mtd: add driver for the flash in Lattice machxo2 FPGAs

This driver provides two MTD devices, one for the configuration data (FPGA bitstream) and another for the general purpose user flash.

Both behave as normal MTD devices bit the configuration one has some extra sysfs entries to synchronize updating.

Signed-off-by Martin Fuzzey <[email protected]>

---
  .../bindings/mtd/lattice-machxo2-fpga.txt          |   32 +
  Documentation/mtd/machxo2-fpga.txt                 |  104 ++
  drivers/mtd/devices/Kconfig                        |   31 +
  drivers/mtd/devices/Makefile                       |    3
  drivers/mtd/devices/machxo2-core.c                 |  929 ++++++++++++++++++++
  drivers/mtd/devices/machxo2-spi.c                  |  114 ++
  drivers/mtd/devices/machxo2.h                      |   24 +
  7 files changed, 1236 insertions(+), 1 deletion(-)

create mode 100644 Documentation/devicetree/bindings/mtd/lattice-machxo2-fpga.txt create mode 100644 Documentation/mtd/machxo2-fpga.txt
create mode 100644 drivers/mtd/devices/machxo2-core.c
create mode 100644 drivers/mtd/devices/machxo2-spi.c
create mode 100644 drivers/mtd/devices/machxo2.h

Documentation/devicetree/bindings/mtd/lattice-machxo2-fpga.txt new file +32 -0

new file mode 100644
index 0000000..2fd30fa
@@ -0,0 +1,32 @@
+MTD SPI driver for the configuration (bitstream) and user flash of the Lattice
+Machxo2 family FPGAs.
+
+Required properties:
+- compatible : lattice,machxo2
+
+The two flash regions of the device are represented by the child nodes:
+	"configflash" : for the configuration data (FPGA bitstream)
+	"userflash" :	for the general purpose flash memory
+
+Both of these child nodes are optional (if the child node is missing no
+mtd device will be created)
+
+Each of these child nodes have the same optional properties:
+- linux,mtd-name : name of mtd to create
+
+
+Example:
+&ecspi2 {
+	mainboard-fpga@2 {
+		compatible = "lattice,machxo2";
+		spi-max-frequency = <25000000>;
+		reg = <2>;
+		configflash {
+			linux,mtd-name = "mainboard-fpga-bitstream";
+		};
+		userflash {
+			linux,mtd-name = "mainboard-fpga-userflash";
+		};
+	};
+};
+

Documentation/mtd/machxo2-fpga.txt new file +104 -0

new file mode 100644
index 0000000..c7727a7
@@ -0,0 +1,104 @@
+The Lattice MachXO2 family of FPGAs contain varying amounts of flash memory.
+
+The memory is divided into two parts:
+
+* Configuration flash :
+	Stores the data that determines the logic implemented by the FPGA
+	(sometimes called a "bitstream").
+	This data is created using the Lattice design tools.
+
+* User flash :
+	General user defined data like any other flash memory.
+
+The amount of each type of memory available is hardware defined and depends
+on the exact chip model.
+
+Each part consists of a single erase block, meaning that the user flash is
+probably not suited as backing store for a filesystem.
+
+The FPGA logic actually "executes" from internal RAM, intialised from the
+configuration flash at power up. This means that it is possible to erase and
+reprogram the configuration flash without affecting the FPGA's function.
+
+In order to access these memories the FPGA is connected to the CPU over a
+SPI or I2C bus (the driver currently only supports SPI).
+This is in addition to any other connection the FPGA may have to the CPU bus
+as part of the functionality of it's programmed design.
+
+The user flash is exposed as a standard MTD device.
+
+=== Sysfs Interface ===
+The configuration flash is also exposed as a standard MTD but there are also
+a few special sysfs entries used to identify the FPGA and control the update
+procedure.
+
+device_id	(ro)
+	4 byte hexadecimal raw device model identifer
+	Eg: 01 2b bo 43
+
+name		(ro)
+	Human readable device type name (determined from device_id)
+	Eg: MachXO2-2000 / MachXO2-1200U (those two devices have the same id)
+
+trace_id	(ro)
+	8 byte hexadecimal unique chip identifer
+	Eg: 55 44 30 80 78 0c 68 4e
+
+usercode	(ro)
+	4 byte hexadecimal user defined data.
+	This is programmed into the device as part of the bitstream and
+	may be used for purposes such as version identification etc.
+	Eg: 00 01 01 02
+
+running		(ro)
+	Boolean flag indicating if the internal RAM has been loaded from
+	the flash and the configuration data accepted.
+
+prog_done	(rw)
+	Boolean flag indicating if the configuration flash memory has been
+	programmed.
+	Erasing the configuration flash will set this to zero.
+	Writing any value will set it to one
+	The FPGA cannot apply the data until this is set
+
+refresh		(wo)
+	Writing any value causes the FPGA to refresh it's RAM from the flash
+	and apply the new configuration.
+
+
+=== Bitstream update example ===
+1) Erase the configuration flash
+	# flash_erase /dev/mtd2 0 0
+	Erasing 49 Kibyte @ 0 -- 100 % complete
+
+	# cat /sys/bus/spi/devices/spi2.2/prog_done
+	0
+
+	The FPGA is still running normally from RAM
+	# cat /sys/bus/spi/devices/spi2.2/usercode
+	00 01 01 00
+
+2) Write the new bitstram
+	# cp bitsteam.bin /dev/mtd2
+
+3) Signal that we have finished writing
+	# echo 1 > /sys/bus/spi/devices/spi2.2/prog_done
+
+4) Request a refresh
+	# echo 1 > /sys/bus/spi/devices/spi2.2/refresh
+
+5) Observe new usercode
+	# cat /sys/bus/spi/devices/spi2.2/usercode
+	00 01 01 02
+
+Note that step 4) is the critical one as it will cause any "hardware"
+implemented in the FPGA to temporarilly disappear. Therefore if the FPGA is
+being used to implement "hardware" devices visible to linux the appropriate
+drivers should be unbound between steps 3 and 4.
+
+Alternatively, step 4 may be omitted and a full power cycle done instead.
+
+In some cases a reboot may be done instead of a power cycle but that will
+depend on the board and bootloader design. It will only work if the bootloader
+requests a refresh using the PROGN electrical signal to the FPGA or sending
+the refresh command over SPI.

