[PATCH v3 1/5] mtd: cfi_cmdset_0002: Add support for polling status register

[Vignesh Raghavendra <vigneshr@xxxxxx>]

HyperFlash devices are compliant with CFI AMD/Fujitsu Extended Command
Set(0x0002) for flash operations, therefore drivers/mtd/chips/cfi_cmdset_0002.c
can be used as is. But these devices do not support DQ polling method of
determining chip ready/good status. These flashes provide Status
Register whose bits can be polled to know status of flash operation.

Cypress HyperFlash datasheet here[1], talks about CFI Amd/Fujitsu
Extended Query version 1.5. Bit 0 of "Software Features supported" field
of CFI Primary Vendor-Specific Extended Query table indicates
presence/absence of status register and Bit 1 indicates whether or not
DQ polling is supported. Using these bits, its possible to determine
whether flash supports DQ polling or need to use Status Register.

Add support for polling Status Register to know device ready/status of
erase/write operations when DQ polling is not supported.
Print error messages on erase/program failure by looking at related
Status Register bits.

[1] https://www.cypress.com/file/213346/download

Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
---
 drivers/mtd/chips/cfi_cmdset_0002.c | 90 +++++++++++++++++++++++++++++
 include/linux/mtd/cfi.h             |  5 ++
 2 files changed, 95 insertions(+)

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 7b7286b4d81e..55c4d81098d5 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -49,6 +49,16 @@
 #define SST49LF008A		0x005a
 #define AT49BV6416		0x00d6
 
+/*
+ * Status Register bit description. Used by flash devices that don't
+ * support DQ polling (Eg.: HyperFlash)
+ */
+#define CFI_SR_DRB		BIT(7)
+#define CFI_SR_ESB		BIT(5)
+#define CFI_SR_PSB		BIT(4)
+#define CFI_SR_WBASB		BIT(3)
+#define CFI_SR_SLSB		BIT(1)
+
 static int cfi_amdstd_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
 static int cfi_amdstd_write_words(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
 static int cfi_amdstd_write_buffers(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
@@ -97,6 +107,48 @@ static struct mtd_chip_driver cfi_amdstd_chipdrv = {
 	.module		= THIS_MODULE
 };
 
+/*
+ * Use status register to poll for Erase/write completion when DQ is not
+ * supported. This is indicated by Bit[1:0] of SoftwareFeatures field in
+ * CFI Primary Vendor-Specific Extended Query table 1.5
+ */
+static int cfi_use_status_reg(struct cfi_private *cfi)
+{
+	struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
+
+	return (extp->MinorVersion >= '5') &&
+		(extp->SoftwareFeatures & 0x3) == 0x1;
+}
+
+static void cfi_check_err_status(struct map_info *map, unsigned long adr)
+{
+	struct cfi_private *cfi = map->fldrv_priv;
+	map_word status;
+
+	if (!cfi_use_status_reg(cfi))
+		return;
+
+	cfi_send_gen_cmd(0x70, cfi->addr_unlock1, 0, map, cfi,
+			 cfi->device_type, NULL);
+	status = map_read(map, adr);
+
+	if (map_word_bitsset(map, status, CMD(0x3a))) {
+		unsigned long chipstatus = MERGESTATUS(status);
+
+		if (chipstatus & CFI_SR_ESB)
+			pr_err("%s erase operation failed, status %lx\n",
+			       map->name, chipstatus);
+		if (chipstatus & CFI_SR_PSB)
+			pr_err("%s program operation failed, status %lx\n",
+			       map->name, chipstatus);
+		if (chipstatus & CFI_SR_WBASB)
+			pr_err("%s buffer program command aborted, status %lx\n",
+			       map->name, chipstatus);
+		if (chipstatus & CFI_SR_SLSB)
+			pr_err("%s sector write protected, status %lx\n",
+			       map->name, chipstatus);
+	}
+}
 
 /* #define DEBUG_CFI_FEATURES */
 
@@ -744,8 +796,22 @@ static struct mtd_info *cfi_amdstd_setup(struct mtd_info *mtd)
  */
 static int __xipram chip_ready(struct map_info *map, unsigned long addr)
 {
+	struct cfi_private *cfi = map->fldrv_priv;
 	map_word d, t;
 
