Re: [PATCH] SST25L (non JEDEC) SPI Flash driver

Ryan Mallon
2009-06-22T21:54:30Z

Hi Linus,

Thanks for the comments. I have removed the dependency on math64.h, I
changed the instances to u32 casts and mod operator (the sst25l flash
chips are quite small so it won't be a problem).

I have also replaced the __devinit/__devexit markers with the
__init/__exit equivalents. In our particular instance the chip is
soldered onto the board so its not hot-pluggable. I think this will be
the case for most people who are using these chips.

Out of curiosity: I'm not too clear on what makes a particular chip
hot-pluggable. I think technically the sst25l chip could be put onto a
hot-pluggable board or power domain. Can't most devices be made
hot-pluggable? Is the general rule to make devices non hot-pluggable if
most/all boards in the mainline do not allow it to be hot-plugged?

Also fixed a warning on the arguments to the min macro pointed out by
Artem Bityitskiy.

Updated patch below:

---
Add support for SST25L (non JEDEC) SPI Flash chips

Signed-off-by: Andre Renaud <andre@bluewatersys.com>
Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>

---

diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 325fab9..c222514 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -104,6 +104,16 @@ config M25PXX_USE_FAST_READ
help
This option enables FAST_READ access supported by ST M25Pxx.

+config MTD_SST25L
+ tristate "Support SST25L (non JEDEC) SPI Flash chips"
+ depends on SPI_MASTER
+ help
+ This enables access to the non JEDEC SST25L SPI flash chips, used
+ for program and data storage.
+
+ Set up your spi devices with the right board-specific platform data,
+ if you want to specify device partitioning.
+
config MTD_SLRAM
tristate "Uncached system RAM"
help
diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
index 0993d5c..ab5c9b9 100644
--- a/drivers/mtd/devices/Makefile
+++ b/drivers/mtd/devices/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_MTD_LART) += lart.o
obj-$(CONFIG_MTD_BLOCK2MTD) += block2mtd.o
obj-$(CONFIG_MTD_DATAFLASH) += mtd_dataflash.o
obj-$(CONFIG_MTD_M25P80) += m25p80.o
+obj-$(CONFIG_MTD_SST25L) += sst25l.o
diff --git a/drivers/mtd/devices/sst25l.c b/drivers/mtd/devices/sst25l.c
new file mode 100644
index 0000000..30658f6
--- /dev/null
+++ b/drivers/mtd/devices/sst25l.c
@@ -0,0 +1,503 @@
+/*
+ * drivers/mtd/sst25l.c
+ *
+ * Driver for SST25L SPI Flash chips
+ *
+ * Copyright (C) 2009 Bluewater Systems Ltd
+ * Author: Andre Renaud <andre@bluewatersys.com>
+ * Author: Ryan Mallon <ryan@bluewatersys.com>
+ *
+ * Based on m25p80.c
+ *
+ * This code 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/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/flash.h>
+
+/* Erases can take up to 3 seconds! */
+#define MAX_READY_WAIT_JIFFIES msecs_to_jiffies(3000)
+
+#define SST25L_CMD_WRSR 0x01 /* Write status register */
+#define SST25L_CMD_WRDI 0x04 /* Write disable */
+#define SST25L_CMD_RDSR 0x05 /* Read status register */
+#define SST25L_CMD_WREN 0x06 /* Write enable */
+#define SST25L_CMD_READ 0x03 /* High speed read */
+
+#define SST25L_CMD_EWSR 0x50 /* Enable write status register */
+#define SST25L_CMD_BLOCK_ERASE 0x52 /* Erase sector */
+#define SST25L_CMD_READ_ID 0x90 /* Read device ID */
+#define SST25L_CMD_AAI_PROGRAM 0xaf /* Auto address increment */
+
+#define SST25L_STATUS_BUSY (1 << 0) /* Chip is busy */
+#define SST25L_STATUS_WREN (1 << 1) /* Write enabled */
