drivers/designware_i2c - add suppor of CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW

Since we agreed on legacy implementation of "eeprom_{read|write}"
(http://patchwork.ozlabs.org/patch/295825/) I had to fix/make it work
again DesignWare I2C driver for cases when 1 EEPROM IC fake I2C with
anumber of "built-in" ICs with different chip addresses.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Tom Rini <trini@ti.com>
cc: Armando Visconti <armando.visconti@st.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Heiko Schocher <hs@denx.de>
Cc: Vipin KUMAR <vipin.kumar@st.com>
Cc: Tom Rix <Tom.Rix@windriver.com>
Cc: Mischa Jonker <mjonker@synopsys.com>
Cc: Kuo-Jung Su <dantesu@faraday-tech.com>

drivers/i2c/designware_i2c.c

@@ -266,6 +266,25 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 {
 	unsigned long start_time_rx;
 
+#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
+	/*
+	 * EEPROM chips that implement "address overflow" are ones
+	 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
+	 * address and the extra bits end up in the "chip address"
+	 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
+	 * four 256 byte chips.
+	 *
+	 * Note that we consider the length of the address field to
+	 * still be one byte because the extra address bits are
+	 * hidden in the chip address.
+	 */
+	chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
+	addr &= ~(CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW << (alen * 8));
+
+	debug("%s: fix addr_overflow: chip %02x addr %02x\n", __func__, chip,
+	      addr);
+#endif
+
 	if (check_params(addr, alen, buffer, len))
 		return 1;
 
@@ -307,6 +326,25 @@ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 	int nb = len;
 	unsigned long start_time_tx;
 
+#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
+	/*
+	 * EEPROM chips that implement "address overflow" are ones
+	 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
+	 * address and the extra bits end up in the "chip address"
+	 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
+	 * four 256 byte chips.
+	 *
+	 * Note that we consider the length of the address field to
+	 * still be one byte because the extra address bits are
+	 * hidden in the chip address.
+	 */
+	chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
+	addr &= ~(CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW << (alen * 8));
+
+	debug("%s: fix addr_overflow: chip %02x addr %02x\n", __func__, chip,
+	      addr);
+#endif
+
 	if (check_params(addr, alen, buffer, len))
 		return 1;