+	if (cfi_use_status_reg(cfi)) {
+		map_word ready = CMD(CFI_SR_DRB);
+		/*
+		 * For chips that support status register, check device
+		 * ready bit
+		 */
+		cfi_send_gen_cmd(0x70, cfi->addr_unlock1, 0, map, cfi,
+				 cfi->device_type, NULL);
+		d = map_read(map, addr);
+
+		return map_word_andequal(map, d, ready, ready);
+	}
+
 	d = map_read(map, addr);
 	t = map_read(map, addr);
 
@@ -769,8 +835,27 @@ static int __xipram chip_ready(struct map_info *map, unsigned long addr)
  */
 static int __xipram chip_good(struct map_info *map, unsigned long addr, map_word expected)
 {
+	struct cfi_private *cfi = map->fldrv_priv;
 	map_word oldd, curd;
 
+	if (cfi_use_status_reg(cfi)) {
+		map_word ready = CMD(CFI_SR_DRB);
+		map_word err = CMD(CFI_SR_PSB | CFI_SR_ESB);
+		/*
+		 * For chips that support status register, check device
+		 * ready bit and Erase/Program status bit to know if
+		 * operation succeeded.
+		 */
+		cfi_send_gen_cmd(0x70, cfi->addr_unlock1, 0, map, cfi,
+				 cfi->device_type, NULL);
+		curd = map_read(map, addr);
+
+		if (map_word_andequal(map, curd, ready, ready))
+			return !map_word_bitsset(map, curd, err);
+
+		return 0;
+	}
+
 	oldd = map_read(map, addr);
 	curd = map_read(map, addr);
 
@@ -1643,6 +1728,7 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
 	/* Did we succeed? */
 	if (!chip_good(map, adr, datum)) {
 		/* reset on all failures. */
+		cfi_check_err_status(map, adr);
 		map_write(map, CMD(0xF0), chip->start);
 		/* FIXME - should have reset delay before continuing */
 
@@ -1900,6 +1986,7 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
 	 * See e.g.
 	 * http://www.spansion.com/Support/Application%20Notes/MirrorBit_Write_Buffer_Prog_Page_Buffer_Read_AN.pdf
 	 */
+	cfi_check_err_status(map, adr);
 	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
 			 cfi->device_type, NULL);
 	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi,
@@ -2106,6 +2193,7 @@ static int do_panic_write_oneword(struct map_info *map, struct flchip *chip,
 
 	if (!chip_good(map, adr, datum)) {
 		/* reset on all failures. */
+		cfi_check_err_status(map, adr);
 		map_write(map, CMD(0xF0), chip->start);
 		/* FIXME - should have reset delay before continuing */
 
@@ -2315,6 +2403,7 @@ static int __xipram do_erase_chip(struct map_info *map, struct flchip *chip)
 	/* Did we succeed? */
 	if (ret) {
 		/* reset on all failures. */
+		cfi_check_err_status(map, adr);
 		map_write(map, CMD(0xF0), chip->start);
 		/* FIXME - should have reset delay before continuing */
 
@@ -2411,6 +2500,7 @@ static int __xipram do_erase_oneblock(struct map_info *map, struct flchip *chip,
 	/* Did we succeed? */
 	if (ret) {
 		/* reset on all failures. */
+		cfi_check_err_status(map, adr);
 		map_write(map, CMD(0xF0), chip->start);
 		/* FIXME - should have reset delay before continuing */
 
diff --git a/include/linux/mtd/cfi.h b/include/linux/mtd/cfi.h
index cbf77168658c..92ac82ac2329 100644
--- a/include/linux/mtd/cfi.h
+++ b/include/linux/mtd/cfi.h
@@ -233,6 +233,11 @@ struct cfi_pri_amdstd {
 	uint8_t  VppMin;
 	uint8_t  VppMax;
 	uint8_t  TopBottom;
+	/* Below field are added from version 1.5 */
+	uint8_t  ProgramSuspend;
+	uint8_t  UnlockBypass;
+	uint8_t  SecureSiliconSector;
+	uint8_t  SoftwareFeatures;
 } __packed;
 
 /* Vendor-Specific PRI for Atmel chips (command set 0x0002) */
-- 
2.21.0


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