Message-ID: <20220522165232.GB90764@yilunxu-OptiPlex-7050>
Date:   Mon, 23 May 2022 00:52:32 +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 v12 2/3] fpga: microchip-spi: add Microchip MPF FPGA
 manager

On Fri, May 13, 2022 at 07:27:54PM +0300, Ivan Bornyakov wrote:
> Add support to the FPGA manager for programming Microchip Polarfire
> FPGAs over slave SPI interface with .dat formatted bitsream image.
> 
> Signed-off-by: Ivan Bornyakov <i.bornyakov@...rotek.ru>
> ---
>  drivers/fpga/Kconfig         |   9 +
>  drivers/fpga/Makefile        |   1 +
>  drivers/fpga/microchip-spi.c | 371 +++++++++++++++++++++++++++++++++++
>  3 files changed, 381 insertions(+)
>  create mode 100644 drivers/fpga/microchip-spi.c
> 
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index 26025dbab353..75806ef5c9ea 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -248,4 +248,13 @@ config FPGA_MGR_VERSAL_FPGA
>  	  configure the programmable logic(PL).
>  
>  	  To compile this as a module, choose M here.
> +
> +config FPGA_MGR_MICROCHIP_SPI
> +	tristate "Microchip Polarfire SPI FPGA manager"
> +	depends on SPI
> +	help
> +	  FPGA manager driver support for Microchip Polarfire FPGAs
> +	  programming over slave SPI interface with .dat formatted
> +	  bitstream image.
> +
>  endif # FPGA
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index e32bfa90f968..5425a15892df 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
>  obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
>  obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
>  obj-$(CONFIG_FPGA_MGR_VERSAL_FPGA)	+= versal-fpga.o
> +obj-$(CONFIG_FPGA_MGR_MICROCHIP_SPI)	+= microchip-spi.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE)		+= altera-pr-ip-core.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)	+= altera-pr-ip-core-plat.o
>  
> diff --git a/drivers/fpga/microchip-spi.c b/drivers/fpga/microchip-spi.c
> new file mode 100644
> index 000000000000..cb59f43000a4
> --- /dev/null
> +++ b/drivers/fpga/microchip-spi.c
> @@ -0,0 +1,371 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Microchip Polarfire FPGA programming over slave SPI interface.
> + */
> +
> +#include <asm/unaligned.h>
> +#include <linux/delay.h>
> +#include <linux/fpga/fpga-mgr.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/spi/spi.h>
> +
> +#define	MPF_SPI_ISC_ENABLE	0x0B
> +#define	MPF_SPI_ISC_DISABLE	0x0C
> +#define	MPF_SPI_READ_STATUS	0x00
> +#define	MPF_SPI_READ_DATA	0x01
> +#define	MPF_SPI_FRAME_INIT	0xAE
> +#define	MPF_SPI_FRAME		0xEE
> +#define	MPF_SPI_PRG_MODE	0x01
> +#define	MPF_SPI_RELEASE		0x23
> +
> +#define	MPF_SPI_FRAME_SIZE	16
> +
> +#define	MPF_HEADER_SIZE_OFFSET	24
> +#define	MPF_DATA_SIZE_OFFSET	55
> +
> +#define	MPF_LOOKUP_TABLE_RECORD_SIZE		9
> +#define	MPF_LOOKUP_TABLE_BLOCK_ID_OFFSET	0
> +#define	MPF_LOOKUP_TABLE_BLOCK_START_OFFSET	1
> +
> +#define	MPF_COMPONENTS_SIZE_ID	5
> +#define	MPF_BITSTREAM_ID	8
> +
> +#define	MPF_BITS_PER_COMPONENT_SIZE	22
> +
> +#define	MPF_STATUS_POLL_TIMEOUT		10000
> +#define	MPF_STATUS_BUSY			BIT(0)
> +#define	MPF_STATUS_READY		BIT(1)
> +#define	MPF_STATUS_SPI_VIOLATION	BIT(2)
> +#define	MPF_STATUS_SPI_ERROR		BIT(3)
> +
> +struct mpf_priv {
> +	struct spi_device *spi;
> +	bool program_mode;
> +};
> +
> +static int mpf_read_status(struct spi_device *spi)
> +{
> +	u8 status = 0, status_command = MPF_SPI_READ_STATUS;
> +	struct spi_transfer xfers[] = {
> +		[0 ... 1] = {
> +			.tx_buf = &status_command,
> +			.rx_buf = &status,
> +			.len = 1,
> +			.cs_change = 1,
> +		}
> +	};
> +	int ret = spi_sync_transfer(spi, xfers, 2);

I remember it is spi_w8r8 for the first time, why we change to
spi_sync_transfer? They behavior differently on spi bus.