+#define SST25L_STATUS_BP0 (1 << 2) /* Block protection 0 */
+#define SST25L_STATUS_BP1 (1 << 3) /* Block protection 1 */
+
+struct sst25l_flash {
+ struct spi_device *spi;
+ struct mutex lock;
+ struct mtd_info mtd;
+
+ int partitioned;
+};
+
+struct flash_info {
+ const char *name;
+ u16 device_id;
+ unsigned page_size;
+ unsigned nr_pages;
+ unsigned erase_size;
+};
+
+#define to_sst25l_flash(x) container_of(x, struct sst25l_flash, mtd)
+
+static struct flash_info __initdata sst25l_flash_info[] = {
+ {"sst25lf020a", 0xbf43, 256, 1024, 32 * 1024},
+ {"sst25lf040a", 0xbf44, 256, 2048, 32 * 1024},
+};
+
+static int sst25l_status(struct sst25l_flash *flash, int *status)
+{
+ u8 command, response;
+ int err;
+
+ command = SST25L_CMD_RDSR;
+ err = spi_write_then_read(flash->spi, &command, 1, &response, 1);
+ if (err < 0)
+ return err;
+
+ *status = response;
+ return 0;
+}
+
+static int sst25l_write_enable(struct sst25l_flash *flash, int enable)
+{
+ u8 command[2];
+ int status, err;
+
+ command[0] = enable ? SST25L_CMD_WREN : SST25L_CMD_WRDI;
+ err = spi_write(flash->spi, command, 1);
+ if (err)
+ return err;
+
+ command[0] = SST25L_CMD_EWSR;
+ err = spi_write(flash->spi, command, 1);
+ if (err)
+ return err;
+
+ command[0] = SST25L_CMD_WRSR;
+ command[1] = enable ? 0 : SST25L_STATUS_BP0 | SST25L_STATUS_BP1;
+ err = spi_write(flash->spi, command, 2);
+ if (err)
+ return err;
+
+ if (enable) {
+ err = sst25l_status(flash, &status);
+ if (err)
+ return err;
+ if (!(status & SST25L_STATUS_WREN))
+ return -EROFS;
+ }
+
+ return 0;
+}
+
+static int sst25l_wait_till_ready(struct sst25l_flash *flash)
+{
+ unsigned long deadline;
+ int status, err;
+
+ deadline = jiffies + MAX_READY_WAIT_JIFFIES;
+ do {
+ err = sst25l_status(flash, &status);
+ if (err)
+ return err;
+ if (!(status & SST25L_STATUS_BUSY))
+ return 0;
+
+ cond_resched();
+ } while (!time_after_eq(jiffies, deadline));
+
+ return -ETIMEDOUT;
+}
+
+static int sst25l_erase_block(struct sst25l_flash *flash, u32 offset)
+{
+ u8 command[4];
+ int err;
+
+ err = sst25l_write_enable(flash, 1);
+ if (err)
+ return err;
+
+ command[0] = SST25L_CMD_BLOCK_ERASE;
+ command[1] = offset >> 16;
+ command[2] = offset >> 8;
+ command[3] = offset;
+ err = spi_write(flash->spi, command, 4);
+ if (err)
+ return err;
+
+ err = sst25l_wait_till_ready(flash);
+ if (err)
+ return err;
+
+ return sst25l_write_enable(flash, 0);
+}
+
+static int sst25l_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+ struct sst25l_flash *flash = to_sst25l_flash(mtd);
+ u32 addr, end;
+ int err;
+
+ /* Sanity checks */
+ if (instr->addr + instr->len > flash->mtd.size)
+ return -EINVAL;
+
+ if ((u32)instr->len % mtd->erasesize)
+ return -EINVAL;
+
+ if ((u32)instr->addr % mtd->erasesize)
+ return -EINVAL;
+
+ addr = instr->addr;
+ end = addr + instr->len;
+
+ mutex_lock(&flash->lock);
+
+ err = sst25l_wait_till_ready(flash);
+ if (err)
+ return err;
+
+ while (addr < end) {
+ err = sst25l_erase_block(flash, addr);
+ if (err) {
+ mutex_unlock(&flash->lock);
+ instr->state = MTD_ERASE_FAILED;
+ dev_err(&flash->spi->dev, "Erase failed\n");
+ return err;
+ }
+
+ addr += mtd->erasesize;
+ }
+
+ mutex_unlock(&flash->lock);
+
+ instr->state = MTD_ERASE_DONE;
+ mtd_erase_callback(instr);
+ return 0;
+}
+
+static int sst25l_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, u_char *buf)
+{
+ struct sst25l_flash *flash = to_sst25l_flash(mtd);