drivers/mtd/devices/Kconfig +31 -0

index c49d0b1..7ecd457 100644
@@ -120,6 +120,37 @@ config MTD_BCM47XXSFLASH
  	  registered by bcma as platform devices. This enables driver for
  	  serial flash memories (only read-only mode is implemented).
 
+config MTD_MACHXO2_CORE
+	tristate "Lattice MACHXO2 family FPGAs"
+	depends on SPI_MASTER
+	help
+	  This provides access to the configuration ( bitstream) and
+	  general purpose flash memories of the Lattice MACHXO2 family FPGAs
+	  See Documenation/mtd/machxo2-fpga for usage information
+
+	  You should also select a bus interface below (currently only
+	  SPI is implemented but the hardware supports I2C too)
+
+config MTD_MACHXO2_CONFIGFLASH
+	boolean "Allow access to MACHXO2 configuration flash"
+	depends on MTD_MACHXO2_CORE
+	help
+	  If selected the configuration flash (bitstream) in the FPGA
+	  will be exposed as a linux MTD device.
+
+config MTD_MACHXO2_USERFLASH
+	boolean "Allow access to MACHXO2 user flash"
+	depends on MTD_MACHXO2_CORE
+	help
+	  If selected the general purpose user flash in the FPGA will
+	  be exposed as a linux MTD device.
+
+config MTD_MACHXO2_SPI
+	tristate "Lattice MACHXO2 family FPGAs using SPI bus interface"
+	depends on MTD_MACHXO2_CORE && SPI_MASTER
+	help
+	  Select this if your MAXCHXO2 FPGA is connected via a SPI bus.
+
  config MTD_SLRAM
  	tristate "Uncached system RAM"
  	help

drivers/mtd/devices/Makefile +2 -1

index c68868f..f39df4a 100644
@@ -17,6 +17,7 @@ obj-$(CONFIG_MTD_SPEAR_SMI)	+= spear_smi.o
  obj-$(CONFIG_MTD_SST25L)	+= sst25l.o
  obj-$(CONFIG_MTD_BCM47XXSFLASH)	+= bcm47xxsflash.o
  obj-$(CONFIG_MTD_ST_SPI_FSM)    += st_spi_fsm.o
-
+obj-$(CONFIG_MTD_MACHXO2_CORE)	+= machxo2-core.o
+obj-$(CONFIG_MTD_MACHXO2_SPI)	+= machxo2-spi.o
 
  CFLAGS_docg3.o			+= -I$(src)

drivers/mtd/devices/machxo2-core.c new file +15 -0

new file mode 100644
index 0000000..07f4bf1
@@ -0,0 +1,929 @@
+/*
+ * Core MTD driver for Lattice MachXO2 family FPGAs
+ *
+ * It supplies 2 mtd devices for accessing:
+ *	Configuration flash (FPGA bitstream)
+ *	Userflash (general user data)
+ *
+ * In addition it provides a number of sysfs attributes to identify the
+ * FPGA and control the programming process.
+ * See Documentation/mtd/machxo2-fpga.txt
+ *
+ * Copyright 2014 Parkeon
+ * Martin Fuzzey <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it under

