Re: [PATCH v2 2/2] fpga: lattice machxo2: Add Lattice MachXO2 support

[Moritz Fischer <mdf@kernel.org>]

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Hi Paolo,

couple of nits inline, looks pretty good already.

On Mon, May 01, 2017 at 03:15:12PM +0200, Paolo Pisati wrote:
> This patch adds support to the FPGA manager for programming
> MachXO2 device’s internal flash memory, via slave SPI.
> 
> Signed-off-by: Paolo Pisati <p.pisati@gmail.com>
> ---
>  drivers/fpga/Kconfig       |   7 ++
>  drivers/fpga/Makefile      |   1 +
>  drivers/fpga/machxo2-spi.c | 214 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 222 insertions(+)
>  create mode 100644 drivers/fpga/machxo2-spi.c
> 
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index c81cb7d..cce135b 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -26,6 +26,13 @@ config FPGA_MGR_ICE40_SPI
>  	help
>  	  FPGA manager driver support for Lattice iCE40 FPGAs over SPI.
>  
> +config FPGA_MGR_MACHXO2_SPI
> +	tristate "Lattice MachXO2 SPI"
> +	depends on SPI
> +	help
> +	 FPGA manager driver support for Lattice MachXO2 configuration
> +	 over slave SPI interface.
> +
>  config FPGA_MGR_SOCFPGA
>  	tristate "Altera SOCFPGA FPGA Manager"
>  	depends on ARCH_SOCFPGA || COMPILE_TEST
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index c6f5d74..cdab1fe 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_FPGA)			+= fpga-mgr.o
>  
>  # FPGA Manager Drivers
>  obj-$(CONFIG_FPGA_MGR_ICE40_SPI)	+= ice40-spi.o
> +obj-$(CONFIG_FPGA_MGR_MACHXO2_SPI)	+= machxo2-spi.o
>  obj-$(CONFIG_FPGA_MGR_SOCFPGA)		+= socfpga.o
>  obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)	+= socfpga-a10.o
>  obj-$(CONFIG_FPGA_MGR_TS73XX)		+= ts73xx-fpga.o
> diff --git a/drivers/fpga/machxo2-spi.c b/drivers/fpga/machxo2-spi.c
> new file mode 100644
> index 0000000..264ef63
> --- /dev/null
> +++ b/drivers/fpga/machxo2-spi.c
> @@ -0,0 +1,214 @@
> +/**
> + * Lattice MachXO2 Slave SPI Driver
> + *
> + * Copyright (C) 2017 Paolo Pisati <p.pisati@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * Manage Lattice FPGA firmware that is loaded over SPI using
> + * the slave serial configuration interface.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/fpga/fpga-mgr.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/spi/spi.h>
> +
> +/* MachXO2 Programming Guide - sysCONFIG Programming Commands */
> +
> +#define ISC_ENABLE		0x000008c6
> +#define ISC_ERASE		0x0000040e
> +#define ISC_PROGRAMDONE		0x0000005e
> +#define LSC_CHECKBUSY		0x000000f0
> +#define LSC_INITADDRESS		0x00000046
> +#define LSC_PROGINCRNV		0x01000070
> +#define LSC_REFRESH		0x00000079
> +
> +#define BUSYFLAG		0x80

Maybe BIT() macro?
> +
> +/*
> + * Max CCLK in Slave SPI mode according to 'MachXO2 Family Data
> + * Sheet' sysCONFIG Port Timing Specifications (3-36)
> + */
> +#define MACHXO2_MAX_SPEED	66000000
> +
> +#define MACHXO2_LOW_DELAY	5	/* us */
> +#define MACHXO2_HIGH_DELAY	200	/* us */
> +
> +#define MACHXO2_OP_SIZE		sizeof(u32)
> +#define MACHXO2_PAGE_SIZE	16
> +#define MACHXO2_BUF_SIZE	(MACHXO2_OP_SIZE + MACHXO2_PAGE_SIZE)
> +
> +static int wait_until_not_busy(struct spi_device *spi)
> +{
> +	u8 rx;
> +	u32 checkbusy = LSC_CHECKBUSY;
> +	int ret;
> +
> +	do {
> +		ret = spi_write_then_read(spi, &checkbusy, MACHXO2_OP_SIZE,
> +					  &rx, sizeof(rx));
> +		if (ret)
> +			return ret;
> +	} while (rx & BUSYFLAG);
> +
> +	return 0;
> +}
> +
> +static enum fpga_mgr_states machxo2_spi_state(struct fpga_manager *mgr)
> +{
> +	return FPGA_MGR_STATE_UNKNOWN;
> +}
> +
> +static int machxo2_write_init(struct fpga_manager *mgr,
> +			      struct fpga_image_info *info,
> +			      const char *buf, size_t count)
> +{
> +	struct spi_device *spi = mgr->priv;
> +	u32 enable = ISC_ENABLE;
> +	u32 erase = ISC_ERASE;
> +	u32 initaddr = LSC_INITADDRESS;
> +	int ret;
> +
> +	if ((info->flags & FPGA_MGR_PARTIAL_RECONFIG)) {
> +		dev_err(&mgr->dev,
> +			"Partial reconfiguration is not supported\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	ret = spi_write(spi, &enable, MACHXO2_OP_SIZE);
> +	if (ret)
> +		goto fail;
> +
> +	udelay(MACHXO2_LOW_DELAY);

Does this have to be a delay, or can this be a sleep?
Can you maybe make the whole thing a chain of transactions
making use of spi_message_init() and trans.delay_usecs?

