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

From: Moritz Fischer <hidden>
Date: 2017-05-01 17:59:48
Also in: linux-fpga, lkml

Hi Paolo,

couple of nits inline, looks pretty good already.

On Mon, May 01, 2017 at 03:15:12PM +0200, Paolo Pisati wrote:

quoted hunk ↗ jump to hunk

This patch adds support to the FPGA manager for programming
MachXO2 device’s internal flash memory, via slave SPI.

Signed-off-by: Paolo Pisati <redacted>
---
 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * 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 [off-list ref]");
+MODULE_DESCRIPTION("Load Lattice FPGA firmware over SPI");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Thanks,
Moritz

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