[MTD] Driver for AT26Fxxx dataflash devices

Add support for AT26Fxxx dataflash devices. These devices have a quite different
commandset than the AT45xxx chips, which are handled by at91_dataflash.c, so a
combined driver turned out to be more ugly than useful.

Tested only on AT26F004.

Signed-off-by: Hans-Jürgen Koch <hjk@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

3 files changed, 494 insertions, 0 deletions

diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 440f6851da69..bef0f0d2c28e 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -60,6 +60,14 @@ config MTD_DATAFLASH
           Sometimes DataFlash chips are packaged inside MMC-format
           cards; at this writing, the MMC stack won't handle those.
 
+config MTD_DATAFLASH26
+        tristate "AT91RM9200 DataFlash AT26xxx"
+        depends on MTD && ARCH_AT91RM9200 && AT91_SPI
+        help
+          This enables access to the DataFlash chip (AT26xxx) on an
+          AT91RM9200-based board.
+          If you have such a board and such a DataFlash, say 'Y'.
+
 config MTD_M25P80
         tristate "Support for M25 SPI Flash"
         depends on MTD && SPI_MASTER && EXPERIMENTAL
diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
index 0f788d5c4bf8..8ab568b3f533 100644
--- a/drivers/mtd/devices/Makefile
+++ b/drivers/mtd/devices/Makefile
@@ -16,4 +16,5 @@ obj-$(CONFIG_MTD_MTDRAM)	+= mtdram.o
 obj-$(CONFIG_MTD_LART)          += lart.o
 obj-$(CONFIG_MTD_BLOCK2MTD)     += block2mtd.o
 obj-$(CONFIG_MTD_DATAFLASH)     += mtd_dataflash.o
+obj-$(CONFIG_MTD_DATAFLASH26)   += at91_dataflash26.o
 obj-$(CONFIG_MTD_M25P80)        += m25p80.o
diff --git a/drivers/mtd/devices/at91_dataflash26.c b/drivers/mtd/devices/at91_dataflash26.c
new file mode 100644
index 000000000000..64ce37f986fc
--- /dev/null
+++ b/drivers/mtd/devices/at91_dataflash26.c
@@ -0,0 +1,485 @@
+/*
+ * Atmel DataFlash driver for Atmel AT91RM9200 (Thunder)
+ * This is a largely modified version of at91_dataflash.c that
+ * supports AT26xxx dataflash chips. The original driver supports
+ * AT45xxx chips.
+ *
+ * Note: This driver was only tested with an AT26F004. It should be
+ * easy to make it work with other AT26xxx dataflash devices, though.
+ *
+ * Copyright (C) 2007 Hans J. Koch <hjk@linutronix.de>
+ * original Copyright (C) SAN People (Pty) Ltd
+ *
+ * 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/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/mtd/mtd.h>
+
+#include <asm/arch/at91_spi.h>
+
+#define DATAFLASH_MAX_DEVICES   4       /* max number of dataflash devices */
+
+#define MANUFACTURER_ID_ATMEL           0x1F
+
+/* command codes */
+
+#define AT26_OP_READ_STATUS             0x05
+#define AT26_OP_READ_DEV_ID             0x9F
+#define AT26_OP_ERASE_PAGE_4K           0x20
+#define AT26_OP_READ_ARRAY_FAST         0x0B
+#define AT26_OP_SEQUENTIAL_WRITE        0xAF
+#define AT26_OP_WRITE_ENABLE            0x06
+#define AT26_OP_WRITE_DISABLE           0x04
+#define AT26_OP_SECTOR_PROTECT          0x36
+#define AT26_OP_SECTOR_UNPROTECT        0x39
+
+/* status register bits */
+
+#define AT26_STATUS_BUSY                0x01
+#define AT26_STATUS_WRITE_ENABLE        0x02
+
+struct dataflash_local
+{
+        int spi;                        /* SPI chip-select number */
+        unsigned int page_size;         /* number of bytes per page */
+};
+
+
+/* Detected DataFlash devices */
+static struct mtd_info* mtd_devices[DATAFLASH_MAX_DEVICES];
+static int nr_devices = 0;
+
+/* Allocate a single SPI transfer descriptor.  We're assuming that if multiple
+   SPI transfers occur at the same time, spi_access_bus() will serialize them.
