Re: [PATCH v9 03/12] mtd: intel-dg: implement region enumeration

[Raag Jadav <raag.jadav@intel.com>]

On Thu, Apr 24, 2025 at 04:25:27PM +0300, Alexander Usyskin wrote:
> In intel-dg, there is no access to the spi controller,
> the information is extracted from the descriptor region.

...

> @@ -22,9 +24,199 @@ struct intel_dg_nvm {
>  		u8 id;
>  		u64 offset;
>  		u64 size;
> +		unsigned int is_readable:1;
> +		unsigned int is_writable:1;
>  	} regions[] __counted_by(nregions);
>  };
>  
> +#define NVM_TRIGGER_REG       0x00000000
> +#define NVM_VALSIG_REG        0x00000010
> +#define NVM_ADDRESS_REG       0x00000040
> +#define NVM_REGION_ID_REG     0x00000044
> +/*
> + * [15:0]-Erase size = 0x0010 4K 0x0080 32K 0x0100 64K
> + * [23:16]-Reserved
> + * [31:24]-Erase MEM RegionID
> + */
> +#define NVM_ERASE_REG         0x00000048
> +#define NVM_ACCESS_ERROR_REG  0x00000070
> +#define NVM_ADDRESS_ERROR_REG 0x00000074
> +
> +/* Flash Valid Signature */
> +#define NVM_FLVALSIG          0x0FF0A55A
> +
> +#define NVM_MAP_ADDR_MASK     GENMASK(7, 0)
> +#define NVM_MAP_ADDR_SHIFT    0x00000004
> +
> +#define NVM_REGION_ID_DESCRIPTOR  0
> +/* Flash Region Base Address */
> +#define NVM_FRBA      0x40
> +/* Flash Region __n - Flash Descriptor Record */
> +#define NVM_FLREG(__n) (NVM_FRBA + ((__n) * 4))
> +/*  Flash Map 1 Register */
> +#define NVM_FLMAP1_REG  0x18
> +#define NVM_FLMSTR4_OFFSET 0x00C
> +
> +#define NVM_ACCESS_ERROR_PCIE_MASK 0x7
> +
> +#define NVM_FREG_BASE_MASK GENMASK(15, 0)
> +#define NVM_FREG_ADDR_MASK GENMASK(31, 16)
> +#define NVM_FREG_ADDR_SHIFT 12
> +#define NVM_FREG_MIN_REGION_SIZE 0xFFF

Should we move these to a header?

> +static inline void idg_nvm_set_region_id(struct intel_dg_nvm *nvm, u8 region)
> +{
> +	iowrite32((u32)region, nvm->base + NVM_REGION_ID_REG);
> +}
> +
> +static inline u32 idg_nvm_error(struct intel_dg_nvm *nvm)
> +{
> +	void __iomem *base = nvm->base;
> +
> +	u32 reg = ioread32(base + NVM_ACCESS_ERROR_REG) & NVM_ACCESS_ERROR_PCIE_MASK;
> +
> +	/* reset error bits */
> +	if (reg)
> +		iowrite32(reg, base + NVM_ACCESS_ERROR_REG);
> +
> +	return reg;
> +}
> +
> +static inline u32 idg_nvm_read32(struct intel_dg_nvm *nvm, u32 address)
> +{
> +	void __iomem *base = nvm->base;
> +
> +	iowrite32(address, base + NVM_ADDRESS_REG);
> +
> +	return ioread32(base + NVM_TRIGGER_REG);
> +}
> +
> +static int idg_nvm_get_access_map(struct intel_dg_nvm *nvm, u32 *access_map)
> +{
> +	u32 flmap1;
> +	u32 fmba;
> +	u32 fmstr4;
> +	u32 fmstr4_addr;

Nit: These are in order of appearance vs reverse xmas tree in other places.
Perhaps make them consistent?

> +	idg_nvm_set_region_id(nvm, NVM_REGION_ID_DESCRIPTOR);
> +
> +	flmap1 = idg_nvm_read32(nvm, NVM_FLMAP1_REG);
> +	if (idg_nvm_error(nvm))
> +		return -EIO;
> +	/* Get Flash Master Baser Address (FMBA) */
> +	fmba = (FIELD_GET(NVM_MAP_ADDR_MASK, flmap1) << NVM_MAP_ADDR_SHIFT);
> +	fmstr4_addr = fmba + NVM_FLMSTR4_OFFSET;
> +
> +	fmstr4 = idg_nvm_read32(nvm, fmstr4_addr);
> +	if (idg_nvm_error(nvm))
> +		return -EIO;
> +
> +	*access_map = fmstr4;
> +	return 0;
> +}
> +
> +static bool idg_nvm_region_readable(u32 access_map, u8 region)
> +{
> +	if (region < 12)

Anything special about 12? Should it have a macro def somewhere?

> +		return access_map & BIT(region + 8); /* [19:8] */
> +	else
> +		return access_map & BIT(region - 12); /* [3:0] */
> +}
> +
> +static bool idg_nvm_region_writable(u32 access_map, u8 region)
> +{
> +	if (region < 12)

Ditto.

> +		return access_map & BIT(region + 20); /* [31:20] */
> +	else
> +		return access_map & BIT(region - 8); /* [7:4] */
> +}

Raag