SPI Flash subsystem

This adds a new SPI flash subsystem.

Currently, only AT45 DataFlash in non-power-of-two mode is supported,
but some preliminary support for other flash types is in place as
well.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

1 files changed, 362 insertions, 0 deletions

diff --git a/drivers/mtd/spi/atmel.c b/drivers/mtd/spi/atmel.c
new file mode 100644
index 0000000..fb7a4a9
--- /dev/null
+++ b/drivers/mtd/spi/atmel.c
@@ -0,0 +1,362 @@
+/*
+ * Atmel SPI DataFlash support
+ *
+ * Copyright (C) 2008 Atmel Corporation
+ */
+#define DEBUG
+#include <common.h>
+#include <malloc.h>
+#include <spi_flash.h>
+
+#include "spi_flash_internal.h"
+
+/* AT45-specific commands */
+#define CMD_AT45_READ_STATUS		0xd7
+#define CMD_AT45_ERASE_PAGE		0x81
+#define CMD_AT45_LOAD_PROG_BUF1		0x82
+#define CMD_AT45_LOAD_BUF1		0x84
+#define CMD_AT45_LOAD_PROG_BUF2		0x85
+#define CMD_AT45_LOAD_BUF2		0x87
+#define CMD_AT45_PROG_BUF1		0x88
+#define CMD_AT45_PROG_BUF2		0x89
+
+/* AT45 status register bits */
+#define AT45_STATUS_P2_PAGE_SIZE	(1 << 0)
+#define AT45_STATUS_READY		(1 << 7)
+
+/* DataFlash family IDs, as obtained from the second idcode byte */
+#define DF_FAMILY_AT26F			0
+#define DF_FAMILY_AT45			1
+#define DF_FAMILY_AT26DF		2	/* AT25DF and AT26DF */
+
+struct atmel_spi_flash_params {
+	u8		idcode1;
+	/* Log2 of page size in power-of-two mode */
+	u8		l2_page_size;
+	u8		pages_per_block;
+	u8		blocks_per_sector;
+	u8		nr_sectors;
+	const char	*name;
+};
+
+struct atmel_spi_flash {
+	const struct atmel_spi_flash_params *params;
+	struct spi_flash flash;
+};
+
+static inline struct atmel_spi_flash *
+to_atmel_spi_flash(struct spi_flash *flash)
+{
+	return container_of(flash, struct atmel_spi_flash, flash);
+}
+
+static const struct atmel_spi_flash_params atmel_spi_flash_table[] = {
+	{
+		.idcode1		= 0x28,
+		.l2_page_size		= 10,
+		.pages_per_block	= 8,
+		.blocks_per_sector	= 32,
+		.nr_sectors		= 32,
+		.name			= "AT45DB642D",
+	},
+};
+
+static int at45_wait_ready(struct spi_flash *flash, unsigned long timeout)
+{
+	struct spi_slave *spi = flash->spi;
+	unsigned long timebase;
+	int ret;
+	u8 cmd = CMD_AT45_READ_STATUS;
+	u8 status;
+
+	timebase = get_timer(0);
+
+	ret = spi_xfer(spi, 8, &cmd, NULL, SPI_XFER_BEGIN);
+	if (ret)
+		return -1;
+
+	do {
+		ret = spi_xfer(spi, 8, NULL, &status, 0);
+		if (ret)
+			return -1;
+
+		if (status & AT45_STATUS_READY)
+			break;
+	} while (get_timer(timebase) < timeout);
+
+	/* Deactivate CS */
+	spi_xfer(spi, 0, NULL, NULL, SPI_XFER_END);
+
+	if (status & AT45_STATUS_READY)
+		return 0;
+
+	/* Timed out */
+	return -1;
+}
+
+/*
+ * Assemble the address part of a command for AT45 devices in
+ * non-power-of-two page size mode.
+ */
+static void at45_build_address(struct atmel_spi_flash *asf, u8 *cmd, u32 offset)
+{
+	unsigned long page_addr;
+	unsigned long byte_addr;
+	unsigned long page_size;
+	unsigned int page_shift;
+
+	/*
+	 * The "extra" space per page is the power-of-two page size
+	 * divided by 32.
