eeprom-93cx6: Add (read-only) support for 8-bit mode

Add read-only support for EEPROMs configured in 8-bit mode (ORG pin connected
to GND).
This will be used by wd719x driver.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/misc/eeprom/eeprom_93cx6.c

@@ -170,7 +170,7 @@ static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
 }
 
 /**
- * eeprom_93cx6_read - Read multiple words from eeprom
+ * eeprom_93cx6_read - Read a word from eeprom
  * @eeprom: Pointer to eeprom structure
  * @word: Word index from where we should start reading
  * @data: target pointer where the information will have to be stored
@@ -234,6 +234,66 @@ void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
 }
 EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
 
+/**
+ * eeprom_93cx6_readb - Read a byte from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @word: Byte index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ *
+ * This function will read a byte of the eeprom data
+ * into the given data pointer.
+ */
+void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
+	u8 *data)
+{
+	u16 command;
+	u16 tmp;
+
+	/*
+	 * Initialize the eeprom register
+	 */
+	eeprom_93cx6_startup(eeprom);
+
+	/*
+	 * Select the read opcode and the byte to be read.
+	 */
+	command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
+	eeprom_93cx6_write_bits(eeprom, command,
+		PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
+
+	/*
+	 * Read the requested 8 bits.
+	 */
+	eeprom_93cx6_read_bits(eeprom, &tmp, 8);
+	*data = tmp & 0xff;
+
+	/*
+	 * Cleanup eeprom register.
+	 */
+	eeprom_93cx6_cleanup(eeprom);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
+
+/**
+ * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @byte: Index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ * @words: Number of bytes that should be read.
+ *
+ * This function will read all requested bytes from the eeprom,
+ * this is done by calling eeprom_93cx6_readb() multiple times.
+ */
+void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
+	u8 *data, const u16 bytes)
+{
+	unsigned int i;
+
+	for (i = 0; i < bytes; i++)
+		eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
+
 /**
  * eeprom_93cx6_wren - set the write enable state
  * @eeprom: Pointer to eeprom structure

include/linux/eeprom_93cx6.h

@@ -75,6 +75,10 @@ extern void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom,
 	const u8 word, u16 *data);
 extern void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom,
 	const u8 word, __le16 *data, const u16 words);
+extern void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom,
+	const u8 byte, u8 *data);
+extern void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom,
+	const u8 byte, u8 *data, const u16 bytes);
 
 extern void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable);