Add support for Atmel AT26DF041

Wicked chip: No WRSR, no write enable command (but swallows our
default one without a problem), supports an auto-erasing page write
(but even without that page writes are recommended to write the
whole page i.e. operate on a completely erased page), mad
requirements on block refreshments if only partly written.

Found on my Intel D946GZIS and tested with my serprog in situ.
Using the page write by setting JEDEC_BYTE_PROGRAM to 0x11 and using
the spi_chip_write_256 command greatly improves performance and works
flawlessly.

Corresponding to flashrom svn r1616.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
diff --git a/spi25.c b/spi25.c
index a65f548..10c5a4a 100644
--- a/spi25.c
+++ b/spi25.c
@@ -741,6 +741,86 @@
 	return 0;
 }
 
+int spi_block_erase_50(struct flashctx *flash, unsigned int addr, unsigned int blocklen)
+{
+	int result;
+	struct spi_command cmds[] = {
+	{
+/*		.writecnt	= JEDEC_WREN_OUTSIZE,
+		.writearr	= (const unsigned char[]){ JEDEC_WREN },
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}, { */
+		.writecnt	= JEDEC_BE_50_OUTSIZE,
+		.writearr	= (const unsigned char[]){
+					JEDEC_BE_50,
+					(addr >> 16) & 0xff,
+					(addr >> 8) & 0xff,
+					(addr & 0xff)
+				},
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}, {
+		.writecnt	= 0,
+		.writearr	= NULL,
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}};
+
+	result = spi_send_multicommand(flash, cmds);
+	if (result) {
+		msg_cerr("%s failed during command execution at address 0x%x\n", __func__, addr);
+		return result;
+	}
+	/* Wait until the Write-In-Progress bit is cleared.
+	 * This usually takes 10 ms, so wait in 1 ms steps.
+	 */
+	while (spi_read_status_register(flash) & SPI_SR_WIP)
+		programmer_delay(1 * 1000);
+	/* FIXME: Check the status register for errors. */
+	return 0;
+}
+
+int spi_block_erase_81(struct flashctx *flash, unsigned int addr, unsigned int blocklen)
+{
+	int result;
+	struct spi_command cmds[] = {
+	{
+/*		.writecnt	= JEDEC_WREN_OUTSIZE,
+		.writearr	= (const unsigned char[]){ JEDEC_WREN },
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}, { */
+		.writecnt	= JEDEC_BE_81_OUTSIZE,
+		.writearr	= (const unsigned char[]){
+					JEDEC_BE_81,
+					(addr >> 16) & 0xff,
+					(addr >> 8) & 0xff,
+					(addr & 0xff)
+				},
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}, {
+		.writecnt	= 0,
+		.writearr	= NULL,
+		.readcnt	= 0,
+		.readarr	= NULL,
+	}};
+
+	result = spi_send_multicommand(flash, cmds);
+	if (result) {
+		msg_cerr("%s failed during command execution at address 0x%x\n", __func__, addr);
+		return result;
+	}
+	/* Wait until the Write-In-Progress bit is cleared.
+	 * This usually takes 8 ms, so wait in 1 ms steps.
+	 */
+	while (spi_read_status_register(flash) & SPI_SR_WIP)
+		programmer_delay(1 * 1000);
+	/* FIXME: Check the status register for errors. */
+	return 0;
+}
+
 int spi_block_erase_60(struct flashctx *flash, unsigned int addr,
 		       unsigned int blocklen)
 {