drivers/mtd/devices/machxo2-core.c new file +104 -0

+
+#include "machxo2.h"
+
+#define MACHXO2_PAGESIZE		16
+#define MACHXO2_DEVICE_ID_LEN		4
+#define MACHXO2_TRACE_ID_LEN		8
+#define MACHXO2_USERCODE_LEN		4
+
+#define MACHXO2_CMD_SET_ADDR			0xb4
+#define MACHXO2_CMD_READ_CONFIG_FLASH		0x73
+#define MACHXO2_CMD_WRITE_CONFIG_FLASH		0x70
+#define MACHXO2_CMD_READ_UFM			0xca
+#define MACHXO2_CMD_WRITE_UFM			0xc9
+#define MACHXO2_CMD_ERASE			0x0e
+#define MACHXO2_CMD_READ_TRACE_ID		{0x19, 0x00, 0x00, 0x00}
+#define MACHXO2_CMD_READ_USERCODE		{0xc0, 0x00, 0x00, 0x00}
+#define MACHXO2_CMD_READ_DEVICE_ID		{0xe0, 0x00, 0x00, 0x00}
+#define MACHXO2_CMD_BYPASS			{0xff, 0xff, 0xff, 0xff}
+#define MACHXO2_CMD_ENABLE_CONFIG_INTERFACE	{0x74, 0x08, 0x00, 0x00}
+#define MACHXO2_CMD_DISABLE_CONFIG_INTERFACE	{0x26, 0x00, 0x00}
+#define MACHXO2_CMD_PROGRAM_DONE		{0x5e, 0x00, 0x00, 0x00}
+#define MACHXO2_CMD_REFRESH			{0x79, 0x00, 0x00}
+#define MACHXO2_CMD_READ_STATUS_REGSITER	{0x3c, 0x00, 0x00, 0x00}
+#define MACHXO2_STATUS_DONE	(1 << 8)
+#define MACHXO2_STATUS_BUSY	(1 << 12)
+#define MACHXO2_STATUS_FAILED	(1 << 13)
+#define MACHXO2_STATUS_ERR_SHIFT 23
+#define MACHXO2_STATUS_ERR_MASK (7 << MACHXO2_STATUS_ERR_SHIFT)
+
+struct machxo2_flash_descriptor {
+	const char *name;
+	uint8_t read_cmd;
+	uint8_t write_cmd;
+	uint8_t set_addr_param;
+	uint8_t erase_param;
+};
+
+struct machxo2_flash {
+	const char *name;
+	uint32_t nr_pages;
+	const struct machxo2_flash_descriptor *descr;
+	struct machxo2 *machxo2;
+	struct mtd_info mtd;
+};
+
+struct machxo2_device_info {
+	uint8_t b2;
+	const char *name;
+	uint32_t cfg_pages;
+	uint32_t ufm_pages;
+	int max_erase_ms;
+};
+
+struct machxo2 {
+	struct device *dev;
+	struct mutex lock;
+	struct machxo2_busops *busops;
+	uint8_t device_id[MACHXO2_DEVICE_ID_LEN];
+	const struct machxo2_device_info *device_info;
+	struct machxo2_flash configflash;
+	struct machxo2_flash userflash;
+};
+
+struct machxo2_addr {
+	uint16_t first_page;
+	uint16_t nr_pages;
+	uint8_t skip_bytes;
+};
+
+/* Values below taken from dataheet TN1246 Table 17-97
+ * For the max erase time we use the value for the config flash (always larger)
+ */
+static struct machxo2_device_info machxo2_device_ids[] = {
+	{0x00, "MachXO2-256",
+		.cfg_pages = 575, .ufm_pages = 0, .max_erase_ms = 700},
+	{0x10, "MachXO2-640",
+		.cfg_pages = 1151, .ufm_pages = 192, .max_erase_ms = 1100},
+	{0x20, "MachXO2-1200 / MachXO2-640U",
+		.cfg_pages = 2175, .ufm_pages = 512, .max_erase_ms = 1400 },
+	{0x30, "MachXO2-2000 / MachXO2-1200U",
+		.cfg_pages = 3198, .ufm_pages = 640, .max_erase_ms = 1900},
+	{0x40, "MachXO2-4000 / MachXO2-2000U",
+		.cfg_pages = 5758, .ufm_pages = 768, .max_erase_ms = 3100},
+	{0x50, "MachXO2-7000",
+		.cfg_pages = 9212, .ufm_pages = 2048, .max_erase_ms = 4800},
+};
+
+
+static const struct machxo2_flash_descriptor machxo2_userflash_descr = {
+	.name = "userflash",
+	.read_cmd = MACHXO2_CMD_READ_UFM,
+	.write_cmd = MACHXO2_CMD_WRITE_UFM,
+	.set_addr_param = 0x40,
+	.erase_param = 0x08,
+};
+
+static const struct machxo2_flash_descriptor machxo2_configflash_descr = {
+	.name = "configflash",
+	.read_cmd = MACHXO2_CMD_READ_CONFIG_FLASH,
+	.write_cmd = MACHXO2_CMD_WRITE_CONFIG_FLASH,
+	.set_addr_param = 0x00,
+	.erase_param = 0x04,
+};
+

drivers/mtd/devices/machxo2-core.c new file +4 -0

+{
+	bool need_lock;
+	int ret;
+

drivers/mtd/devices/machxo2-core.c new file +34 -0

+}
+
+static const struct machxo2_device_info *machxo2_parse_device_id(uint8_t *buf)
+{
+	int i;
+
+	if (buf[0] != 0x01 || buf[1] != 0x2B || buf[3] != 0x43)
+		return NULL;
+
+	for (i = 0; i < ARRAY_SIZE(machxo2_device_ids); i++) {
+		if ((buf[2] & 0x7F) ==  machxo2_device_ids[i].b2)
+			return &machxo2_device_ids[i];
+	}
+	return NULL;
+}
+
+static int machxo2_identify_device(struct machxo2 *machxo2)
+{
+	uint8_t trace_id[MACHXO2_TRACE_ID_LEN];
+	uint8_t usercode[MACHXO2_USERCODE_LEN];
+	int ret;
+
+	ret = machxo2_read_device_id(machxo2, machxo2->device_id);
+	if (ret)
+		return ret;
+
+	ret = machxo2_read_trace_id(machxo2, trace_id);
+	if (ret)
+		return ret;
+
+	ret = machxo2_read_usercode(machxo2, usercode);
+	if (ret)
+		return ret;
+

drivers/mtd/devices/machxo2-core.c new file +11 -0

+	return -ENODEV;
+}
+
+/* ============================================================= */
+/* MTD */
+/* ============================================================= */
+static void machxo2_make_address(struct mtd_info *mtd,
+	uint32_t from, uint32_t len, struct machxo2_addr *addr)
+{
+	addr->first_page = from / MACHXO2_PAGESIZE;
+	addr->skip_bytes = from % MACHXO2_PAGESIZE;

drivers/mtd/devices/machxo2-core.c new file +22 -0

+{
+	int err;
+
+	if (!(status & MACHXO2_STATUS_FAILED))
+		return 0;
+
+
+	err = (status & MACHXO2_STATUS_ERR_MASK) >> MACHXO2_STATUS_ERR_SHIFT;
+	dev_err(dev, "Failed %s err=0x%x\n", operation, err);
+
+	return -EIO;
+}
+
+static int machxo2_read_status(struct machxo2 *machxo2, uint32_t *status_out)
+{
+	uint8_t cmd[] = MACHXO2_CMD_READ_STATUS_REGSITER;
+	uint32_t status;
+	int ret;
+
+	ret = machxo2_transceive(machxo2,
+					cmd, sizeof(cmd),
+					&status, sizeof(status));