> +	ret = spi_write(spi, &erase, MACHXO2_OP_SIZE);
> +	if (ret)
> +		goto fail;
> +
> +	ret = wait_until_not_busy(spi);
> +	if (ret)
> +		goto fail;
> +
> +	ret = spi_write(spi, &initaddr, MACHXO2_OP_SIZE);
> +	if (ret)
> +		goto fail;
> +
> +	return 0;
> +
> +fail:
> +	dev_err(&mgr->dev, "Error during FPGA init.\n");
> +	return ret;
> +}
> +
> +static int machxo2_write(struct fpga_manager *mgr, const char *buf,
> +			 size_t count)
> +{
> +	struct spi_device *spi = mgr->priv;
> +	u32 progincr = LSC_PROGINCRNV;
> +	u8 payload[MACHXO2_BUF_SIZE];
> +	int i, ret;
> +
> +	if (count % MACHXO2_PAGE_SIZE != 0) {
> +		dev_err(&mgr->dev, "Malformed payload.\n");
> +		return -EINVAL;
> +	}
> +
> +	memcpy(payload, &progincr, MACHXO2_OP_SIZE);
> +	for (i = 0; i < count; i += MACHXO2_PAGE_SIZE) {
> +		memcpy(&payload[MACHXO2_OP_SIZE], &buf[i], MACHXO2_PAGE_SIZE);
> +		ret = spi_write(spi, payload, MACHXO2_BUF_SIZE);
> +		if (ret) {
> +			dev_err(&mgr->dev, "Error loading the bitstream.\n");
> +			return ret;
> +		}
> +		udelay(MACHXO2_HIGH_DELAY);
> +	}

Same here.
> +
> +	return 0;
> +}
> +
> +static int machxo2_write_complete(struct fpga_manager *mgr,
> +				  struct fpga_image_info *info)
> +{
> +	struct spi_device *spi = mgr->priv;
> +	u32 progdone = ISC_PROGRAMDONE;
> +	u32 refresh = LSC_REFRESH;
> +	int ret;
> +
> +	ret = spi_write(spi, &progdone, MACHXO2_OP_SIZE);
> +	if (ret)
> +		goto fail;
> +
> +	udelay(MACHXO2_HIGH_DELAY);

See above.
> +	/* yep, LSC_REFRESH is 3 bytes long actually */
> +	ret = spi_write(spi, &refresh, MACHXO2_OP_SIZE - 1);
> +	if (ret)
> +		goto fail;
> +
> +	return 0;
> +
> +fail:
> +	dev_err(&mgr->dev, "Refresh failed.\n");
> +	return ret;
> +}
> +
> +static const struct fpga_manager_ops machxo2_ops = {
> +	.state = machxo2_spi_state,
> +	.write_init = machxo2_write_init,
> +	.write = machxo2_write,
> +	.write_complete = machxo2_write_complete,
> +};
> +
> +static int machxo2_spi_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +
> +	if (spi->max_speed_hz > MACHXO2_MAX_SPEED) {
> +		dev_err(dev, "Speed is too high\n");
> +		return -EINVAL;
> +	}
> +
> +	return fpga_mgr_register(dev, "Lattice MachXO2 SPI FPGA Manager",
> +				 &machxo2_ops, spi);
> +}
> +
> +static int machxo2_spi_remove(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +
> +	fpga_mgr_unregister(dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id of_match[] = {
> +	{ .compatible = "lattice,machxo2-slave-spi", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, of_match);
> +
> +static const struct spi_device_id lattice_ids[] = {
> +	{ "machxo2-slave-spi", 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(spi, lattice_ids);
> +
> +static struct spi_driver machxo2_spi_driver = {
> +	.driver = {
> +		.name = "machxo2-slave-spi",
> +		.of_match_table = of_match_ptr(of_match),
> +	},
> +	.probe = machxo2_spi_probe,
> +	.remove = machxo2_spi_remove,
> +	.id_table = lattice_ids,
> +};
> +
> +module_spi_driver(machxo2_spi_driver)
> +
> +MODULE_AUTHOR("Paolo Pisati <p.pisati@gmail.com>");
> +MODULE_DESCRIPTION("Load Lattice FPGA firmware over SPI");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.7.4
> 

Thanks,
Moritz

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