+ struct spi_transfer transfer[2];
+ struct spi_message message;
+ u8 command[4];
+ int ret;
+
+ /* Sanity checking */
+ if (len == 0)
+ return 0;
+
+ if (from + len > flash->mtd.size)
+ return -EINVAL;
+
+ if (retlen)
+ *retlen = 0;
+
+ spi_message_init(&message);
+ memset(&transfer, 0, sizeof(transfer));
+
+ command[0] = SST25L_CMD_READ;
+ command[1] = from >> 16;
+ command[2] = from >> 8;
+ command[3] = from;
+
+ transfer[0].tx_buf = command;
+ transfer[0].len = sizeof(command);
+ spi_message_add_tail(&transfer[0], &message);
+
+ transfer[1].rx_buf = buf;
+ transfer[1].len = len;
+ spi_message_add_tail(&transfer[1], &message);
+
+ mutex_lock(&flash->lock);
+
+ /* Wait for previous write/erase to complete */
+ ret = sst25l_wait_till_ready(flash);
+ if (ret) {
+ mutex_unlock(&flash->lock);
+ return ret;
+ }
+
+ spi_sync(flash->spi, &message);
+
+ if (retlen && message.actual_length > sizeof(command))
+ *retlen += message.actual_length - sizeof(command);
+
+ mutex_unlock(&flash->lock);
+ return 0;
+}
+
+static int sst25l_write(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const u_char *buf)
+{
+ struct sst25l_flash *flash = to_sst25l_flash(mtd);
+ int i, j, ret, bytes, copied = 0;
+ u8 command[5];
+
+ /* Sanity checks */
+ if (!len)
+ return 0;
+
+ if (to + len > flash->mtd.size)
+ return -EINVAL;
+
+ if ((u32)to % mtd->writesize)
+ return -EINVAL;
+
+ mutex_lock(&flash->lock);
+
+ ret = sst25l_write_enable(flash, 1);
+ if (ret)
+ goto out;
+
+ for (i = 0; i < len; i += mtd->writesize) {
+ ret = sst25l_wait_till_ready(flash);
+ if (ret)
+ goto out;
+
+ /* Write the first byte of the page */
+ command[0] = SST25L_CMD_AAI_PROGRAM;
+ command[1] = (to + i) >> 16;
+ command[2] = (to + i) >> 8;
+ command[3] = (to + i);
+ command[4] = buf[i];
+ ret = spi_write(flash->spi, command, 5);
+ if (ret < 0)
+ goto out;
+ copied++;
+
+ /*
+ * Write the remaining bytes using auto address
+ * increment mode
+ */
+ bytes = min(mtd->writesize, (u32)(len - i));
+ for (j = 1; j < bytes; j++, copied++) {
+ ret = sst25l_wait_till_ready(flash);
+ if (ret)
+ goto out;
+
+ command[1] = buf[i + j];
+ ret = spi_write(flash->spi, command, 2);
+ if (ret)
+ goto out;
+ }
+ }
+
+out:
+ ret = sst25l_write_enable(flash, 0);
+
+ if (retlen)
+ *retlen = copied;
+
+ mutex_unlock(&flash->lock);
+ return ret;
+}
+
+static struct flash_info *__init sst25l_match_device(struct spi_device *spi)
+{
+ struct flash_info *flash_info = NULL;
+ u8 command[4], response;
+ int i, err;
+ u16 id;
+
+ command[0] = SST25L_CMD_READ_ID;
+ command[1] = 0;
+ command[2] = 0;
+ command[3] = 0;
+ err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
+ if (err < 0) {
+ dev_err(&spi->dev, "error reading device id msb\n");
+ return NULL;
+ }
+
+ id = response << 8;
+
+ command[0] = SST25L_CMD_READ_ID;
+ command[1] = 0;
+ command[2] = 0;
+ command[3] = 1;
+ err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
+ if (err < 0) {
+ dev_err(&spi->dev, "error reading device id lsb\n");
+ return NULL;
+ }
+
+ id |= response;
+
+ for (i = 0; i < ARRAY_SIZE(sst25l_flash_info); i++)
+ if (sst25l_flash_info[i].device_id == id)
+ flash_info = &sst25l_flash_info[i];
+
+ if (!flash_info)
+ dev_err(&spi->dev, "unknown id %.4x\n", id);
+
+ return flash_info;
+}
+
+static int __init sst25l_probe(struct spi_device *spi)
+{
+ struct flash_info *flash_info;
+ struct sst25l_flash *flash;
+ struct flash_platform_data *data;