drivers/mtd/devices/machxo2-core.c new file +616 -0

+{
+	uint32_t status;
+	int i, ret;
+
+	for (i = 0; i < retries; i++) {
+		ret = machxo2_read_status(flash->machxo2, &status);
+		if (ret)
+			return ret;
+
+		if (!(status & MACHXO2_STATUS_BUSY)) {
+			dev_dbg(&flash->mtd.dev, "Wait %s done loop %d\n",
+							operation, i);
+			return machxo2_check_error_code(&flash->mtd.dev,
+							status, operation);
+		}
+
+		if (poll_us < 1000)
+			udelay(poll_us);
+		else
+			msleep(poll_us / 1000);
+	}
+	return -ETIMEDOUT;
+}
+
+static int machxo2_flash_enable_interface(struct machxo2_flash *flash)
+{
+	uint8_t cmd[] = MACHXO2_CMD_ENABLE_CONFIG_INTERFACE;
+	int ret;
+
+	ret = machxo2_transceive(flash->machxo2, cmd, sizeof(cmd), NULL, 0);
+	if (ret)
+		return ret;
+
+	/* Datasheet: Enable time 5us
+	 * So poll every 2us with 5 max polls */
+	return machxo2_flash_wait_not_busy(flash, 2, 5, "enable");
+}
+
+static int machxo2_flash_disable_interface(struct machxo2_flash *flash)
+{
+	struct machxo2 *machxo2 = flash->machxo2;
+	uint8_t disable[] = MACHXO2_CMD_DISABLE_CONFIG_INTERFACE;
+	uint8_t bypass[] = MACHXO2_CMD_BYPASS;
+	int ret;
+
+	ret = machxo2_transceive(machxo2, disable, sizeof(disable), NULL, 0);
+	if (ret)
+		return ret;
+
+	return machxo2_transceive(machxo2, bypass, sizeof(bypass), NULL, 0);
+}
+
+
+/* Do a transceive wrapped in enable, disable */
+static int machxo2_trasceive_wait_with_enable(struct machxo2 *machxo2,
+				const void *send_buf, unsigned send_len,
+				void *recv_buf, unsigned recv_len,
+				unsigned poll_us, int retries,
+				const char *name)
+{
+	int ret;
+
+	machxo2_lock(machxo2);
+
+	ret = machxo2_flash_enable_interface(&machxo2->configflash);
+	if (ret)
+		goto out;
+
+	ret = machxo2_transceive(machxo2, send_buf, send_len,
+					recv_buf, recv_len);
+
+	if (!ret && poll_us)
+		ret = machxo2_flash_wait_not_busy(&machxo2->configflash,
+							poll_us, retries,
+							name);
+
+	machxo2_flash_disable_interface(&machxo2->configflash);
+
+out:
+	machxo2_unlock(machxo2);
+	return ret;
+}
+
+static int machxo2_set_page_address(struct machxo2_flash *flash, uint16_t page)
+{
+	uint8_t cmd[] = { MACHXO2_CMD_SET_ADDR, 0x00, 0x00, 0x00,
+				flash->descr->set_addr_param, 0x00,
+				(page & 0x3F00) >>  8,
+				(page & 0xFF)};
+
+	return machxo2_transceive(flash->machxo2, cmd, sizeof(cmd), NULL, 0);
+}
+
+
+static int machxo2_write_page(struct machxo2_flash *flash, const uint8_t *buf)
+{
+	uint8_t cmd[MACHXO2_PAGESIZE + 4] = {
+			flash->descr->write_cmd, 0x00, 0x00, 0x01 };
+	int ret;
+
+	memcpy(cmd + 4, buf, MACHXO2_PAGESIZE);
+
+	ret = machxo2_transceive(flash->machxo2, cmd, sizeof(cmd), NULL, 0);
+	if (ret)
+		return ret;
+
+	/* Datasheet: Write time 200us
+	 * So poll every 50us with 10 max polls */
+	return machxo2_flash_wait_not_busy(flash, 50, 10, "write");
+}
+
+
+static int machxo2_flash_read_pages(
+		struct machxo2_flash *flash, uint16_t nr_pages, uint8_t *buf)
+{
+	uint8_t cmd[] = {	flash->descr->read_cmd, 0x10,
+				(nr_pages & 0x3F00) >>  8,
+				(nr_pages & 0xFF)};
+
+	return machxo2_transceive(flash->machxo2,
+			cmd, sizeof(cmd), buf, nr_pages * MACHXO2_PAGESIZE);
+}
+
+static int machxo2_mtd_read(struct mtd_info *mtd,
+		loff_t from, size_t len,
+		size_t *retlen, u_char *buf)
+{
+	struct machxo2_flash *flash = mtd->priv;
+	struct machxo2 *machxo2 = flash->machxo2;
+	int ret;
+	struct machxo2_addr addr;
+
+	dev_dbg(&mtd->dev, "read: from=%llu size=%zu\n", from, len);
+
+	machxo2_lock(machxo2);
+
+	ret = machxo2_flash_enable_interface(flash);
+	if (ret)
+		goto out;
+
+	machxo2_make_address(mtd, from, len, &addr);
+	ret = machxo2_set_page_address(flash, addr.first_page);
+	if (ret)
+		goto out_disable;
+
+	if (addr.nr_pages == 1 && addr.skip_bytes == 0) {
+		ret = machxo2_flash_read_pages(flash, 1, buf);
+	} else {
+		/* Warning: this will not work for I2C mode which returns
+		 * data differently for > 1 page reads.
+		 * However I2C mode is not implemented yet */
+		uint8_t *tmp;
+
+		/* For > 1 page read chip returns a dummp page first */
+		if (addr.nr_pages > 1) {
+			addr.nr_pages++;
+			addr.skip_bytes += MACHXO2_PAGESIZE;
+		}
+
+		tmp = kmalloc(addr.nr_pages * MACHXO2_PAGESIZE, GFP_KERNEL);
+		if (!tmp) {
+			ret = -ENOMEM;
+			goto out_disable;
+		}
+
+		ret = machxo2_flash_read_pages(flash, addr.nr_pages, tmp);
+		if (!ret)
+			memcpy(buf, tmp + addr.skip_bytes, len);
+		kfree(tmp);
+	}
+	if (!ret)
+		*retlen = len;
+
+out_disable:
+	machxo2_flash_disable_interface(flash);
+
+out:
+	machxo2_unlock(machxo2);
+	return ret;
+}
+
+
+static int machxo2_mtd_write(struct mtd_info *mtd,
+		loff_t to, size_t len,
+		size_t *retlen, const u_char *buf)
+{
+	struct machxo2_flash *flash = mtd->priv;
+	struct machxo2 *machxo2 = flash->machxo2;
+	int ret;
+	struct machxo2_addr addr;
+	uint8_t tmp[MACHXO2_PAGESIZE];
+	uint32_t remaining = len;
+
+	dev_dbg(&mtd->dev, "write: to=%llu size=%zu\n", to, len);
+
