eeprom: at25: allow page sizes greater than 16 bit

Storage technologies like FRAM have no "write pages", the whole chip can
be written within one SPI transfer. For these chips, the page size can
be set equal to the device size. Currently available devices are already
bigger than 64 kiB.
Signed-off-by: Christian Eggers <ceggers@arri.de>
Link: https://lore.kernel.org/r/20200727111218.26926-1-ceggers@arri.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/eeprom/at25.c

@@ -261,7 +261,7 @@ static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
 
 	if (device_property_read_u32(dev, "pagesize", &val) == 0 ||
 	    device_property_read_u32(dev, "at25,page-size", &val) == 0) {
-		chip->page_size = (u16)val;
+		chip->page_size = val;
 	} else {
 		dev_err(dev, "Error: missing \"pagesize\" property\n");
 		return -ENODEV;

include/linux/spi/eeprom.h

@@ -14,7 +14,7 @@
 struct spi_eeprom {
 	u32		byte_len;
 	char		name[10];
-	u16		page_size;		/* for writes */
+	u32		page_size;		/* for writes */
 	u16		flags;
 #define	EE_ADDR1	0x0001			/*  8 bit addrs */
 #define	EE_ADDR2	0x0002			/* 16 bit addrs */