+   If this is not valid, then either (i) each dataflash 'priv' structure
+   needs it's own transfer descriptor, (ii) we lock this one, or (iii) use
+   another mechanism.   */
+static struct spi_transfer_list* spi_transfer_desc;
+
+/*
+ * Perform a SPI transfer to access the DataFlash device.
+ */
+static int do_spi_transfer(int nr, char* tx, int tx_len, char* rx, int rx_len,
+                char* txnext, int txnext_len, char* rxnext, int rxnext_len)
+{
+        struct spi_transfer_list* list = spi_transfer_desc;
+
+        list->tx[0] = tx;       list->txlen[0] = tx_len;
+        list->rx[0] = rx;       list->rxlen[0] = rx_len;
+
+        list->tx[1] = txnext;   list->txlen[1] = txnext_len;
+        list->rx[1] = rxnext;   list->rxlen[1] = rxnext_len;
+
+        list->nr_transfers = nr;
+        /* Note: spi_transfer() always returns 0, there are no error checks */
+        return spi_transfer(list);
+}
+
+/*
+ * Return the status of the DataFlash device.
+ */
+static unsigned char at91_dataflash26_status(void)
+{
+        unsigned char command[2];
+
+        command[0] = AT26_OP_READ_STATUS;
+        command[1] = 0;
+
+        do_spi_transfer(1, command, 2, command, 2, NULL, 0, NULL, 0);
+
+        return command[1];
+}
+
+/*
+ * Poll the DataFlash device until it is READY.
+ */
+static unsigned char at91_dataflash26_waitready(void)
+{
+        unsigned char status;
+
+        while (1) {
+                status = at91_dataflash26_status();
+                if (!(status & AT26_STATUS_BUSY))
+                        return status;
+        }
+}
+
+/*
+ * Enable/disable write access
+ */
+ static void at91_dataflash26_write_enable(int enable)
+{
+        unsigned char cmd[2];
+
+        DEBUG(MTD_DEBUG_LEVEL3, "write_enable: enable=%i\n", enable);
+
+        if (enable)
+                cmd[0] = AT26_OP_WRITE_ENABLE;
+        else
+                cmd[0] = AT26_OP_WRITE_DISABLE;
+        cmd[1] = 0;
+
+        do_spi_transfer(1, cmd, 2, cmd, 2, NULL, 0, NULL, 0);
+}
+
+/*
+ * Protect/unprotect sector
+ */
+ static void at91_dataflash26_sector_protect(loff_t addr, int protect)
+{
+        unsigned char cmd[4];
+
+        DEBUG(MTD_DEBUG_LEVEL3, "sector_protect: addr=0x%06x prot=%d\n",
+               addr, protect);
+
+        if (protect)
+                cmd[0] = AT26_OP_SECTOR_PROTECT;
+        else
+                cmd[0] = AT26_OP_SECTOR_UNPROTECT;
+        cmd[1] = (addr & 0x00FF0000) >> 16;
+        cmd[2] = (addr & 0x0000FF00) >> 8;
+        cmd[3] = (addr & 0x000000FF);
+
+        do_spi_transfer(1, cmd, 4, cmd, 4, NULL, 0, NULL, 0);
+}
+
+/*
+ * Erase blocks of flash.
