[PATCH v2] mtd: m25p80: add support for PMC SPI flash

[Luka Perkov <luka@openwrt.org>]

From: Michel Stempin <michel.stempin@wanadoo.fr>

This patch adds support for PMC (now Chingis, part of ISSI) Pm25LV512 (512
kBbit), Pm25LV010 (1 Mbit) and Pm25LQ032 (32 Mbit) SPI flash.

Two generations of PMC SPI flash chips are addressed:

1) Pm25LV512 and Pm25LV010 - These have 4KB sectors and 32KB blocks. The 4KB
sector erase uses a non-standard opcode (0xd7). They do not support JEDEC RDID
(0x9f), and so they can only be detected by matching their name string with
pre-configured platform data. Because of the cascaded acquisitions, the
datasheet is no longer available on the current manufacturer's website,
although it is still commonly used in some recent wireless routers [1]. Only
public datasheet available seems to be on GeoCities [2].

2) Pm25LQ032 - A newer generation flash, with 4KB sectors and 32KB blocks. It
uses the standard erase and JEDEC read-ID opcodes. Manufacturer's datasheet is
available [3].

[1] https://forum.openwrt.org/viewtopic.php?pid=186360#p186360
[2] http://www.geocities.jp/scottle556/pdf/Pm25LV512-010.pdf
[3] http://www.chingistek.com/img/Product_Files/Pm25LQ032C%20datasheet%20v1.6.1.pdf

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Michel Stempin <michel.stempin@wanadoo.fr>
CC: Brian Norris <computersforpeace@gmail.com>
CC: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---

Changes in v2:
 - style and documentation improvements

 drivers/mtd/devices/m25p80.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 2f3d2a5..4d45ce4 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -45,6 +45,7 @@
 #define	OPCODE_BE_4K		0x20	/* Erase 4KiB block */
 #define	OPCODE_BE_32K		0x52	/* Erase 32KiB block */
 #define	OPCODE_CHIP_ERASE	0xc7	/* Erase whole flash chip */
+#define	OPCODE_BE_4K_PMC	0xd7	/* Erase 4KiB block on PMC chips*/
 #define	OPCODE_SE		0xd8	/* Sector erase (usually 64KiB) */
 #define	OPCODE_RDID		0x9f	/* Read JEDEC ID */
 
@@ -682,6 +683,7 @@ struct flash_info {
 #define	SECT_4K		0x01		/* OPCODE_BE_4K works uniformly */
 #define	M25P_NO_ERASE	0x02		/* No erase command needed */
 #define	SST_WRITE	0x04		/* use SST byte programming */
+#define	SECT_4K_PMC	0x08		/* OPCODE_BE_4K_PMC works uniformly */
 };
 
 #define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags)	\
@@ -762,6 +764,11 @@ static const struct spi_device_id m25p_ids[] = {
 	{ "n25q128a13",  INFO(0x20ba18, 0, 64 * 1024, 256, 0) },
 	{ "n25q256a", INFO(0x20ba19, 0, 64 * 1024, 512, SECT_4K) },
 
+	/* PMC -- pm25x "blocks" are 32K, sectors are 4K */
+	{ "pm25lv512", INFO(0, 0, 32 * 1024, 2, SECT_4K_PMC) },
+	{ "pm25lv010", INFO(0, 0, 32 * 1024, 4, SECT_4K_PMC) },
+	{ "pm25lq032", INFO(0x7F9D46, 0, 64 * 1024,  64, SECT_4K) },
+
 	/* Spansion -- single (large) sector size only, at least
 	 * for the chips listed here (without boot sectors).
 	 */
@@ -1014,6 +1021,9 @@ static int m25p_probe(struct spi_device *spi)
 	if (info->flags & SECT_4K) {
 		flash->erase_opcode = OPCODE_BE_4K;
 		flash->mtd.erasesize = 4096;
+	} else if (info->flags & SECT_4K_PMC) {
+		flash->erase_opcode = OPCODE_BE_4K_PMC;
+		flash->mtd.erasesize = 4096;
 	} else {
 		flash->erase_opcode = OPCODE_SE;
 		flash->mtd.erasesize = info->sector_size;
-- 
1.8.3.4