+	machxo2_lock(machxo2);
+
+	ret = machxo2_flash_enable_interface(flash);
+	if (ret)
+		goto out;
+
+	machxo2_make_address(mtd, to, len, &addr);
+	ret = machxo2_set_page_address(flash, addr.first_page);
+	if (ret)
+		goto out_disable;
+
+	if (addr.skip_bytes > 0) {
+		/* Write the first partial page */
+		uint32_t count = MACHXO2_PAGESIZE - addr.skip_bytes;
+
+		if (count > remaining)
+			count = remaining;
+		dev_dbg(&mtd->dev, "write: head partial page %d\n", count);
+
+		ret = machxo2_flash_read_pages(flash, 1, tmp);
+		if (ret)
+			goto out_disable;
+
+		ret = machxo2_set_page_address(flash, addr.first_page);
+		if (ret)
+			goto out_disable;
+
+		memcpy(tmp + addr.skip_bytes, buf, count);
+		ret = machxo2_write_page(flash, tmp);
+		if (ret)
+			goto out_disable;
+
+		buf += count;
+		remaining -= count;
+	}
+
+	/* Writa all complete pages */
+	while (remaining >= MACHXO2_PAGESIZE) {
+		dev_dbg(&mtd->dev, "write: full page remaining=%d\n",
+								remaining);
+		ret = machxo2_write_page(flash, buf);
+		if (ret)
+			goto out_disable;
+		buf += MACHXO2_PAGESIZE;
+		remaining -= MACHXO2_PAGESIZE;
+	}
+
+
+	if (remaining > 0) {
+		/* Write final partial page */
+		dev_dbg(&mtd->dev, "write: partial page remaining=%d\n",
+								remaining);
+		ret = machxo2_flash_read_pages(flash, 1, tmp);
+		if (ret)
+			goto out_disable;
+
+		memcpy(tmp, buf, remaining);
+
+		ret = machxo2_set_page_address(flash,
+			addr.first_page + addr.nr_pages - 1);
+		if (ret)
+			goto out_disable;
+
+		ret = machxo2_write_page(flash, tmp);
+		if (ret)
+			goto out_disable;
+
+		remaining = 0;
+	}
+
+out_disable:
+	machxo2_flash_disable_interface(flash);
+	*retlen = len - remaining;
+
+out:
+	machxo2_unlock(machxo2);
+	dev_dbg(&mtd->dev, "write done ret=%d retlen=%zu", ret, *retlen);
+	return ret;
+}
+
+
+static int machxo2_mtd_erase(struct mtd_info *mtd,
+		struct erase_info *instr)
+{
+	struct machxo2_flash *flash = mtd->priv;
+	struct machxo2 *machxo2 = flash->machxo2;
+	uint8_t cmd[] = { MACHXO2_CMD_ERASE, flash->descr->erase_param, 0, 0 };
+	int ret;
+	int pollms;
+
+	dev_dbg(&mtd->dev, "erase\n");
+
+	machxo2_lock(machxo2);
+
+	ret = machxo2_flash_enable_interface(flash);
+	if (ret)
+		goto out;
+
+	ret = machxo2_transceive(machxo2, cmd, sizeof(cmd), NULL, 0);
+	if (ret)
+		goto out_disable;
+
+	pollms = 200;
+	ret = machxo2_flash_wait_not_busy(flash,
+			pollms * 1000,
+			(machxo2->device_info->max_erase_ms + 500) / pollms,
+			"erase");
+
+out_disable:
+	machxo2_flash_disable_interface(flash);
+
+out:
+	machxo2_unlock(machxo2);
+
+	dev_dbg(&mtd->dev, "erase done ret=%d", ret);
+	if (!ret) {
+		instr->state = MTD_ERASE_DONE;
+		mtd_erase_callback(instr);
+	}
+
+	return ret;
+}
+
+static int machxo2_flash_add(struct machxo2_flash *flash)
+{
+	struct device *dev = flash->machxo2->dev;
+	struct mtd_info *mtd = &flash->mtd;
+	struct device_node *np;
+	int ret;
+
+	np = of_find_node_by_name(dev->of_node, flash->descr->name);
+	if (of_property_read_string(np, "linux,mtd-name", &mtd->name)) {
+		flash->name = kasprintf(GFP_KERNEL, "%s-%s",
+					dev_name(dev), flash->descr->name);
+		if (!flash->name)
+			return -ENOMEM;
+
+		mtd->name = flash->name;
+	}
+
+	mtd->size = flash->nr_pages * MACHXO2_PAGESIZE;
+	mtd->erasesize = mtd->size;
+	mtd->writesize = MACHXO2_PAGESIZE;
+	mtd->owner = THIS_MODULE;
+	mtd->type = MTD_NANDFLASH;
+	mtd->flags = MTD_WRITEABLE;
+	mtd->_erase = machxo2_mtd_erase;
+	mtd->_read = machxo2_mtd_read;
+	mtd->_write = machxo2_mtd_write;
+	mtd->priv = flash;
+	mtd->dev.parent = dev;
+
+	ret = mtd_device_register(mtd, NULL, 0);
+	if (ret) {
+		dev_err(dev, "Unable to register MTD device, aborting!\n");
+		goto out_err;
+	}
+
+	dev_info(dev, "mtd%d: (%s) size %uKiB.\n",
+				mtd->index, mtd->name,
+				(uint32_t)(mtd->size >> 10));
+	return 0;
+
+out_err:
+	kfree(flash->name);
+	return ret;
+}
+
+static void machxo2_flash_remove(struct machxo2_flash *flash)
+{
+	mtd_device_unregister(&flash->mtd);
+	kfree(flash->name);
+}
+
+
+/* ============================================================= */
+/* Sysfs */
+/* ============================================================= */
+
+static ssize_t show_device_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%*ph\n",
+			sizeof(machxo2->device_id), machxo2->device_id);
+}
+
+static ssize_t show_device_name(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	const struct machxo2_device_info *found;
+
+	found = machxo2_parse_device_id(machxo2->device_id);
+
+	return sprintf(buf, "%s\n", found ? found->name : "unknown");
+}
+
+
+static ssize_t show_trace_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint8_t trace_id[MACHXO2_TRACE_ID_LEN];
+	int ret;
+
+	ret = machxo2_read_trace_id(machxo2, trace_id);
+	if (ret)
+		return ret;
+	return sprintf(buf, "%*ph\n",
+			sizeof(trace_id), trace_id);
+}
+
+static ssize_t show_usercode(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint8_t usercode[MACHXO2_USERCODE_LEN];
