>
>> Cc: Jagan Teki <jteki at openedev.com>
>> ---
>>   arch/arm/include/asm/arch-mvebu/spi.h | 17 ++++++++++++-----
>>   drivers/spi/kirkwood_spi.c            |  6 ++++++
>>   2 files changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/arch-mvebu/spi.h b/arch/arm/include/asm/arch-mvebu/spi.h
>> index e512dce..4b66499 100644
>> --- a/arch/arm/include/asm/arch-mvebu/spi.h
>> +++ b/arch/arm/include/asm/arch-mvebu/spi.h
>> @@ -32,13 +32,15 @@ struct kwspi_registers {
>>   #define SCK_MPP10      (1 << 1)
>>   #define MISO_MPP11     (1 << 2)
>>
>> +/* Control Register */
>> +#define KWSPI_CSN_ACT          (1 << 0) /* Activates serial memory interface */
>> +#define KWSPI_SMEMRDY          (1 << 1) /* SerMem Data xfer ready */
>> +#define KWSPI_CS_SHIFT         2       /* chip select shift */
>> +#define KWSPI_CS_MASK          0x7     /* chip select mask */
>> +
>> +/* Configuration Register */
>>   #define KWSPI_CLKPRESCL_MASK   0x1f
>>   #define KWSPI_CLKPRESCL_MIN    0x12
>> -#define KWSPI_CSN_ACT          1 /* Activates serial memory interface */
>> -#define KWSPI_SMEMRDY          (1 << 1) /* SerMem Data xfer ready */
>> -#define KWSPI_IRQUNMASK                1 /* unmask SPI interrupt */
>> -#define KWSPI_IRQMASK          0 /* mask SPI interrupt */
>> -#define KWSPI_SMEMRDIRQ                1 /* SerMem data xfer ready irq */
>>   #define KWSPI_XFERLEN_1BYTE    0
>>   #define KWSPI_XFERLEN_2BYTE    (1 << 5)
>>   #define KWSPI_XFERLEN_MASK     (1 << 5)
>> @@ -47,6 +49,11 @@ struct kwspi_registers {
>>   #define KWSPI_ADRLEN_3BYTE     (2 << 8)
>>   #define KWSPI_ADRLEN_4BYTE     (3 << 8)
>>   #define KWSPI_ADRLEN_MASK      (3 << 8)
>> +
>> +#define KWSPI_IRQUNMASK                1 /* unmask SPI interrupt */
>> +#define KWSPI_IRQMASK          0 /* mask SPI interrupt */
>> +#define KWSPI_SMEMRDIRQ                1 /* SerMem data xfer ready irq */
>> +
>>   #define KWSPI_TIMEOUT          10000
>>
>>   #endif /* __KW_SPI_H__ */
>> diff --git a/drivers/spi/kirkwood_spi.c b/drivers/spi/kirkwood_spi.c
>> index 7890796..fa30be4 100644
>> --- a/drivers/spi/kirkwood_spi.c
>> +++ b/drivers/spi/kirkwood_spi.c
>> @@ -280,6 +280,12 @@ static int mvebu_spi_xfer(struct udevice *dev, unsigned int bitlen,
>>          struct udevice *bus = dev->parent;
>>          struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
>>
>> +#ifdef CONFIG_ARCH_MVEBU
>> +       clrsetbits_le32(&plat->spireg->ctrl,
>> +                       KWSPI_CS_MASK << KWSPI_CS_SHIFT,
>> +                       spi_chip_select(dev) << KWSPI_CS_SHIFT);
>> +#endif
>
> This looks clearing a desired cs from 'sf probe' why is this need
> here?

Its not clearing a CS but configuring the CS number in the CTRL
register. This configured CS number will get enabled or disabled
exactly the same way as when its zero (without this patch) in
the existing spi_cs_activate/deactivate functions

> I think we can do the desired cs activate or deactivate through
> existing spi_cs_activate/deactivate functions itself.

This is exactly what this patch does. The CS number is
configured with the clrsetbits_le32() call above. And activated /
deactivated in the existing functions.

Or do you mean something else?

Thanks,
Stefan