+ int i;
+
+ flash_info = sst25l_match_device(spi);
+ if (!flash_info)
+ return -ENODEV;
+
+ flash = kzalloc(sizeof(struct sst25l_flash), GFP_KERNEL);
+ if (!flash)
+ return -ENOMEM;
+
+ flash->spi = spi;
+ mutex_init(&flash->lock);
+ dev_set_drvdata(&spi->dev, flash);
+
+ data = spi->dev.platform_data;
+ if (data && data->name)
+ flash->mtd.name = data->name;
+ else
+ flash->mtd.name = dev_name(&spi->dev);
+
+ flash->mtd.type = MTD_NORFLASH;
+ flash->mtd.flags = MTD_CAP_NORFLASH;
+ flash->mtd.erasesize = flash_info->erase_size;
+ flash->mtd.writesize = flash_info->page_size;
+ flash->mtd.size = flash_info->page_size * flash_info->nr_pages;
+ flash->mtd.erase = sst25l_erase;
+ flash->mtd.read = sst25l_read;
+ flash->mtd.write = sst25l_write;
+
+ dev_info(&spi->dev, "%s (%lld Kbytes)\n", flash_info->name,
+ (long long)flash->mtd.size >> 10);
+
+ DEBUG(MTD_DEBUG_LEVEL2,
+ "mtd .name = %s, .size = 0x%llx (%lldMiB) "
+ ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
+ flash->mtd.name,
+ (long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
+ flash->mtd.erasesize, flash->mtd.erasesize / 1024,
+ flash->mtd.numeraseregions);
+
+ if (flash->mtd.numeraseregions)
+ for (i = 0; i < flash->mtd.numeraseregions; i++)
+ DEBUG(MTD_DEBUG_LEVEL2,
+ "mtd.eraseregions[%d] = { .offset = 0x%llx, "
+ ".erasesize = 0x%.8x (%uKiB), "
+ ".numblocks = %d }\n",
+ i, (long long)flash->mtd.eraseregions[i].offset,
+ flash->mtd.eraseregions[i].erasesize,
+ flash->mtd.eraseregions[i].erasesize / 1024,
+ flash->mtd.eraseregions[i].numblocks);
+
+ if (mtd_has_partitions()) {
+ struct mtd_partition *parts = NULL;
+ int nr_parts = 0;
+
+ if (mtd_has_cmdlinepart()) {
+ static const char *part_probes[] =
+ {"cmdlinepart", NULL};
+
+ nr_parts = parse_mtd_partitions(&flash->mtd,
+ part_probes,
+ &parts, 0);
+ }
+
+ if (nr_parts <= 0 && data && data->parts) {
+ parts = data->parts;
+ nr_parts = data->nr_parts;
+ }
+
+ if (nr_parts > 0) {
+ for (i = 0; i < nr_parts; i++) {
+ DEBUG(MTD_DEBUG_LEVEL2, "partitions[%d] = "
+ "{.name = %s, .offset = 0x%llx, "
+ ".size = 0x%llx (%lldKiB) }\n",
+ i, parts[i].name,
+ (long long)parts[i].offset,
+ (long long)parts[i].size,
+ (long long)(parts[i].size >> 10));
+ }
+
+ flash->partitioned = 1;
+ return add_mtd_partitions(&flash->mtd,
+ parts, nr_parts);
+ }
+
+ } else if (data->nr_parts) {
+ dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",
+ data->nr_parts, data->name);
+ }
+
+ return add_mtd_device(&flash->mtd) == 1 ? -ENODEV : 0;
+}
+
+static int __exit sst25l_remove(struct spi_device *spi)
+{
+ struct sst25l_flash *flash = dev_get_drvdata(&spi->dev);
+ int ret;
+
+ if (mtd_has_partitions() && flash->partitioned)
+ ret = del_mtd_partitions(&flash->mtd);
+ else
+ ret = del_mtd_device(&flash->mtd);
+ if (ret == 0)
+ kfree(flash);
+ return ret;
+}
+
+static struct spi_driver sst25l_driver = {
+ .driver = {
+ .name = "sst25l",
+ .bus = &spi_bus_type,
+ .owner = THIS_MODULE,
+ },
+ .probe = sst25l_probe,
+ .remove = __exit_p(sst25l_remove),
+};
+
+static int __init sst25l_init(void)
+{
+ return spi_register_driver(&sst25l_driver);
+}
+
+static void __exit sst25l_exit(void)
+{
+ spi_unregister_driver(&sst25l_driver);
+}
+
+module_init(sst25l_init);
+module_exit(sst25l_exit);
+
+MODULE_DESCRIPTION("MTD SPI driver for SST25L Flash chips");
+MODULE_AUTHOR("Andre Renaud <andre@bluewatersys.com>, "
+ "Ryan Mallon <ryan@bluewatersys.com>");
+MODULE_LICENSE("GPL");