+	int ret;
+
+	ret = machxo2_read_usercode(machxo2, usercode);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%*ph\n",
+			sizeof(usercode), usercode);
+}
+
+static ssize_t show_running(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint32_t status;
+	int ret;
+
+	/* Reading status without enabling interface gives RAM state
+	 * Hence DONE => FPGA running */
+	ret = machxo2_read_status(machxo2, &status);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%d\n", status & MACHXO2_STATUS_DONE ? 1 : 0);
+}
+
+
+static ssize_t show_prog_done(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint32_t status;
+	int ret;
+
+	machxo2_lock(machxo2);
+
+	/* Reading status after enabling interface gives FLASH state
+	 * Hence DONE => config FLASH programmed */
+	ret = machxo2_flash_enable_interface(&machxo2->configflash);
+	if (ret)
+		goto out;
+
+	ret = machxo2_read_status(machxo2, &status);
+	machxo2_flash_disable_interface(&machxo2->configflash);
+
+	if (ret)
+		return ret;
+
+	ret = sprintf(buf, "%d\n", status & MACHXO2_STATUS_DONE ? 1 : 0);
+
+out:
+	machxo2_unlock(machxo2);
+	return ret;
+}
+
+static ssize_t store_prog_done(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint8_t cmd[] = MACHXO2_CMD_PROGRAM_DONE;
+	int ret;
+
+	/* Datasheet: Write time 200us so poll every 50us with 10 max polls */
+	ret = machxo2_trasceive_wait_with_enable(machxo2,
+			cmd, sizeof(cmd), NULL, 0, 50, 10, "set_prog_done");
+
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+
+static ssize_t store_refresh(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct machxo2 *machxo2 = dev_get_drvdata(dev);
+	uint8_t cmd[] = MACHXO2_CMD_REFRESH;
+	uint32_t status;
+	int ret;
+
+	ret = machxo2_transceive(machxo2, cmd, sizeof(cmd), NULL, 0);
+	if (ret)
+		return ret;
+
+	msleep(25); /* Datasheet gives 3.8ms tREFRESH for largest device */
+
+	ret = machxo2_read_status(machxo2, &status);
+	if (ret)
+		return ret;
+
+	if (status & MACHXO2_STATUS_DONE)
+		return count;
+
+	/* The chip didn't like the configuration data */
+	dev_err(dev, "Refresh failed status=%d\n",
+		(status & MACHXO2_STATUS_ERR_MASK) >> MACHXO2_STATUS_ERR_SHIFT);
+
+	return -EBADMSG;
+}
+
+
+static DEVICE_ATTR(device_id, S_IRUGO, show_device_id, NULL);
+static DEVICE_ATTR(name, S_IRUGO, show_device_name, NULL);
+static DEVICE_ATTR(trace_id, S_IRUGO, show_trace_id, NULL);
+static DEVICE_ATTR(usercode, S_IRUGO, show_usercode, NULL);
+static DEVICE_ATTR(running, S_IRUGO, show_running, NULL);
+static DEVICE_ATTR(prog_done, S_IRUGO | S_IWUSR,
+				show_prog_done, store_prog_done);
+static DEVICE_ATTR(refresh, S_IWUSR, NULL, store_refresh);
+
+static struct attribute *machxo2_sysfs_entries[] = {
+	&dev_attr_device_id.attr,
+	&dev_attr_name.attr,
+	&dev_attr_trace_id.attr,
+	&dev_attr_usercode.attr,
+	&dev_attr_running.attr,
+	&dev_attr_prog_done.attr,
+	&dev_attr_refresh.attr,
+	NULL,
+};
+
+static struct attribute_group machxo2_attr_group = {
+	.attrs	= machxo2_sysfs_entries,
+};
+
+/* ============================================================= */
+/* Init */
+/* ============================================================= */
+
+struct machxo2 *machxo2_create(struct device *dev,
+					struct machxo2_busops *busops)
+{
+	struct machxo2 *machxo2;
+	struct machxo2_flash *flash;
+	int ret;
+
+	machxo2 = devm_kzalloc(dev, sizeof(*machxo2), GFP_KERNEL);
+	if (!machxo2)
+		return ERR_PTR(-ENOMEM);
+
+	machxo2->dev = dev;
+	machxo2->busops = busops;
+
+	mutex_init(&machxo2->lock);
+
+	machxo2_lock(machxo2);
+	ret = machxo2_identify_device(machxo2);
+	machxo2_unlock(machxo2);
+
+	if (ret)
+		goto fail_identify;
+
+#ifdef CONFIG_MTD_MACHXO2_CONFIGFLASH
+	flash = &machxo2->configflash;
+	flash->machxo2 = machxo2;
+	flash->descr = &machxo2_configflash_descr;
+	flash->nr_pages = machxo2->device_info->cfg_pages;
+	ret = machxo2_flash_add(flash);
+	if (ret)
+		goto fail_configflash;
+#endif
+
+#ifdef CONFIG_MTD_MACHXO2_USERFLASH
+	if (machxo2->device_info->ufm_pages > 0) {
+		flash = &machxo2->userflash;
+		flash->machxo2 = machxo2;
+		flash->descr = &machxo2_userflash_descr;
+		flash->nr_pages = machxo2->device_info->ufm_pages;
+		ret = machxo2_flash_add(flash);
+		if (ret)
+			goto fail_userflash;
+	}
+#endif
+
+	ret = sysfs_create_group(&machxo2->dev->kobj, &machxo2_attr_group);
+	if (ret)
+		goto fail_sysfs;
+
+	return machxo2;
+
+fail_sysfs:
+	machxo2_flash_remove(&machxo2->userflash);
+fail_userflash:
+	machxo2_flash_remove(&machxo2->configflash);
+fail_configflash:
+fail_identify:
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(machxo2_create);
+
+void machxo2_destroy(struct machxo2 *machxo2)
+{
+	machxo2_flash_remove(&machxo2->userflash);
+	sysfs_remove_group(&machxo2->dev->kobj, &machxo2_attr_group);
+}
+EXPORT_SYMBOL_GPL(machxo2_destroy);
+
+MODULE_DESCRIPTION("MTD driver for Lattice MachXO2 family FPGAs");
+MODULE_AUTHOR("Martin Fuzzey <[email protected]>");
+MODULE_LICENSE("GPL v2");