+ */
+static int at91_dataflash26_erase(struct mtd_info *mtd,
+                                  struct erase_info *instr)
+{
+        struct dataflash_local *priv = (struct dataflash_local *) mtd->priv;
+        unsigned char cmd[4];
+
+        DEBUG(MTD_DEBUG_LEVEL1, "dataflash_erase: addr=0x%06x len=%i\n",
+               instr->addr, instr->len);
+
+        /* Sanity checks */
+        if (priv->page_size != 4096)
+                return -EINVAL; /* Can't handle other sizes at the moment */
+
+        if (   ((instr->len % mtd->erasesize) != 0)
+            || ((instr->len % priv->page_size) != 0)
+            || ((instr->addr % priv->page_size) != 0)
+            || ((instr->addr + instr->len) > mtd->size))
+                return -EINVAL;
+
+        spi_access_bus(priv->spi);
+
+        while (instr->len > 0) {
+                at91_dataflash26_write_enable(1);
+                at91_dataflash26_sector_protect(instr->addr, 0);
+                at91_dataflash26_write_enable(1);
+                cmd[0] = AT26_OP_ERASE_PAGE_4K;
+                cmd[1] = (instr->addr & 0x00FF0000) >> 16;
+                cmd[2] = (instr->addr & 0x0000FF00) >> 8;
+                cmd[3] = (instr->addr & 0x000000FF);
+
+                DEBUG(MTD_DEBUG_LEVEL3, "ERASE: (0x%02x) 0x%02x 0x%02x"
+                                        "0x%02x\n",
+                        cmd[0], cmd[1], cmd[2], cmd[3]);
+
+                do_spi_transfer(1, cmd, 4, cmd, 4, NULL, 0, NULL, 0);
+                at91_dataflash26_waitready();
+
+                instr->addr += priv->page_size;  /* next page */
+                instr->len -= priv->page_size;
+        }
+
+        at91_dataflash26_write_enable(0);
+        spi_release_bus(priv->spi);
+
+        /* Inform MTD subsystem that erase is complete */
+        instr->state = MTD_ERASE_DONE;
+        if (instr->callback)
+                instr->callback(instr);
+
+        return 0;
+}
+
+/*
+ * Read from the DataFlash device.
+ *   from   : Start offset in flash device
+ *   len    : Number of bytes to read
+ *   retlen : Number of bytes actually read
+ *   buf    : Buffer that will receive data
+ */
+static int at91_dataflash26_read(struct mtd_info *mtd, loff_t from, size_t len,
+                                 size_t *retlen, u_char *buf)
+{
+        struct dataflash_local *priv = (struct dataflash_local *) mtd->priv;
+        unsigned char cmd[5];
+
+        DEBUG(MTD_DEBUG_LEVEL1, "dataflash_read: %lli .. %lli\n",
+              from, from+len);
+
+        *retlen = 0;
+
+        /* Sanity checks */
+        if (!len)
+                return 0;
+        if (from + len > mtd->size)
+                return -EINVAL;
+
+        cmd[0] = AT26_OP_READ_ARRAY_FAST;
+        cmd[1] = (from & 0x00FF0000) >> 16;
+        cmd[2] = (from & 0x0000FF00) >> 8;
+        cmd[3] = (from & 0x000000FF);
+        /* cmd[4] is a "Don't care" byte  */
+
+        DEBUG(MTD_DEBUG_LEVEL3, "READ: (0x%02x) 0x%02x 0x%02x 0x%02x\n",
+               cmd[0], cmd[1], cmd[2], cmd[3]);
+
+        spi_access_bus(priv->spi);
+        do_spi_transfer(2, cmd, 5, cmd, 5, buf, len, buf, len);
+        spi_release_bus(priv->spi);
+
+        *retlen = len;
+        return 0;
+}
+
+/*
+ * Write to the DataFlash device.
