Re: [PATCH v4 2/4] fpga: dfl: Add DFHv1 Register Definitions

[Ilpo Järvinen]

On Thu, 20 Oct 2022, matthew.gerlach@xxxxxxxxxxxxxxx wrote:

> From: Basheer Ahmed Muddebihal <basheer.ahmed.muddebihal@xxxxxxxxxxxxxxx>
> 
> This patch adds the definitions for DFHv1 header and related register
> bitfields.
> 
> Signed-off-by: Basheer Ahmed Muddebihal <basheer.ahmed.muddebihal@xxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> ---
> v4: s/MSIX/MSI_X/g
>     move kerneldoc to implementation
>     don't change copyright date
> 
> v3:
>     keep DFHv1 definitions "hidden" in drivers/fpga/dfl.h
> 
> v2: clean up whitespace and one line comments
>     remove extra space in commit
>     use uniform number of digits in constants
>     don't change copyright date because of removed content
> 
> dfl.h s/MSIX/MSI_X/g move kerneldoc
> ---
>  drivers/fpga/dfl.h  | 33 +++++++++++++++++++++++++++++++++
>  include/linux/dfl.h | 11 +++++++++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index 06cfcd5e84bb..45e6e1359a67 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -74,11 +74,44 @@
>  #define DFH_REVISION		GENMASK_ULL(15, 12)	/* Feature revision */
>  #define DFH_NEXT_HDR_OFST	GENMASK_ULL(39, 16)	/* Offset to next DFH */
>  #define DFH_EOL			BIT_ULL(40)		/* End of list */
> +#define DFH_VERSION		GENMASK_ULL(59, 52)	/* DFH version */
>  #define DFH_TYPE		GENMASK_ULL(63, 60)	/* Feature type */
>  #define DFH_TYPE_AFU		1
>  #define DFH_TYPE_PRIVATE	3
>  #define DFH_TYPE_FIU		4
>  
> +/*
> + * DFHv1 Register Offset definitons
> + * In DHFv1, DFH + GUID + CSR_START + CSR_SIZE_GROUP + PARAM_HDR + PARAM_DATA
> + * as common header registers
> + */
> +#define DFHv1_CSR_ADDR		0x18  /* CSR Register start address */
> +#define DFHv1_CSR_SIZE_GRP	0x20  /* Size of Reg Block and Group/tag */
> +#define DFHv1_PARAM_HDR		0x28  /* Optional First Param header */
> +
> +/*
> + * CSR Rel Bit, 1'b0 = relative (offset from feature DFH start),
> + * 1'b1 = absolute (ARM or other non-PCIe use)
> + */
> +#define DFHv1_CSR_ADDR_REL	BIT_ULL(0)
> +
> +/* CSR Header Register Bit Definitions */
> +#define DFHv1_CSR_ADDR_MASK       GENMASK_ULL(63, 1)  /* 63:1 of CSR address */
> +
> +/* CSR SIZE Goup Register Bit Definitions */
> +#define DFHv1_CSR_SIZE_GRP_INSTANCE_ID	GENMASK_ULL(15, 0)	/* Enumeration instantiated IP */
> +#define DFHv1_CSR_SIZE_GRP_GROUPING_ID	GENMASK_ULL(30, 16)	/* Group Features/interfaces */
> +#define DFHv1_CSR_SIZE_GRP_HAS_PARAMS	BIT_ULL(31)		/* Presence of Parameters */
> +#define DFHv1_CSR_SIZE_GRP_SIZE		GENMASK_ULL(63, 32)	/* Size of CSR Block in bytes */

SIZE -> SZ would remove two letters w/o loss of info (remember to 
rename the offset too if you make this change).

> +/* PARAM Header Register Bit Definitions */
> +#define DFHv1_PARAM_HDR_ID		GENMASK_ULL(15, 0) /* Id of this Param  */
> +#define DFHv1_PARAM_HDR_VERSION		GENMASK_ULL(31, 16) /* Version Param */
> +#define DFHv1_PARAM_HDR_NEXT_OFFSET	GENMASK_ULL(63, 32) /* Offset of next Param */
> +#define DFHv1_PARAM_HDR_NEXT_EOL	BIT_ULL(0)
> +#define DFHv1_PARAM_HDR_NEXT_MASK	GENMASK_ULL(1, 0)
> +#define DFHv1_PARAM_DATA		0x08  /* Offset of Param data from Param header */
> +
>  /* Next AFU Register Bitfield */
>  #define NEXT_AFU_NEXT_DFH_OFST	GENMASK_ULL(23, 0)	/* Offset to next AFU */
>  
> diff --git a/include/linux/dfl.h b/include/linux/dfl.h
> index 431636a0dc78..fea9e16d35b6 100644
> --- a/include/linux/dfl.h
> +++ b/include/linux/dfl.h
> @@ -11,6 +11,17 @@
>  #include <linux/device.h>
>  #include <linux/mod_devicetable.h>
>  
> +#define DFHv1_PARAM_ID_MSI_X		0x1
> +#define DFHv1_PARAM_MSI_X_STARTV	0x0
> +#define DFHv1_PARAM_MSI_X_NUMV		0x4
> +
> +#define DFHv1_PARAM_ID_CLK_FRQ    0x2
> +#define DFHv1_PARAM_ID_FIFO_LEN   0x3
> +
> +#define DFHv1_PARAM_ID_REG_LAYOUT 0x4
> +#define DFHv1_PARAM_ID_REG_WIDTH  GENMASK_ULL(63, 32)
> +#define DFHv1_PARAM_ID_REG_SHIFT  GENMASK_ULL(31, 0)

Any particular reason why MSI_X parameters are given as offsets and 
these REG_LAYOUT ones as bitfields (both are 32-bit)?

The naming here would indicate that DFHv1_PARAM_ID_REG_WIDTH is one of the 
parameters but it's part of param data instead. I suppose you'd want 
DFHv1_PARAM_REG_LAYOUT_WIDTH instead.

-- 
 i.