drivers/mtd/devices/machxo2-spi.c new file +23 -0

new file mode 100644
index 0000000..e4421fd
@@ -0,0 +1,114 @@
+/*
+ * SPI bus interface for Lattice MachXO2 family FPGAs
+ *
+ * Copyright (C) 2014 Parkeon
+ * Martin Fuzzey <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#include "machxo2.h"
+
+
+static const struct spi_device_id machxo2_spi_device_id[] = {
+	{
+		.name = "machxo2",
+	}, {
+		/* sentinel */

drivers/mtd/devices/machxo2-spi.c new file +39 -0

+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct spi_message msg;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = send_buf,
+			.len = send_len,
+		},
+		{
+			.rx_buf = recv_buf,
+			.len = recv_len,
+		}
+	};
+
+	spi_message_init_with_transfers(&msg, xfers, ARRAY_SIZE(xfers));
+
+	return spi_sync(spi, &msg);
+}
+
+
+static struct machxo2_busops machxo2_spi_busops = {
+	.transceive = machxo2_spi_transceive,
+};
+
+
+static int machxo2_spi_probe(struct spi_device *spi)
+{
+	struct machxo2 *machxo2;
+
+	machxo2 =  machxo2_create(&spi->dev, &machxo2_spi_busops);
+	if (IS_ERR(machxo2))
+		return PTR_ERR(machxo2);
+
+	spi_set_drvdata(spi, machxo2);
+
+	return 0;
+}
+
+

drivers/mtd/devices/machxo2-spi.c new file +9 -0

+		.of_match_table = machxo2_dt_ids,
+	},
+	.probe		= machxo2_spi_probe,
+	.remove		= machxo2_spi_remove,
+};
+
+
+static int __init machxo2_init(void)
+{

drivers/mtd/devices/machxo2-spi.c new file +3 -0

+MODULE_AUTHOR("Martin Fuzzey <[email protected]>");
+MODULE_DESCRIPTION("MachXO2 FPGA SPI bus driver");
+MODULE_LICENSE("GPL");

drivers/mtd/devices/machxo2.h new file +9 -0

new file mode 100644
index 0000000..e0213d0
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2014 Parkeon
+ * Martin Fuzzey <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ */
+#ifndef __DRIVERS_MTD_MACHXO2_H

Quoted 6 lines · Martin Fuzzey

This driver provides two MTD devices, one for the configuration data (FPGA bitstream) and another for the general purpose user flash.