+	 */
+	page_shift = asf->params->l2_page_size;
+	page_size = (1 << page_shift) + (1 << (page_shift - 5));
+	page_shift++;
+	page_addr = offset / page_size;
+	byte_addr = offset % page_size;
+
+	cmd[0] = page_addr >> (16 - page_shift);
+	cmd[1] = page_addr << (page_shift - 8) | (byte_addr >> 8);
+	cmd[2] = byte_addr;
+}
+
+static int dataflash_read_fast_p2(struct spi_flash *flash,
+		u32 offset, size_t len, void *buf)
+{
+	u8 cmd[5];
+
+	cmd[0] = CMD_READ_ARRAY_FAST;
+	cmd[1] = offset >> 16;
+	cmd[2] = offset >> 8;
+	cmd[3] = offset;
+	cmd[4] = 0x00;
+
+	return spi_flash_read_common(flash, cmd, sizeof(cmd), buf, len);
+}
+
+static int dataflash_read_fast_at45(struct spi_flash *flash,
+		u32 offset, size_t len, void *buf)
+{
+	struct atmel_spi_flash *asf = to_atmel_spi_flash(flash);
+	u8 cmd[5];
+
+	cmd[0] = CMD_READ_ARRAY_FAST;
+	at45_build_address(asf, cmd + 1, offset);
+	cmd[4] = 0x00;
+
+	return spi_flash_read_common(flash, cmd, sizeof(cmd), buf, len);
+}
+
+static int dataflash_write_at45(struct spi_flash *flash,
+		u32 offset, size_t len, const void *buf)
+{
+	struct atmel_spi_flash *asf = to_atmel_spi_flash(flash);
+	unsigned long page_addr;
+	unsigned long byte_addr;
+	unsigned long page_size;
+	unsigned int page_shift;
+	size_t chunk_len;
+	size_t actual;
+	int ret;
+	u8 cmd[4];
+
+	page_shift = asf->params->l2_page_size;
+	page_size = (1 << page_shift) + (1 << (page_shift - 5));
+	page_shift++;
+	page_addr = offset / page_size;
+	byte_addr = offset % page_size;
+
+	ret = spi_claim_bus(flash->spi);
+	if (ret) {
+		debug("SF: Unable to claim SPI bus\n");
+		return ret;
+	}
+
+	for (actual = 0; actual < len; actual += chunk_len) {
+		chunk_len = min(len - actual, page_size - byte_addr);
+
+		/* Use the same address bits for both commands */
+		cmd[0] = CMD_AT45_LOAD_BUF1;
+		cmd[1] = page_addr >> (16 - page_shift);
+		cmd[2] = page_addr << (page_shift - 8) | (byte_addr >> 8);
+		cmd[3] = byte_addr;
+
+		ret = spi_flash_cmd_write(flash->spi, cmd, 4,
+				buf + actual, chunk_len);
+		if (ret < 0) {
+			debug("SF: Loading AT45 buffer failed\n");
+			goto out;
+		}
+
+		cmd[0] = CMD_AT45_PROG_BUF1;
+		ret = spi_flash_cmd_write(flash->spi, cmd, 4, NULL, 0);
+		if (ret < 0) {
+			debug("SF: AT45 page programming failed\n");
+			goto out;
+		}
+
+		ret = at45_wait_ready(flash, SPI_FLASH_PROG_TIMEOUT);
+		if (ret < 0) {
+			debug("SF: AT45 page programming timed out\n");
+			goto out;
+		}
+
+		page_addr++;
+		byte_addr = 0;
+	}
+
+	debug("SF: AT45: Successfully programmed %u bytes @ 0x%x\n",
+			len, offset);
+	ret = 0;
+
+out:
+	spi_release_bus(flash->spi);
+	return ret;
+}
+
+int dataflash_erase_at45(struct spi_flash *flash, u32 offset, size_t len)
+{
+	struct atmel_spi_flash *asf = to_atmel_spi_flash(flash);
+	unsigned long page_addr;
+	unsigned long page_size;
+	unsigned int page_shift;
+	size_t actual;
+	int ret;
+	u8 cmd[4];
+
+	/*
+	 * TODO: This function currently uses page erase only. We can
+	 * probably speed things up by using block and/or sector erase
+	 * when possible.