+ *   to     : Start offset in flash device
+ *   len    : Number of bytes to write
+ *   retlen : Number of bytes actually written
+ *   buf    : Buffer containing the data
+ */
+static int at91_dataflash26_write(struct mtd_info *mtd, loff_t to, size_t len,
+                                  size_t *retlen, const u_char *buf)
+{
+        struct dataflash_local *priv = (struct dataflash_local *) mtd->priv;
+        unsigned int addr, buf_index = 0;
+        int ret = -EIO, sector, last_sector;
+        unsigned char status, cmd[5];
+
+        DEBUG(MTD_DEBUG_LEVEL1, "dataflash_write: %lli .. %lli\n", to, to+len);
+
+        *retlen = 0;
+
+        /* Sanity checks */
+        if (!len)
+                return 0;
+        if (to + len > mtd->size)
+                return -EINVAL;
+
+        spi_access_bus(priv->spi);
+
+        addr = to;
+        last_sector = -1;
+
+        while (buf_index < len) {
+                sector = addr / priv->page_size;
+                /* Write first byte if a new sector begins */
+                if (sector != last_sector) {
+                        at91_dataflash26_write_enable(1);
+                        at91_dataflash26_sector_protect(addr, 0);
+                        at91_dataflash26_write_enable(1);
+
+                        /* Program first byte of a new sector */
+                        cmd[0] = AT26_OP_SEQUENTIAL_WRITE;
+                        cmd[1] = (addr & 0x00FF0000) >> 16;
+                        cmd[2] = (addr & 0x0000FF00) >> 8;
+                        cmd[3] = (addr & 0x000000FF);
+                        cmd[4] = buf[buf_index++];
+                        do_spi_transfer(1, cmd, 5, cmd, 5, NULL, 0, NULL, 0);
+                        status = at91_dataflash26_waitready();
+                        addr++;
+                        /* On write errors, the chip resets the write enable
+                           flag. This also happens after the last byte of a
+                           sector is successfully programmed. */
+                        if (   ( !(status & AT26_STATUS_WRITE_ENABLE))
+                            && ((addr % priv->page_size) != 0) ) {
+                                DEBUG(MTD_DEBUG_LEVEL1,
+                                        "write error1: addr=0x%06x, "
+                                        "status=0x%02x\n", addr, status);
+                                goto write_err;
+                        }
+                        (*retlen)++;
+                        last_sector = sector;
+                }
+
+                /* Write subsequent bytes in the same sector */
+                cmd[0] = AT26_OP_SEQUENTIAL_WRITE;
+                cmd[1] = buf[buf_index++];
+                do_spi_transfer(1, cmd, 2, cmd, 2, NULL, 0, NULL, 0);
+                status = at91_dataflash26_waitready();
+                addr++;
+
+                if (   ( !(status & AT26_STATUS_WRITE_ENABLE))
+                    && ((addr % priv->page_size) != 0) ) {
+                        DEBUG(MTD_DEBUG_LEVEL1, "write error2: addr=0x%06x, "
+                                "status=0x%02x\n", addr, status);
+                        goto write_err;
+                }
+
+                (*retlen)++;
+        }
+
+        ret = 0;
+        at91_dataflash26_write_enable(0);
+write_err:
+        spi_release_bus(priv->spi);
+        return ret;
+}
+
+/*
+ * Initialize and register DataFlash device with MTD subsystem.
+ */
+static int __init add_dataflash(int channel, char *name, int nr_pages,
+                                int pagesize)
+{
+        struct mtd_info *device;
+        struct dataflash_local *priv;
+
+        if (nr_devices >= DATAFLASH_MAX_DEVICES) {
+                printk(KERN_ERR "at91_dataflash26: Too many devices "
+                                "detected\n");
+                return 0;
+        }
+
+        device = kzalloc(sizeof(struct mtd_info) + strlen(name) + 8,
+                         GFP_KERNEL);
+        if (!device)
+                return -ENOMEM;
+
+        device->name = (char *)&device[1];
+        sprintf(device->name, "%s.spi%d", name, channel);
+        device->size = nr_pages * pagesize;
+        device->erasesize = pagesize;
+        device->owner = THIS_MODULE;
+        device->type = MTD_DATAFLASH;
+        device->flags = MTD_CAP_NORFLASH;
+        device->erase = at91_dataflash26_erase;
+        device->read = at91_dataflash26_read;
+        device->write = at91_dataflash26_write;
+
+        priv = (struct dataflash_local *)kzalloc(sizeof(struct dataflash_local),
+                GFP_KERNEL);
+        if (!priv) {
+                kfree(device);
+                return -ENOMEM;
+        }
+
+        priv->spi = channel;
+        priv->page_size = pagesize;
+        device->priv = priv;
+
+        mtd_devices[nr_devices] = device;
+        nr_devices++;
+        printk(KERN_INFO "at91_dataflash26: %s detected [spi%i] (%i bytes)\n",
+               name, channel, device->size);
+
+        return add_mtd_device(device);
+}
+
+/*
+ * Detect and initialize DataFlash device connected to specified SPI channel.
