linux-kernel - Re: [PATCH v13 2/3] fpga: microchip-spi: add Microchip MPF FPGA manager

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Date:   Sun, 29 May 2022 20:39:54 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Ivan Bornyakov <i.bornyakov@...rotek.ru>
Cc:     mdf@...nel.org, hao.wu@...el.com, trix@...hat.com,
        Conor.Dooley@...rochip.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-fpga@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        system@...rotek.ru
Subject: Re: [PATCH v13 2/3] fpga: microchip-spi: add Microchip MPF FPGA
 manager

On Thu, May 26, 2022 at 09:13:43PM +0300, Ivan Bornyakov wrote:
> Add support to the FPGA manager for programming Microchip Polarfire
> FPGAs over slave SPI interface with .dat formatted bitsream image.

>From previous mail thread, there are still some hardware operations yet
to be clarified, so I may need a Reviewed-by from Conor.Dooley@...rochip.com.

[...]


> +static int mpf_ops_parse_header(struct fpga_manager *mgr,
> +				struct fpga_image_info *info,
> +				const char *buf, size_t count)
> +{
> +	size_t component_size_byte_num, component_size_byte_off,
> +	       components_size_start, bitstream_start, i,
> +	       block_id_offset, block_start_offset;
> +	u8 header_size, blocks_num, block_id;

I think component_size_byte_num, component_size_byte_off, i should be size_t
are all simple numbers irrelated to data size, so maybe u32 is just good.

Thanks,
Yilun

> +	u32 block_start, component_size;
> +	u16 components_num;
> +
> +	if (!buf) {
> +		dev_err(&mgr->dev, "Image buffer is not provided\n");
> +		return -EINVAL;
> +	}
> +
> +	header_size = *(buf + MPF_HEADER_SIZE_OFFSET);
> +	if (header_size > count) {
> +		info->header_size = header_size;
> +		return -EAGAIN;
> +	}
> +
> +	/*
> +	 * Go through look-up table to find out where actual bitstream starts
> +	 * and where sizes of components of the bitstream lies.
> +	 */
> +	blocks_num = *(buf + header_size - 1);
> +	block_id_offset = header_size + MPF_LOOKUP_TABLE_BLOCK_ID_OFFSET;
> +	block_start_offset = header_size + MPF_LOOKUP_TABLE_BLOCK_START_OFFSET;
> +
> +	header_size += blocks_num * MPF_LOOKUP_TABLE_RECORD_SIZE;
> +	if (header_size > count) {
> +		info->header_size = header_size;
> +		return -EAGAIN;
> +	}
> +
> +	components_size_start = 0;
> +	bitstream_start = 0;
> +
> +	while (blocks_num--) {
> +		block_id = *(buf + block_id_offset);
> +		block_start = get_unaligned_le32(buf + block_start_offset);
> +
> +		switch (block_id) {
> +		case MPF_BITSTREAM_ID:
> +			info->header_size = bitstream_start = block_start;
> +			if (block_start > count)
> +				return -EAGAIN;
> +
> +			break;
> +		case MPF_COMPONENTS_SIZE_ID:
> +			components_size_start = block_start;
> +			break;
> +		default:
> +			break;
> +		}
> +
> +		if (bitstream_start && components_size_start)
> +			break;
> +
> +		block_id_offset += MPF_LOOKUP_TABLE_RECORD_SIZE;
> +		block_start_offset += MPF_LOOKUP_TABLE_RECORD_SIZE;
> +	}
> +
> +	if (!bitstream_start || !components_size_start) {
> +		dev_err(&mgr->dev, "Failed to parse header look-up table\n");
> +		return -EFAULT;
> +	}
> +
> +	/*
> +	 * Parse bitstream size.
> +	 * Sizes of components of the bitstream are 22-bits long placed next
> +	 * to each other. Image header should be extended by now up to where
> +	 * actual bitstream starts, so no need for overflow check anymore.
> +	 */
> +	components_num = get_unaligned_le16(buf + MPF_DATA_SIZE_OFFSET);
> +
> +	for (i = 0; i < components_num; i++) {
> +		component_size_byte_num =
> +			(i * MPF_BITS_PER_COMPONENT_SIZE) / BITS_PER_BYTE;
> +		component_size_byte_off =
> +			(i * MPF_BITS_PER_COMPONENT_SIZE) % BITS_PER_BYTE;
> +
> +		component_size = get_unaligned_le32(buf +
> +						    components_size_start +
> +						    component_size_byte_num);
> +		component_size >>= component_size_byte_off;
> +		component_size &= GENMASK(MPF_BITS_PER_COMPONENT_SIZE - 1, 0);
> +
> +		info->data_size += component_size * MPF_SPI_FRAME_SIZE;
> +	}
> +
> +	return 0;
> +}