Both behave as normal MTD devices bit the configuration one has some extra sysfs entries to synchronize updating.

drivers/mtd/devices/machxo2-core.c line 25

Quoted 7 lines

Signed-off-by Martin Fuzzey <[email protected]>

drivers/mtd/devices/machxo2-core.c new file +6 -0

+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mutex.h>
+#include <linux/of.h>

Includes in alphabetical order...

drivers/mtd/devices/machxo2-core.c line 139

Quoted 7 lines

drivers/mtd/devices/machxo2-core.c new file +7 -0

+
+static void machxo2_lock(struct machxo2 *machxo2)
+{
+    if (!mutex_trylock(&machxo2->lock)) {
+        dev_dbg(machxo2->dev, "wait for %s from %pf\n",
+                __func__, __builtin_return_address(0));
+

dev_dbg(machxo2->dev, "wait for %s from %pf\n",

    __func__, __builtin_return_address(0));

+static int machxo2_transceive(

drivers/mtd/devices/machxo2-core.c line 157

Quoted 3 lines

drivers/mtd/devices/machxo2-core.c new file +3 -0

+            struct machxo2 *machxo2,
+            const void *send_buf, unsigned send_len,
+            void *recv_buf, unsigned recv_len)

static int machxo2_transceive(struct machxo2 *machxo2,
const void *send_buf, unsigned send_len, void *recv_buf, unsigned recv_len)

Quoted 10 lines

drivers/mtd/devices/machxo2-spi.c new file +9 -0

+static const struct spi_device_id machxo2_spi_device_id[] = {
+    {
+        .name = "machxo2",
+    }, {
+        /* sentinel */
+    }
+};
+MODULE_DEVICE_TABLE(spi, machxo2_spi_device_id);
+

drivers/mtd/devices/machxo2-spi.c line 33

Quoted 6 lines

drivers/mtd/devices/machxo2-spi.c new file +6 -0

+static const struct of_device_id machxo2_dt_ids[] = {
+    { .compatible = "lattice,machxo2"},
+    { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, machxo2_dt_ids);
+

move the device ids after probe()/remove()...

drivers/mtd/devices/machxo2-spi.c line 38

Quoted 5 lines

drivers/mtd/devices/machxo2-spi.c new file +5 -0

+
+static int  machxo2_spi_transceive(
+            struct device *dev,
+            const void *send_buf, unsigned send_len,
+            void *recv_buf, unsigned recv_len)

proper alignment...

static int machxo2_spi_transceive(struct device *dev,
const void *send_buf, unsigned send_len, void *recv_buf, unsigned recv_len)

drivers/mtd/devices/machxo2-spi.c line 92

Quoted 6 lines

drivers/mtd/devices/machxo2-spi.c new file +5 -0

+static struct spi_driver machxo2_spi_driver = {
+    .id_table = machxo2_spi_device_id,
+    .driver = {
+        .name    = "machxo2",
+        .owner    = THIS_MODULE,

we can drop owner field...

Quoted 13 lines

drivers/mtd/devices/machxo2-spi.c new file +13 -0

+        .of_match_table = machxo2_dt_ids,
+    },
+    .probe        = machxo2_spi_probe,
+    .remove        = machxo2_spi_remove,
+};
+
+
+static int __init machxo2_init(void)
+{
+    return spi_register_driver(&machxo2_spi_driver);
+}
+subsys_initcall(machxo2_init);
+

drivers/mtd/devices/machxo2-spi.c line 111

Quoted 6 lines

drivers/mtd/devices/machxo2-spi.c new file +6 -0

+static void __exit machxo2_exit(void)
+{
+    spi_unregister_driver(&machxo2_spi_driver);
+}
+module_exit(machxo2_exit);
+

module_spi_driver()...?

drivers/mtd/devices/machxo2.h line 19

Quoted 8 lines

drivers/mtd/devices/machxo2.h new file +8 -0

+struct machxo2;
+struct machxo2_busops {
+    int (*transceive)(
+            struct device *dev,
+            const void *send_buf, unsigned send_len,
+            void *recv_buf, unsigned recv_len);
+};
+

proper indentation...

int (*transceive)(struct device *dev,
const void *send_buf, unsigned send_len, void *recv_buf, unsigned recv_len);

drivers/mtd/devices/machxo2.h line 22

Quoted 3 lines

drivers/mtd/devices/machxo2.h new file +3 -0

+struct machxo2 *machxo2_create(struct device *dev,
+            struct machxo2_busops *busops);
+

struct machxo2 *machxo2_create(struct device *dev,

                   struct machxo2_busops *busops);

This patch has coding style problems.. run checkpatch on this patch..

+

Quoted 10 lines

drivers/mtd/devices/machxo2-core.c line 139

Quoted 6 lines

drivers/mtd/devices/machxo2-core.c new file +6 -0

+static void machxo2_lock(struct machxo2 *machxo2)
+{
+    if (!mutex_trylock(&machxo2->lock)) {
+        dev_dbg(machxo2->dev, "wait for %s from %pf\n",
+                __func__, __builtin_return_address(0));
+

dev_dbg(machxo2->dev, "wait for %s from %pf\n",

    __func__, __builtin_return_address(0));

Sorry, not understanding here.
You want the second line to be LESS intented??

Coding style (chapter 2) says:
Descendants are always substantially shorter than the parent and are placed substantially to the right

Idem for the others

Quoted 6 lines

+static int machxo2_transceive(

Quoted 3 lines

drivers/mtd/devices/machxo2-core.c new file +3 -0

+            struct machxo2 *machxo2,
+            const void *send_buf, unsigned send_len,
+            void *recv_buf, unsigned recv_len)

Quoted 8 lines

drivers/mtd/devices/machxo2.h line 22

Quoted 3 lines

drivers/mtd/devices/machxo2.h new file +3 -0

+struct machxo2 *machxo2_create(struct device *dev,
+            struct machxo2_busops *busops);
+

struct machxo2 *machxo2_create(struct device *dev,

                   struct machxo2_busops *busops);

Same again - is it just too much indenting?
I don't see anything wrong here