And why we need to xfer the same message twice? If it relates to
some HW behavior, we'd better add some comments here.

> +
> +	if ((status & MPF_STATUS_SPI_VIOLATION) ||
> +	    (status & MPF_STATUS_SPI_ERROR))
> +		ret = -EIO;
> +
> +	return ret ? : status;
> +}
> +
> +static enum fpga_mgr_states mpf_ops_state(struct fpga_manager *mgr)
> +{
> +	struct mpf_priv *priv = mgr->priv;
> +	struct spi_device *spi;
> +	bool program_mode;
> +	int status;
> +
> +	spi = priv->spi;
> +	program_mode = priv->program_mode;
> +	status = mpf_read_status(spi);
> +
> +	if (!program_mode && !status)
> +		return FPGA_MGR_STATE_OPERATING;
> +
> +	return FPGA_MGR_STATE_UNKNOWN;
> +}
> +
> +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 = 0, bitstream_start = 0,
> +	       block_id_offset, block_start_offset, i;

The initialization should be listed after declaration, so swap the 2
lines

Why the component_size_byte_num, component_size_byte_off, i should be size_t?

> +	u8 header_size, blocks_num, block_id;
> +	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;
> +	}
> +
> +	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;

Why doesn't check the components_size_start against count, any difference
with bitstream_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);

Some check against count?

> +		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;
> +}
> +
> +static int poll_status_not_busy(struct spi_device *spi, u8 mask)

The function name is confusing, it does more than polling busy bit.
mpf_poll_status is better?

> +{
> +	int status, timeout = MPF_STATUS_POLL_TIMEOUT;
> +
> +	while (timeout--) {
> +		status = mpf_read_status(spi);
> +		if (status < 0 ||
> +		    (!(status & MPF_STATUS_BUSY) && (!mask || (status & mask))))

Please make the judgements easier to read.

	if (status < 0)
		return status;

	if (status & MPF_STATUS_BUSY)
		continue;

	if (!mask || (status & mask))
		return status;

Is that OK for you?
> +			return status;
> +	}
> +
> +	return -EBUSY;
> +}
> +
> +static int mpf_spi_write(struct spi_device *spi, const void *buf, size_t buf_size)
> +{
> +	int status = poll_status_not_busy(spi, 0);
> +
> +	if (status < 0)
> +		return status;
> +
> +	return spi_write(spi, buf, buf_size);
> +}
> +
> +static int mpf_spi_write_then_read(struct spi_device *spi,
> +				   const void *txbuf, size_t txbuf_size,
> +				   void *rxbuf, size_t rxbuf_size)
> +{
> +	const u8 read_command[] = { MPF_SPI_READ_DATA };
> +	int ret;
> +
> +	ret = mpf_spi_write(spi, txbuf, txbuf_size);
> +	if (ret)
> +		return ret;
> +
> +	ret = poll_status_not_busy(spi, MPF_STATUS_READY);
> +	if (ret < 0)
> +		return ret;
> +
> +	return spi_write_then_read(spi, read_command, sizeof(read_command),
> +				   rxbuf, rxbuf_size);
> +}
> +
> +static int mpf_ops_write_init(struct fpga_manager *mgr,
> +			      struct fpga_image_info *info, const char *buf,
> +			      size_t count)
> +{
> +	const u8 program_mode[] = { MPF_SPI_FRAME_INIT, MPF_SPI_PRG_MODE };
> +	const u8 isc_en_command[] = { MPF_SPI_ISC_ENABLE };
> +	struct mpf_priv *priv = mgr->priv;
> +	struct device *dev = &mgr->dev;
> +	struct spi_device *spi;
> +	u32 isc_ret;
> +	int ret;
> +
> +	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
> +		dev_err(dev, "Partial reconfiguration is not supported\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	spi = priv->spi;
> +
> +	ret = mpf_spi_write_then_read(spi, isc_en_command, sizeof(isc_en_command),
> +				      &isc_ret, sizeof(isc_ret));
> +	if (ret || isc_ret) {
> +		dev_err(dev, "Failed to enable ISC: %d\n", ret ? : isc_ret);

%d for a u32 variable? Maybe just list the 2 values.