+	 */
+
+	page_shift = asf->params->l2_page_size;
+	page_size = (1 << page_shift) + (1 << (page_shift - 5));
+	page_shift++;
+	page_addr = offset / page_size;
+
+	if (offset % page_size || len % page_size) {
+		debug("SF: Erase offset/length not multiple of page size\n");
+		return -1;
+	}
+
+	cmd[0] = CMD_AT45_ERASE_PAGE;
+	cmd[3] = 0x00;
+
+	ret = spi_claim_bus(flash->spi);
+	if (ret) {
+		debug("SF: Unable to claim SPI bus\n");
+		return ret;
+	}
+
+	for (actual = 0; actual < len; actual += page_size) {
+		cmd[1] = page_addr >> (16 - page_shift);
+		cmd[2] = page_addr << (page_shift - 8);
+
+		ret = spi_flash_cmd_write(flash->spi, cmd, 4, NULL, 0);
+		if (ret < 0) {
+			debug("SF: AT45 page erase failed\n");
+			goto out;
+		}
+
+		ret = at45_wait_ready(flash, SPI_FLASH_PAGE_ERASE_TIMEOUT);
+		if (ret < 0) {
+			debug("SF: AT45 page erase timed out\n");
+			goto out;
+		}
+
+		page_addr++;
+	}
+
+	debug("SF: AT45: Successfully erased %u bytes @ 0x%x\n",
+			len, offset);
+	ret = 0;
+
+out:
+	spi_release_bus(flash->spi);
+	return ret;
+}
+
+struct spi_flash *spi_flash_probe_atmel(struct spi_slave *spi, u8 *idcode)
+{
+	const struct atmel_spi_flash_params *params;
+	unsigned long page_size;
+	unsigned int family;
+	struct atmel_spi_flash *asf;
+	unsigned int i;
+	int ret;
+	u8 status;
+
+	for (i = 0; i < ARRAY_SIZE(atmel_spi_flash_table); i++) {
+		params = &atmel_spi_flash_table[i];
+		if (params->idcode1 == idcode[1])
+			break;
+	}
+
+	if (i == ARRAY_SIZE(atmel_spi_flash_table)) {
+		debug("SF: Unsupported DataFlash ID %02x\n",
+				idcode[1]);
+		return NULL;
+	}
+
+	asf = malloc(sizeof(struct atmel_spi_flash));
+	if (!asf) {
+		debug("SF: Failed to allocate memory\n");
+		return NULL;
+	}
+
+	asf->params = params;
+	asf->flash.spi = spi;
+	asf->flash.name = params->name;
+
+	/* Assuming power-of-two page size initially. */
+	page_size = 1 << params->l2_page_size;
+
+	family = idcode[1] >> 5;
+
+	switch (family) {
+	case DF_FAMILY_AT45:
+		/*
+		 * AT45 chips have configurable page size. The status
+		 * register indicates which configuration is active.
+		 */
+		ret = spi_flash_cmd(spi, CMD_AT45_READ_STATUS, &status, 1);
+		if (ret)
+			goto err;
+
+		debug("SF: AT45 status register: %02x\n", status);
+
+		if (!(status & AT45_STATUS_P2_PAGE_SIZE)) {
+			asf->flash.read = dataflash_read_fast_at45;
+			asf->flash.write = dataflash_write_at45;
+			asf->flash.erase = dataflash_erase_at45;
+			page_size += 1 << (params->l2_page_size - 5);
+		} else {
+			asf->flash.read = dataflash_read_fast_p2;
+		}
+
+		break;
+
+	case DF_FAMILY_AT26F:
+	case DF_FAMILY_AT26DF:
+		asf->flash.read = dataflash_read_fast_p2;
+		break;
+
+	default:
+		debug("SF: Unsupported DataFlash family %u\n", family);
+		goto err;
+	}
+
+	asf->flash.size = page_size * params->pages_per_block
+				* params->blocks_per_sector
+				* params->nr_sectors;
+
+	debug("SF: Detected %s with page size %u, total %u bytes\n",
+			params->name, page_size, asf->flash.size);
+
+	return &asf->flash;
+
+err:
+	free(asf);
+	return NULL;
+}