Add driver for the ST M95xxx SPI EEPROM

This chip is used in a number of boards manufactured by Calao-Systems
which should be supported soon. This driver provides the necessary
spi_read and spi_write functions necessary to communicate with the chip.

Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/drivers/mtd/spi/eeprom_m95xxx.c b/drivers/mtd/spi/eeprom_m95xxx.c
new file mode 100644
index 0000000..59f80e3
--- /dev/null
+++ b/drivers/mtd/spi/eeprom_m95xxx.c
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2009
+ * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <spi.h>
+
+#define SPI_EEPROM_WREN		0x06
+#define SPI_EEPROM_RDSR		0x05
+#define SPI_EEPROM_READ		0x03
+#define SPI_EEPROM_WRITE	0x02
+
+#ifndef CONFIG_DEFAULT_SPI_BUS
+#define CONFIG_DEFAULT_SPI_BUS 0
+#endif
+
+#ifndef CONFIG_DEFAULT_SPI_MODE
+#define CONFIG_DEFAULT_SPI_MODE SPI_MODE_0
+#endif
+
+ssize_t spi_read (uchar *addr, int alen, uchar *buffer, int len)
+{
+	struct spi_slave *slave;
+	u8 cmd = SPI_EEPROM_READ;
+
+	slave = spi_setup_slave(CONFIG_DEFAULT_SPI_BUS, 1, 1000000,
+			CONFIG_DEFAULT_SPI_MODE);
+	spi_claim_bus(slave);
+
+	/* command */
+	if(spi_xfer(slave, 8, &cmd, NULL, SPI_XFER_BEGIN))
+		return -1;
+
+	/*
+	 * if alen == 3, addr[0] is the block number, we never use it here. All we
+	 * need are the lower 16 bits
+	 */
+	if (alen == 3)
+		addr++;
+
+	/* address, and data */
+	if(spi_xfer(slave, 16, addr, NULL, 0))
+		return -1;
+	if(spi_xfer(slave, 8 * len, NULL, buffer, SPI_XFER_END))
+		return -1;
+
+	spi_release_bus(slave);
+	spi_free_slave(slave);
+	return len;
+}
+
+ssize_t spi_write (uchar *addr, int alen, uchar *buffer, int len)
+{
+	struct spi_slave *slave;
+	int i;
+	char buf[3];
+
+	slave = spi_setup_slave(CONFIG_DEFAULT_SPI_BUS, 1, 1000000,
+			CONFIG_DEFAULT_SPI_MODE);
+	spi_claim_bus(slave);
+
+	buf[0] = SPI_EEPROM_WREN;
+	if(spi_xfer(slave, 8, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END))
+		return -1;
+
+	buf[0] = SPI_EEPROM_WRITE;
+
+	/* As for reading, drop addr[0] if alen is 3 */
+	if (alen == 3) {
+		alen--;
+		addr++;
+	}
+
+	memcpy(buf + 1, addr, alen);
+	/* command + addr, then data */
+	if(spi_xfer(slave, 24, buf, NULL, SPI_XFER_BEGIN))
+		return -1;
+	if(spi_xfer(slave, len * 8, buffer, NULL, SPI_XFER_END))
+		return -1;
+
+	reset_timer_masked();
+	do {
+		buf[0] = SPI_EEPROM_RDSR;
+		buf[1] = 0;
+		spi_xfer(slave, 16, buf, buf, SPI_XFER_BEGIN | SPI_XFER_END);
+
+		if (!(buf[1] & 1))
+			break;
+
+	} while (get_timer_masked() < CONFIG_SYS_SPI_WRITE_TOUT);
+
+	if (buf[1] & 1)
+		printf ("*** spi_write: Time out while writing!\n");
+
+	spi_release_bus(slave);
+	spi_free_slave(slave);
+	return len;
+}