+ *
+ */
+
+struct dataflash26_types {
+        unsigned char id0;
+        unsigned char id1;
+        char *name;
+        int pagesize;
+        int nr_pages;
+};
+
+struct dataflash26_types df26_types[] = {
+        {
+                .id0 = 0x04,
+                .id1 = 0x00,
+                .name = "AT26F004",
+                .pagesize = 4096,
+                .nr_pages = 128,
+        },
+        {
+                .id0 = 0x45,
+                .id1 = 0x01,
+                .name = "AT26DF081A", /* Not tested ! */
+                .pagesize = 4096,
+                .nr_pages = 256,
+        },
+};
+
+static int __init at91_dataflash26_detect(int channel)
+{
+        unsigned char status, cmd[5];
+        int i;
+
+        spi_access_bus(channel);
+        status = at91_dataflash26_status();
+
+        if (status == 0 || status == 0xff) {
+                printk(KERN_ERR "at91_dataflash26_detect: status error %d\n",
+                        status);
+                spi_release_bus(channel);
+                return -ENODEV;
+        }
+
+        cmd[0] = AT26_OP_READ_DEV_ID;
+        do_spi_transfer(1, cmd, 5, cmd, 5, NULL, 0, NULL, 0);
+        spi_release_bus(channel);
+
+        if (cmd[1] != MANUFACTURER_ID_ATMEL)
+                return -ENODEV;
+
+        for (i = 0; i < ARRAY_SIZE(df26_types); i++) {
+                if (   cmd[2] == df26_types[i].id0
+                    && cmd[3] == df26_types[i].id1)
+                        return add_dataflash(channel,
+                                                df26_types[i].name,
+                                                df26_types[i].nr_pages,
+                                                df26_types[i].pagesize);
+        }
+
+        printk(KERN_ERR "at91_dataflash26_detect: Unsupported device "
+                        "(0x%02x/0x%02x)\n", cmd[2], cmd[3]);
+        return -ENODEV;
+}
+
+static int __init at91_dataflash26_init(void)
+{
+        spi_transfer_desc = kmalloc(sizeof(struct spi_transfer_list),
+                                    GFP_KERNEL);
+        if (!spi_transfer_desc)
+                return -ENOMEM;
+
+        /* DataFlash (SPI chip select 0) */
+        at91_dataflash26_detect(0);
+
+#ifdef CONFIG_MTD_AT91_DATAFLASH_CARD
+        /* DataFlash card (SPI chip select 3) */
+        at91_dataflash26_detect(3);
+#endif
+        return 0;
+}
+
+static void __exit at91_dataflash26_exit(void)
+{
+        int i;
+
+        for (i = 0; i < DATAFLASH_MAX_DEVICES; i++) {
+                if (mtd_devices[i]) {
+                        del_mtd_device(mtd_devices[i]);
+                        kfree(mtd_devices[i]->priv);
+                        kfree(mtd_devices[i]);
+                }
+        }
+        nr_devices = 0;
+        kfree(spi_transfer_desc);
+}
+
+module_init(at91_dataflash26_init);
+module_exit(at91_dataflash26_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Hans J. Koch");
+MODULE_DESCRIPTION("DataFlash AT26xxx driver for Atmel AT91RM9200");