FRAM memory access optimization.

diff --git a/common/cmd_eeprom.c b/common/cmd_eeprom.c
index 80b8ccc1e8d08d0d695254a6ab13314fbf5d8256..2d4c9f6c42d57c93fc05b5318b6b8c3a4ce6a90a 100644 (file)
--- a/common/cmd_eeprom.c
+++ b/common/cmd_eeprom.c
@@ -22,6 +22,21 @@
  *
  */
 
+/*
+ * Support for read and write access to EEPROM like memory devices. This
+ * includes regular EEPROM as well as  FRAM (ferroelectic nonvolaile RAM).
+ * FRAM devices read and write data at bus speed. In particular, there is no
+ * write delay. Also, there is no limit imposed on the numer of bytes that can
+ * be transferred with a single read or write.
+ * 
+ * Use the following configuration options to ensure no unneeded performance
+ * degradation (typical for EEPROM) is incured for FRAM memory:
+ * 
+ * #define CFG_I2C_FRAM
+ * #undef CFG_EEPROM_PAGE_WRITE_DELAY_MS
+ *
+ */
+
 #include <common.h>
 #include <config.h>
 #include <command.h>
@@ -122,7 +137,11 @@ int eeprom_read (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cnt
         * because the next page may be in a different device.
         */
        while (offset < end) {
-               unsigned alen, len, maxlen;
+               unsigned alen, len;
+#if !defined(CFG_I2C_FRAM)
+               unsigned maxlen;
+#endif
+
 #if CFG_I2C_EEPROM_ADDR_LEN == 1 && !defined(CONFIG_SPI_X)
                uchar addr[2];
 
@@ -144,12 +163,21 @@ int eeprom_read (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cnt
 
                addr[0] |= dev_addr;            /* insert device address */
 
+               len = end - offset;
+
+               /*
+                * For a FRAM device there is no limit on the number of the
+                * bytes that can be ccessed with the single read or write
+                * operation.
+                */
+#if !defined(CFG_I2C_FRAM)
                maxlen = 0x100 - blk_off;
                if (maxlen > I2C_RXTX_LEN)
                        maxlen = I2C_RXTX_LEN;
-               len    = end - offset;
                if (len > maxlen)
                        len = maxlen;
+#endif
+
 #ifdef CONFIG_SPI
                spi_read (addr, alen, buffer, len);
 #else
@@ -159,6 +187,7 @@ int eeprom_read (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cnt
                buffer += len;
                offset += len;
        }
+
        return rcode;
 }
 
@@ -191,7 +220,11 @@ int eeprom_write (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cn
         */
 
        while (offset < end) {
-               unsigned alen, len, maxlen;
+               unsigned alen, len;
+#if !defined(CFG_I2C_FRAM)
+               unsigned maxlen;
+#endif
+
 #if CFG_I2C_EEPROM_ADDR_LEN == 1 && !defined(CONFIG_SPI_X)
                uchar addr[2];
 
@@ -213,6 +246,15 @@ int eeprom_write (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cn
 
                addr[0] |= dev_addr;            /* insert device address */
 
+               len = end - offset;
+
+               /*
+                * For a FRAM device there is no limit on the number of the
+                * bytes that can be ccessed with the single read or write
+                * operation.
+                */
+#if !defined(CFG_I2C_FRAM)
+
 #if defined(CFG_EEPROM_PAGE_WRITE_BITS)
 
 #define        EEPROM_PAGE_SIZE        (1 << CFG_EEPROM_PAGE_WRITE_BITS)
@@ -225,9 +267,10 @@ int eeprom_write (unsigned dev_addr, unsigned offset, uchar *buffer, unsigned cn
                if (maxlen > I2C_RXTX_LEN)
                        maxlen = I2C_RXTX_LEN;
 
-               len = end - offset;
                if (len > maxlen)
                        len = maxlen;
+#endif
+
 #ifdef CONFIG_SPI
                spi_write (addr, alen, buffer, len);
 #else

diff --git a/common/cmd_i2c.c b/common/cmd_i2c.c
index 9c02ceb153c3356300d87365104f7102a204fc56..2e44c7fde1e674e94df03381a35d279d29e49a29 100644 (file)
--- a/common/cmd_i2c.c
+++ b/common/cmd_i2c.c
@@ -295,7 +295,13 @@ int do_i2c_mw ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
                 * chip doesn't respond.  This apparently isn't a
                 * universal feature so we don't take advantage of it.
                 */
+/*
+ * No write delay with FRAM devices.
+ */
+#if !defined(CFG_I2C_FRAM)
                udelay(11000);
+#endif
+
 #if 0
                for(timeout = 0; timeout < 10; timeout++) {
                        udelay(2000);

diff --git a/include/configs/o2dnt.h b/include/configs/o2dnt.h
index 12a732d9f185646d4c59f99609835873746deaab..2d44cea4046f824dd1c9ec59569fd7fc21c2f78c 100644 (file)
--- a/include/configs/o2dnt.h
+++ b/include/configs/o2dnt.h
@@ -158,6 +158,7 @@
  * 0x50 ... 0x57 each 256 bytes in size
  *
  */
+#define CFG_I2C_FRAM
 #define CFG_I2C_EEPROM_ADDR            0x50    /* 1010000x */
 #define CFG_I2C_EEPROM_ADDR_LEN                1
 #define CFG_EEPROM_PAGE_WRITE_BITS     3