> +		return -EFAULT;
> +	}
> +
> +	ret = mpf_spi_write(spi, program_mode, sizeof(program_mode));
> +	if (ret) {
> +		dev_err(dev, "Failed to enter program mode: %d\n", ret);
> +		return ret;
> +	}
> +
> +	priv->program_mode = true;
> +
> +	return 0;
> +}
> +
> +static int mpf_ops_write(struct fpga_manager *mgr, const char *buf, size_t count)
> +{
> +	u8 tmp_buf[MPF_SPI_FRAME_SIZE + 1] = { MPF_SPI_FRAME, };
> +	struct mpf_priv *priv = mgr->priv;
> +	struct device *dev = &mgr->dev;
> +	struct spi_device *spi;
> +	int ret, i;
> +
> +	if (count % MPF_SPI_FRAME_SIZE) {
> +		dev_err(dev, "Bitstream size is not a multiple of %d\n",
> +			MPF_SPI_FRAME_SIZE);
> +		return -EINVAL;
> +	}
> +
> +	spi = priv->spi;
> +
> +	for (i = 0; i < count / MPF_SPI_FRAME_SIZE; i++) {
> +		memcpy(tmp_buf + 1, buf + i * MPF_SPI_FRAME_SIZE,
> +		       MPF_SPI_FRAME_SIZE);
> +
> +		ret = mpf_spi_write(spi, tmp_buf, sizeof(tmp_buf));

As I mentioned before, is it possible we use spi_sync_transfer to avoid
memcpy the whole bitstream?

> +		if (ret) {
> +			dev_err(dev, "Failed to write bitstream frame %d/%zd\n",

%zu for size_t

> +				i, count / MPF_SPI_FRAME_SIZE);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int mpf_ops_write_complete(struct fpga_manager *mgr,
> +				  struct fpga_image_info *info)
> +{
> +	const u8 isc_dis_command[] = { MPF_SPI_ISC_DISABLE };
> +	const u8 release_command[] = { MPF_SPI_RELEASE };
> +	struct mpf_priv *priv = mgr->priv;
> +	struct device *dev = &mgr->dev;
> +	struct spi_device *spi;
> +	int ret;
> +
> +	spi = priv->spi;
> +
> +	ret = mpf_spi_write(spi, isc_dis_command, sizeof(isc_dis_command));
> +	if (ret) {
> +		dev_err(dev, "Failed to disable ISC: %d\n", ret);
> +		return ret;
> +	}
> +
> +	usleep_range(1000, 2000);
> +
> +	ret = mpf_spi_write(spi, release_command, sizeof(release_command));
> +	if (ret) {
> +		dev_err(dev, "Failed to exit program mode: %d\n", ret);
> +		return ret;
> +	}
> +
> +	priv->program_mode = false;
> +
> +	return 0;
> +}
> +
> +static const struct fpga_manager_ops mpf_ops = {
> +	.state = mpf_ops_state,
> +	.initial_header_size = 71,
> +	.parse_header = mpf_ops_parse_header,
> +	.write_init = mpf_ops_write_init,
> +	.write = mpf_ops_write,
> +	.write_complete = mpf_ops_write_complete,
> +};
> +
> +static int mpf_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct fpga_manager *mgr;
> +	struct mpf_priv *priv;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->spi = spi;
> +
> +	mgr = devm_fpga_mgr_register(dev, "Microchip Polarfire SPI FPGA Manager",
> +				     &mpf_ops, priv);
> +
> +	return PTR_ERR_OR_ZERO(mgr);
> +}
> +
> +static const struct spi_device_id mpf_spi_ids[] = {
> +	{ .name = "mpf-spi-fpga-mgr", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(spi, mpf_spi_ids);
> +
> +#if IS_ENABLED(CONFIG_OF)
> +static const struct of_device_id mpf_of_ids[] = {
> +	{ .compatible = "microchip,mpf-spi-fpga-mgr" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, mpf_of_ids);
> +#endif /* IS_ENABLED(CONFIG_OF) */
> +
> +static struct spi_driver mpf_driver = {
> +	.probe = mpf_probe,
> +	.id_table = mpf_spi_ids,
> +	.driver = {
> +		.name = "microchip_mpf_spi_fpga_mgr",
> +		.of_match_table = of_match_ptr(mpf_of_ids),
> +	},
> +};
> +
> +module_spi_driver(mpf_driver);
> +
> +MODULE_DESCRIPTION("Microchip Polarfire SPI FPGA Manager");
> +MODULE_LICENSE("GPL");
> -- 
> 2.35.1
> 

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