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Date:   Sun, 22 May 2022 23:22:55 +0300
From:   Ivan Bornyakov <i.bornyakov@metrotek.ru>
To:     Xu Yilun <yilun.xu@intel.com>
Cc:     mdf@kernel.org, hao.wu@intel.com, trix@redhat.com,
        Conor.Dooley@microchip.com, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, linux-fpga@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        system@metrotek.ru
Subject: Re: [PATCH v12 2/3] fpga: microchip-spi: add Microchip MPF FPGA
 manager
Message-ID: <20220522202255.f6a2x4owvg7nfzks@x260>
References: <20220513162755.16201-1-i.bornyakov@metrotek.ru>
 <20220513162755.16201-3-i.bornyakov@metrotek.ru>
 <20220522165232.GB90764@yilunxu-OptiPlex-7050>
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In-Reply-To: <20220522165232.GB90764@yilunxu-OptiPlex-7050>
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On Mon, May 23, 2022 at 12:52:32AM +0800, Xu Yilun wrote:
> 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@metrotek.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.

On v8 Conor reported that spi_w8r8 was not correct way to read the status,
despite that my HW was giving reasonable result.

See https://lore.kernel.org/linux-fpga/7fcde9aa-c086-33e1-1619-04663bfeff85@microchip.com/#t

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

On v11 Conor reported that he observed inadequate status readings, and
double status reads fixed that. There is also a hint in Microchip's
"SPI-DirectC User Guide" that status should be read two times, but not a
clear statement.

See https://lore.kernel.org/linux-fpga/4b752147-1a09-a4af-bc5d-3b132b84ef49@conchuod.ie/#t

Anyway, I'll add some words.

> > +
> > +	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?

It's a safe bet for offsets inside image buffer.

> > +	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?

bitstream_start is in fact a synonym for info->header_size, while
components_size_start is somewhere in the header. Thus, data at offset
'components_size_start' is accessed when count is not less then
info->header_size.

> > +			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?

Same, also see comment just above for-loop.

> > +		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?

Well, my intention was to denote that we poll status until busy bit is
not set. I have no strong feelings for this function naming, tho.

> > +{
> > +	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?

Yeah, sure.

> > +			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.

Ok, will do.

> > +		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?

Unfortunately, I didn't succeed with spi_sunc_transfer here. May be
Conor or other folks with more insight on Microchip's HW would be able
to eliminate this memcpy...

> > +		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
> >